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Zane Meyers
2025-12-01 22:02:56 -05:00
parent c088008669 9ffaa7c95d
commit d1ce25f1aa
17 changed files with 7565 additions and 369 deletions
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.gitignore
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Vendored
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"content": "---\nid:\naliases: []\ntags: []\n---\n# HVAC Calculations\n\n## Units\n\n### British Thermal Unit\n\nUnit of heat energy\n\nThere are several definitions of the Btu,\nHVAC uses the IT definition,\nabbreviated Btu<sub>IT</sub>\n\n$$\n\\begin{align*}\n1 \\text{Btu}_\\text{IT} &= \\left( 4.1868 \\times 453.59237 \\times{\\frac{5}{9}} \\right) \\text{J} \\\\\n&\\approx 1055.056 \\text{J}\n\\end{align*}\n$$\n\nMore common than Btu itself is\nthousand British thermal units per hour (MBH),\na unit of power.\n\n$$\n\\begin{align*}\n1 \\text{MBH} &= 1000 \\text{Btu/hr} \\\\\n&\\approx 3.412 \\text{W}\n\\end{align*}\n$$\n\n### Ton of Refrigeration (TR or TOR)\n\nUnit of power\n\n> [!info] Also Known As\n> * refrigeration ton (RT)\n> * ton (refrigeration)\n\n$$\n\\begin{align*}\n1 \\text{TR} &= 12000 \\text{Btu}_\\text{IT}/\\text{h} \\\\\n&\\approx 3516.853 \\text{W}\n\\end{align*}\n$$\n\n### Cubic Feet per Minute (CFM)\n\nUnit of volumetric flow\n\n## Measures\n\n### Airflow\n\n* CFM\n\nExternal static pressure (ESP)\nmeasured in inches of water\n\n### Heating/Cooling Capacity\n\n* Tons (refrigeration)\n* MBH\n\nEntering air temperature (EAT)\nLeaving air temperature (LAT)\nMixed air temperature (MAT)\n\nLatent heat\nSensible heat\n\nSensible -> dry bulb\nLatent -> wet bulb\n\n#### ???\n\nOSA EAT (F)\nEXH EAT (F)\n\nIN S.L.\nOUT ALT.\n\n### Efficiency\n\n* η (eta)\n",
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"content": "# Windows Setup\n\n## Clone This Vault\n\n1. Create a [GitHub](https://github.com/)\n account if you don't have one already.\n\n2. Install [Git](https://git-scm.com/)\n\n ```\n winget install Git.Git\n ```\n\n3. Clone this repo\n\n ```\n git clone https://github.com/ZaneMeyers/zmVault\n ```\n\n> [!important]\n> If you're reading this,\n> you probably have push access to this repo.\n> Please do me a favor and don't use it.\n> It won't be destructive, but it may be annoying.\n\nIf you make unintended changes to this vault:\n\n```\ncd zmVault\ngit reset --hard\n```\n\n## Setup Obsidian\n\n1. Download and install [Obsidian](https://obsidian.md/)\n\n## Create Your Own Vault\n\n### Create a GitHub Repository\n\n<!-- TODO: -->\n\n### Create and Push your Vault\n\n```\nmkdir myVault\ngit init\ngit add README.md\ngit commit -m \"first commit\"\ngit branch -M main\ngit remote add origin https://github.com/ExampleName/myVault.git\ngit push -u origin main\n```\n\n### Set Up Your Vault\n\nAdd and enable the Git Community Plugin.\n\n<!-- TODO: -->\n",
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extracting-pdf-panel-schedules.md
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---
id:
aliases: []
tags: []
title: Extracting PDF Panel Schedules
---
# Extracting PDF Panel Schedules
Extract relevant pages
Crop Sheet Titles
Reduce File Size > Crop Content
Export to HTML
Edit HTML
Open HTML in Excel
game-theory.md
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@@ -1,3 +1,9 @@
---
id:
aliases: []
tags: []
title: Game Theory
---
# Game Theory
## Domains
@@ -56,4 +62,4 @@ bid prices are hidden from the bidders.
### Ultimatum Game
### Dictator Game
### Dictator Game
nfpa-70_110_requirements-for-electrical-installations.md
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@@ -26,7 +26,71 @@ and tunnel installations.
> [!info] Informational Note:
> See Informative Annex J for information regarding ADA accessibility design.
<!-- TODO: TEXT OMITTED -->
### 110.2 Approval.
The conductors and equipment required or permitted by this Code shall be acceptable only if approved.
> [!info] Informational Note:
> See 90.7, Examination of Equipment for Safety, and 110.3, Examination, Identification, Installation, and Use of
Equipment. See definitions of Approved, Identified, Labeled, and Listed.
### 110.3 Examination, Identification, Installation, Use, and Listing (Product Certification) of Equipment.
#### 110.3(A) Examination.
In judging equipment, considerations such as the following shall be evaluated:
* (1) Suitability for installation and use in conformity with this Code
> [!info] Informational Note No. 1:
> Equipment may be new, reconditioned, refurbished, or remanufactured.
> [!info] Informational Note No. 2:
> Suitability of equipment use may be identified by a description marked on or provided with a product to identify the suitability of the product for a specific purpose, environment, or application. Special conditions of use or other limitations and other pertinent information may be marked on the equipment, included in the product instructions, or included in the appropriate listing and labeling information. Suitability of equipment may be evidenced by listing or labeling.
* (2) Mechanical strength and durability, including, for parts designed to enclose and protect other equipment, the adequacy of the protection thus provided
* (3) Wire-bending and connection space
* (4) Electrical insulation
* (5) Heating effects under normal conditions of use and also under abnormal conditions likely to arise in service
* (6) Arcing effects
* (7) Classification by type, size, voltage, current capacity, and specific use
* (8) Other factors that contribute to the practical safeguarding of persons using or likely to come in contact with the equipment
#### 110.3(B) Installation and Use.
Equipment that is listed, labeled, or both shall be installed and used in accordance with any instructions included in the listing or labeling.
#### 110.3(C) Listing.
Product testing, evaluation, and listing (product certification) shall be performed by recognized qualified electrical testing laboratories and shall be in accordance with applicable product standards recognized as achieving equivalent and effective safety for equipment installed to comply with this Code.
> [!info] Informational Note:
> The Occupational Safety and Health Administration (OSHA) recognizes qualified electrical testing laboratories that perform evaluations, testing, and certification of certain products to ensure that they meet the requirements of both the construction and general industry OSHA electrical standards. If the listing (product certification) is done under a qualified electrical testing laboratory program, this listing mark signifies that the tested and certified product complies with the requirements of one or more appropriate product safety test standards.
### 110.4 Voltages.
Throughout this Code, the voltage considered shall be that at which the circuit operates. The voltage rating of electrical equipment shall not be less than the nominal voltage of a circuit to which it is connected.
### 110.5 Conductors.
Conductors used to carry current shall be of copper, aluminum, or copper-clad aluminum unless otherwise provided in this Code.
Where the conductor material is not specified, the sizes given in this Code shall apply to copper conductors. Where other materials are used, the size shall be changed accordingly.
### 110.6 Conductor Sizes.
Conductor sizes are expressed in American Wire Gage (AWG) or in circular mils.
### 110.7 Wiring Integrity.
Completed wiring installations shall be free from short circuits, ground faults, or any connections to ground other than as required or permitted elsewhere in this Code.
### 110.8 Wiring Methods
@@ -37,7 +101,83 @@ shall be permitted to be installed
in any type of building or occupancy,
except as otherwise provided in this Code.
<!-- TODO: TEXT OMITTED -->
### 110.9 Interrupting Rating.
Equipment intended to interrupt current at fault levels shall have an interrupting rating at nominal circuit voltage at least equal to the current that is available at the line terminals of the equipment.
Equipment intended to interrupt current at other than fault levels shall have an interrupting rating at nominal circuit voltage at least equal to the current that must be interrupted.
### 110.10 Circuit Impedance, Short-Circuit Current Ratings, and Other Characteristics.
The overcurrent protective devices, the total impedance, the equipment short-circuit current ratings, and other characteristics of the circuit to be protected shall be selected and coordinated to permit the circuit protective devices used to clear a fault to do so without extensive damage to the electrical equipment of the circuit. This fault shall be assumed to be either between two or more of the circuit conductors or between any circuit conductor and the equipment grounding conductor(s) permitted in 250.118. Listed equipment applied in accordance with their listing shall be considered to meet the requirements of this section.
### 110.11 Deteriorating Agents.
Unless identified for use in the operating environment, no conductors or equipment shall be located in damp or wet locations; where exposed to gases, fumes, vapors, liquids, or other agents that have a deteriorating effect on the conductors or equipment; or where exposed to excessive temperatures.
> [!info] Informational Note No. 1:
> See 300.6 for protection against corrosion.
> [!info] Informational Note No. 2:
> Some cleaning and lubricating compounds can cause severe deterioration of many plastic materials used for insulating and structural applications in equipment.
Equipment not identified for outdoor use and equipment identified only for indoor use, such as "dry locations," "indoor use only," "damp locations," or enclosure Types 1, 2, 5, 12, 12K, and/or 13, shall be protected against damage from the weather during construction.
> [!info] Informational Note No. 3:
> See Table 110.28 for appropriate enclosure-type designations.
> [!info] Informational Note No. 4:
> Minimum flood provisions are provided in NFPA 5000-2015 Building Construction and Safety Code, the
International Building Code (IBC), and the International Residential Code for One- and Two-Family Dwellings (IRC).
### 110.12 Mechanical Execution of Work.
Electrical equipment shall be installed in a neat and workmanlike manner.
> [!info] Informational Note:
> Accepted industry practices are described in ANSI/NECA 1-2015, Standard for Good Workmanship in Electrical
Construction, and other ANSI-approved installation standards.
#### 110.12(A) Unused Openings.
Unused openings, other than those intended for the operation of equipment, those intended for mounting purposes, or those permitted as part of the design for listed equipment, shall be closed to afford protection substantially equivalent to the wall of the equipment.
Where metallic plugs or plates are used with nonmetallic enclosures, they shall be recessed at least 6 mm (1/4 in.) from the outer surface of the enclosure.
#### 110.12(B) Integrity of Electrical Equipment and Connections.
Internal parts of electrical equipment, including busbars, wiring terminals, insulators, and other surfaces, shall not be damaged or contaminated by foreign materials such as paint, plaster, cleaners, abrasives, or corrosive residues. There shall be no damaged parts that may adversely affect safe operation or mechanical strength of the equipment such as parts that are broken; bent; cut; or deteriorated by corrosion, chemical action, or overheating.
#### 110.12(C) Cables and Conductors.
Cables and conductors installed exposed on the surfaces of ceilings and sidewalls shall be supported by the building structure in such a manner that the cables and conductors will not be damaged by normal building use. Such cables and conductors shall be secured by hardware including straps, staples, cable ties, hangers, or similar fittings designed and installed so as not to damage the cable. The installation shall also conform with 300.4 and 300.11. Nonmetallic cable ties and other nonmetallic cable accessories used to secure and support cables in other spaces used for environmental air (plenums) shall be listed as having low smoke and heat release properties.
> [!info] Informational Note No. 1:
> Accepted industry practices are described in ANSI/ NECA/FOA 301-2009, Standard for Installing and Testing
Fiber Optic Cables, and other ANSI-approved installation standards.
> [!info] Informational Note No. 2:
> See 4.3.11.2.6.5 and 4.3.11.5.5.6 of NFPA 90A-2018, Standard for the Installation of Air-Conditioning and
Ventilating Systems, for discrete combustible components installed in accordance with 300.22(C).
> [!info] Informational Note No. 3:
> Paint, plaster, cleaners, abrasives, corrosive residues, or other contaminants may result in an undetermined alteration of optical fiber cable properties.
### 110.13 Mounting and Cooling of Equipment.
#### 110.13(A) Mounting.
Electrical equipment shall be firmly secured to the surface on which it is mounted. Wooden plugs driven into holes in masonry, concrete, plaster, or similar materials shall not be used.
#### 110.13(B) Cooling.
Electrical equipment that depends on the natural circulation of air and convection principles for cooling of exposed surfaces shall be installed so that room airflow over such surfaces is not prevented by walls or by adjacent installed equipment. For equipment designed for floor mounting, clearance between top surfaces and adjacent surfaces shall be provided to dissipate rising warm air.
Electrical equipment provided with ventilating openings shall be installed so that walls or other obstructions do not prevent the free circulation of air through the equipment.
### 110.14 Electrical Connections.
@@ -135,7 +275,161 @@ Informational Note No. 3:
Additional information for torquing threaded connections and terminations
can be found in Section 8.11 of NFPA 70B-2019, Recommended Practice for Electrical Equipment Maintenance.
<!-- TODO: TEXT OMITTED -->
### 110.15 High-Leg Marking.
On a 4-wire, delta-connected system where the midpoint of one phase winding is grounded, only the conductor or busbar having the higher phase voltage to ground shall be durably and permanently marked by an outer finish that is orange in color or by other effective means. Such identification shall be placed at each point on the system where a connection is made if the grounded conductor is also present.
### 110.16 Arc-Flash Hazard Warning.
#### 110.16(A) General.
Electrical equipment, such as switchboards, switchgear, panelboards, industrial control panels, meter socket enclosures, and motor control centers, that is in other than dwelling units, and is likely to require examination, adjustment, servicing, or maintenance while energized, shall be field or factory marked to warn qualified persons of potential electric arc flash hazards. The marking shall meet the requirements in 110.21(B) and shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.
#### 110.16(B) Service Equipment.
In other than dwelling units, in addition to the requirements in 110.16(A), a permanent label shall be field or factory applied to service equipment rated 1200 amps or more. The label shall meet the requirements of 110.21(B) and contain the following information:
* (1) Nominal system voltage
* (2) Available fault current at the service overcurrent protective devices
* (3) The clearing time of service overcurrent protective devices based on the available fault current at the service equipment
* (4) The date the label was applied
> [!important] Exception:
> Service equipment labeling shall not be required if an arc flash label is applied in accordance with acceptable industry practice.
> [!info] Informational Note No. 1:
> NFPA 70E-2018, Standard for Electrical Safety in the Workplace, provides guidance, such as determining severity of potential exposure, planning safe work practices, arc flash labeling, and selecting personal protective equipment.
> [!info] Informational Note No. 2:
> ANSI Z535.4-2011, Product Safety Signs and Labels, provides guidelines for the design of safety signs and labels for application to products.
> [!info] Informational Note No. 3:
> Acceptable industry practices for equipment labeling are described in NFPA 70E-2018, Standard for Electrical
Safety in the Workplace. This standard provides specific criteria for developing arc-flash labels for equipment that provides nominal system voltage, incident energy levels, arc-flash boundaries, minimum required levels of personal protective equipment, and so forth.
### 110.18 Arcing Parts.
Parts of electrical equipment that in ordinary operation produce arcs, sparks, flames, or molten metal shall be enclosed or separated and isolated from all combustible material.
> [!info] Informational Note:
> For hazardous (classified) locations, see Articles 500 through 517. For motors, see 430.14.
### 110.19 Light and Power from Railway Conductors.
Circuits for lighting and power shall not be connected to any system that contains trolley wires with a ground return.
> [!important] Exception:
> Such circuit connections shall be permitted in car houses, power houses, or passenger and freight stations operated in connection with electric railways.
### 110.21 Marking.
#### 110.21(A) Equipment Markings.
##### 110.21(A)(1) General.
The manufacturer's name, trademark, or other descriptive marking by which the organization responsible for the product can be identified shall be placed on all electrical equipment. Other markings that indicate voltage, current, wattage, or other ratings shall be provided as specified elsewhere in this Code. The marking or label shall be of sufficient durability to withstand the environment involved.
##### 110.21(A)(2) Reconditioned Equipment.
Reconditioned equipment shall be marked with the name, trademark, or other descriptive marking by which the organization responsible for reconditioning the electrical equipment can be identified, along with the date of the reconditioning.
Reconditioned equipment shall be identified as "reconditioned" and the original listing mark removed. Approval of the reconditioned equipment shall not be based solely on the equi pment's original listing.
> [!important] Exception:
> In industrial occupancies, where conditions of maintenance and supervision ensure that only qualified persons service the equipment, the markings indicated in 110.21(A)(2) shall not be required for equipment that is reconditioned by the owner or operator as part of a regular equipment maintenance program.
> [!info] Informational Note No. 1:
> Industry standards are available for application of reconditioned and refurbished equipment.
> [!info] Informational Note No. 2:
> The term reconditioned may be interchangeable with the terms rebuilt, refurbished, or remanufactured.
> [!info] Informational Note No. 3:
> The original listing mark may include the mark of the certifying body and not the entire equipment label.
#### 110.21(B) Field-Applied Hazard Markings.
Where caution, warning, or danger signs or labels are required by this Code, the labels shall meet the following requirements:
* (1) The marking shall warn of the hazards using effective words, colors, symbols, or any combination thereof.
> [!info] Informational Note:
> ANSI Z535.4-2011, Product Safety Signs and Labels, provides guidelines for suitable font sizes, words, colors, symbols, and location requirements for labels.
* (2) The label shall be permanently affixed to the equipment or wiring method and shall not be handwritten.
> [!important] Exception to (2):
> Portions of labels or markings that are variable,
> or that could be subject to changes,
> shall be permitted to be handwritten and shall be legible.
* (3) The label shall be of sufficient durability to withstand the environment involved.
> [!info] Informational Note:
> ANSI Z535.4-2011, Product Safety Signs and Labels, provides guidelines for the design and durability of safety signs and labels for application to electrical equipment.
### 110.22 Identification of Disconnecting Means.
#### 110.22(A) General.
Each disconnecting means shall be legibly marked to indicate its purpose unless located and arranged so the purpose is evident. In other than one- or two-family dwellings, the marking shall include the identification of the circuit source that supplies the disconnecting means. The marking shall be of sufficient durability to withstand the environment involved.
#### 110.22(B) Engineered Series Combination Systems.
Equipment enclosures for circuit breakers or fuses applied in compliance with series combination ratings selected under engineering supervision in accordance with 240.86(A) shall be legibly marked in the field as directed by the engineer to indicate the equipment has been applied with a series combination rating. The marking shall meet the requirements in 110.21(B) and shall be readily visible and state the following:
```
CAUTION --- ENGINEERED SERIES COMBINATION SYSTEM RATED _______ AMPERES.
IDENTIFIED REPLACEMENT COMPONENTS REQUIRED.
```
#### 110.22(C) Tested Series Combination Systems.
Equipment enclosures for circuit breakers or fuses applied in compliance with the series combination ratings marked on the equipment by the manufacturer in accordance with 240.86(B) shall be legibly marked in the field to indicate the equipment has been applied with a series combination rating. The marking shall meet the requirements in 110.21(B) and shall be readily visible and state the following:
```
CAUTION --- SERIES COMBINATION SYSTEM RATED ____ AMPERES.
IDENTIFIED REPLACEMENT COMPONENTS REQUIRED.
```
> [!info] Informational Note:
> See IEEE 3004.5-2014 Recommended Practice for the Application of Low-Voltage Circuit Breakers in Industrial and Commercial Power Systems, for further information on series tested systems.
### 110.23 Current Transformers.
Unused current transformers associated with potentially energized circuits shall be short-circuited.
### 110.24 Available Fault Current.
#### 110.24(A) Field Marking.
Service equipment at other than dwelling units shall be legibly marked in the field with the available fault current. The field marking(s) shall include the date the fault-current calculation was performed and be of sufficient durability to withstand the environment involved.
The calculation shall be documented and made available to those authorized to design, install, inspect, maintain, or operate the system.
> [!info] Informational Note No. 1:
> The available fault-current marking(s) addressed in 110.24 is related to required short-circuit current and interrupting ratings of equipment. NFPA 70E-2018, Standard for Electrical Safety in the Workplace, provides assistance in determining the severity of potential exposure, planning safe work practices, and selecting personal protective equipment.
> [!info] Informational Note No. 2:
> Values of available fault current for use in determining appropriate minimum short-circuit current and interrupting ratings of service equipment are available from electric utilities in published or other forms.
#### 110.24(B) Modifications.
When modifications to the electrical installation occur that affect the available fault current at the service, the available fault current shall be verified or recalculated as necessary to ensure the service equipment ratings are sufficient for the available fault current at the line terminals of the equipment. The required field marking(s) in 110.24(A) shall be adjusted to reflect the new level of available fault current.
> [!important] Exception:
> The field marking requirements in 110.24(A) and 110.24(B) shall not be required in industrial installations where conditions of maintenance and supervision ensure that only qualified persons service the equipment.
### 110.25 Lockable Disconnecting Means.
If a disconnecting means is required to be lockable open elsewhere in this Code, it shall be capable of being locked in the open position. The provisions for locking shall remain in place with or without the lock installed.
> [!important] Exception:
> Locking provisions for a cord-and-plug connection shall not be required to remain in place without the lock installed.
## Part II. 1000 Volts, Nominal, or Less
@@ -177,16 +471,16 @@ Minimum Clear Distance
Note: Where the conditions are as follows:
* Condition 1 -- Exposed live parts on one side of the working space
* Condition 1 --- Exposed live parts on one side of the working space
and no live or grounded parts on the other side of the working space,
or exposed live parts on both sides of the working space
that are effectively guarded by insulating materials.
* Condition 2 -- Exposed live parts on one side of the working space
* Condition 2 --- Exposed live parts on one side of the working space
and grounded parts on the other side of the working space.
Concrete, brick, or tile walls shall be considered as grounded.
* Condition 3 -- Exposed live parts on both sides of the working space.
* Condition 3 --- Exposed live parts on both sides of the working space.
(a) _Dead-Front Assemblies._
Working space shall not be required in the back or sides of assemblies, such as dead-front switchboards, switchgear, or motor control centers, where all connections and all renewable or adjustable parts, such as fuses or switches, are accessible from locations other than the back or sides. Where rear access is required to work on nonelectrical parts on the back of enclosed equipment, a minimum horizontal working space of 762 mm (30 in.) shall be provided.
@@ -194,7 +488,70 @@ Working space shall not be required in the back or sides of assemblies, such as
(b) _Low Voltage._
By special permission, smaller working spaces shall be permitted where all exposed live parts operate at not greater than 30 volts rms, 42 volts peak, or 60 volts dc.
<!-- TODO: TEXT OMITTED -->
##### 110.26(A)(2) Width of Working Space.
The width of the working space in front of the electrical equipment shall be the width of the equipment or 762 mm (30 in.), whichever is greater. In all cases, the work space shall permit at least a 90 degree opening of equipment doors or hinged panels.
##### 110.26(A)(3) Height of Working Space.
The work space shall be clear and extend from the grade, floor, or platform to a height of 2.0 m (61/2 ft) or the height of the equipment, whichever is greater. Within the height requirements of this section, other equipment or support structures, such as concrete pads, associated with the electrical installation and located above or below the electrical equipment shall be permitted to extend not more than 150 mm (6 in.) beyond the front of the electrical equipment.
> [!important] Exception No. 1:
> On battery systems mounted on open racks, the top clearance shall comply with 480.10(D).
> [!important] Exception No. 2:
> In existing dwelling units, service equipment or panelboards that do not exceed 200 amperes shall be permitted in spaces where the height of the working space is less than 2.0 m (61/2 ft).
> [!important] Exception No. 3:
> Meters that are installed in meter sockets shall be permitted to extend beyond the other equipment. The meter socket shall be required to follow the rules of this section.
##### 110.26(A)(4) Limited Access.
Where equipment operating at 1000 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized is required by installation instructions or function to be located in a space with limited access, all of the following shall apply:
* (1) Where equipment is installed above a lay-in ceiling,
there shall be an opening not smaller than 559 mm × 559 mm (22 in. × 22 in.),
or in a crawl space,
there shall be an accessible opening not smaller than 559 mm × 762 mm (22 in. × 30 in.).
* (2) The width of the working space
shall be the width of the equipment enclosure or a minimum of 762 mm (30 in.),
whichever is greater.
* (3) All enclosure doors or hinged panels
shall be capable of opening a minimum of 90 degrees.
* (4) The space in front of the enclosure shall comply with the depth requirements of Table 110.26(A)(1). The maximum height of the working space shall be the height necessary to install the equipment in the limited space. A horizontal ceiling structural member or access panel shall be permitted in this space.
##### 110.26(A)(5) Separation from High-Voltage Equipment.
Where switches, cutouts, or other equipment operating at 1000 volts, nominal, or less are installed in a vault, room, or enclosure where there are exposed live parts or exposed wiring operating over 1000 volts, nominal, the high-voltage equipment shall be effectively separated from the space occupied by the low-voltage equipment by a suitable partition, fence, or screen.
#### 110.26(B) Clear Spaces.
Working space required by this section shall not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be suitably guarded.
#### 110.26(C) Entrance to and Egress from Working Space.
##### 110.26(C)(1) Minimum Required.
At least one entrance of sufficient area shall be provided to give access to and egress from working space about electrical equipment.
##### 110.26(C)(2) Large Equipment.
For large equipment that contains overcurrent devices, switching devices, or control devices, there shall be one entrance to and egress from the required working space not less than 610 mm (24 in.) wide and 2.0 m (61/2 ft) high at each end of the working space. This requirement shall apply to either of the following conditions:
* (1) For equipment rated 1200 amperes or more and over 1.8 m (6 ft) wide
* (2) For service disconnecting means installed in accordance with 230.71 where the combined ampere rating is 1200 amperes or more and over 1.8 m (6 ft) wide
Open equipment doors shall not impede the entry to or egress from the working space.
A single entrance to and egress from the required working space shall be permitted where either of the conditions in 110.26(C)(2)(a) or (C)(2)(b) is met.
* (a) Unobstructed Egress. Where the location permits a continuous and unobstructed way of egress travel, a single entrance to the working space shall be permitted.
* (b) Extra Working Space. Where the depth of the working space is twice that required by 110.26(A)(1), a single entrance shall be permitted. It shall be located such that the distance from the equipment to the nearest edge of the entrance is not less than the minimum clear distance specified in Table 110.26(A)(1) for equipment operating at that voltage and in that condition.
#### 110.26(C)(3) Personnel Doors.
@@ -205,10 +562,10 @@ less than 7.6 m (25 ft) from the nearest edge of the working space,
the door(s) shall open in the direction of egress
and be equipped with listed panic hardware or listed fire exit hardware.
Informational Note:
For information on panic hardware, see UL 305, Standard For Safety For Panic Hardware.
For fire exit hardware, see UL 305, Standard For Panic Hardware,
and UL 10C, Standard for Safety for Positive Pressure Fire Tests of Door Assemblies.
> [!info] Informational Note:
> For information on panic hardware, see UL 305, Standard For Safety For Panic Hardware.
> For fire exit hardware, see UL 305, Standard For Panic Hardware,
> and UL 10C, Standard for Safety for Positive Pressure Fire Tests of Door Assemblies.
#### 110.26(D) Illumination.
@@ -278,3 +635,512 @@ Outdoor installations shall comply with 110.26(E)(2)(a) through (E)(2)(c).
#### 110.26(F) Locked Electrical Equipment Rooms or Enclosures.
Electrical equipment rooms or enclosures housing electrical apparatus that are controlled by a lock(s) shall be considered accessible to qualified persons.
### 110.27 Guarding of Live Parts.
#### 110.27(A) Live Parts Guarded Against Accidental Contact.
Except as elsewhere required or permitted by this Code, live parts of electrical equipment operating at 50 to 1000 volts, nominal shall be guarded against accidental contact by approved enclosures or by any of the following means:
* (1) By location in a room, vault, or similar enclosure that is accessible only to qualified persons.
* (2) By permanent, substantial partitions or screens arranged so that only qualified persons have access to the space within reach of the live parts. Any openings in such partitions or screens shall be sized and located so that persons are not likely to come into accidental contact with the live parts or to bring conducting objects into contact with them.
* (3) By location on a balcony, gallery, or platform elevated and arranged so as to exclude unqualified persons.
* (4) By elevation above the floor or other working surface as follows:
* a. A minimum of 2.5 m (8 ft) for 50 volts to 300 volts between ungrounded conductors
* b. A minimum of 2.6 m (8 ft 6 in.) for 301 volts to 600 volts between ungrounded conductors
* c. A minimum of 2.62 m (8 ft 7 in.) for 601 volts to 1000 volts between ungrounded conductors
#### 110.27(B) Prevent Physical Damage.
In locations where electrical equipment is likely to be exposed to physical damage, enclosures or guards shall be so arranged and of such strength as to prevent such damage.
#### 110.27(C) Warning Signs.
Entrances to rooms and other guarded locations that contain exposed live parts shall be marked with conspicuous warning signs forbidding unqualified persons to enter. The marking shall meet the requirements in 110.21(B).
> [!info] Informational Note:
> For motors, see 430.232 and 430.233. For over 1000 volts, see 110.34.
### 110.28 Enclosure Types.
Enclosures (other than surrounding fences or walls covered in 110.31) of switchboards, switchgear, panelboards, industrial control panels, motor control centers, meter sockets, enclosed switches, transfer switches, power outlets, circuit breakers, adjustable-speed drive systems, pullout switches, portable power distribution equipment, termination boxes, general-purpose transformers, fire pump controllers, fire pump motors, and motor controllers, rated not over 1000 volts nominal and intended for such locations, shall be marked with an enclosure-type number as shown in Table 110.28.
Table 110.28 shall be used for selecting these enclosures for use in specific locations other than hazardous (classified) locations. The enclosures are not intended to protect against conditions such as condensation, icing, corrosion, or contamination that may occur within the enclosure or enter via the raceway or unsealed openings.
#### Table 110.28 Enclosure Selection
For Outdoor Use
| Provides a Degree of Protection Against the Following Environmental Conditions | 3 | 3R | 3S | 3X | 3RX | 3SX | 4 | 4X | 6 | 6P |
| ------------------------------------------------------------------------------ | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Incidental contact with the enclosed equipment | X | X | X | X | X | X | X | X | X | X |
| Rain, snow, and sleet | X | X | X | X | X | X | X | X | X | X |
| Sleet* | --- | --- | X | --- | --- | X | --- | --- | --- | --- |
| Windblown dust | X | --- | X | X | --- | X | X | X | X | X |
| Hosedown | --- | --- | --- | --- | --- | --- | X | X | X | X |
| Corrosive agents | --- | --- | --- | X | X | X | --- | X | --- | X |
| Temporary submersion | --- | --- | --- | --- | --- | --- | --- | --- | X | X |
| Prolonged submersion | --- | --- | --- | --- | --- | --- | --- | --- | --- | X |
\*Mechanism shall be operable when ice covered.
For Indoor Use
| Provides a Degree of Protection Against the Following Environmental Conditions | 1 | 2 | 4 | 4X | 5 | 6 | 6P | 12 | 12K | 13 |
| ------------------------------------------------------------------------------ | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Incidental contact with the enclosed equipment | X | X | X | X | X | X | X | X | X | X |
| Falling dirt | X | X | X | X | X | X | X | X | X | X |
| Falling liquids and light splashing | --- | X | X | X | X | X | X | X | X | X |
| Circulating dust, lint, fibers, and flyings | --- | --- | X | X | --- | X | X | X | X | X |
| Settling airborne dust, lint, fibers, and flyings | --- | --- | X | X | X | X | X | X | X | X |
| Hosedown and splashing water | --- | --- | X | X | --- | X | X | --- | --- | --- |
| Oil and coolant seepage | --- | --- | --- | --- | --- | --- | --- | X | X | X |
| Oil or coolant spraying and splashing | --- | --- | --- | --- | --- | --- | --- | --- | --- | X |
| Corrosive agents | --- | --- | --- | X | --- | --- | X | --- | --- | --- |
| Temporary submersion | --- | --- | --- | --- | --- | X | X | --- | --- | --- |
| Prolonged submersion | --- | --- | --- | --- | --- | --- | X | --- | --- | --- |
> [!info] Informational Note No. 1:
> The term _raintight_ is typically used
> in conjunction with Enclosure Types 3, 3S, 3SX, 3X, 4, 4X, 6, and 6P.
> The term _rainproof_ is typically used
> in conjunction with Enclosure Types 3R and 3RX.
> The term _watertight_ is typically used
> in conjunction with Enclosure Types 4, 4X, 6, and 6P.
> The term _driptight_ is typically used
> in conjunction with Enclosure Types 2, 5, 12, 12K, and 13.
> The term _dusttight_ is typically used
> in conjunction with Enclosure Types 3, 3S, 3SX, 3X, 4, 4X, 5, 6, 6P, 12, 12K, and 13.
> [!info] Informational Note No. 2:
> Ingress protection (IP) ratings may be found in ANSI/IEC 60529,
> Degrees of Protection Provided by Enclosures.
> IP ratings are not a substitute for Enclosure Type ratings.
> [!info] Informational Note No. 3:
> Dusttight enclosures are suitable for use in hazardous locations
> in accordance with 502.10(B)(4), 503.10(A)(2), and 506.15(C)(9).
> [!info] Informational Note No. 4:
> Dusttight enclosures are suitable for use in unclassified locations
> and in Class II, Division 2; Class III;
> and Zone 22 hazardous (classified) locations.
## Part III. Over 1000 Volts, Nominal
### 110.30 General.
Conductors and equipment used on circuits over 1000 volts, nominal, shall comply with Part I of this article and with 110.30 through 110.41, which supplement or modify Part I.
In no case shall this part apply to equipment on the supply side of the service point.
### 110.31 Enclosure for Electrical Installations.
Electrical installations in a vault, room, or closet or in an area surrounded by a wall, screen, or fence, access to which is controlled by a lock(s) or other approved means, shall be considered to be accessible to qualified persons only. The type of enclosure used in a given case shall be designed and constructed according to the nature and degree of the hazard(s) associated with the installation.
For installations other than equipment as described in 110.31(D), a wall, screen, or fence shall be used to enclose an outdoor electrical installation to deter access by persons who are not qualified. A fence shall not be less than 2.1 m (7 ft) in height or a combination of
1.8 m (6 ft) or more of fence fabric and a 300 mm (1 ft) or more extension utilizing three or more strands of barbed wire or equivalent.
The distance from the fence to live parts shall be not less than given in Table 110.31.
Table 110.31 Minimum Distance from Fence to Live Parts
| Nominal Voltage | Minimum Distance to Live Parts |
|:---------------:|:------------------------------:|
| 1001--13,799 | 3.05 m (10 ft) |
| 13,800--230,000 | 4.57 m (15 ft) |
| Over 230,000 | 5.49 m (18 ft) |
Note: For clearances of conductors for specific system voltages and typical BIL ratings,
see ANSI/IEEE C2-2017, National Electrical Safety Code.
> [!info] Informational Note:
> See Article 450 for construction requirements for transformer vaults.
#### 110.31(A) Electrical Vaults.
Where an electrical vault is required or specified
for conductors and equipment
110.31(A)(1) to (A)(5) shall apply.
##### 110.31(A)(1) Walls and Roof.
The walls and roof shall be constructed of materials that have adequate structural strength for the conditions, with a minimum fire rating of 3 hours. For the purpose of this section, studs and wallboard construction shall not be permitted.
##### 110.31(A)(2) Floors.
The floors of vaults in contact with the earth shall be of concrete that is not less than 102 mm (4 in.) thick, but where the vault is constructed with a vacant space or other stories below it, the floor shall have adequate structural strength for the load imposed on it and a minimum fire resistance of 3 hours.
##### 110.31(A)(3) Doors.
Each doorway leading into a vault from the building interior
shall be provided with a tight-fitting door that has a minimum fire rating of 3 hours.
The authority having jurisdiction
shall be permitted to require such a door for an exterior wall opening where conditions warrant.
> [!important] Exception to (1), (2), and (3):
> Where the vault is protected with automatic sprinkler,
> water spray, carbon dioxide, or halon,
> construction with a 1-hour rating shall be permitted.
##### 110.31(A)(4) Locks.
Doors shall be equipped with locks, and doors shall be kept locked, with access allowed only to qualified persons. Personnel doors shall open in the direction of egress and be equipped with listed panic hardware or listed fire exit hardware.
##### 110.31(A)(5) Transformers.
Where a transformer is installed in a vault as required by Article 450, the vault shall be constructed in accordance with the requirements of Part III of Article 450.
> [!info] Informational Note No. 1:
> For additional information, see ANSI/ASTM E119-2018a, Method for Fire Tests of Building Construction and
Materials, and NFPA 80-2019, Standard for Fire Doors and Other Opening Protectives.
> [!info] Informational Note No. 2:
> A typical 3-hour construction is 150 mm (6 in.) thick reinforced concrete.
#### 110.31(B) Indoor Installations.
##### 110.31(B)(1) In Places Accessible to Unqualified Persons.
Indoor electrical installations that are accessible to unqualified persons shall be made with metal-enclosed equipment. Switchgear, transformers, pull boxes, connection boxes, and other similar associated equipment shall be marked with appropriate caution signs.
Openings in ventilated dry-type transformers or similar openings in other equipment shall be designed so that foreign objects inserted through these openings are deflected from energized parts.
##### 110.31(B)(2) In Places Accessible to Qualified Persons Only.
Indoor electrical installations considered accessible only to qualified persons in accordance with this section shall comply with 110.34, 110.36, and 490.24.
#### 110.31(C) Outdoor Installations.
##### 110.31(C)(1) In Places Accessible to Unqualified Persons.
Outdoor electrical installations that are open to unqualified persons shall comply with Parts I, II, and III of Article 225.
##### 110.31(C)(2) In Places Accessible to Qualified Persons Only.
Outdoor electrical installations that have exposed live parts shall be accessible to qualified persons only in accordance with the first paragraph of this section and shall comply with 110.34, 110.36, and 490.24.
#### 110.31(D) Enclosed Equipment Accessible to Unqualified Persons.
Ventilating or similar openings in equipment shall be designed such that foreign objects inserted through these openings are deflected from energized parts. Where exposed to physical damage from vehicular traffic, suitable guards shall be provided. Equipment located outdoors and accessible to unqualified persons shall be designed such that exposed nuts or bolts cannot be readily removed, permitting access to live parts. Where equipment is accessible to unqualified persons and the bottom of the enclosure is less than
2.5 m (8 ft) above the floor or grade level, the enclosure door or hinged cover shall be kept locked. Doors and covers of enclosures used solely as pull boxes, splice boxes, or junction boxes shall be locked, bolted, or screwed on. Underground box covers that weigh over 45.4 kg (100 lb) shall be considered as meeting this requirement.
### 110.32 Work Space About Equipment.
Sufficient space shall be provided and maintained about electrical equipment to permit ready and safe operation and maintenance of such equipment. Where energized parts are exposed, the minimum clear work space shall be not less than 2.0 m (61/2 ft) high
(measured vertically from the floor or platform) and the width of the equipment or 914 mm (3 ft) wide (measured parallel to the equipment), whichever is greater. The depth shall be as required in 110.34(A). In all cases, the work space shall permit at least a 90degree opening of doors or hinged panels. Within the height requirements of this section, other equipment that is associated with the electrical installation and is located above or below the electrical equipment shall be permitted to extend not more than 150 mm (6 in.) beyond the front of the electrical equipment. Working space required by this section shall not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be suitably guarded.
### 110.33 Entrance to Enclosures and Access to Working Space.
#### 110.33(A) Entrance.
At least one entrance to enclosures for electrical installations as described in 110.31
not less than 610 mm (24 in.) wide and 2.0 m (6 1/2 ft) high
shall be provided to give access to the working space about electrical equipment.
##### 110.33(A)(1) Large Equipment.
On switchgear and control panels exceeding 1.8 m (6 ft) in width,
there shall be one entrance at each end of the equipment.
A single entrance to the required working space
shall be permitted where either of the conditions in 110.33(A)(1)(a) or (A)(1)(b) is met.
* (a) Unobstructed Exit.
Where the location permits a continuous and unobstructed way of exit travel, a single entrance to the working space shall be permitted.
* (b) Extra Working Space.
Where the depth of the working space is twice that required by 110.34(A),
a single entrance shall be permitted.
It shall be located so that the distance from the equipment
to the nearest edge of the entrance
is not less than the minimum clear distance specified in Table 110.34(A)
for equipment operating at that voltage and in that condition.
##### 110.33(A)(2) Guarding.
Where bare energized parts at any voltage or insulated energized parts above 1000 volts, nominal, are located adjacent to such entrance, they shall be suitably guarded.
##### 110.33(A)(3) Personnel Doors.
Where there are personnel doors intended for entrance to and egress from the working space less than 7.6 m (25 ft) from the nearest edge of the working space, the doors shall open in the direction of egress and be equipped with listed panic hardware or listed fire exit hardware.
#### 110.33(B) Access.
Permanent ladders or stairways shall be provided to give safe access to the working space around electrical equipment installed on platforms, balconies, or mezzanine floors or in attic or roof rooms or spaces.
### 110.34 Work Space and Guarding.
#### 110.34(A) Working Space.
Except as elsewhere required or permitted in this Code, equipment likely to require examination, adjustment, servicing, or maintenance while energized shall have clear working space in the direction of access to live parts of the electrical equipment and shall be not less than specified in Table 110.34(A). Distances shall be measured from the live parts, if such are exposed, or from the enclosure front or opening if such are enclosed.
> [!important] Exception:
> Working space shall not be required in back of equipment such as switchgear or control assemblies where there are no renewable or adjustable parts (such as fuses or switches) on the back and where all connections are accessible from locations other than the back. Where rear access is required to work on nonelectrical parts on the back of enclosed equipment, a minimum working space of 762 mm (30 in.) horizontally shall be provided.
##### Table 110.34(A) Minimum Depth of Clear Working Space at Electrical Equipment
| Nominal Voltage to Ground | Condition | Minimum Clear Distance |
|:-------------------------:| ----------- |:----------------------:|
| 1001--2500 V | Condition 1 | 900 mm (3 ft) |
| 1001--2500 V | Condition 2 | 1.2 m (4 ft) |
| 1001--2500 V | Condition 3 | 1.5 m (5 ft) |
| 2501--9000 V | Condition 1 | 1.2 m (4 ft) |
| 2501--9000 V | Condition 2 | 1.5 m (5 ft) |
| 2501--9000 V | Condition 3 | 1.8 m (6 ft) |
| 9001--25,000 V | Condition 1 | 1.5 m (5 ft) |
| 9001--25,000 V | Condition 2 | 1.8 m (6 ft) |
| 9001--25,000 V | Condition 3 | 2.8 m (9 ft) |
| 25,001 V--75 kV | Condition 1 | 1.8 m (6 ft) |
| 25,001 V--75 kV | Condition 2 | 2.5 m (8 ft) |
| 25,001 V--75 kV | Condition 3 | 3.0 m (10 ft) |
| Above 75 kV | Condition 1 | 2.5 m (8 ft) |
| Above 75 kV | Condition 2 | 3.0 m (10 ft) |
| Above 75 kV | Condition 3 | 3.7 m (12 ft) |
Note:
Where the conditions are as follows:
* (1) **Condition 1** ---
Exposed live parts on one side of the working space and no live or grounded parts on the other side of the working space, or exposed live parts on both sides of the working space that are effectively guarded by insulating materials.
* (2) **Condition 2** ---
Exposed live parts on one side of the working space and grounded parts on the other side of the working space. Concrete, brick, or tile walls shall be considered as grounded.
* (3) **Condition 3** ---
Exposed live parts on both sides of the working space.
#### 110.34(B) Separation from Low-Voltage Equipment.
Where switches, cutouts, or other equipment operating at 1000 volts, nominal, or less are installed in a vault, room, or enclosure where there are exposed live parts or exposed wiring operating at over 1000 volts, nominal, the high-voltage equipment shall be effectively separated from the space occupied by the low-voltage equipment by a suitable partition, fence, or screen.
> [!important] Exception:
> Switches or other equipment operating at 1000 volts, nominal, or less and serving only equipment within the high-voltage vault, room, or enclosure shall be permitted to be installed in the high-voltage vault, room, or enclosure without a partition, fence, or screen if accessible to qualified persons only.
#### 110.34(C) Locked Rooms or Enclosures.
The entrance to all buildings, vaults, rooms, or enclosures containing exposed live parts or exposed conductors operating at over
1000 volts, nominal, shall be kept locked unless such entrances are under the observation of a qualified person at all times.
Permanent and conspicuous danger signs shall be provided. The danger sign shall meet the requirements in 110.21(B) and shall read as follows:
DANGER --- HIGH VOLTAGE --- KEEP OUT
#### 110.34(D) Illumination.
Illumination shall be provided for all working spaces about electrical equipment. Control by automatic means only shall not be permitted.
The lighting outlets shall be arranged so that persons changing lamps or making repairs on the lighting system are not endangered by live parts or other equipment.
The points of control shall be located so that persons are not likely to come in contact with any live part or moving part of the equipment while turning on the lights.
#### 110.34(E) Elevation of Unguarded Live Parts.
Unguarded live parts above working space shall be maintained at elevations not less than required by Table 110.34(E).
Table 110.34(E) Elevation of Unguarded Live Parts
Above Working Space
Nominal Voltage
Between Phases
Elevation m ft
1001--7500 V 2.7 9
7501--35,000 V 2.9 9 ft 6 in.
Over 35 kV Add 9.5 mm per kV above 35 kV
Add 0.37 in. per kV above 35 kV
#### 110.34(F) Protection of Service Equipment, Switchgear, and Industrial Control Assemblies.
Pipes or ducts foreign to the electrical installation and requiring periodic maintenance or whose malfunction would endanger the operation of the electrical system shall not be located in the vicinity of the service equipment, switchgear, or industrial control assemblies. Protection shall be provided where necessary to avoid damage from condensation leaks and breaks in such foreign systems. Piping and other facilities shall not be considered foreign if provided for fire protection of the electrical installation.
### 110.36 Circuit Conductors.
Circuit conductors shall be permitted to be installed in raceways; in cable trays; as metal-clad cable Type MC; as bare wire, cable, and busbars; or as Type MV cables or conductors as provided in 300.37, 300.39, 300.40, and 300.50. Bare live conductors shall comply with 490.24.
Insulators, together with their mounting and conductor attachments, where used as supports for wires, single-conductor cables, or busbars, shall be capable of safely withstanding the maximum magnetic forces that would prevail if two or more conductors of a circuit were subjected to short-circuit current.
Exposed runs of insulated wires and cables that have a bare lead sheath or a braided outer covering shall be supported in a manner designed to prevent physical damage to the braid or sheath. Supports for lead-covered cables shall be designed to prevent electrolysis of the sheath.
### 110.40 Temperature Limitations at Terminations.
Conductors shall be permitted to be terminated based on the 90°C (194°F) temperature rating and ampacity as given in Table
311.60(C)(67) through Table 311.60(C)(86), unless otherwise identified.
### 110.41 Inspections and Tests.
#### 110.41(A) Pre-energization and Operating Tests.
Where required elsewhere in this Code, the complete electrical system design, including settings for protective, switching, and control circuits, shall be prepared in advance and made available on request to the authority having jurisdiction and shall be tested when first installed on-site.
#### 110.41(B) Test Report.
A test report covering the results of the tests required in 110.41(A) shall be available to the authority having jurisdiction prior to energization and made available to those authorized to install, operate, test, and maintain the system.
## Part IV. Tunnel Installations over 1000 Volts, Nominal
### 110.51 General.
#### 110.51(A) Covered.
This part shall apply to the installation and use of high-voltage power distribution and utilization equipment that is portable, mobile, or both, such as substations, trailers, cars, mobile shovels, draglines, hoists, drills, dredges, compressors, pumps, conveyors, underground excavators, and the like.
#### 110.51(B) Other Articles.
The requirements of this part shall be additional to, or amendatory of, those prescribed in Articles 100 through 490 of this Code.
#### 110.51(C) Protection Against Physical Damage.
Conductors and cables in tunnels shall be located above the tunnel floor and so placed or guarded to protect them from physical damage.
### 110.52 Overcurrent Protection.
Motor-operated equipment shall be protected from overcurrent in accordance with Parts III, IV, and V of Article 430. Transformers shall be protected from overcurrent in accordance with 450.3.
### 110.53 Conductors.
High-voltage conductors in tunnels shall be installed in metal conduit or other metal raceway, Type MC cable, or other approved multiconductor cable. Multiconductor portable cable shall be permitted to supply mobile equipment.
### 110.54 Bonding and Equipment Grounding Conductors.
#### 110.54(A) Grounded and Bonded.
All non--current-carrying metal parts of electrical equipment and all metal raceways and cable sheaths shall be solidly grounded and bonded to all metal pipes and rails at the portal and at intervals not exceeding 300 m (1000 ft) throughout the tunnel.
#### 110.54(B) Equipment Grounding Conductors.
An equipment grounding conductor shall be run with circuit conductors inside the metal raceway or inside the multiconductor cable jacket. The equipment grounding conductor shall be permitted to be insulated or bare.
### 110.55 Transformers, Switches, and Electrical Equipment.
All transformers, switches, motor controllers, motors, rectifiers, and other equipment installed belowground shall be protected from physical damage by location or guarding.
### 110.56 Energized Parts.
Bare terminals of transformers, switches, motor controllers, and other equipment shall be enclosed to prevent accidental contact with energized parts.
### 110.57 Ventilation System Controls.
Electrical controls for the ventilation system shall be arranged so that the airflow can be reversed.
### 110.58 Disconnecting Means.
A switch or circuit breaker that simultaneously opens all ungrounded conductors of the circuit shall be installed within sight of each transformer or motor location for disconnecting the transformer or motor. The switch or circuit breaker for a transformer shall have an ampere rating not less than the ampacity of the transformer supply conductors. The switch or circuit breaker for a motor shall comply with the applicable requirements of Article 430.
### 110.59 Enclosures.
Enclosures for use in tunnels shall be dripproof, weatherproof, or submersible as required by the environmental conditions. Switch or contactor enclosures shall not be used as junction boxes or as raceways for conductors feeding through or tapping off to other switches, unless the enclosures comply with 312.8.
## Part V. Manholes and Other Electrical Enclosures Intended for Personnel Entry
### 110.70 General.
Electrical enclosures intended for personnel entry and specifically fabricated for this purpose shall be of sufficient size to provide safe work space about electrical equipment with live parts that is likely to require examination, adjustment, servicing, or maintenance while energized. Such enclosures shall have sufficient size to permit ready installation or withdrawal of the conductors employed without damage to the conductors or to their insulation. They shall comply with this part.
> [!important] Exception:
> Where electrical enclosures covered by Part V of this article are part of an industrial wiring system operating under conditions of maintenance and supervision that ensure that only qualified persons monitor and supervise the system, they shall be permitted to be designed and installed in accordance with appropriate engineering practice. If required by the authority having jurisdiction, design documentation shall be provided.
### 110.71 Strength.
Manholes, vaults, and their means of access shall be designed under qualified engineering supervision and shall withstand all loads likely to be imposed on the structures.
> [!info] Informational Note:
> See ANSI C2-2007, National Electrical Safety Code, for additional information on the loading that can be expected to bear on underground enclosures.
### 110.72 Cabling Work Space.
A clear work space not less than 900 mm (3 ft) wide shall be provided where cables are located on both sides, and not less than
750 mm (21/2 ft) where cables are only on one side. The vertical headroom shall be not less than 1.8 m (6 ft) unless the opening is within 300 mm (1 ft), measured horizontally, of the adjacent interior side wall of the enclosure.
> [!important] Exception:
> A manhole containing only one or more of the following shall be permitted to have one of the horizontal work space dimensions reduced to 600 mm (2 ft) where the other horizontal clear work space is increased so the sum of the two dimensions is not less than 1.8 m (6 ft):
* (1) Optical fiber cables as covered in Article 770
* (2) Power-limited fire alarm circuits supplied in accordance with 760.121
* (3) Class 2 or Class 3 remote-control and signaling circuits, or both, supplied in accordance with 725.121
### 110.73 Equipment Work Space.
Where electrical equipment with live parts that is likely to require examination, adjustment, servicing, or maintenance while energized is installed in a manhole, vault, or other enclosure designed for personnel access, the work space and associated requirements in 110.26 shall be met for installations operating at 1000 volts or less. Where the installation is over 1000 volts, the work space and associated requirements in 110.34 shall be met. A manhole access cover that weighs over 45.4 kg (100 lb) shall be considered as meeting the requirements of 110.34(C).
### 110.74 Conductor Installation.
Conductors installed in manholes and other enclosures intended for personnel entry shall be cabled, racked up, or arranged in an approved manner that provides ready and safe access for persons to enter for installation and maintenance. The installation shall comply with 110.74(A) or 110.74(B), as applicable.
#### 110.74(A) 1000 Volts, Nominal, or Less.
Wire bending space for conductors operating at 1000 volts or less shall be provided in accordance with the requirements of 314.28.
#### 110.74(B) Over 1000 Volts, Nominal.
Conductors operating at over 1000 volts shall be provided with bending space in accordance with 314.71(A) and (B), as applicable.
> [!important] Exception:
> Where 314.71(B) applies, each row or column of ducts on one wall of the enclosure shall be calculated individually, and the single row or column that provides the maximum distance shall be used.
### 110.75 Access to Manholes.
#### 110.75(A) Dimensions.
Rectangular access openings shall not be less than 650 mm × 550 mm (26 in. × 22 in.). Round access openings in a manhole shall be not less than 650 mm (26 in.) in diameter.
> [!important] Exception:
> A manhole that has a fixed ladder that does not obstruct the opening or that contains only one or more of the following shall be permitted to reduce the minimum cover diameter to 600 mm (2 ft):
* (1) Optical fiber cables as covered in Article 770
* (2) Power-limited fire alarm circuits supplied in accordance with 760.121
* (3) Class 2 or Class 3 remote-control and signaling circuits, or both, supplied in accordance with 725.121
#### 110.75(B) Obstructions.
Manhole openings shall be free of protrusions that could injure personnel or prevent ready egress.
#### 110.75(C) Location.
Manhole openings for personnel shall be located where they are not directly above electrical equipment or conductors in the enclosure.
Where this is not practicable, either a protective barrier or a fixed ladder shall be provided.
#### 110.75(D) Covers.
Covers shall be over 45 kg (100 lb) or otherwise designed to require the use of tools to open. They shall be designed or restrained so they cannot fall into the manhole or protrude sufficiently to contact electrical conductors or equipment within the manhole.
#### 110.75(E) Marking.
Manhole covers shall have an identifying mark or logo that prominently indicates their function, such as "electric."
### 110.76 Access to Vaults and Tunnels.
#### 110.76(A) Location.
Access openings for personnel shall be located where they are not directly above electrical equipment or conductors in the enclosure.
Other openings shall be permitted over equipment to facilitate installation, maintenance, or replacement of equipment.
#### 110.76(B) Locks.
In addition to compliance with the requirements of 110.34, if applicable, access openings for personnel shall be arranged such that a person on the inside can exit when the access door is locked from the outside, or in the case of normally locking by padlock, the locking arrangement shall be such that the padlock can be closed on the locking system to prevent locking from the outside.
### 110.77 Ventilation.
Where manholes, tunnels, and vaults have communicating openings into enclosed areas used by the public, ventilation to open air shall be provided wherever practicable.
### 110.78 Guarding.
Where conductors or equipment, or both, could be contacted by objects falling or being pushed through a ventilating grating, both conductors and live parts shall be protected in accordance with the requirements of 110.27(A)(2) or 110.31(B)(1), depending on the voltage.
### 110.79 Fixed Ladders.
Fixed ladders shall be corrosion resistant.
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nfpa-70_210_branch-circuits.md
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@@ -19,7 +19,348 @@ title: Article 210 Branch Circuits
This article provides the general requirements for branch circuits.
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### 210.3 Other Articles for Specific-Purpose Branch Circuits.
Table 210.3 lists references for specific equipment and applications not located in Chapters 5, 6, and 7 that amend or supplement the requirements of this article.
Table 210.3 Specific-Purpose Branch Circuits
| Equipment | Article | Section |
| --------------------------------------------------------------------------- | ------- | --------------------- |
| Air-conditioning and refrigerating equipment | | 440.6, 440.31, 440.32 |
| Busways | | 368.17 |
| Central heating equipment other than fixed electric space-heating equipment | | 422.12 |
| Fixed electric heating equipment for pipelines and vessels | | 427.4 |
| Fixed electric space-heating equipment | | 424.3 |
| Fixed outdoor electrical deicing and snow-melting equipment | | 426.4 |
| Infrared lamp industrial heating equipment | | 422.48, 424.3 |
| Motors, motor circuits, and controllers | 430 | |
| Switchboards and panelboards | | 408.52 |
### 210.4 Multiwire Branch Circuits.
#### 210.4(A) General.
Branch circuits recognized by this article shall be permitted as multiwire circuits. A multiwire circuit shall be permitted to be considered as multiple circuits. All conductors of a multiwire branch circuit shall originate from the same panelboard or similar distribution equipment.
> [!info] Informational Note No. 1:
> A 3-phase, 4-wire, wye-connected power system used to supply power to nonlinear loads may necessitate that the power system design allow for the possibility of high harmonic currents on the neutral conductor.
> [!info] Informational Note No. 2:
> See 300.13(B) for continuity of grounded conductors on multiwire circuits.
#### 210.4(B) Disconnecting Means.
Each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates.
> [!info] Informational Note:
> See 240.15(B) for information on the use of single-pole circuit breakers as the disconnecting means.
#### 210.4(C) Line-to-Neutral Loads.
Multiwire branch circuits shall supply only line-to-neutral loads.
> [!important] Exception No. 1:
> A multiwire branch circuit that supplies only one utilization equipment.
> [!important] Exception No. 2:
> Where all ungrounded conductors of the multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device.
#### 210.4(D) Grouping.
The ungrounded and grounded circuit conductors of each multiwire branch circuit shall be grouped in accordance with 200.4(B).
### 210.5 Identification for Branch Circuits.
#### 210.5(A) Grounded Conductor.
The grounded conductor of a branch circuit shall be identified in accordance with 200.6.
#### 210.5(B) Equipment Grounding Conductor.
The equipment grounding conductor shall be identified in accordance with 250.119.
#### 210.5(C) Identification of Ungrounded Conductors.
Ungrounded conductors shall be identified in accordance with 210.5(C)(1) or (2), as applicable.
##### 210.5(C)(1) Branch Circuits Supplied from More Than One Nominal Voltage System.
Where the premises wiring system has branch circuits supplied from more than one nominal voltage system, each ungrounded conductor of a branch circuit shall be identified by phase or line and by system voltage class at all termination, connection, and splice points in compliance with 210.5(C)(1)(a) and (b). Different systems within the same premises that have the same system voltage class shall be permitted to use the same identification.
* (a) _Means of Identification._
The means of identification shall be permitted to be by separate color coding, marking tape, tagging, or other approved means.
* (b) _Posting of Identification Means._
The method utilized for conductors originating within each branch-circuit panelboard or similar branch-circuit distribution equipment shall be documented in a manner that is readily available or shall be permanently posted at each branch-circuit panelboard or similar branch-circuit distribution equipment. The label shall be of sufficient durability to withstand the environment involved and shall not be handwritten.
> [!important] Exception:
> In existing installations where a voltage system(s) already exists and a different voltage system is being added, it shall be permissible to mark only the new system voltage. Existing unidentified systems shall not be required to be identified at each termination, connection, and splice point in compliance with 210.5(C)(1)(a) and (b). Labeling shall be required at each voltage system distribution equipment to identify that only one voltage system has been marked for a new system(s). The new system label(s) shall include the words "other unidentified systems exist on the premises."
##### 210.5(C)(2) Branch Circuits Supplied from Direct-Current Systems.
Where a branch circuit is supplied from a dc system operating at more than 60 volts, each ungrounded conductor of 4 AWG or larger shall be identified by polarity at all termination, connection, and splice points by marking tape, tagging, or other approved means; each ungrounded conductor of 6 AWG or smaller shall be identified by polarity at all termination, connection, and splice points in compliance with 210.5(C) (2) (a) and (b). The identification methods utilized for conductors originating within each branch-circuit panelboard or similar branch-circuit distribution equipment shall be documented in a manner that is readily available or shall be permanently posted at each branch-circuit panelboard or similar branch-circuit distribution equipment.
* (a) Positive Polarity, Sizes 6 AWG or Smaller. Where the positive polarity of a dc system does not serve as the connection point for the grounded conductor, each positive ungrounded conductor shall be identified by one of the following means:
* (1) A continuous red outer finish
* (2) A continuous red stripe durably marked along the conductor's entire length on insulation of a color other than green, white, gray, or black
* (3) Imprinted plus signs (+) or the word POSITIVE or POS durably marked on insulation of a color other than green, white, gray, or black and repeated at intervals not exceeding 610 mm (24 in.) in accordance with 310.8(B)
* (4) An approved permanent marking means such as sleeving or shrink-tubing that is suitable for the conductor size, at all termination, connection, and splice points, with imprinted plus signs (+) or the word POSITIVE or POS durably marked on insulation of a color other than green, white, gray, or black
* (b) Negative Polarity, Sizes 6 AWG or Smaller. Where the negative polarity of a dc system does not serve as the connection point for the grounded conductor, each negative ungrounded conductor shall be identified by one of the following means:
* (1) A continuous black outer finish
* (2) A continuous black stripe durably marked along the conductor's entire length on insulation of a color other than green, white, gray, or red
* (3) Imprinted minus signs (--) or the word NEGATIVE or NEG durably marked on insulation of a color other than green, white, gray, or red and repeated at intervals not exceeding 610 mm (24 in.) in accordance with 310.8(B)
* (4) An approved permanent marking means such as sleeving or shrink-tubing that is suitable for the conductor size, at all termination, connection, and splice points, with imprinted minus signs (--) or the word NEGATIVE or NEG durably marked on insulation of a color other than green, white, gray, or red
### 210.6 Branch-Circuit Voltage Limitations.
The nominal voltage of branch circuits shall not exceed the values permitted by 210.6(A) through (E).
#### 210.6(A) Occupancy Limitation.
In dwelling units and guest rooms or guest suites of hotels, motels, and similar occupancies, the voltage shall not exceed 120 volts, nominal, between conductors that supply the terminals of the following:
* (1) Luminaires
* (2) Cord-and-plug-connected loads 1440 volt-amperes, nominal,
or less or less than 1/4 hp
#### 210.6(B) 120 Volts Between Conductors.
Circuits not exceeding 120 volts, nominal, between conductors shall be permitted to supply the following:
* (1) The terminals of lampholders applied within their voltage ratings
* (2) Auxiliary equipment of electric-discharge lamps
> [!info] Informational Note:
> See 410.137 for auxiliary equipment limitations.
* (3) Cord-and-plug-connected or permanently connected utilization equipment
#### 210.6(C) 277 Volts to Ground.
Circuits exceeding 120 volts, nominal, between conductors but not exceeding 277 volts, nominal, to ground shall be permitted to supply cord-and-plug-connected or permanently connected utilization equipment, or the following types of listed luminaires:
* (1) Electric-discharge luminaires with integral ballasts
* (2) LED luminaires with LED drivers between the branch circuit and the lampholders
* (3) Incandescent or LED luminaires, equipped with medium-base or smaller screw shell lampholders, where the lampholders are supplied at 120 volts or less from the output of a stepdown autotransformer, LED driver, or other type of power supply that is an integral component of the luminaire
> [!info] Informational Note:
> See 410.90 for requirements regarding the connection of screw shell lampholders to grounded conductors.
* (4) Luminaires equipped with mogul-base screw shell lampholders
* (5) Luminaires equipped with lampholders, other than the screw shell type, when used within their voltage ratings of their lampholders
* (6) Luminaires without lampholders
> [!info] Informational Note:
> Luminaires with nonserviceable LEDs are examples of luminaires without lampholders.
* (7) Auxiliary equipment of electric-discharge or LED-type lamps
> [!info] Informational Note:
> See 410.137 for auxiliary equipment limitations.
* (8) Luminaires converted with listed retrofit kits incorporating integral LED light sources or accepting LED lamps that also conforms with 210.6(C)(1), (C)(2), (C)(3), (C)(4), or (C)(5)
#### 210.6(D) 600 Volts Between Conductors.
Circuits exceeding 277 volts, nominal, to ground and not exceeding 600 volts, nominal, between conductors shall be permitted to supply the following:
* (1) The auxiliary equipment of electric-discharge lamps mounted in permanently installed luminaires where the luminaires are mounted in accordance with one of the following:
* a. Not less than a height of 6.7 m (22 ft) on poles or similar structures for the illumination of outdoor areas such as highways, roads, bridges, athletic fields, or parking lots
* b. Not less than a height of 5.5 m (18 ft) on other structures such as tunnels
> [!info] Informational Note:
> See 410.137 for auxiliary equipment limitations.
* (2) Cord-and-plug-connected or permanently connected utilization equipment other than luminaires
* (3) Luminaires powered from direct-current systems where either of the following apply:
* a. The luminaire contains a listed, dc-rated ballast that provides isolation between the dc power source and the lamp circuit and protection from electric shock when changing lamps.
* b. The luminaire contains a listed, dc-rated ballast and has no provision for changing lamps.
> [!important] Exception No. 1 to (B), (C), and (D):
> For lampholders of infrared industrial heating appliances as provided in 425.14.
> [!important] Exception No. 2 to (B), (C), and (D):
> For railway properties as described in 110.19.
#### 210.6(E) Over 600 Volts Between Conductors.
Circuits exceeding 600 volts, nominal, between conductors shall be permitted to supply utilization equipment in installations where conditions of maintenance and supervision ensure that only qualified persons service the installation.
### 210.7 Multiple Branch Circuits.
Where two or more branch circuits supply devices or equipment on the same yoke or mounting strap, a means to simultaneously disconnect the ungrounded supply conductors shall be provided at the point at which the branch circuits originate.
### 210.8 Ground-Fault Circuit-Interrupter Protection for Personnel.
Ground-fault circuit-interrupter protection for personnel shall be provided as required in 210.8(A) through (F). The ground-fault circuit interrupter shall be installed in a readily accessible location.
> [!info] Informational Note No. 1:
> See 215.9 for ground-fault circuit-interrupter protection for personnel on feeders.
> [!info] Informational Note No. 2:
> See 422.5(A) for GFCI requirements for appliances.
> [!info] Informational Note No. 3:
> See 555.9 for GFCI requirements for boat hoists.
> [!info] Informational Note No. 4:
> Additional GFCI requirements for specific circuits and equipment are contained in Chapters 4, 5, and 6.
For the purposes of this section, when determining the distance from receptacles the distance shall be measured as the shortest path the supply cord of an appliance connected to the receptacle would follow without piercing a floor, wall, ceiling, or fixed barrier, or the shortest path without passing through a window.
#### 210.8(A) Dwelling Units.
All 125-volt through 250-volt receptacles installed in the locations specified in 210.8(A)(1) through (A) (11) and supplied by single-phase branch circuits rated 150 volts or less to ground shall have ground-fault circuit-interrupter protection for personnel.
* (1) Bathrooms
* (2) Garages and also accessory buildings that have a floor located at or below grade level not intended as habitable rooms and limited to storage areas, work areas, and areas of similar use
* (3) Outdoors
> [!important] Exception to (3):
> Receptacles that are not readily accessible
> and are supplied by a branch circuit dedicated to electric snowmelting,
> deicing, or pipeline and vessel heating equipment
> shall be permitted to be installed in accordance with 426.28 or 427.22, as applicable.
* (4) Crawl spaces --- at or below grade level
* (5) Basements
> [!important] Exception to (5):
> A receptacle supplying only a permanently installed fire alarm or burglar alarm system shall not be required to have ground-fault circuit-interrupter protection.
> [!info] Informational Note:
> See 760.41(B) and 760.121(B) for power supply requirements for fire alarm systems.
Receptacles installed under the exception to 210.8(A)(5) shall not be considered as meeting the requirements of 210.52(G).
* (6) Kitchens --- where the receptacles are installed to serve the countertop surfaces
* (7) Sinks --- where receptacles are installed within 1.8 m (6 ft) from the top inside edge of the bowl of the sink
* (8) Boathouses
* (9) Bathtubs or shower stalls --- where receptacles are installed within 1.8 m (6 ft) of the outside edge of the bathtub or shower stall
* (10) Laundry areas
> [!important] Exception to (1) through (3), (5) through (8), and (10):
> Listed locking support and mounting receptacles utilized in combination with compatible attachment fittings installed for the purpose of serving a ceiling luminaire or ceiling fan shall not be required to be ground-fault circuit-interrupter protected. If a general-purpose convenience receptacle is integral to the ceiling luminaire or ceiling fan, GFCI protection shall be provided.
* (11) Indoor damp and wet locations
#### 210.8(B) Other Than Dwelling Units.
All 125-volt through 250-volt receptacles supplied by single-phase branch circuits rated 150 volts or less to ground, 50 amperes or less, and all receptacles supplied by three-phase branch circuits rated 150 volts or less to ground, 100 amperes or less, installed in the locations specified in 210.8(B)(1) through (B)(12) shall have ground-fault circuit-interrupter protection for personnel.
* (1) Bathrooms
* (2) Kitchens or areas with a sink and permanent provisions for either food preparation or cooking
* (3) Rooftops
> [!important] Exception:
> Receptacles on rooftops shall not be required to be readily accessible other than from the rooftop.
* (4) Outdoors
Exception No. 1 to (3) and (4): Receptacles that are not readily accessible and are supplied by a branch circuit dedicated to electric snow-melting, deicing, or pipeline and vessel heating equipment shall be permitted to be installed in accordance with
426.28 or 427.22, as applicable.
Exception No. 2 to (4): In industrial establishments only, where the conditions of maintenance and supervision ensure that only qualified personnel are involved, an assured equipment grounding conductor program as specified in 590.6(B)(2) shall be permitted for only those receptacle outlets used to supply equipment that would create a greater hazard if power is interrupted or having a design that is not compatible with GFCI protection.
* (5) Sinks --- where receptacles are installed within 1.8 m (6 ft) from the top inside edge of the bowl of the sink
Exception No. 1 to (5): In industrial laboratories, receptacles used to supply equipment where removal of power would introduce a greater hazard shall be permitted to be installed without GFCI protection.
Exception No. 2 to (5): Receptacles located in patient bed locations of Category 2 (general care) or Category 1 (critical care) spaces of health care facilities shall be permitted to comply with 517.21.
* (6) Indoor damp and wet locations
* (7) Locker rooms with associated showering facilities
* (8) Garages, accessory buildings, service bays, and similar areas other than vehicle exhibition halls and showrooms
* (9) Crawl spaces --- at or below grade level
* (10) Unfinished areas of basements
Exception to (1) through (5), (8), and (10): Listed locking support and mounting receptacles utilized in combination with compatible attachment fittings installed for the purpose of serving a ceiling luminaire or ceiling fan shall not be required to be ground-fault circuit-interrupter protected. If a general-purpose convenience receptacle is integral to the ceiling luminaire or ceiling fan, GFCI protection shall be provided.
* (11) Laundry areas
* (12) Bathtubs and shower stalls --- where receptacles are installed within 1.8 m (6 ft) of the outside edge of the bathtub or shower stall
#### 210.8(C) Crawl Space Lighting Outlets.
GFCI protection shall be provided for lighting outlets not exceeding 120 volts installed in crawl spaces.
#### 210.8(D) Specific Appliances.
Unless GFCI protection is provided in accordance with 422.5(B)(3) through (B)(5), the outlets supplying the appliances specified in
422.5(A) shall have GFCI protection in accordance with 422.5(B)(1) or (B)(2).
Where the appliance is a vending machine as specified in 422.5(A)(5) and GFCI protection is not provided in accordance with 422.5(B)
* (3) or (B)(4), branch circuits supplying vending machines shall have GFCI protection in accordance with 422.5(B)(1) or (B)(2).
#### 210.8(E) Equipment Requiring Servicing.
GFCI protection shall be provided for the receptacles required by 210.63.
#### 210.8(F) Outdoor Outlets.
All outdoor outlets for dwellings, other than those covered in 210.8(A)(3), Exception to (3), that are supplied by single-phase branch circuits rated 150 volts to ground or less, 50 amperes or less, shall have ground-fault circuit-interrupter protection for personnel.
> [!important] Exception:
> Ground-fault circuit-interrupter protection shall not be required on lighting outlets other than those covered in 210.8(C).
### 210.9 Circuits Derived from Autotransformers.
Branch circuits shall not be derived from autotransformers unless the circuit supplied has a grounded conductor that is electrically connected to a grounded conductor of the system supplying the autotransformer.
> [!important] Exception No. 1:
> An autotransformer shall be permitted without the connection to a grounded conductor where transforming from a nominal 208 volts to a nominal 240-volt supply or similarly from 240 volts to 208 volts.
> [!important] Exception No. 2:
> In industrial occupancies, where conditions of maintenance and supervision ensure that only qualified persons service the installation, autotransformers shall be permitted to supply nominal 600-volt loads from nominal 480-volt systems, and 480-volt loads from nominal 600-volt systems, without the connection to a similar grounded conductor.
### 210.10 Ungrounded Conductors Tapped from Grounded Systems.
Two-wire dc circuits and ac circuits of two or more ungrounded conductors shall be permitted to be tapped from the ungrounded conductors of circuits that have a grounded neutral conductor. Switching devices in each tapped circuit shall have a pole in each ungrounded conductor. All poles of multipole switching devices shall manually switch together where such switching devices also serve as a disconnecting means as required by the following:
* (1) 410.93 for double-pole switched lampholders
* (2) 410.104(B) for electric-discharge lamp auxiliary equipment switching devices
* (3) 422.31(B) for an appliance
* (4) 424.20 for a fixed electric space-heating unit
* (5) 426.51 for electric deicing and snow-melting equipment
* (6) 430.85 for a motor controller
* (7) 430.103 for a motor
### 210.11 Branch Circuits Required.
@@ -72,10 +413,10 @@ to supply bathroom(s) receptacle outlet(s) required by 210.52(D)
and any countertop and similar work surface receptacle outlets.
Such circuits shall have no other outlets.
Exception:
Where the 20-ampere circuit supplies a single bathroom,
outlets for other equipment within the same bathroom
shall be permitted to be supplied in accordance with 210.23(A)(1) and (A)(2).
> [!important] Exception:
> Where the 20-ampere circuit supplies a single bathroom,
> outlets for other equipment within the same bathroom
> shall be permitted to be supplied in accordance with 210.23(A)(1) and (A)(2).
##### 210.11(C)(4) Garage Branch Circuits.
@@ -85,11 +426,104 @@ to supply receptacle outlets required by 210.52(G)(1)
for attached garages and in detached garages with electric power.
This circuit shall have no other outlets.
Exception:
This circuit shall be permitted to supply
readily accessible outdoor receptacle outlets.
> [!important] Exception:
> This circuit shall be permitted to supply
> readily accessible outdoor receptacle outlets.
<!-- TODO: TEXT OMITTED -->
### 210.12 Arc-Fault Circuit-Interrupter Protection.
Arc-fault circuit-interrupter protection shall be provided as required in 210.12(A), (B), (C), and (D). The arc-fault circuit interrupter shall be installed in a readily accessible location.
#### 210.12(A) Dwelling Units.
All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas shall be protected by any of the means described in 210.12(A)(1) through (6):
* (1) A listed combination-type arc-fault circuit interrupter installed to provide protection of the entire branch circuit
* (2) A listed branch/feeder-type AFCI installed at the origin of the branch-circuit in combination with a listed outlet branch-circuit-type arc-fault circuit interrupter installed at the first outlet box on the branch circuit. The first outlet box in the branch circuit shall be marked to indicate that it is the first outlet of the circuit.
* (3) A listed supplemental arc protection circuit breaker installed at the origin of the branch circuit in combination with a listed outlet branch-circuit-type arc-fault circuit interrupter installed at the first outlet box on the branch circuit where all of the following conditions are met:
* a. The branch-circuit wiring shall be continuous from the branch-circuit overcurrent device to the outlet branch-circuit arcfault circuit interrupter.
* b. The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 15.2 m (50 ft) for a 14 AWG conductor or 21.3 m (70 ft) for a 12 AWG conductor.
* c. The first outlet box in the branch circuit shall be marked to indicate that it is the first outlet of the circuit.
* (4) A listed outlet branch-circuit-type arc-fault circuit interrupter installed at the first outlet on the branch circuit in combination with a listed branch-circuit overcurrent protective device where all of the following conditions are met:
* a. The branch-circuit wiring shall be continuous from the branch-circuit overcurrent device to the outlet branch-circuit arcfault circuit interrupter.
* b. The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 15.2 m (50 ft) for a 14 AWG conductor or 21.3 m (70 ft) for a 12 AWG conductor.
* c. The first outlet box in the branch circuit shall be marked to indicate that it is the first outlet of the circuit.
* d. The combination of the branch-circuit overcurrent device and outlet branch-circuit AFCI shall be identified as meeting the requirements for a system combination-type AFCI and shall be listed as such.
* (5) If metal raceway, metal wireways, metal auxiliary gutters, or Type MC, or Type AC cable meeting the applicable requirements of
250.118, with metal boxes, metal conduit bodies, and metal enclosures are installed for the portion of the branch circuit between the branch-circuit overcurrent device and the first outlet, it shall be permitted to install a listed outlet branch-circuit-type AFCI at the first outlet to provide protection for the remaining portion of the branch circuit.
* (6) Where a listed metal or nonmetallic conduit or tubing or Type MC cable is encased in not less than 50 mm (2 in.) of concrete for the portion of the branch circuit between the branch-circuit overcurrent device and the first outlet, it shall be permitted to install a listed outlet branch-circuit-type AFCI at the first outlet to provide protection for the remaining portion of the branch circuit.
> [!important] Exception:
> AFCI protection shall not be required for an individual branch circuit supplying a fire alarm system installed in accordance with 760.41(B) or 760.121(B). The branch circuit shall be installed in a metal raceway, metal auxiliary gutter, steel-armored cable, Type
MC or Type AC, meeting the applicable requirements of 250.118, with metal boxes, conduit bodies, and enclosures.
> [!info] Informational Note No. 1:
> For information on combination-type and branch/feeder-type arc-fault circuit interrupters, see UL 1699-2011,
Standard for Arc-Fault Circuit Interrupters. For information on outlet branch-circuit type arc-fault circuit interrupters, see UL Subject
1699A, Outline of Investigation for Outlet Branch Circuit Arc-Fault Circuit-Interrupters. For information on system combination AFCIs, see UL Subject 1699C, Outline of Investigation for System Combination Arc-Fault Circuit Interrupters.
> [!info] Informational Note No. 2:
> See 29.6.3(5) of NFPA 72-2013, National Fire Alarm and Signaling Code, for information related to secondary power-supply requirements for smoke alarms installed in dwelling units.
> [!info] Informational Note No. 3:
> See 760.41(B) and 760.121(B) for power-supply requirements for fire alarm systems.
#### 210.12(B) Dormitory Units.
All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets and devices installed in dormitory unit bedrooms, living rooms, hallways, closets, bathrooms, and similar rooms shall be protected by any of the means described in 210.12(A)(1) through (6).
210.12(C) Guest Rooms, Guest Suites, and Patient Sleeping Rooms in Nursing Homes and Limited-Care
Facilities.
All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets and devices installed in guest rooms and guest suites of hotels and motels and patient sleeping rooms in nursing homes and limited-care facilities shall be protected by any of the means described in 210.12(A)(1) through (6).
210.12(D) Branch Circuit Extensions or Modifications --- Dwelling Units, Dormitory Units, and Guest
Rooms and Guest Suites.
Where branch circuit wiring for any of the areas specified in 210.12(A), (B), or (C) is modified, replaced, or extended, the branch circuit shall be protected by one of the following:
* (1) By any of the means described in 210.12(A)(1) through (A)(6)
* (2) A listed outlet branch-circuit-type AFCI located at the first receptacle outlet of the existing branch circuit
> [!important] Exception:
> AFCI protection shall not be required where the extension of the existing branch circuit conductors is not more than 1.8 m
(6 ft) and does not include any additional outlets or devices, other than splicing devices. This measurement shall not include the conductors inside an enclosure, cabinet, or junction box.
### 210.13 Ground-Fault Protection of Equipment.
Each branch-circuit disconnect rated 1000 A or more and installed on solidly grounded wye electrical systems of more than 150 volts to ground, but not exceeding 600 volts phase-to-phase, shall be provided with ground-fault protection of equipment in accordance with
230.95.
> [!info] Informational Note:
> For buildings that contain health care occupancies, see the requirements of 517.17.
> [!important] Exception No. 1:
> This section shall not apply to a disconnecting means for a continuous industrial process where a nonorderly shutdown will introduce additional or increased hazards.
> [!important] Exception No. 2:
> This section shall not apply if ground-fault protection of equipment is provided on the supply side of the branch circuit and on the load side of any transformer supplying the branch circuit.
### 210.15 Reconditioned Equipment.
The following shall not be reconditioned:
* (1) Equipment that provides ground-fault circuit-interrupter protection for personnel
* (2) Equipment that provides arc-fault circuit-interrupter protection
* (3) Equipment that provides ground-fault protection of equipment
### 210.17 Guest Rooms and Guest Suites.
Guest rooms and guest suites that are provided with permanent provisions for cooking shall have branch circuits installed to meet the rules for dwelling units.
## Part II. Branch-Circuit Ratings
@@ -110,9 +544,7 @@ shall determine the circuit rating.
> where conditions of maintenance and supervision ensure
> that only qualified persons service the equipment.
### 210.19 Conductors -- Minimum Ampacity and Size.
<!-- TODO: TEXT OMITTED -->
### 210.19 Conductors --- Minimum Ampacity and Size.
#### 210.19(A) Branch Circuits Not More Than 600 Volts.
@@ -137,13 +569,89 @@ for equipment terminations.
or correction factors in accordance with
[[nfpa-70_310_conductors_for_general_wiring#310.15 Ampacity Tables.|310.15]].
> [!important] Exception No. 1 to (1)(a):
> If the assembly, including the overcurrent devices protecting the branch circuit(s), is listed for operation at
100 percent of its rating, the ampacity of the branch-circuit conductors shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load in accordance with 110.14(C).
> [!important] Exception No. 2 to (1)(a) and (1)(b):
> Where a portion of a branch circuit is connected at both its supply and load ends to separately installed pressure connections as covered in 110.14(C)(2), it shall be permitted to have an allowable ampacity, in accordance with 310.15, not less than the sum of the continuous load plus the noncontinuous load. No portion of a branch circuit installed under this exception shall extend into an enclosure containing either the branch-circuit supply or the branch-circuit load terminations.
##### 210.19(A)(2) Branch Circuits with More than One Receptacle.
Conductors of branch circuits supplying more than one receptacle
for cord-and-plug-connected portable loads
shall have an ampacity of not less than the rating of the branch circuit.
<!-- TODO: TEXT OMITTED -->
##### 210.19(A)(3) Household Ranges and Cooking Appliances.
Branch-circuit conductors supplying household ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances shall have an ampacity not less than the rating of the branch circuit and not less than the maximum load to be served. For ranges of 8 3/4 kW or more rating, the minimum branch-circuit rating shall be 40 amperes.
> [!important] Exception No. 1:
> Conductors tapped from a branch circuit not exceeding 50 amperes supplying electric ranges, wall-mounted electric ovens, and counter-mounted electric cooking units shall have an ampacity of not less than 20 amperes and shall be sufficient for the load to be served. These tap conductors include any conductors that are a part of the leads supplied with the appliance that are smaller than the branch-circuit conductors. The taps shall not be longer than necessary for servicing the appliance.
> [!important] Exception No. 2:
> The neutral conductor of a 3-wire branch circuit supplying a household electric range, a wall-mounted oven, or a counter-mounted cooking unit shall be permitted to be smaller than the ungrounded conductors where the maximum demand of a range of 83/4 kW or more rating has been calculated according to Column C of Table 220.55, but such conductor shall have an ampacity of not less than 70 percent of the branch-circuit rating and shall not be smaller than 10 AWG.
##### 210.19(A)(4) Other Loads.
Branch-circuit conductors that supply loads other than those specified in 210.3 and other than cooking appliances as covered in
210.19(A)(3) shall have an ampacity sufficient for the loads served and shall not be smaller than 14 AWG.
> [!important] Exception No. 1:
> Tap conductors shall have an ampacity sufficient for the load served. In addition, they shall have an ampacity of not less than 15 for circuits rated less than 40 amperes and not less than 20 for circuits rated at 40 or 50 amperes and only where these tap conductors supply any of the following loads:
* (1) Individual lampholders or luminaires with taps extending not longer than 450 mm (18 in.) beyond any portion of the lampholder or luminaire
* (2) A luminaire having tap conductors as provided in 410.117
* (3) Individual outlets, other than receptacle outlets, with taps not over 450 mm (18 in.) long
* (4) Infrared lamp industrial heating appliances
* (5) Nonheating leads of deicing and snow-melting cables and mats
> [!important] Exception No. 2:
> Fixture wires and flexible cords shall be permitted to be smaller than 14 AWG as permitted by 240.5.
#### 210.19(B) Branch Circuits Over 600 Volts.
The ampacity of conductors shall be in accordance with 310.14 and 311.60, as applicable. Branch-circuit conductors over 600 volts shall be sized in accordance with 210.19(B)(1) or (B)(2).
##### 210.19(B)(1) General.
The ampacity of branch-circuit conductors shall not be less than 125 percent of the designed potential load of utilization equipment that will be operated simultaneously.
##### 210.19(B)(2) Supervised Installations.
For supervised installations, branch-circuit conductor sizing shall be permitted to be determined by qualified persons under engineering supervision. Supervised installations are defined as those portions of a facility where both of the following conditions are met:
* (1) Conditions of design and installation are provided under engineering supervision.
* (2) Qualified persons with documented training and experience in over 600-volt systems provide maintenance, monitoring, and servicing of the system.
### 210.20 Overcurrent Protection.
Branch-circuit conductors and equipment shall be protected by overcurrent protective devices that have a rating or setting that complies with 210.20(A) through (D).
#### 210.20(A) Continuous and Noncontinuous Loads.
Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the rating of the overcurrent device shall not be less than the noncontinuous load plus 125 percent of the continuous load.
> [!important] Exception:
> Where the assembly, including the overcurrent devices protecting the branch circuit(s), is listed for operation at 100 percent of its rating, the ampere rating of the overcurrent device shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load.
#### 210.20(B) Conductor Protection.
Conductors shall be protected in accordance with 240.4. Flexible cords and fixture wires shall be protected in accordance with 240.5.
#### 210.20(C) Equipment.
The rating or setting of the overcurrent protective device shall not exceed that specified in the applicable articles referenced in Table
240.3 for equipment.
#### 210.20(D) Outlet Devices.
The rating or setting shall not exceed that specified in 210.21 for outlet devices.
### 210.21 Outlet Devices.
@@ -292,7 +800,55 @@ or other utilization equipment.
Branch circuits larger than 50 amperes
shall supply only nonlighting outlet loads.
<!-- TODO: TEXT OMITTED -->
### 210.24 Branch-Circuit Requirements --- Summary.
The requirements for circuits that have two or more outlets or receptacles, other than the receptacle circuits of 210.11(C)(1), (C)(2), and
(C)(3), are summarized in Table 210.24. This table provides only a summary of minimum requirements. See 210.19, 210.20, and
210.21 for the specific requirements applying to branch circuits.
Table 210.24 Summary of Branch-Circuit Requirements
Circuit Rating 15 A 20 A 30 A 40 A 50 A
Conductors (min. size):
Circuit Rating 15 A 20 A 30 A 40 A 50 A
Circuit wires 14 12 10 8 6
Taps 14 14 14 12 12
Fixture wires and cords
--- see 240.5
Overcurrent Protection 15 A 20 A 30 A 40 A 50 A
Outlet devices:
Lampholders permitted Any type Any type Heavy duty Heavy duty Heavy duty
Receptacle rating 15 max. A 15 or 20 A 30 A 40 or 50 A 50 A
Maximum Load 15 A 20 A 30 A 40 A 50 A
Permissible load See 210.23(A) See 210.23(A) See 210.23(B) See 210.23(C) See 210.23(C)
These gauges are for copper conductors.
For receptacle rating of cord-connected electric-discharge luminaires, see 410.62(C).
### 210.25 Branch Circuits in Buildings with More Than One Occupancy.
#### 210.25(A) Dwelling Unit Branch Circuits.
Branch circuits in each dwelling unit shall supply only loads within that dwelling unit or loads associated only with that dwelling unit.
#### 210.25(B) Common Area Branch Circuits.
Branch circuits installed for lighting, central alarm, signal, communications, or other purposes for public or common areas of a twofamily dwelling, a multifamily dwelling, or a multi-occupancy building shall not be supplied from equipment that supplies an individual dwelling unit or tenant space.
> [!info] Informational Note:
> Examples of public or common areas include, but are not limited to, lobbies, corridors, stairways, laundry rooms, roofs, elevators, washrooms, store rooms, driveways (parking), and mechanical rooms.
## Part III. Required Outlets
@@ -301,8 +857,8 @@ shall supply only nonlighting outlet loads.
[[nfpa-70_100_definitions#Receptacle Outlet.|Receptacle outlets]]
shall be installed as specified in 210.52 through 210.65.
Informational Note:
See Informative Annex J for information regarding ADA accessibility design.
> [!info] Informational Note:
> See Informative Annex J for information regarding ADA accessibility design.
#### 210.50(A) Cord Pendants.
@@ -329,14 +885,14 @@ This section provides requirements for 125-volt, 15- and 20-ampere receptacle ou
The receptacles required by this section
shall be in addition to any receptacle that is as follows:
1. Part of a luminaire or appliance, or
* (1) Part of a luminaire or appliance, or
2. Controlled by a listed wall-mounted control device
in accordance with 210.70(A)(1), Exception No. 1, or
* (2) Controlled by a listed wall-mounted control device
in accordance with 210.70(A)(1), Exception No. 1, or
3. Located within cabinets or cupboards, or
* (3) Located within cabinets or cupboards, or
4. Located more than 1.7 m (5 1⁄2 ft) above the floor
* (4) Located more than 1.7 m (5 1/2 ft) above the floor
Permanently installed electric baseboard heaters
equipped with factory-installed receptacle outlets
@@ -345,9 +901,9 @@ shall be permitted as the required outlet or outlets
for the wall space utilized by such permanently installed heaters.
Such receptacle outlets shall not be connected to the heater circuits.
Informational Note:
Listed baseboard heaters include instructions
that may not permit their installation below receptacle outlets.
> [!info] Informational Note:
> Listed baseboard heaters include instructions
> that may not permit their installation below receptacle outlets.
#### 210.52(A) General Provisions.
@@ -369,15 +925,11 @@ is more than 1.8 m (6 ft) from a receptacle outlet.
As used in this section, a wall space shall include the following:
1. Any space 600 mm (2 ft) or more in width
(including space measured around corners)
and unbroken along the floor line by doorways and similar openings,
fireplaces, and fixed cabinets that do not have countertops or similar work surfaces
* (1) Any space 600 mm (2 ft) or more in width (including space measured around corners) and unbroken along the floor line by doorways and similar openings, fireplaces, and fixed cabinets that do not have countertops or similar work surfaces
2. The space occupied by fixed panels in walls, excluding sliding panels
* (2) The space occupied by fixed panels in walls, excluding sliding panels
3. The space afforded by fixed room dividers,
such as freestanding bar-type counters or railings
* (3) The space afforded by fixed room dividers, such as freestanding bar-type counters or railings
##### 210.52(A)(3) Floor Receptacles.
@@ -400,23 +952,27 @@ shall serve all wall and floor receptacle outlets covered by 210.52(A),
all countertop outlets covered by 210.52(C),
and receptacle outlets for refrigeration equipment.
Exception No. 1: In addition to the required receptacles specified by 210.52,
switched receptacles supplied from a general-purpose 15- or 20-ampere branch circuit
as required in 210.70(A)(1), Exception No. 1, shall be permitted.
> [!important] Exception No. 1:
> In addition to the required receptacles specified by 210.52,
> switched receptacles supplied from a general-purpose 15- or 20-ampere branch circuit
> as required in 210.70(A)(1), Exception No. 1, shall be permitted.
Exception No. 2: In addition to the required receptacles specified by 210.52,
a receptacle outlet to serve a specific appliance
shall be permitted to be supplied from an individual branch circuit rated 15 amperes or greater.
> [!important] Exception No. 2:
> In addition to the required receptacles specified by 210.52,
> a receptacle outlet to serve a specific appliance
> shall be permitted to be supplied from an individual branch circuit rated 15 amperes or greater.
##### 210.52(B)(2) No Other Outlets.
The two or more small-appliance branch circuits specified in 210.52(B)(1) shall have no other outlets.
Exception No. 1: A receptacle installed solely for the electrical supply to and support
of an electric clock in any of the rooms specified in 210.52(B)(1).
> [!important] Exception No. 1:
> A receptacle installed solely for the electrical supply to and support
> of an electric clock in any of the rooms specified in 210.52(B)(1).
Exception No. 2: Receptacles installed to provide power for supplemental equipment and lighting
on gas-fired ranges, ovens, or counter-mounted cooking units.
> [!important] Exception No. 2:
> Receptacles installed to provide power for supplemental equipment and lighting
> on gas-fired ranges, ovens, or counter-mounted cooking units.
##### 210.52(B)(3) Kitchen Receptacle Requirements.
@@ -447,12 +1003,10 @@ Receptacle outlets shall be installed
so that no point along the wall line is more than 600 mm (24 in.) measured horizontally
from a receptacle outlet in that space.
Exception:
Receptacle outlets shall not be required directly behind a range,
counter-mounted cooking unit, or sink
in the installation described in Figure 210.52(C)(1).
^210.52(C)(1), Exception
> [!important] Exception: ^52c1-ex
> Receptacle outlets shall not be required directly behind a range,
> counter-mounted cooking unit, or sink
> in the installation described in Figure 210.52(C)(1).
##### Figure 210.52(C)(1) Determination of Area Behind a Range, Counter-Mounted Cooking Unit, or Sink.
@@ -502,14 +1056,14 @@ or rangetops as covered in 210.52(C)(1), Exception,
or appliances occupying assigned spaces
shall not be considered as these required outlets.
Informational Note No. 1:
See 406.5(E) and 406.5(G) for installation of receptacles in countertops
and 406.5(F) and 406.5(G) for installation of receptacles in work surfaces.
See 380.10 for installation of multioutlet assemblies.
> [!info] Informational Note No. 1:
> See 406.5(E) and 406.5(G) for installation of receptacles in countertops
> and 406.5(F) and 406.5(G) for installation of receptacles in work surfaces.
> See 380.10 for installation of multioutlet assemblies.
Informational Note No. 2:
See Annex J and ANSI/ICC A117.1-2009,
Standard on Accessible and Usable Buildings and Facilities.
> [!info] Informational Note No. 2:
> See Annex J and ANSI/ICC A117.1-2009,
> Standard on Accessible and Usable Buildings and Facilities.
#### 210.52(D) Bathrooms.
@@ -524,22 +1078,23 @@ below the top of the basin or basin countertop.
Receptacle outlet assemblies listed for use in countertops
shall be permitted to be installed in the countertop.
Informational Note:
See 406.5(E) and 406.5(G) for requirements for installation of receptacles in countertops.
> [!info] Informational Note:
> See 406.5(E) and 406.5(G) for requirements for installation of receptacles in countertops.
#### 210.52(E) Outdoor Outlets.
Outdoor receptacle outlets
shall be installed in accordance with 210.52(E)(1) through (E)(3).
Informational Note: See 210.8(A)(3).
> [!info] Informational Note:
> See [[#210.8(A)(3) |210.8(A)(3)]].
##### 210.52(E)(1) One-Family and Two-Family Dwellings.
For a one-family dwelling
and each unit of a two-family dwelling that is at grade level,
at least one receptacle outlet readily accessible from grade
and not more than 2.0 m (6 1⁄2 ft) above grade level
and not more than 2.0 m (6 1/2 ft) above grade level
shall be installed at the front and back of the dwelling.
##### 210.52(E)(2) Multifamily Dwellings.
@@ -548,13 +1103,13 @@ For each dwelling unit of a multifamily dwelling
where the dwelling unit is located at grade level
and provided with individual exterior entrance/egress,
at least one receptacle outlet readily accessible from grade
and not more than 2.0 m (6 1⁄2 ft) above grade level shall be installed.
and not more than 2.0 m (6 1/2 ft) above grade level shall be installed.
##### 210.52(E)(3) Balconies, Decks, and Porches.
Balconies, decks, and porches that are within 102 mm (4 in.) horizontally of the dwelling unit
shall have at least one receptacle outlet accessible from the balcony, deck, or porch.
The receptacle outlet shall not be located more than 2.0 m (6 1⁄2 ft)
The receptacle outlet shall not be located more than 2.0 m (6 1/2 ft)
above the balcony, deck, or porch walking surface.
#### 210.52(F) Laundry Areas.
@@ -562,16 +1117,16 @@ above the balcony, deck, or porch walking surface.
In dwelling units, at least one receptacle outlet
shall be installed in areas designated for the installation of laundry equipment.
Exception No. 1:
A receptacle for laundry equipment
shall not be required in a dwelling unit of a multifamily building
where laundry facilities are provided on the premises
for use by all building occupants.
> [!important] Exception No. 1:
> A receptacle for laundry equipment
> shall not be required in a dwelling unit of a multifamily building
> where laundry facilities are provided on the premises
> for use by all building occupants.
Exception No. 2:
A receptacle for laundry equipment
shall not be required in other than one-family dwellings
where laundry facilities are not to be installed or permitted.
> [!important] Exception No. 2:
> A receptacle for laundry equipment
> shall not be required in other than one-family dwellings
> where laundry facilities are not to be installed or permitted.
#### 210.52(G) Basements, Garages, and Accessory Buildings.
@@ -584,11 +1139,11 @@ These receptacles shall be in addition to receptacles required for specific equi
In each attached garage and in each detached garage with electric power,
at least one receptacle outlet shall be installed in each vehicle bay
and not more than 1.7 m (5 1⁄2 ft) above the floor.
and not more than 1.7 m (5 1/2 ft) above the floor.
Exception:
Garage spaces not attached to an individual dwelling unit of a multifamily dwelling
shall not require a receptacle outlet in each vehicle bay.
> [!important] Exception:
> Garage spaces not attached to an individual dwelling unit of a multifamily dwelling
> shall not require a receptacle outlet in each vehicle bay.
##### 210.52(G)(2) Accessory Buildings.
@@ -674,3 +1229,86 @@ requires dedicated equipment space as specified in [[nfpa-70_110_requirements-fo
the required receptacle outlet shall be located
within the same room or area as the electrical equipment
and shall not be connected to the load side of the equipment's branch-circuit disconnecting means.
### 210.65 Meeting Rooms.
#### 210.65(A) General.
Each meeting room of not more than 93 m (1000 ft ) in other than dwelling units shall have outlets for nonlocking-type, 125-volt, 15- or 20-ampere receptacles. The outlets shall be installed in accordance with 210.65(B). Where a room or space is provided with movable partition(s), each room size shall be determined with the partition in the position that results in the smallest size meeting room.
> [!info] Informational Note No. 1:
> For the purposes of this section, meeting rooms are typically designed or intended for the gathering of seated occupants for such purposes as conferences, deliberations, or similar purposes, where portable electronic equipment such as computers, projectors, or similar equipment is likely to be used.
> [!info] Informational Note No. 2:
> Examples of rooms that are not meeting rooms include auditoriums, schoolrooms, and coffee shops.
#### 210.65(B) Receptacle Outlets Required.
The total number of receptacle outlets, including floor outlets and receptacle outlets in fixed furniture, shall not be less than as determined in (1) and (2).
##### 210.65(B)(1) Receptacle Outlets in Fixed Walls.
The required number of receptacle outlets shall be determined in accordance with 210.52(A)(1) through (A)(4). These receptacle outlets shall be permitted to be located as determined by the installer, designer, or building owner.
##### 210.65(B)(2) Floor Outlets.
A meeting room with any floor dimension that is 3.7 m (12 ft) or greater in any direction and that has a floor area of at least 20 m
(215 ft ) shall have at least one floor receptacle outlet, or at least one floor outlet to serve receptacle(s), located at a distance not less than 1.8 m (6 ft) from any fixed wall for each 20 m (215 ft ) or major portion of floor space.
> [!info] Informational Note No. 1:
> See 314.27(B) for floor boxes used for receptacles located in the floor.
> [!info] Informational Note No. 2:
> See Article 518 for assembly occupancies designed for 100 or more persons.
### 210.70 Lighting Outlets Required.
Lighting outlets shall be installed where specified in 210.70(A), (B), and (C).
#### 210.70(A) Dwelling Units.
In dwelling units, lighting outlets shall be installed in accordance with 210.70(A)(1), (A)(2), and (A)(3).
##### 210.70(A)(1) Habitable Rooms.
At least one lighting outlet controlled by a listed wall-mounted control device shall be installed in every habitable room, kitchen, and bathroom. The wall-mounted control device shall be located near an entrance to the room on a wall.
> [!important] Exception No. 1:
> In other than kitchens and bathrooms, one or more receptacles controlled by a listed wall-mounted control device shall be permitted in lieu of lighting outlets.
> [!important] Exception No. 2:
> Lighting outlets shall be permitted to be controlled by occupancy sensors that are (1) in addition to listed wall-mounted control devices or (2) located at a customary wall switch location and equipped with a manual override that will allow the sensor to function as a wall switch.
##### 210.70(A)(2) Additional Locations.
Additional lighting outlets shall be installed in accordance with the following:
* (1) At least one lighting outlet controlled by a listed wall-mounted control device shall be installed in hallways, stairways, attached garages, and detached garages with electric power.
* (2) For dwelling units, attached garages, and detached garages with electric power, at least one lighting outlet controlled by a listed wall-mounted control device shall be installed to provide illumination on the exterior side of outdoor entrances or exits with grade-level access. A vehicle door in a garage shall not be considered as an outdoor entrance or exit.
2 2
2
2
2 2
* (3) Where one or more lighting outlet(s) are installed for interior stairways, there shall be a listed wall-mounted control device at each floor level and landing level that includes an entryway to control the lighting outlet(s) where the stairway between floor levels has six risers or more.
Exception to (A)(2)(1), (A)(2)(2), and (A)(2)(3): In hallways, in stairways, and at outdoor entrances, remote, central, or automatic control of lighting shall be permitted.
* (4) Lighting outlets controlled in accordance with 210.70(A)(2)(3) shall not be controlled by use of listed wall-mounted control devices unless they provide the full range of dimming control at each location.
#### 210.70(B) Guest Rooms or Guest Suites.
In hotels, motels, or similar occupancies, guest rooms or guest suites shall have at least one lighting outlet controlled by a listed wallmounted control device installed in every habitable room and bathroom.
> [!important] Exception No. 1:
> In other than bathrooms and kitchens where provided, one or more receptacles controlled by a listed wall-mounted control device shall be permitted in lieu of lighting outlets.
> [!important] Exception No. 2:
> Lighting outlets shall be permitted to be controlled by occupancy sensors that are (1) in addition to listed wall-mounted control devices or (2) located at a customary wall switch location and equipped with a manual override that allows the sensor to function as a wall switch.
#### 210.70(C) All Occupancies.
For attics and underfloor spaces, utility rooms, and basements, at least one lighting outlet containing a switch or controlled by a wall switch or listed wall-mounted control device shall be installed where these spaces are used for storage or contain equipment requiring servicing. A point of control shall be at each entry that permits access to the attic and underfloor space, utility room, or basement.
Where a lighting outlet is installed for equipment requiring service, the lighting outlet shall be installed at or near the equipment.
nfpa-70_220_load-calculations.md
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@@ -24,30 +24,138 @@ Part II provides calculation methods for branch-circuit loads.
Parts III and IV provide calculation methods for feeder and service loads.
Part V provides calculation methods for farm loads.
Informational Note No. 1:
See examples in Informative Annex D.
> [!info] Informational Note No. 1:
> See examples in Informative Annex D.
Informational Note No. 2:
See Figure 220.1 for information on the organization of Article 220.
> [!info] Informational Note No. 2:
> See Figure 220.1 for information on the organization of Article 220.
### Figure 220.1 Branch-Circuit, Feeder, and Service Load Calculation Methods.
<!-- TODO: FIGURE OMITTED -->
<!-- TODO: TEXT OMITTED -->
### 220.3 Other Articles for Specific-Purpose Calculations.
### 220.14 Other Loads -- All Occupancies.
Table 220.3 shall provide references for specific-purpose calculation requirements not located in Chapters 5, 6, or 7 that amend or supplement the requirements of this article.
Table 220.3 Specific-Purpose Calculation References
| Calculation | Article | Section (or Part) |
| --------------------------------------------------------------------------------- | ------- | ----------------- |
| Air-conditioning and refrigerating equipment, branch-circuit conductor sizing | 440 | Part IV |
| Fixed electric heating equipment for pipelines and vessels, branch-circuit sizing | 427 | 427.4 |
| Fixed electric space-heating equipment, branch-circuit sizing | 424 | 424.3 |
| Fixed outdoor electric deicing and snow-melting equipment, branch-circuit sizing | 426 | 426.4 |
| Motors, feeder demand factor | 430 | 430.26 |
| Motors, multimotor and combination-load equipment | 430 | 430.25 |
| Motors, several motors or a motor(s) and other load(s) | 430 | 430.24 |
| Over 600-volt branch-circuit calculations | 210 | 210.19(B) |
| Over 600-volt feeder calculations | 215 | 215.2(B) |
| Phase converters, conductors | 455 | 455.6 |
| Storage-type water heaters | 422 | 422.11(E) |
### 220.5 Calculations.
#### 220.5(A) Voltages.
Unless other voltages are specified, for purposes of calculating branch-circuit and feeder loads, nominal system voltages of 120, 120/240, 208Y/120, 240, 347, 480Y/277, 480, 600Y/347, and 600 volts shall be used.
#### 220.5(B) Fractions of an Ampere.
Calculations shall be permitted to be rounded to the nearest whole ampere, with decimal fractions smaller than 0.5 dropped.
## Part II. Branch-Circuit Load Calculations
### 220.10 General.
Branch-circuit loads shall be calculated as shown in 220.12, 220.14, and 220.16.
### 220.11 Floor Area.
The floor area for each floor shall be calculated from the outside dimensions of the building, dwelling unit, or other area involved. For dwelling units, the calculated floor area shall not include open porches, garages, or unused or unfinished spaces not adaptable for future use.
### 220.12 Lighting Load for Non-Dwelling Occupancies.
#### 220.12(A) General.
A unit load of not less than that specified in Table 220.12 for non-dwelling occupancies and the floor area determined in 220.11 shall be used to calculate the minimum lighting load. Motors rated less than 1/8 HP and connected to a lighting circuit shall be considered general lighting load.
> [!info] Informational Note:
> The unit values of Table 220.12 are based on minimum load conditions and 100 percent power factor and may not provide sufficient capacity for the installation contemplated.
#### 220.12(B) Energy Code.
Where the building is designed and constructed to comply with an energy code adopted by the local authority, the lighting load shall be permitted to be calculated using the unit values specified in the energy code where the following conditions are met:
* (1) A power monitoring system is installed that will provide continuous information regarding the total general lighting load of the building.
* (2) The power monitoring system will be set with alarm values to alert the building owner or manager if the lighting load exceeds the values set by the energy code. Automatic means to take action to reduce the connected load shall be permitted.
* (3) The demand factors specified in 220.42 are not applied to the general lighting load.
* (4) The continuous load multiplier of 125 percent shall be applied.
Table 220.12 General Lighting Loads by Non-Dwelling Occupancy
| Type of Occupancy | Volt-amperes/m<sup>2</sup> | Volt-amperes/ft<sup>2</sup> |
| --------------------------------------------------------------------------------------------------- | -------------------------- | --------------------------- |
| Automotive facility | 16 | 1.5 |
| Convention center | 15 | 1.4 |
| Courthouse | 15 | 1.4 |
| Dormitory | 16 | 1.5 |
| Exercise center | 15 | 1.4 |
| Fire station | 14 | 1.3 |
| Gymnasium<sup>a</sup> | 18 | 1.7 |
| Health care clinic | 17 | 1.6 |
| Hospital | 17 | 1.6 |
| Hotels and motels, including apartment houses without provisions for cooking by tenants<sup>b</sup> | 18 | 1.7 |
| Library | 16 | 1.5 |
| Manufacturing facility<sup>c</sup> | 24 | 2.2 |
| Motion picture theater | 17 | 1.6 |
| Museum | 17 | 1.6 |
| Office<sup>d</sup> | 14 | 1.3 |
| Parking garage<sup>e</sup> | 3 | 0.3 |
| Penitentiary | 13 | 1.2 |
| Performing arts theater | 16 | 1.5 |
| Police station | 14 | 1.3 |
| Post office | 17 | 1.6 |
| Religious facility | 24 | 2.2 |
| Restaurant<sup>f</sup> | 16 | 1.5 |
| Retail<sup>g,h</sup> | 20 | 1.9 |
| School/university | 33 | 3 |
| Sports arena | 33 | 3 |
| Town hall | 15 | 1.4 |
| Transportation | 13 | 1.2 |
| Warehouse | 13 | 1.2 |
| Workshop | 18 | 1.7 |
Note: The 125 percent multiplier for a continuous load as specified in 210.20(A) is included when using the unit loads in this table for calculating the minimum lighting load for a specified occupancy.
<sup>a</sup>Armories and auditoriums are considered gymnasium-type occupancies.
<sup>b</sup>Lodge rooms are similar to hotels and motels.
<sup>c</sup>Industrial commercial loft buildings are considered manufacturing-type occupancies.
<sup>d</sup>Banks are office-type occupancies.
<sup>e</sup>Garages --- commercial (storage) are considered parking garage occupancies.
<sup>f</sup>Clubs are considered restaurant occupancies.
<sup>g</sup>Barber shops and beauty parlors are considered retail occupancies.
<sup>h</sup>Stores are considered retail occupancies.
### 220.14 Other Loads --- All Occupancies.
In all occupancies, the minimum load for each outlet
for general-use receptacles and outlets not used for general illumination
shall not be less than that calculated in 220.14(A) through (M),
the loads shown being based on nominal branch-circuit voltages.
Exception:
The loads of outlets serving switchboards and switching frames in telephone exchanges
shall be waived from the calculations.
<!-- TODO: TEXT OMITTED -->
> [!important] Exception:
> The loads of outlets serving switchboards and switching frames in telephone exchanges shall be waived from the calculations.
#### 220.14(A) Specific Appliances or Loads.
@@ -125,13 +233,13 @@ and [[nfpa-70_210_branch-circuits#210.11(C)(2) Laundry Branch Circuits.|(C)(2)]]
#### 220.14(J) Dwelling Units.
In one-family, two-family, and multifamily dwellings,
the minimum unit load shall be not less than 33 volt-amperes/m$^2$ (3 volt-amperes/ft$^2$).
the minimum unit load shall be not less than 33 volt-amperes/m<sup>2</sup> (3 volt-amperes/ft<sup>2</sup>).
The lighting and receptacle outlets specified in 220.14(J)(1), (J)(2), and (J)(3)
are included in the minimum unit load.
No additional load calculations shall be required for such outlets.
The minimum lighting load shall be determined using the minimum unit load
and the floor area as determined in 220.11 for dwelling occupancies.
Motors rated less than 1⁄8 hp and connected to a lighting circuit
Motors rated less than 1/8 hp and connected to a lighting circuit
shall be considered part of the minimum lighting load.
* (1) All general-use receptacle outlets of 20-ampere rating or less,
@@ -146,11 +254,533 @@ shall be calculated to be the larger of (1) or (2):
* (1) The calculated load from 220.14(I)
after all demand factors have been applied
* (2) 11 volt-amperes/m$^2$ or 1 volt-ampere/ft$^2$
* (2) 11 volt-amperes/m<sup>2</sup> or 1 volt-ampere/ft<sup>2</sup>
#### 220.14(L) Other Outlets.
Other outlets not covered in 220.14(A) through (K)
shall be calculated based on 180 volt-amperes per outlet.
<!-- TODO: TEXT OMITTED -->
#### 220.14(M) Hotel and Motel Occupancies.
In guest rooms or guest suites of hotels and motels, the lighting and receptacle outlets specified in 220.14(M)(1), (M)(2), and (M)(3) are included in the minimum unit load in Table 220.12. No additional load calculations shall be required for such outlets. The minimum lighting load shall be determined using the minimum unit load and the floor area as determined in 220.11 for hotel and motel occupancies.
* (1) All general-use receptacle outlets of 20-ampere rating or less, including receptacles connected to the circuits in 210.11(C)(3) and 210.11(C)(4)
* (2) The receptacle outlets specified in 210.52(E)(3)
* (3) The lighting outlets specified in 210.70
### 220.16 Loads for Additions to Existing Installations.
#### 220.16(A) Dwelling Units.
Loads added to an existing dwelling unit(s) shall comply with the following as applicable:
* (1) Loads for structural additions to an existing dwelling unit or for a previously unwired portion of an existing dwelling unit shall be calculated in accordance with 220.14.
* (2) Loads for new circuits or extended circuits in previously wired dwelling units shall be calculated in accordance with 220.14.
#### 220.16(B) Other Than Dwelling Units.
Loads for new circuits or extended circuits in other than dwelling units shall be calculated in accordance with either 220.12 or 220.14, as applicable.
### 220.18 Maximum Loads.
The total load shall not exceed the rating of the branch circuit, and it shall not exceed the maximum loads specified in 220.18(A) through (C) under the conditions specified therein.
#### 220.18(A) Motor-Operated and Combination Loads.
Where a circuit supplies only motor-operated loads, Article 430 shall apply. Where a circuit supplies only air-conditioning equipment, refrigerating equipment, or both, Article 440 shall apply. For circuits supplying loads consisting of motor-operated utilization equipment that is fastened in place and has a motor larger than 1/8 hp in combination with other loads, the total calculated load shall be based on 125 percent of the largest motor load plus the sum of the other loads.
#### 220.18(B) Inductive and LED Lighting Loads.
For circuits supplying lighting units that have ballasts, transformers, autotransformers, or LED drivers, the calculated load shall be based on the total ampere ratings of such units and not on the total watts of the lamps.
#### 220.18(C) Range Loads.
It shall be permissible to apply demand factors for range loads in accordance with Table 220.55, including Note 4.
## Part III. Feeder and Service Load Calculations
### 220.40 General.
The calculated load of a feeder or service shall not be less than the sum of the loads on the branch circuits supplied, as determined by Part II of this article, after any applicable demand factors permitted by Part III or IV or required by Part V have been applied.
> [!info] Informational Note:
> See Examples D1(a) through D10 in Informative Annex D. See 220.18(B) for the maximum load in amperes permitted for lighting units operating at less than 100 percent power factor.
### 220.42 General Lighting.
The demand factors specified in Table 220.42 shall apply to that portion of the total branch-circuit load calculated for general illumination. They shall not be applied in determining the number of branch circuits for general illumination.
#### Table 220.42 Lighting Load Demand Factors
| Type of Occupancy | Portion of Lighting Load to Which Demand Factor Applies (Volt-Amperes) | Demand Factor (%) |
| --------------------------------------------------------------------------------------- | ---------------------------------------------------------------------- | ----------------- |
| Dwelling units | First 3000 at | 100 |
| ... | From 3001 to 120,000 at | 35 |
| ... | Remainder over 120,000 at | 25 |
| Hotels and motels, including apartment houses without provision for cooking by tenants* | First 20,000 or less at | 60 |
| ... | From 20,001 to 100,000 at | 50 |
| ... | Remainder over 100,000 at | 35 |
| Warehouses (storage) | First 12,500 or less at | 100 |
| ... | Remainder over 12,500 at | 50 |
| All others | Total volt-amperes | 100 |
\*The demand factors of this table shall not apply to the calculated load of feeders or services supplying areas in hotels and motels where the entire lighting is likely to be used at one time, as in ballrooms or dining rooms.
### 220.43 Show-Window and Track Lighting.
#### 220.43(A) Show Windows.
For show-window lighting, a load of not less than 660 volt-amperes/linear meter or 200 volt-amperes/linear foot shall be included for a show window, measured horizontally along its base.
> [!info] Informational Note:
> See 220.14(G) for branch circuits supplying show windows.
#### 220.43(B) Track Lighting.
For track lighting in other than dwelling units or guest rooms or guest suites of hotels or motels, an additional load of 150 volt-amperes shall be included for every 600 mm (2 ft) of lighting track or fraction thereof. Where multicircuit track is installed, the load shall be considered to be divided equally between the track circuits.
> [!important] Exception:
> If the track lighting is supplied through a device that limits the current to the track, the load shall be permitted to be calculated based on the rating of the device used to limit the current.
### 220.44 Receptacle Loads --- Other Than Dwelling Units.
Receptacle loads calculated in accordance with 220.14(H) and (I) shall be permitted to be made subject to the demand factors given in Table 220.42 or Table 220.44.
#### Table 220.44 Demand Factors for Non-Dwelling Receptacle Loads
| Portion of Receptacle Load to Which Demand Factor Applies (Volt-Amperes) | Demand Factor (%) |
| ------------------------------------------------------------------------ | ----------------- |
| First 10 kVA or less at | 100 |
| Remainder over 10 kVA at | 50 |
### 220.50 Motors.
Motor loads shall be calculated in accordance with 430.24, 430.25, and 430.26 and with 440.6 for hermetic refrigerant motor-compressors.
### 220.51 Fixed Electric Space Heating.
Fixed electric space-heating loads shall be calculated at 100 percent of the total connected load. However, in no case shall a feeder or service load current rating be less than the rating of the largest branch circuit supplied.
> [!important] Exception:
> Where reduced loading of the conductors results from units operating on duty-cycle, intermittently, or from all units not operating at the same time, the authority having jurisdiction may grant permission for feeder and service conductors to have an ampacity less than 100 percent, provided the conductors have an ampacity for the load so determined.
### 220.52 Small-Appliance and Laundry Loads --- Dwelling Unit.
#### 220.52(A) Small-Appliance Circuit Load.
In each dwelling unit, the load shall be calculated at 1500 volt-amperes for each 2-wire small-appliance branch circuit as covered by 210.11(C)(1). Where the load is subdivided through two or more feeders, the calculated load for each shall include not less than 1500 volt-amperes for each 2-wire small-appliance branch circuit. These loads shall be permitted to be included with the general lighting load and subjected to the demand factors provided in Table 220.42.
> [!important] Exception:
> The individual branch circuit permitted by 210.52(B)(1), Exception No. 2, shall be permitted to be excluded from the calculation required by 220.52.
#### 220.52(B) Laundry Circuit Load.
A load of not less than 1500 volt-amperes shall be included for each 2-wire laundry branch circuit installed as covered by 210.11(C)(2).
This load shall be permitted to be included with the general lighting load and shall be subjected to the demand factors provided in Table 220.42.
### 220.53 Appliance Load --- Dwelling Unit(s).
It shall be permissible to apply a demand factor of 75 percent to the nameplate rating load of four or more appliances rated 1/4 hp or greater, or 500 watts or greater, that are fastened in place, and that are served by the same feeder or service in a one-family, two-family, or multifamily dwelling. This demand factor shall not apply to:
* (1) Household electric cooking equipment that is fastened in place
* (2) Clothes dryers
* (3) Space heating equipment
* (4) Air-conditioning equipment
### 220.54 Electric Clothes Dryers --- Dwelling Unit(s).
The load for household electric clothes dryers in a dwelling unit(s) shall be either 5000 watts (volt-amperes) or the nameplate rating, whichever is larger, for each dryer served. The use of the demand factors in Table 220.54 shall be permitted. Where two or more single-phase dryers are supplied by a 3-phase, 4-wire feeder or service, the total load shall be calculated on the basis of twice the maximum number connected between any two phases. Kilovolt-amperes (kVA) shall be considered equivalent to kilowatts (kW) for loads calculated in this section.
#### Table 220.54 Demand Factors for Household Electric Clothes Dryers
| Number of Dryers | Demand Factor (%) |
| ---------------- | ------------------------------------------ |
| 1--4 | 100 |
| 5 | 85 |
| 6 | 75 |
| 7 | 65 |
| 8 | 60 |
| 9 | 55 |
| 10 | 50 |
| 11 | 47 |
| 12--23 | 47% minus 1% for each dryer exceeding 11 |
| 24--42 | 35% minus 0.5% for each dryer exceeding 23 |
| 43 and over | 25% |
The load for household electric ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances individually rated in excess of 13/4 kW shall be permitted to be calculated in accordance with Table 220.55. Kilovolt-amperes (kVA) shall be considered equivalent to kilowatts (kW) for loads calculated under this section.
Where two or more single-phase ranges are supplied by a 3- phase, 4-wire feeder or service, the total load shall be calculated on the basis of twice the maximum number connected between any two phases.
#### Table 220.55 Demand Factors and Loads for Household Electric Ranges, Wall-Mounted Ovens, Counter-Mounted Cooking Units, and Other Household Cooking Appliances over 1 3/4 kW Rating (Column C to be used in all cases except as otherwise permitted in Note 3.)
| Number of Appliances | Demand Factor (%), Column A (Less than 3 1/2 kW Rating) | Demand Factor (%), Column B (3 1/2 kW through 8 3/4 kW Rating) | Column C Maximum Demand (kW) (Not over 12 kW Rating) |
|:--------------------:| -------------------------------------------------------:| --------------------------------------------------------------:| ---------------------------------------------------- |
| 1 | 80 | 80 | 8 |
| 2 | 75 | 65 | 11 |
| 3 | 70 | 55 | 14 |
| 4 | 66 | 50 | 17 |
| 5 | 62 | 45 | 20 |
| 6 | 59 | 43 | 21 |
| 7 | 56 | 40 | 22 |
| 8 | 53 | 36 | 23 |
| 9 | 51 | 35 | 24 |
| 10 | 49 | 34 | 25 |
| 11 | 47 | 32 | 26 |
| 12 | 45 | 32 | 27 |
| 13 | 43 | 32 | 28 |
| 14 | 41 | 32 | 29 |
| 15 | 40 | 32 | 30 |
| 16 | 39 | 28 | 31 |
| 17 | 38 | 28 | 32 |
| 18 | 37 | 28 | 33 |
| 19 | 36 | 28 | 34 |
| 20 | 35 | 28 | 35 |
| 21 | 34 | 26 | 36 |
| 22 | 33 | 26 | 37 |
| 23 | 32 | 26 | 38 |
| 24 | 31 | 26 | 39 |
| 25 | 30 | 26 | 40 |
| 26--30 | 30 | 24 | 15 kW + 1 kW for each range |
| 31--40 | 30 | 22 | |
| 41--50 | 30 | 20 | 25 kW + 3/4 kW for each range |
| 51--60 | 30 | 18 | |
| 61 and over | 30 | 16 | |
Notes:
1. Over 12 kW through 27 kW ranges all of same rating. For ranges individually rated more than 12 kW but not more than 27 kW, the maximum demand in Column C shall be increased 5 percent for each additional kilowatt of rating or major fraction thereof by which the rating of individual ranges exceeds 12 kW.
2. Over 83/4 kW through 27 kW ranges of unequal ratings. For ranges individually rated more than 83/4 kW and of different ratings, but none exceeding 27 kW, an average value of rating shall be calculated by adding together the ratings of all ranges to obtain the total connected load (using 12 kW for any range rated less than 12 kW) and dividing by the total number of ranges. Then the maximum demand in Column C shall be increased 5 percent for each kilowatt or major fraction thereof by which this average value exceeds 12 kW.
3. Over 13/4 kW through 83/4 kW. In lieu of the method provided in Column C, it shall be permissible to add the nameplate ratings of all household cooking appliances rated more than 13/4 kW but not more than 83/4 kW and multiply the sum by the demand factors specified in Column A or Column B for the given number of appliances. Where the rating of cooking appliances falls under both Column A and Column B, the demand factors for each column shall be applied to the appliances for that column, and the results added together.
4. Branch-Circuit Load. It shall be permissible to calculate the branch-circuit load for one range in accordance with Table 220.55. The branch-circuit load for one wall-mounted oven or one counter-mounted cooking unit shall be the nameplate rating of the appliance. The branch-circuit load for a counter-mounted cooking unit and not more than two wall-mounted ovens, all supplied from a single branch circuit and located in the same room, shall be calculated by adding the nameplate rating of the individual appliances and treating this total as equivalent to one range.
5. This table shall also apply to household cooking appliances rated over 1 3/4 kW and used in instructional programs.
> [!info] Informational Note No. 1:
> See the examples in Informative Annex D.
> [!info] Informational Note No. 2:
> See Table 220.56 for commercial cooking equipment.
### 220.56 Kitchen Equipment --- Other Than Dwelling Unit(s).
It shall be permissible to calculate the load for commercial electric cooking equipment, dishwasher booster heaters, water heaters, and other kitchen equipment in accordance with Table 220.56. These demand factors shall be applied to all equipment that has either thermostatic control or intermittent use as kitchen equipment. These demand factors shall not apply to space-heating, ventilating, or air-conditioning equipment.
However, in no case shall the feeder or service calculated load be less than the sum of the largest two kitchen equipment loads.
#### Table 220.56 Demand Factors for Kitchen Equipment --- Other Than Dwelling Unit(s)
| Number of Units of Equipment | Demand Factor (%) |
| ---------------------------- | -----------------:|
| 1 | 100 |
| 2 | 100 |
| 3 | 90 |
| 4 | 80 |
| 5 | 70 |
| 6 and over | 65 |
### 220.60 Noncoincident Loads.
Where it is unlikely that two or more noncoincident loads will be in use simultaneously, it shall be permissible to use only the largest load(s) that will be used at one time for calculating the total load of a feeder or service. Where a motor is part of the noncoincident load and is not the largest of the noncoincident loads, 125 percent of the motor load shall be used in the calculation if it is the largest motor.
### 220.61 Feeder or Service Neutral Load.
#### 220.61(A) Basic Calculation.
The feeder or service neutral load shall be the maximum unbalance of the load determined by this article. The maximum unbalanced load shall be the maximum net calculated load between the neutral conductor and any one ungrounded conductor.
> [!important] Exception:
> For 3-wire, 2-phase or 5-wire, 2-phase systems, the maximum unbalanced load shall be the maximum net calculated load between the neutral conductor and any one ungrounded conductor multiplied by 140 percent.
#### 220.61(B) Permitted Reductions.
A service or feeder supplying the following loads shall be permitted to have an additional demand factor of 70 percent applied to the amount in 220.61(B)(1) or portion of the amount in 220.61(B)(2) determined by the following basic calculations:
* (1) A feeder or service supplying household electric ranges, wall-mounted ovens, counter-mounted cooking units, and electric dryers, where the maximum unbalanced load has been determined in accordance with Table 220.55 for ranges and Table 220.54 for dryers
* (2) That portion of the unbalanced load in excess of 200 amperes where the feeder or service is supplied from a 3-wire dc or single-phase ac system; or a 4-wire, 3-phase system; or a 3-wire, 2-phase system; or a 5-wire, 2-phase system
> [!info] Informational Note:
> See Examples D1(a), D1(b), D2(b), D4(a), and D5(a) in Informative Annex D.
#### 220.61(C) Prohibited Reductions.
There shall be no reduction of the neutral or grounded conductor capacity applied to the amount in 220.61(C)(1), or portion of the amount in (C)(2), from that determined by the basic calculation:
* (1) Any portion of a 3-wire circuit consisting of 2 ungrounded conductors and the neutral conductor of a 4-wire, 3-phase, wye-connected system
* (2) That portion consisting of nonlinear loads supplied from a 4-wire, wye-connected, 3-phase system
> [!info] Informational Note:
> A 3-phase, 4-wire, wye-connected power system used to supply power to nonlinear loads may necessitate that the power system design allow for the possibility of high harmonic neutral conductor currents.
## Part IV. Optional Feeder and Service Load Calculations
### 220.80 General.
Optional feeder and service load calculations shall be permitted in accordance with Part IV.
### 220.82 Dwelling Unit.
#### 220.82(A) Feeder and Service Load.
This section applies to a dwelling unit having the total connected load served by a single 120/240-volt or 208Y/120-volt set of 3-wire service or feeder conductors with an ampacity of 100 or greater. It shall be permissible to calculate the feeder and service loads in accordance with this section instead of the method specified in Part III of this article. The calculated load shall be the result of adding the loads from 220.82(B) and (C). Feeder and service-entrance conductors whose calculated load is determined by this optional calculation shall be permitted to have the neutral load determined by 220.61.
#### 220.82(B) General Loads.
The general calculated load shall be not less than 100 percent of the first 10 kVA plus 40 percent of the remainder of the following loads:
* (1) 33 volt-amperes/m or 3 volt-amperes/ft for general lighting and general-use receptacles. The floor area for each floor shall be calculated from the outside dimensions of the dwelling unit. The calculated floor area shall not include open porches, garages, or unused or unfinished spaces not adaptable for future use.
* (2) 1500 volt-amperes for each 2-wire, 20-ampere small-appliance branch circuit and each laundry branch circuit covered in 210.11(C)(1) and (C)(2).
* (3) The nameplate rating of the following:
* a. All appliances that are fastened in place, permanently connected, or located to be on a specific circuit
* b. Ranges, wall-mounted ovens, counter-mounted cooking units
* c. Clothes dryers that are not connected to the laundry branch circuit specified in item (2)
* d. Water heaters
* (4) The nameplate ampere or kVA rating of all permanently connected motors not included in item (3).
#### 220.82(C) Heating and Air-Conditioning Load.
The largest of the following six selections (load in kVA) shall be included:
* (1) 100 percent of the nameplate rating(s) of the air conditioning and cooling.
* (2) 100 percent of the nameplate rating(s) of the heat pump when the heat pump is used without any supplemental electric heating.
* (3) 100 percent of the nameplate rating(s) of the heat pump compressor and 65 percent of the supplemental electric heating for central electric space-heating systems. If the heat pump compressor is prevented from operating at the same time as the supplementary heat, it does not need to be added to the supplementary heat for the total central space heating load.
* (4) 65 percent of the nameplate rating(s) of electric space heating if less than four separately controlled units.
* (5) 40 percent of the nameplate rating(s) of electric space heating if four or more separately controlled units.
* (6) 100 percent of the nameplate ratings of electric thermal storage and other heating systems where the usual load is expected to be continuous at the full nameplate value. Systems qualifying under this selection shall not be calculated under any other selection in 220.82(C).
### 220.83 Existing Dwelling Unit.
This section shall be permitted to be used to determine if the existing service or feeder is of sufficient capacity to serve additional loads.
Where the dwelling unit is served by a 120/240-volt or 208Y/120-volt, 3-wire service, it shall be permissible to calculate the total load in accordance with 220.83(A) or (B).
### 220.83(A) Where Additional Air-Conditioning Equipment or Electric Space-Heating Equipment Is Not to Be Installed.
The following percentages shall be used for existing and additional new loads.
| Load (kVA) | Percent of Load |
| ---------------------- | ---------------:|
| First 8 kVA of load at | 100 |
| Remainder of load at | 40 |
Load calculations shall include the following:
* (1) General lighting and general-use receptacles at 33 volt-amperes/m or 3 volt-amperes/ft as determined by 220.12
* (2) 1500 volt-amperes for each 2-wire, 20-ampere small-appliance branch circuit and each laundry branch circuit covered in 210.11(C)(1) and (C)(2)
* (3) The nameplate rating of the following:
* a. All appliances that are fastened in place, permanently connected, or located to be on a specific circuit
* b. Ranges, wall-mounted ovens, counter-mounted cooking units
* c. Clothes dryers that are not connected to the laundry branch circuit specified in item (2)
* d. Water heaters
### 220.83(B) Where Additional Air-Conditioning Equipment or Electric Space-Heating Equipment Is to Be Installed.
The following percentages shall be used for existing and additional new loads. The larger connected load of air conditioning or space heating, but not both, shall be used.
| Load | Percent of Load |
| -------------------------------------------------------- | ---------------:|
| Air-conditioning equipment | 100 |
| Central electric space heating | 100 |
| Less than four separately controlled space-heating units | 100 |
| First 8 kVA of all other loads | 100 |
| Remainder of all other loads | 40 |
Other loads shall include the following:
* (1) General lighting and general-use receptacles at 33 volt-amperes/m or 3 volt-amperes/ft as determined by 220.12
* (2) 1500 volt-amperes for each 2-wire, 20-ampere small-appliance branch circuit and each laundry branch circuit covered in 210.11(C)(1) and (C)(2)
* (3) The nameplate rating of the following:
* a. All appliances that are fastened in place, permanently connected, or located to be on a specific circuit
* b. Ranges, wall-mounted ovens, counter-mounted cooking units
* c. Clothes dryers that are not connected to the laundry branch circuit specified in item (2)
* d. Water heaters
### 220.84 Multifamily Dwelling.
#### 220.84(A) Feeder or Service Load.
It shall be permissible to calculate the load of a feeder or service that supplies three or more dwelling units of a multifamily dwelling in accordance with Table 220.84 instead of Part III of this article if all the following conditions are met:
* (1) No dwelling unit is supplied by more than one feeder.
* (2) Each dwelling unit is equipped with electric cooking equipment
> [!important] Exception:
> When the calculated load for multifamily dwellings without electric cooking in Part III of this article exceeds that calculated under Part IV for the identical load plus electric cooking (based on 8 kW per unit), the lesser of the two loads shall be permitted to be used.
* (3) Each dwelling unit is equipped with either electric space heating or air conditioning, or both. Feeders and service conductors whose calculated load is determined by this optional calculation shall be permitted to have the neutral load determined by
220.61.
#### 220.84(B) House Loads.
House loads shall be calculated in accordance with Part III of this article and shall be in addition to the dwelling unit loads calculated in accordance with Table 220.84.
##### Table 220.84 Optional Calculations --- Demand Factors for Three or More Multifamily Dwelling Units
| Number of Dwelling Units | Demand Factor (%) |
|:------------------------:| -----------------:|
| 3--5 | 45 |
| 6--7 | 44 |
| 8--10 | 43 |
| 11 | 42 |
| 12--13 | 41 |
| 14--15 | 40 |
| 16--17 | 39 |
| 18--20 | 38 |
| 21 | 37 |
| 22--23 | 36 |
| 24--25 | 35 |
| 26--27 | 34 |
| 28--30 | 33 |
| 31 | 32 |
| 32--33 | 31 |
| 34--36 | 30 |
| 37--38 | 29 |
| 39--42 | 28 |
| 43--45 | 27 |
| 46--50 | 26 |
| 51--55 | 25 |
| 56--61 | 24 |
| 62 and over | 23 |
#### 220.84(C) Calculated Loads.
The calculated load to which the demand factors of Table 220.84 apply shall include the following:
* (1) 33 volt-amperes/m or 3 volt-amperes/ft for general lighting and general-use receptacles
* (2) 1500 volt-amperes for each 2-wire, 20-ampere small-appliance branch circuit and each laundry branch circuit covered in 210.11(C)(1) and (C)(2)
* (3) The nameplate rating of the following:
* a. All appliances that are fastened in place, permanently connected, or located to be on a specific circui
* b. Ranges, wall-mounted ovens, counter-mounted cooking units
* c. Clothes dryers that are not connected to the laundry branch circuit specified in item (2)
* d. Water heaters
* (4) The nameplate ampere or kVA rating of all permanently connected motors not included in item (3)
* (5) The larger of the air-conditioning load or the fixed electric space-heating load
### 220.85 Two Dwelling Units.
Where two dwelling units are supplied by a single feeder and the calculated load under Part III of this article exceeds that for three identical units calculated under 220.84, the lesser of the two loads shall be permitted to be used.
### 220.86 Schools.
The calculation of a feeder or service load for schools shall be permitted in accordance with Table 220.86 in lieu of Part III of this article where equipped with electric space heating, air conditioning, or both. The connected load to which the demand factors of Table 220.86 apply shall include all of the interior and exterior lighting, power, water heating, cooking, other loads, and the larger of the air-conditioning load or space-heating load within the building or structure.
Feeders and service conductors whose calculated load is determined by this optional calculation shall be permitted to have the neutral load determined by 220.61. Where the building or structure load is calculated by this optional method, feeders within the building or structure shall have ampacity as permitted in Part III of this article; however, the ampacity of an individual feeder shall not be required to be larger than the ampacity for the entire building.
This section shall not apply to portable classroom buildings.
#### Table 220.86 Optional Method --- Demand Factors for Feeders and Service Conductors for Schools
| Connected Load | Demand Factor (Percent) |
| -------------------------------------------------------- | ----------------------- |
| First 33 VA/m2 Plus, (3 VA/ft2) at | 100 |
| Over 33 through 220 VA/m2 Plus, (3 through 20 VA/ft2) at | 75 |
| Remainder over 220 VA/m 2 (20 VA/ft2) at | 25 |
### 220.87 Determining Existing Loads.
The calculation of a feeder or service load for existing installations shall be permitted to use actual maximum demand to determine the existing load under all of the following conditions:
* (1) The maximum demand data is available for a 1-year period.
> [!important] Exception:
> If the maximum demand data for a 1-year period is not available, the calculated load shall be permitted to be based on the maximum demand (the highest average kilowatts reached and maintained for a 15-minute interval) continuously recorded over a minimum 30-day period using a recording ammeter or power meter connected to the highest loaded phase of the feeder or service, based on the initial loading at the start of the recording. The recording shall reflect the maximum demand of the feeder or service by being taken when the building or space is occupied and shall include by measurement or calculation the larger of the heating or cooling equipment load, and other loads that may be periodic in nature due to seasonal or similar conditions.
* (2) The maximum demand at 125 percent plus the new load does not exceed the ampacity of the feeder or rating of the service.
* (3) The feeder has overcurrent protection in accordance with 240.4, and the service has overload protection in accordance with 230.90.
> [!important] Exception:
> If the feeder or service has any renewable energy system (i.e., solar photovoltaic systems or wind electric systems) or employs any form of peak load shaving, this calculation method shall not be permitted.
### 220.88 New Restaurants.
Calculation of a service or feeder load, where the feeder serves the total load, for a new restaurant shall be permitted in accordance with Table 220.88 in lieu of Part III of this article.
The overload protection of the service conductors shall be in accordance with 230.90 and 240.4.
Feeder conductors shall not be required to be of greater ampacity than the service conductors.
Service or feeder conductors whose calculated load is determined by this optional calculation shall be permitted to have the neutral load determined by 220.61.
#### Table 220.88 Optional Method --- Permitted Load Calculations for Service and Feeder Conductors for New Restaurants
| Total Connected Load (kVA) | All Electric Restaurant Calculated Loads (kVA) | Not All Electric Restaurant Calculated Loads (kVA) |
|:--------------------------:| ---------------------------------------------- | -------------------------------------------------- |
| 0--200 | 80% | 100% |
| 201--325 | 10% (amount over 200) + 160.0 | 50% (amount over 200) + 200.0 |
| 326--800 | 50% (amount over 325) + 172.5 | 45% (amount over 325) + 262.5 |
| Over 800 | 50% (amount over 800) + 410.0 | 20% (amount over 800) + 476.3 |
Note: Add all electrical loads, including both heating and cooling loads, to calculate the total connected load. Select the one demand factor that applies from the table, then multiply the total connected load by this single demand factor.
## Part V. Farm Load Calculations
### 220.100 General.
Farm loads shall be calculated in accordance with Part V.
### 220.102 Farm Loads --- Buildings and Other Loads.
#### 220.102(A) Dwelling Unit.
The feeder or service load of a farm dwelling unit shall be calculated in accordance with the provisions for dwellings in Part III or IV of this article. Where the dwelling has electric heat and the farm has electric grain-drying systems, Part IV of this article shall not be used to calculate the dwelling load where the dwelling and farm loads are supplied by a common service.
#### 220.102(B) Other Than Dwelling Unit.
Where a feeder or service supplies a farm building or other load having two or more separate branch circuits, the load for feeders, service conductors, and service equipment shall be calculated in accordance with demand factors not less than indicated in Table
220.102.
#### Table 220.102 Method for Calculating Farm Loads for Other Than Dwelling Unit
| Ampere Load at 240 Volts Maximum | Demand Factor (%) |
| ------------------------------------------------------------- | ----------------- |
| The greater of the following: | |
| All loads that are expected to operate simultaneously, or | 100 |
| 125 percent of the full load current of the largest motor, or | |
| First 60 amperes of the load | |
| Next 60 amperes of all other loads | 50 |
| Remainder of other loads | 25 |
### 220.103 Farm Loads --- Total.
Where supplied by a common service, the total load of the farm for service conductors and service equipment shall be calculated in accordance with the farm dwelling unit load and demand factors specified in Table 220.103. Where there is equipment in two or more farm equipment buildings or for loads having the same function, such loads shall be calculated in accordance with Table 220.102 and shall be permitted to be combined as a single load in Table 220.103 for calculating the total load.
#### Table 220.103 Method for Calculating Total Farm Load
| Individual Loads Calculated in Accordance with Table 220.102 | Demand Factor (%) |
| ------------------------------------------------------------ | ----------------- |
| Largest load | 100 |
| Second largest load | 75 |
| Third largest load | 65 |
| Remaining loads | 50 |
Note: To this total load, add the load of the farm dwelling unit calculated in accordance with Part III or IV of this article. Where the dwelling has electric heat and the farm has electric grain-drying systems, Part IV of this article shall not be used to calculate the dwelling load.
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#### 250.122(A) General.
Copper, aluminum, or copper-clad aluminum equipment grounding conductors of the wire type shall not be smaller than shown in Table
250.122. The equipment grounding conductor shall not be required to be larger than the circuit conductors supplying the equipment. If a cable tray, a raceway, or a cable armor or sheath is used as the equipment grounding conductor, as provided in 250.118 and
250.134(1), it shall comply with 250.4(A)(5) or (B)(4).
Copper, aluminum, or copper-clad aluminum equipment grounding conductors of the wire type
shall not be smaller than shown in Table 250.122.
The equipment grounding conductor shall not be required
to be larger than the circuit conductors supplying the equipment.
If a cable tray, a raceway, or a cable armor or sheath is used as the equipment grounding conductor,
as provided in 250.118 and 250.134(1), it shall comply with 250.4(A)(5) or (B)(4).
Equipment grounding conductors shall be permitted to be sectioned within a multiconductor cable, provided the combined circular mil area complies with Table 250.122.
@@ -1807,9 +1810,7 @@ The equipment grounding conductor in a flexible cord with the largest circuit co
#### 250.122(F) Conductors in Parallel.
For circuits of parallel conductors as permitted in 310.10(G), the equipment grounding conductor shall be installed in accordance with
##### 250.122(F)(1) or (F) (2).
For circuits of parallel conductors as permitted in 310.10(G), the equipment grounding conductor shall be installed in accordance with 250.122(F)(1) or (F) (2).
##### 250.122(F)(1) Conductor Installations in Raceways, Auxiliary Gutters, or Cable Trays.
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---
id:
aliases:
- nec-440
tags:
- authorship/other
- destiny/uncertain
- exclude-from-word-count
- status/incomplete
- topic/construction/electrical
- type/media
title: Article 440 Air-Conditioning and Refrigerating Equipment
---
# Article 440 Air-Conditioning and Refrigerating Equipment
## Part I. General
### 440.1 Scope.
This article applies to electric motor-driven air-conditioning and refrigerating equipment and to the branch circuits and controllers for such equipment. It provides for the special considerations necessary for circuits supplying hermetic refrigerant motor-compressors and for any air-conditioning or refrigerating equipment that is supplied from a branch circuit that supplies a hermetic refrigerant motor-compressor.
#### 440.2 Definitions.
The definitions in this section shall apply only within this article.
##### Branch-Circuit Selection Current.
The value in amperes to be used instead of the rated-load current in determining the ratings of motor branch-circuit conductors, disconnecting means, controllers, and branch-circuit short-circuit and ground-fault protective devices wherever the running overload protective device permits a sustained current greater than the specified percentage of the rated-load current. The value of branch-circuit selection current will always be equal to or greater than the marked rated-load current.
##### Leakage-Current Detector-Interrupter (LCDI).
A device provided in a power supply cord or cord set that senses leakage current flowing between or from the cord conductors and interrupts the circuit at a predetermined level of leakage current.
##### Rated-Load Current.
The current of a hermetic refrigerant motor-compressor resulting when it is operated at the rated load, rated voltage, and rated frequency of the equipment it serves.
### 440.3 Other Articles.
#### 440.3(A) Article 430.
These provisions are in addition to, or amendatory of,
the provisions of Article 430 and other articles in this Code,
which apply except as modified in this article.
#### 440.3(B) Articles 422, 424, or 430.
The rules of Articles 422, 424, or 430, as applicable,
shall apply to air-conditioning and refrigerating equipment
that does not incorporate a hermetic refrigerant motor-compressor.
This equipment includes devices
that employ refrigeration compressors driven by conventional motors,
furnaces with air-conditioning evaporator coils installed,
fan-coil units, remote forced air-cooled condensers,
remote commercial refrigerators, and so forth.
#### 440.3(C) Article 422.
Equipment such as room air conditioners,
household refrigerators and freezers,
drinking water coolers, and beverage dispensers
shall be considered appliances,
and Article 422 shall also apply.
#### 440.3(D) Other Applicable Articles.
Hermetic refrigerant motor-compressors,
circuits, controllers, and equipment
shall also comply with the applicable provisions of Table 440.3(D).
##### Table 440.3(D) Other Articles
| Equipment/Occupancy | Article | Section |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------- | ------- |
| Capacitors | | 460.9 |
| Commercial garages, aircraft hangars, motor fuel dispensing facilities, bulk storage plants, spray application, dipping, and coating processes, and inhalation anesthetizing locations | 511, 513, 514, 515, 516, and 517 Part IV | |
| Hazardous (classified) locations | 500--503, 505, and 506 | |
| Motion picture and television studios and similar locations | 530 | |
| Resistors and reactors | 470 | |
### 440.4 Marking on Hermetic Refrigerant Motor-Compressors and Equipment.
#### 440.4(A) Hermetic Refrigerant Motor-Compressor Nameplate.
A hermetic refrigerant motor-compressor shall be provided with a nameplate that shall indicate the manufacturer's name, trademark, or symbol; identifying designation; phase; voltage; and frequency.
The rated-load current in amperes of the motor-compressor shall be marked by the equipment manufacturer on either or both the motor-compressor nameplate and the nameplate of the equipment in which the motor-compressor is used.
The locked-rotor current of each single-phase motor-compressor having a rated-load current of more than 9 amperes at 115 volts, or more than 4.5 amperes at 230 volts, and each polyphase motor-compressor shall be marked on the motor-compressor nameplate.
Where a thermal protector complying with 440.52(A)(2) and (B)(2) is used,
the motor-compressor nameplate or the equipment nameplate
shall be marked with the words "thermally protected."
Where a protective system complying with 440.52(A)(4) and (B)(4)
is used and is furnished with the equipment,
the equipment nameplate shall be marked with the words,
"thermally protected system."
Where a protective system complying with 440.52(A) (4) and (B)(4) is specified,
the equipment nameplate shall be appropriately marked.
#### 440.4(B) Multimotor and Combination-Load Equipment.
Multimotor and combination-load equipment shall be provided with a visible nameplate marked with the maker's name, the rating in volts, frequency and number of phases, minimum supply circuit conductor ampacity, the maximum rating of the branch-circuit short-circuit and ground-fault protective device, and the short-circuit current rating of the motor controllers or industrial control panel. The ampacity shall be calculated by using Part IV and counting all the motors and other loads that will be operated at the same time. The branch-circuit short-circuit and ground-fault protective device rating shall not exceed the value calculated by using Part III. Multimotor or combination-load equipment for use on two or more circuits shall be marked with the above information for each circuit.
> [!important] Exception No. 1:
> Multimotor and combination-load equipment that is suitable under the provisions of this article for connection to a single 15- or 20-ampere, 120-volt, or a 15-ampere, 208- or 240-volt, single-phase branch circuit shall be permitted to be marked as a single load.
> [!important] Exception No. 2:
> The minimum supply circuit conductor ampacity and the maximum rating of the branch-circuit short-circuit and groundfault protective device shall not be required to be marked on a room air conditioner complying with 440.62(A).
> [!important] Exception No. 3:
> Multimotor and combination-load equipment used in one- and two-family dwellings or cord-and-attachment-plugconnected equipment shall not be required to be marked with a short-circuit current rating.
#### 440.4(C) Branch-Circuit Selection Current.
A hermetic refrigerant motor-compressor, or equipment containing such a compressor, having a protection system that is approved for use with the motor-compressor that it protects and that permits continuous current in excess of the specified percentage of nameplate rated-load current given in 440.52(B)(2) or (B)(4) shall also be marked with a branch-circuit selection current that complies with
440.52(B)(2) or (B)(4). This marking shall be provided by the equipment manufacturer and shall be on the nameplate(s) where the rated-load current(s) appears.
### 440.5 Marking on Controllers.
A controller shall be marked with the manufacturer's name, trademark, or symbol; identifying designation; voltage; phase; full-load and locked-rotor current (or horsepower) rating; and other data as may be needed to properly indicate the motor-compressor for which it is suitable.
### 440.6 Ampacity and Rating.
The size of conductors for equipment covered by this article shall be selected from Table 310.16 through Table 310.19 or calculated in accordance with 310.14 as applicable. The required ampacity of conductors and rating of equipment shall be determined according to
440.6(A) and 440.6(B).
#### 440.6(A) Hermetic Refrigerant Motor-Compressor.
For a hermetic refrigerant motor-compressor, the rated-load current marked on the nameplate of the equipment in which the motorcompressor is employed shall be used in determining the rating or ampacity of the disconnecting means, the branch-circuit conductors, the controller, the branch-circuit short-circuit and ground-fault protection, and the separate motor overload protection. Where no ratedload current is shown on the equipment nameplate, the rated-load current shown on the compressor nameplate shall be used.
> [!important] Exception No. 1:
> Where so marked, the branch-circuit selection current shall be used instead of the rated-load current to determine the rating or ampacity of the disconnecting means, the branch-circuit conductors, the controller, and the branch-circuit short-circuit and ground-fault protection.
> [!important] Exception No. 2:
> For cord-and-plug-connected equipment, the nameplate marking shall be used in accordance with 440.22(B), Exception No. 2.
#### 440.6(B) Multimotor Equipment.
For multimotor equipment employing a shaded-pole or permanent split-capacitor-type fan or blower motor, the full-load current for such motor marked on the nameplate of the equipment in which the fan or blower motor is employed shall be used instead of the horsepower rating to determine the ampacity or rating of the disconnecting means, the branch-circuit conductors, the controller, the branch-circuit short-circuit and ground-fault protection, and the separate overload protection. This marking on the equipment nameplate shall not be less than the current marked on the fan or blower motor nameplate.
### 440.7 Highest Rated (Largest) Motor.
In determining compliance with this article and with 430.24, 430.53(B) and 430.53(C), and 430.62(A), the highest rated (largest) motor shall be considered to be the motor that has the highest rated-load current. Where two or more motors have the same highest ratedload current, only one of them shall be considered as the highest rated (largest) motor. For other than hermetic refrigerant motorcompressors, and fan or blower motors as covered in 440.6(B), the full-load current used to determine the highest rated motor shall be the equivalent value corresponding to the motor horsepower rating selected from Table 430.248, Table 430.249, or Table 430.250.
> [!important] Exception:
> Where so marked, the branch-circuit selection current shall be used instead of the rated-load current in determining the highest rated (largest) motor-compressor.
### 440.8 Single Machine.
An air-conditioning or refrigerating system shall be considered to be a single machine under the provisions of 430.87, Exception No. 1, and 430.112, Exception. The motors shall be permitted to be located remotely from each other.
### 440.9 Grounding and Bonding.
Where equipment is installed outdoors on a roof, an equipment grounding conductor of the wire type shall be installed in outdoor portions of metallic raceway systems that use compression-type fittings.
### 440.10 Short-Circuit Current Rating.
#### 440.10(A) Installation.
Motor controllers or industrial control panels of multimotor and combination-load equipment shall not be installed where the available fault current exceeds its short-circuit current rating as marked in accordance with 440.4(B).
#### 440.10(B) Documentation.
When motor controllers or industrial control panels of multimotor and combination-load equipment are required to be marked with a short circuit current rating, the available fault current and the date the available fault current calculation was performed shall be documented and made available to those authorized to inspect, install, or maintain the installation.
## Part II. Disconnecting Means
### 440.11 General.
Part II is intended to require disconnecting means capable of disconnecting air-conditioning and refrigerating equipment, including motor-compressors and controllers from the circuit conductors.
### 440.12 Rating and Interrupting Capacity.
#### 440.12(A) Hermetic Refrigerant Motor-Compressor.
A disconnecting means serving a hermetic refrigerant motor-compressor shall be selected on the basis of the nameplate rated-load current or branch-circuit selection current, whichever is greater, and locked-rotor current, respectively, of the motor-compressor as follows.
##### 440.12(A)(1) Ampere Rating.
The ampere rating shall be at least 115 percent of the nameplate rated-load current or branch-circuit selection current, whichever is greater.
> [!important] Exception:
> A listed unfused motor circuit switch, without fuseholders, having a horsepower rating not less than the equivalent horsepower determined in accordance with 440.12(A)(2) shall be permitted to have an ampere rating less than 115 percent of the specified current.
##### 440.12(A)(2) Equivalent Horsepower.
To determine the equivalent horsepower in complying with the requirements of 430.109, the horsepower rating shall be selected from
Table 430.248, Table 430.249, or Table 430.250 corresponding to the rated-load current or branch-circuit selection current, whichever is greater, and also the horsepower rating from Table 430.251(A) or Table 430.251(B) corresponding to the locked-rotor current. In case the nameplate rated-load current or branch-circuit selection current and locked-rotor current do not correspond to the currents shown in
Table 430.248, Table 430.249, Table 430.250, Table 430.251(A), or Table 430.251(B), the horsepower rating corresponding to the next higher value shall be selected. In case different horsepower ratings are obtained when applying these tables, a horsepower rating at least equal to the larger of the values obtained shall be selected.
#### 440.12(B) Combination Loads.
Where the combined load of two or more hermetic refrigerant motor-compressors or one or more hermetic refrigerant motorcompressor with other motors or loads may be simultaneous on a single disconnecting means, the rating for the disconnecting means shall be determined in accordance with 440.12(B)(1) and (B)(2).
##### 440.12(B)(1) Horsepower Rating.
The horsepower rating of the disconnecting means shall be determined from the sum of all currents, including resistance loads, at the rated-load condition and also at the locked-rotor condition. The combined rated-load current and the combined locked-rotor current so obtained shall be considered as a single motor for the purpose of this requirement as required by 440.12(B)(1)(a) and (B) (1) (b).
* (a) The full-load current equivalent to the horsepower rating of each motor, other than a hermetic refrigerant motor-compressor, and fan or blower motors as covered in 440.6(B) shall be selected from Table 430.248, Table 430.249, or Table 430.250. These fullload currents shall be added to the motor-compressor rated-load current(s) or branch-circuit selection current(s), whichever is greater, and to the rating in amperes of other loads to obtain an equivalent full-load current for the combined load.
* (b) The locked-rotor current equivalent to the horsepower rating of each motor, other than a hermetic refrigerant motor-compressor, shall be selected from Table 430.251(A) or Table 430.251(B), and, for fan and blower motors of the shaded-pole or permanent split-capacitor type marked with the locked-rotor current, the marked value shall be used. The locked-rotor currents shall be added to the motor-compressor locked-rotor current(s) and to the rating in amperes of other loads to obtain an equivalent locked-rotor current for the combined load. Where two or more motors or other loads such as resistance heaters, or both, cannot be started simultaneously, appropriate combinations of locked-rotor and rated-load current or branch-circuit selection current, whichever is greater, shall be an acceptable means of determining the equivalent locked-rotor current for the simultaneous combined load.
> [!important] Exception:
> Where part of the concurrent load is a resistance load and the disconnecting means is a switch rated in horsepower and amperes, the switch used shall be permitted to have a horsepower rating not less than the combined load to the motor-compressor(s) and other motor(s) at the locked-rotor condition, if the ampere rating of the switch is not less than this locked-rotor load plus the resistance load.
##### 440.12(B)(2) Full-Load Current Equivalent.
The ampere rating of the disconnecting means shall be at least 115 percent of the sum of all currents at the rated-load condition determined in accordance with 440.12(B)(1).
> [!important] Exception:
> A listed unfused motor circuit switch, without fuseholders, having a horsepower rating not less than the equivalent horsepower determined by 440.12(B)(1) shall be permitted to have an ampere rating less than 115 percent of the sum of all currents.
#### 440.12(C) Small Motor-Compressors.
For small motor-compressors not having the locked-rotor current marked on the nameplate, or for small motors not covered by Table
430.247, Table 430.248, Table 430.249, or Table 430.250, the locked-rotor current shall be assumed to be six times the rated-load current.
#### 440.12(D) Disconnecting Means.
Every disconnecting means in the refrigerant motor-compressor circuit between the point of attachment to the feeder and the point of connection to the refrigerant motor-compressor shall comply with the requirements of 440.12.
#### 440.12(E) Disconnecting Means Rated in Excess of 100 Horsepower.
Where the rated-load or locked-rotor current as determined above would indicate a disconnecting means rated in excess of 100 hp,
430.109(E) shall apply.
### 440.13 Cord-Connected Equipment.
For cord-connected equipment such as room air conditioners, household refrigerators and freezers, drinking water coolers, and beverage dispensers, a separable connector or an attachment plug and receptacle shall be permitted to serve as the disconnecting means.
> [!info] Informational Note:
> For room air conditioners, see 440.63.
### 440.14 Location.
Disconnecting means shall be located within sight from, and readily accessible from the air-conditioning or refrigerating equipment. The disconnecting means shall be permitted to be installed on or within the air-conditioning or refrigerating equipment.
The disconnecting means shall not be located on panels that are designed to allow access to the air-conditioning or refrigeration equipment or to obscure the equipment nameplate(s).
> [!important] Exception No. 1:
> Where the disconnecting means provided in accordance with 430.102(A) is lockable in accordance with 110.25 and the refrigerating or air-conditioning equipment is essential to an industrial process in a facility with written safety procedures, and where the conditions of maintenance and supervision ensure that only qualified persons service the equipment, a disconnecting means within sight from the equipment shall not be required.
> [!important] Exception No. 2:
> Where an attachment plug and receptacle serve as the disconnecting means in accordance with 440.13, their location shall be accessible but shall not be required to be readily accessible.
> [!info] Informational Note No. 1:
> See Parts VII and IX of Article 430 for additional requirements.
> [!info] Informational Note No. 2:
> See 110.26.
## Part III. Branch-Circuit Short-Circuit and Ground-Fault Protection
### 440.21 General.
Part III specifies devices intended to protect the branch-circuit conductors, control apparatus, and motors in circuits supplying hermetic refrigerant motor-compressors against overcurrent due to short circuits and ground faults. They are in addition to or amendatory of
Article 240.
### 440.22 Application and Selection.
#### 440.22(A) Rating or Setting for Individual Motor-Compressor.
The motor-compressor branch-circuit short-circuit and ground-fault protective device shall be capable of carrying the starting current of the motor. A protective device having a rating or setting not exceeding 175 percent of the motor-compressor rated-load current or branch-circuit selection current, whichever is greater, shall be permitted, provided that, where the protection specified is not sufficient for the starting current of the motor, the rating or setting shall be permitted to be increased but shall not exceed 225 percent of the motor rated-load current or branch-circuit selection current, whichever is greater.
> [!important] Exception:
> The rating of the branch-circuit short-circuit and ground-fault protective device shall not be required to be less than 15 amperes.
#### 440.22(B) Rating or Setting for Equipment.
The equipment branch-circuit short-circuit and ground-fault protective device shall be capable of carrying the starting current of the equipment. Where the hermetic refrigerant motor-compressor is the only load on the circuit, the protection shall comply with 440.22(A).
Where the equipment incorporates more than one hermetic refrigerant motor-compressor or a hermetic refrigerant motor-compressor and other motors or other loads, the equipment short-circuit and ground-fault protection shall comply with 430.53 and 440.22(B)(1) and
(B)(2).
##### 440.22(B)(1) Motor-Compressor Largest Load.
Where a hermetic refrigerant motor-compressor is the largest load connected to the circuit, the rating or setting of the branch-circuit short-circuit and ground-fault protective device shall not exceed the value specified in 440.22(A) for the largest motor-compressor plus the sum of the rated-load current or branch-circuit selection current, whichever is greater, of the other motor-compressor(s) and the ratings of the other loads supplied.
##### 440.22(B)(2) Motor-Compressor Not Largest Load.
Where a hermetic refrigerant motor-compressor is not the largest load connected to the circuit, the rating or setting of the branch-circuit short-circuit and ground-fault protective device shall not exceed a value equal to the sum of the rated-load current or branch-circuit selection current, whichever is greater, rating(s) for the motor-compressor(s) plus the value specified in 430.53(C)(4) where other motor loads are supplied, or the value specified in 240.4 where only nonmotor loads are supplied in addition to the motor-compressor(s).
> [!important] Exception No. 1:
> Equipment that starts and operates on a 15- or 20-ampere 120-volt, or 15-ampere 208- or 240-volt single-phase branch circuit, shall be permitted to be protected by the 15- or 20-ampere overcurrent device protecting the branch circuit, but if the maximum branch-circuit short-circuit and ground-fault protective device rating marked on the equipment is less than these values, the circuit protective device shall not exceed the value marked on the equipment nameplate.
> [!important] Exception No. 2:
> The nameplate marking of cord-and-plug-connected equipment rated not greater than 250 volts, single-phase, such as household refrigerators and freezers, drinking water coolers, and beverage dispensers, shall be used in determining the branch-circuit requirements, and each unit shall be considered as a single motor unless the nameplate is marked otherwise.
#### 440.22(C) Protective Device Rating Not to Exceed the Manufacturer's Values.
Where maximum protective device ratings shown on a manufacturer's overload relay table for use with a motor controller are less than the rating or setting selected in accordance with 440.22(A) and (B), the protective device rating shall not exceed the manufacturer's values marked on the equipment.
## Part IV. Branch-Circuit Conductors
### 440.31 General.
Part IV and Article 310 specify ampacities of conductors required to carry the motor current without overheating under the conditions specified, except as modified in 440.6(A), Exception No. 1.
These articles shall not apply to integral conductors of motors, to motor controllers and the like, or to conductors that form an integral part of approved equipment.
### 440.32 Single Motor-Compressor.
Branch-circuit conductors supplying a single motor-compressor shall have an ampacity not less than the greater of:
* (1) 125 percent of the motor-compressor rated-load current
* (2) 125 percent of the branch-circuit selection current
For a wye-start, delta-run connected motor-compressor, the selection of branch-circuit conductors between the controller and the motor-compressor shall be permitted to be based on 72 percent of either the motor-compressor rated-load current or the branch-circuit selection current, whichever is greater.
> [!info] Informational Note:
> The individual motor circuit conductors of wye-start, delta-run connected motor-compressors carry 58 percent of the rated load current. The multiplier of 72 percent is obtained by multiplying 58 percent by 1.25.
### 440.33 Motor-Compressor(s) With or Without Additional Motor Loads.
Conductors supplying one or more motor-compressor(s) with or without an additional motor load(s) shall have an ampacity not less than the sum of each of the following:
* (1) The sum of the rated-load or branch-circuit selection current, whichever is greater, of all motor-compressor(s)
* (2) The sum of the full-load current rating of all other motors
* (3) 25 percent of the highest motor-compressor or motor full load current in the group
> [!important] Exception No. 1:
> Where the circuitry is interlocked so as to prevent the starting and running of a second motor-compressor or group of motor-compressors, the conductor size shall be determined from the largest motor-compressor or group of motor-compressors that is to be operated at a given time.
> [!important] Exception No. 2:
> The branch-circuit conductors for room air conditioners shall be in accordance with Part VII of Article 440.
### 440.34 Combination Load.
Conductors supplying a motor-compressor load in addition to other load(s) as calculated from Article 220 and other applicable articles shall have an ampacity sufficient for the other load(s) plus the required ampacity for the motor-compressor load determined in accordance with 440.33 or, for a single motor-compressor, in accordance with 440.32.
> [!important] Exception:
> Where the circuitry is interlocked so as to prevent simultaneous operation of the motor-compressor(s) and all other loads connected, the conductor size shall be determined from the largest size required for the motor-compressor(s) and other loads to be operated at a given time.
### 440.35 Multimotor and Combination-Load Equipment.
The ampacity of the conductors supplying multimotor and combination-load equipment shall not be less than the minimum circuit ampacity marked on the equipment in accordance with 440.4(B).
## Part V. Controllers for Motor-Compressors
### 440.41 Rating.
#### 440.41(A) Motor-Compressor Controller.
A motor-compressor controller shall have both a continuous-duty full-load current rating and a locked-rotor current rating not less than the nameplate rated-load current or branch-circuit selection current, whichever is greater, and locked-rotor current, respectively, of the compressor. In case the motor controller is rated in horsepower but is without one or both of the foregoing current ratings, equivalent currents shall be determined from the ratings as follows. Table 430.248, Table 430.249, and Table 430.250 shall be used to determine the equivalent full-load current rating. Table 430.251(A) and Table 430.251(B) shall be used to determine the equivalent locked-rotor current ratings.
#### 440.41(B) Controller Serving More Than One Load.
A controller serving more than one motor-compressor or a motor-compressor and other loads shall have a continuous-duty full-load current rating and a locked-rotor current rating not less than the combined load as determined in accordance with 440.12(B).
## Part VI. Motor-Compressor and Branch-Circuit Overload Protection
### 440.51 General.
Part VI specifies devices intended to protect the motor-compressor, the motor-control apparatus, and the branch-circuit conductors against excessive heating due to motor overload and failure to start.
> [!info] Informational Note:
> See 240.4(G) for application of Parts III and VI of Article 440.
### 440.52 Application and Selection.
#### 440.52(A) Protection of Motor-Compressor.
Each motor-compressor shall be protected against overload and failure to start by one of the following means:
* (1) A separate overload relay that is responsive to motor-compressor current. This device shall be selected to trip at not more than
140 percent of the motor-compressor rated-load current.
* (2) A thermal protector integral with the motor-compressor, approved for use with the motor-compressor that it protects on the basis that it will prevent dangerous overheating of the motor-compressor due to overload and failure to start. If the current-interrupting device is separate from the motor-compressor and its control circuit is operated by a protective device integral with the motorcompressor, it shall be arranged so that the opening of the control circuit will result in interruption of current to the motorcompressor.(3) A fuse or inverse time circuit breaker responsive to motor current, which shall also be permitted to serve as the branch-circuit short-circuit and ground-fault protective device. This device shall be rated at not more than 125 percent of the motor-compressor rated-load current. It shall have sufficient time delay to permit the motor-compressor to start and accelerate its load. The equipment or the motor-compressor shall be marked with this maximum branch-circuit fuse or inverse time circuit breaker rating.
* (4) A protective system, furnished or specified and approved for use with the motor-compressor that it protects on the basis that it will prevent dangerous overheating of the motor-compressor due to overload and failure to start. If the current-interrupting device is separate from the motor-compressor and its control circuit is operated by a protective device that is not integral with the current-interrupting device, it shall be arranged so that the opening of the control circuit will result in interruption of current to the motor-compressor.
#### 440.52(B) Protection of Motor-Compressor Control Apparatus and Branch-Circuit Conductors.
The motor-compressor controller(s), the disconnecting means, and the branch-circuit conductors shall be protected against overcurrent due to motor overload and failure to start by one of the following means, which shall be permitted to be the same device or system protecting the motor-compressor in accordance with 440.52(A):
> [!important] Exception:
> Overload protection of motor-compressors and equipment on 15- and 20-ampere, single-phase, branch circuits shall be permitted to be in accordance with 440.54 and 440.55.
* (1) An overload relay selected in accordance with 440.52(A) (1)
* (2) A thermal protector applied in accordance with 440.52(A)(2), that will not permit a continuous current in excess of 156 percent of the marked rated-load current or branch-circuit selection current
* (3) A fuse or inverse time circuit breaker selected in accordance with 440.52(A)(3)
* (4) A protective system, in accordance with 440.52(A)(4), that will not permit a continuous current in excess of 156 percent of the marked rated-load current or branch-circuit selection current
### 440.53 Overload Relays.
Overload relays and other devices for motor overload protection that are not capable of opening short circuits shall be protected by fuses or inverse time circuit breakers with ratings or settings in accordance with Part III unless identified for group installation or for partwinding motors and marked to indicate the maximum size of fuse or inverse time circuit breaker by which they shall be protected.
> [!important] Exception:
> The fuse or inverse time circuit breaker size marking shall be permitted on the nameplate of the equipment in which the overload relay or other overload device is used.
440.54 Motor-Compressors and Equipment on 15- or 20-Ampere Branch Circuits --- Not Cord- and
Attachment-Plug-Connected.
Overload protection for motor-compressors and equipment used on 15- or 20-ampere 120-volt, or 15-ampere 208- or 240-volt singlephase branch circuits as permitted in Article 210 shall be permitted as indicated in 440.54(A) and 440.54(B).
#### 440.54(A) Overload Protection.
The motor-compressor shall be provided with overload protection selected as specified in 440.52(A). Both the controller and motor overload protective device shall be identified for installation with the short-circuit and ground-fault protective device for the branch circuit to which the equipment is connected.
#### 440.54(B) Time Delay.
The short-circuit and ground-fault protective device protecting the branch circuit shall have sufficient time delay to permit the motorcompressor and other motors to start and accelerate their loads.
440.55 Cord- and Attachment-Plug-Connected Motor-Compressors and Equipment on 15- or 20-Ampere
Branch Circuits.
Overload protection for motor-compressors and equipment that are cord- and attachment-plug-connected and used on 15- or 20ampere
120-volt, or 15-ampere 208- or 240-volt, single-phase branch circuits as permitted in Article 210 shall be permitted as indicated in 440.55(A), (B), and (C).
#### 440.55(A) Overload Protection.
The motor-compressor shall be provided with overload protection as specified in 440.52(A). Both the controller and the motor overload protective device shall be identified for installation with the short-circuit and ground-fault protective device for the branch circuit to which the equipment is connected.
#### 440.55(B) Attachment Plug and Receptacle or Cord Connector Rating.
The rating of the attachment plug and receptacle or cord connector shall not exceed 20 amperes at 125 volts or 15 amperes at
250 volts.
#### 440.55(C) Time Delay.
The short-circuit and ground-fault protective device protecting the branch circuit shall have sufficient time delay to permit the motorcompressor and other motors to start and accelerate their loads.
## Part VII. Provisions for Room Air Conditioners
### 440.60 General.
Part VII shall apply to electrically energized room air conditioners that control temperature and humidity. For the purpose of Part VII, a room air conditioner (with or without provisions for heating) shall be considered as an ac appliance of the air-cooled window, console, or in-wall type that is installed in the conditioned room and that incorporates a hermetic refrigerant motor-compressor(s). Part VII covers equipment rated not over 250 volts, single phase, and the equipment shall be permitted to be cord- and attachment-plug-connected.
A room air conditioner that is rated 3-phase or rated over 250 volts shall be directly connected to a wiring method recognized in
Chapter 3, and Part VII shall not apply.
### 440.61 Grounding.
The enclosures of room air conditioners shall be connected to the equipment grounding conductor in accordance with 250.110,
250.112, and 250.114.
### 440.62 Branch-Circuit Requirements.
#### 440.62(A) Room Air Conditioner as a Single Motor Unit.
A room air conditioner shall be considered as a single motor unit in determining its branch-circuit requirements where all the following conditions are met:
* (1) It is cord- and attachment-plug-connected.
* (2) Its rating is not more than 40 amperes and 250 volts, single phase.
* (3) Total rated-load current is shown on the room air-conditioner nameplate rather than individual motor currents.
* (4) The rating of the branch-circuit short-circuit and ground-fault protective device does not exceed the ampacity of the branchcircuit conductors or the rating of the receptacle, whichever is less.
#### 440.62(B) Where No Other Loads Are Supplied.
The total marked rating of a cord- and attachment-plug-connected room air conditioner shall not exceed 80 percent of the rating of a branch circuit where no other loads are supplied.
#### 440.62(C) Where Lighting Units or Other Appliances Are Also Supplied.
The total marked rating of a cord- and attachment-plug-connected room air conditioner shall not exceed 50 percent of the rating of a branch circuit where lighting outlets, other appliances, or general-use receptacles are also supplied. Where the circuitry is interlocked to prevent simultaneous operation of the room air conditioner and energization of other outlets on the same branch circuit, a cord- and attachment-plug-connected room air conditioner shall not exceed 80 percent of the branch-circuit rating.
### 440.63 Disconnecting Means.
An attachment plug and receptacle or cord connector shall be permitted to serve as the disconnecting means for a single-phase room air conditioner rated 250 volts or less if (1) the manual controls on the room air conditioner are readily accessible and located within
1.8 m (6 ft) of the floor, or (2) an approved manually operable disconnecting means is installed in a readily accessible location within sight from the room air conditioner.
### 440.64 Supply Cords.
Where a flexible cord is used to supply a room air conditioner, the length of such cord shall not exceed 3.0 m (10 ft) for a nominal, 120volt rating or 1.8 m (6 ft) for a nominal, 208- or 240-volt rating.
### 440.65 Protection Devices.
Single-phase cord- and plug-connected room air conditioners shall be provided with one of the following factory-installed devices:
* (1) Leakage-current detector-interrupter (LCDI)
* (2) Arc-fault circuit interrupter (AFCI)
* (3) Heat detecting circuit interrupter (HDCI)
The protection device shall be an integral part of the attachment plug or be located in the power supply cord within 300 mm (12 in.) of the attachment plug.
nfpa-70_national-electric-code.md
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@@ -28,8 +28,8 @@ title: "NFPA 70: National Electric Code"
* [[nfpa-70_215_feeders|215 Feeders]]
* [[nfpa-70_220_load-calculations|220 Branch-Circuit, Feeder, and Service Load Calculations]]
* [[nfpa-70_225|225 Outside Branch Circuits and Feeders]]
* [[nfpa-70_230|230 Services]]
* [[nfpa-70_240|240 Overcurrent Protection]]
* [[nfpa-70_230_services|230 Services]]
* [[nfpa-70_240_overcurrent-protection|240 Overcurrent Protection]]
* [[nfpa-70_242|242 Overvoltage Protection]]
* [[nfpa-70_250_grounding-and-bonding|250 Grounding and Bonding]]
@@ -99,7 +99,7 @@ title: "NFPA 70: National Electric Code"
* [[nfpa-70_426|426 Fixed Outdoor Electric Deicing and Snow-Melting Equipment]]
* [[nfpa-70_427|427 Fixed Electric Heating Equipment for Pipelines and Vessels]]
* [[nfpa-70_430_motors|430 Motors, Motor Circuits, and Controllers]]
* [[nfpa-70_440|440 Air-Conditioning and Refrigerating Equipment]]
* [[nfpa-70_440_hvac-equipment|440 Air-Conditioning and Refrigerating Equipment]]
* [[nfpa-70_445|445 Generators]]
* [[nfpa-70_450_transformers|450 Transformers and Transformer Vaults (Including Secondary Ties)]]
* [[nfpa-70_455|455 Phase Converters]]
portfolio-theory-for-construction-estimating.md
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---
id:
aliases: []
tags: []
title: Portfolio Theory for Construction Estimating
---
# Portfolio Theory for Construction Estimating
Projects are like investments in that they have a cost and return.
They are different in that, in the case of construction,
the return is known, but the cost must be estimated.
## Terms
https://en.wikipedia.org/wiki/Discounted_cash_flow
https://en.wikipedia.org/wiki/Valuation_(finance)
https://en.wikipedia.org/wiki/Time_value_of_money
https://en.wikipedia.org/wiki/Time_preference
## Resources
https://www.wiley.com/en-us/Wiley+Series+in+Probability+and+Statistics-c-1345
https://www.wiley.com/en-us/Structural+Equation+Modeling%3A+Applications+Using+Mplus%2C+2nd+Edition-p-00045072
https://www.wiley.com/en-us/Game-Theoretic+Foundations+for+Probability+and+Finance+-p-00027121
https://www.wiley.com/en-us/Loss+Models%3A+From+Data+to+Decisions%2C+5th+Edition-p-00014549
this-notebook.md
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@@ -67,6 +67,7 @@ but this notebook uses [[semantic-line-breaks]]
for text wrapping.
I shoot for less than 90 columns.
This line of text (which is precisely 90 characters) is the maximum length for prose here.
## Licensing