vault backup: 2025-10-03 15:08:33
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-26
@@ -1,13 +1,33 @@
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{
|
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|
||||
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||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
@@ -171,30 +191,6 @@
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||||
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|
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|
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|
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
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|
||||
"path": "estimating-culture.md"
|
||||
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|
||||
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|
||||
"basename": "estimating-as-code",
|
||||
"path": "estimating-as-code.md"
|
||||
},
|
||||
{
|
||||
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||||
"path": "breakdown-objects.md"
|
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|
||||
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|
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+86
-6
@@ -3,10 +3,56 @@ id:
|
||||
aliases: []
|
||||
tags:
|
||||
- destiny/fleeting
|
||||
- status/incomplete
|
||||
- topic/electrical
|
||||
- type/encyclopedia
|
||||
---
|
||||
# Feeder Sizing
|
||||
# Conductor Sizing
|
||||
|
||||
## "The 80% Rule"
|
||||
|
||||
"The 80% Rule" is a rule of thumb
|
||||
referring to a common convention of several articles
|
||||
including:
|
||||
|
||||
- [[nfpa-70_article-210_branch-circuits#210.19(A)(1) General.]]
|
||||
- [[nfpa-70_article-215_feeders#215.2(A)(1) General.]]
|
||||
|
||||
which paraphrased states:
|
||||
|
||||
> ... the minimum conductor size shall have an ampacity
|
||||
> not less than the noncontinuous load
|
||||
> plus 125 percent of the continuous load
|
||||
|
||||
When the rule is repeated,
|
||||
the noncontinuous load is ignored
|
||||
and it is stated that conductors are suitable
|
||||
for 80% their listed rating,
|
||||
since 80% is the reciprocal of 125%.
|
||||
|
||||
## Branch Circuits
|
||||
|
||||
### Receptacle Branch
|
||||
|
||||
> [!important]
|
||||
> There is no maximum number of receptacles per circuit _in any occupancy_.
|
||||
|
||||
It is a common misconception that the limit
|
||||
can be calculated with a formula like
|
||||
|
||||
$$
|
||||
\frac{1.25(180VA)}{120V} = 1.875A, \quad \frac{20A}{1.875A} = 10.\bar{6}
|
||||
$$
|
||||
|
||||
but the 180VA per yoke load specified in
|
||||
[[nfpa-70_article-220_load-calculations#220.14(I) Receptacle Outlets.|220.14(I)]]
|
||||
is specifically for calculating service and feeder sizing.
|
||||
|
||||
Per [[nfpa-70_article-210_branch-circuits#210.19(A)(1) General.|210.19(A)(1)]]
|
||||
a receptacle branch circuit's load
|
||||
is the load of the equipment intended to be served by it.
|
||||
|
||||
## Feeders
|
||||
|
||||
> [!cite] 250.122 Size of Equipment Grounding Conductors
|
||||
> **(A) General.** Copper, aluminum, or copper-clad aluminum
|
||||
@@ -37,15 +83,49 @@ Given a minimum ampacity, find all valid configurations.
|
||||
|
||||
Rank by total cost of install.
|
||||
|
||||
## Complexity to Ignore
|
||||
### Complexity to Ignore
|
||||
|
||||
### Conductor Material
|
||||
#### Conductor Material
|
||||
|
||||
Tinned copper and copper-clad aluminum conductors
|
||||
can be assumed out of scope.
|
||||
|
||||
## Complexity to Respect
|
||||
### Complexity to Respect
|
||||
|
||||
#### Equipment Grounding Conductor Material
|
||||
|
||||
Wire and EGC conductors are usually assumed to match,
|
||||
but it is sometimes preferable to use a copper EGC
|
||||
with high-amp aluminum parallel feeds.
|
||||
but it is sometimes necessary to use a copper EGC with aluminum wires,
|
||||
either for spec requirements or conduit fill considerations.
|
||||
|
||||
## Voltage Drop
|
||||
|
||||
$$
|
||||
V_d = \frac{ I \times R \times L \times M }{ P }
|
||||
$$
|
||||
|
||||
where
|
||||
- $V_d$ = Voltage Drop in volts ($V$)
|
||||
- $I$ = Current in Amperes ($A$)
|
||||
- $R$ = Linear resistance in ohms per foot ($\Omega\text{ft}^{-1}$)
|
||||
- $L$ = Length of wire one way in feet ($\text{ft}$)
|
||||
- $M$ = Multiplier
|
||||
- $2$ for 1-phase
|
||||
- $\sqrt{3}$ for 3-phase
|
||||
- $P$ = Number of parallel runs
|
||||
|
||||
It is often more useful to know the maximum length
|
||||
a certain wiring configuration is suitable for.
|
||||
|
||||
$$
|
||||
L = \frac{ V_d }{ I \times M } \times \frac{ P }{ R }
|
||||
$$
|
||||
|
||||
- $L$ = Max length of wire one way in feet ($\text{ft}$)
|
||||
- $\frac{ V_d }{ I \times M }$ = Max circuit resistance in ohms ($\Omega$)
|
||||
- $\frac{ P }{ R }$ = ??? in feet per ohm ($\text{ft}\Omega^{-1}$)
|
||||
|
||||
> [!info] Ohm's Law
|
||||
> $$
|
||||
> V = I \times R, \quad R = \frac{ V }{ I }, \quad I = \frac{ V }{ R }
|
||||
> $$
|
||||
|
||||
@@ -0,0 +1,123 @@
|
||||
---
|
||||
id:
|
||||
aliases:
|
||||
- nec-110
|
||||
tags:
|
||||
- authorship/other
|
||||
- destiny/uncertain
|
||||
- status/incomplete
|
||||
- topic/electrical
|
||||
- type/encyclopedia
|
||||
---
|
||||
# Article 110 Requirements for Electrical Installations
|
||||
|
||||
## Part I. General
|
||||
|
||||
### 110.1 Scope.
|
||||
|
||||
This article covers general requirements
|
||||
for the examination and approval, installation and use,
|
||||
access to and spaces about electrical conductors and equipment;
|
||||
enclosures intended for personnel entry;
|
||||
and tunnel installations.
|
||||
|
||||
> [!info] Informational Note:
|
||||
> See Informative Annex J for information regarding ADA accessibility design.
|
||||
|
||||
<!-- TODO: TEXT OMITTED -->
|
||||
|
||||
### 110.14 Electrical Connections.
|
||||
|
||||
Because of different characteristics of dissimilar metals,
|
||||
devices such as pressure terminal
|
||||
or pressure splicing connectors and soldering lugs
|
||||
shall be identified for the material of the conductor
|
||||
and shall be properly installed and used.
|
||||
Conductors of dissimilar metals
|
||||
shall not be intermixed in a terminal or splicing connector
|
||||
where physical contact occurs between dissimilar conductors
|
||||
(such as copper and aluminum or aluminum and copper-clad aluminum),
|
||||
unless the device is identified for the purpose and conditions of use.
|
||||
Materials such as solder, fluxes, inhibitors, and compounds,
|
||||
where employed, shall be suitable for the use
|
||||
and shall be of a type that will not adversely affect
|
||||
the conductors, installation, or equipment.
|
||||
Connectors and terminals for conductors more finely stranded
|
||||
than Class B and Class C stranding as shown in Chapter 9, Table 10,
|
||||
shall be identified for the specific conductor class or classes.
|
||||
|
||||
#### 110.14(C) Temperature Limitations.
|
||||
|
||||
The temperature rating associated with the ampacity of a conductor
|
||||
shall be selected and coordinated so as not to exceed the lowest
|
||||
temperature rating of any connected termination, conductor, or device.
|
||||
Conductors with temperature ratings higher than specified for
|
||||
terminations shall be permitted to be used
|
||||
for ampacity adjustment, correction, or both.
|
||||
|
||||
##### 110.14(C)(1) Equipment Provisions.
|
||||
|
||||
The determination of termination provisions of equipment
|
||||
shall be based on 110.14(C)(1)(a) or (C)(1)(b).
|
||||
Unless the equipment is listed and marked otherwise,
|
||||
conductor ampacities used in determining equipment termination provisions
|
||||
shall be based on Table 310.16 as appropriately modified by 310.12.
|
||||
|
||||
* (a) Termination provisions of equipment for circuits rated 100 amperes or less,
|
||||
or marked for 14 AWG through 1 AWG conductors,
|
||||
shall be used only for one of the following:
|
||||
* (1) Conductors rated 60°C (140°F).
|
||||
* (2) Conductors with higher temperature ratings,
|
||||
provided the ampacity of such conductors
|
||||
is determined based on the 60°C (140°F) ampacity of the conductor size used.
|
||||
* (3) Conductors with higher temperature ratings
|
||||
if the equipment is listed and identified for use with such conductors.
|
||||
* (4) For motors marked with design letters B, C, or D,
|
||||
conductors having an insulation rating of 75°C (167°F) or higher
|
||||
shall be permitted to be used,
|
||||
provided the ampacity of such conductors
|
||||
does not exceed the 75°C (167°F) ampacity.
|
||||
|
||||
* (b) Termination provisions of equipment
|
||||
for circuits rated over 100 amperes,
|
||||
or marked for conductors larger than 1 AWG,
|
||||
shall be used only for one of the following:
|
||||
* (1) Conductors rated 75°C (167°F)
|
||||
* (2) Conductors with higher temperature ratings,
|
||||
provided the ampacity of such conductors
|
||||
does not exceed the 75°C (167°F) ampacity of the conductor size used,
|
||||
or up to their ampacity if the equipment is listed and identified
|
||||
for use with such conductors
|
||||
|
||||
##### 110.14(C)(2) Separate Connector Provisions.
|
||||
|
||||
Separately installed pressure connectors shall be used with conductors at the ampacities not exceeding the ampacity at the listed and identified temperature rating of the connector.
|
||||
|
||||
Informational Note:
|
||||
With respect to 110.14(C)(1) and (C)(2),
|
||||
equipment markings or listing information may additionally restrict
|
||||
the sizing and temperature ratings of connected conductors.
|
||||
|
||||
#### 110.14(D) Terminal Connection Torque.
|
||||
|
||||
Tightening torque values for terminal connections
|
||||
shall be as indicated on equipment
|
||||
or in installation instructions provided by the manufacturer.
|
||||
An approved means shall be used to achieve the indicated torque value.
|
||||
|
||||
Informational Note No. 1:
|
||||
Examples of approved means of achieving the indicated torque values
|
||||
include torque tools or devices such as shear bolts
|
||||
or breakaway-style devices with visual indicators
|
||||
that demonstrate that the proper torque has been applied.
|
||||
|
||||
Informational Note No. 2:
|
||||
The equipment manufacturer can be contacted
|
||||
if numeric torque values are not indicated on the equipment
|
||||
or if the installation instructions are not available.
|
||||
Informative Annex I of UL Standard 486A-486B, Standard for Safety-Wire Connectors,
|
||||
provides torque values in the absence of manufacturer's recommendations.
|
||||
|
||||
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.
|
||||
@@ -0,0 +1,293 @@
|
||||
---
|
||||
id:
|
||||
aliases:
|
||||
- nec-210
|
||||
tags:
|
||||
- authorship/other
|
||||
- destiny/uncertain
|
||||
- status/incomplete
|
||||
- topic/electrical
|
||||
- type/encyclopedia
|
||||
---
|
||||
# NEC Article 210 Branch Circuits
|
||||
|
||||
## Part I. General Provisions
|
||||
|
||||
### 210.1 Scope.
|
||||
|
||||
This article provides the general requirements for branch circuits.
|
||||
|
||||
<!-- TODO: TEXT OMITTED -->
|
||||
|
||||
### 210.11 Branch Circuits Required.
|
||||
|
||||
Branch circuits for lighting and for appliances,
|
||||
including motor-operated appliances,
|
||||
shall be provided to supply the loads calculated in accordance with 220.10.
|
||||
In addition, branch circuits shall be provided for specific loads not covered by 220.10
|
||||
where required elsewhere in this Code
|
||||
and for dwelling unit loads as specified in 210.11(C).
|
||||
|
||||
#### 210.11(A) Number of Branch Circuits.
|
||||
|
||||
The minimum number of branch circuits
|
||||
shall be determined from the total calculated load
|
||||
and the size or rating of the circuits used.
|
||||
In all installations, the number of circuits
|
||||
shall be sufficient to supply the load served.
|
||||
In no case shall the load on any circuit exceed the maximum specified by 220.18.
|
||||
|
||||
#### 210.11(B) Load Evenly Proportioned Among Branch Circuits.
|
||||
|
||||
Where the load is calculated on the basis of volt-amperes per square meter or per square foot,
|
||||
the wiring system up to and including the branch-circuit panelboard(s)
|
||||
shall be provided to serve not less than the calculated load.
|
||||
This load shall be evenly proportioned
|
||||
among multioutlet branch circuits within the panelboard(s).
|
||||
Branch-circuit overcurrent devices and circuits
|
||||
shall be required to be installed only to serve the connected load.
|
||||
|
||||
#### 210.11(C) Dwelling Units.
|
||||
|
||||
##### 210.11(C)(1) Small-Appliance Branch Circuits.
|
||||
|
||||
In addition to the number of branch circuits required by other parts of this section,
|
||||
two or more 20-ampere small-appliance branch circuits shall be provided
|
||||
for all receptacle outlets specified by 210.52(B).
|
||||
|
||||
##### 210.11(C)(2) Laundry Branch Circuits.
|
||||
|
||||
In addition to the number of branch circuits required by other parts of this section,
|
||||
at least one additional 20-ampere branch circuit shall be provided
|
||||
to supply the laundry receptacle outlet(s) required by 210.52(F).
|
||||
This circuit shall have no other outlets.
|
||||
|
||||
##### 210.11(C)(3) Bathroom Branch Circuits.
|
||||
|
||||
In addition to the number of branch circuits required by other parts of this section,
|
||||
one or more 120-volt, 20-ampere branch circuit shall be provided
|
||||
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).
|
||||
|
||||
##### 210.11(C)(4) Garage Branch Circuits.
|
||||
|
||||
In addition to the number of branch circuits required by other parts of this section,
|
||||
at least one 120-volt, 20-ampere branch circuit shall be installed
|
||||
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.
|
||||
|
||||
<!-- TODO: TEXT OMITTED -->
|
||||
|
||||
## Part II. Branch-Circuit Ratings
|
||||
|
||||
### 210.18 Rating.
|
||||
|
||||
Branch circuits recognized by this article
|
||||
shall be rated in accordance with the maximum permitted ampere rating
|
||||
or setting of the overcurrent device.
|
||||
The rating for other than individual branch circuits
|
||||
shall be 15, 20, 30, 40, and 50 amperes.
|
||||
Where conductors of higher ampacity are used for any reason,
|
||||
the ampere rating or setting of the specified overcurrent device
|
||||
shall determine the circuit rating.
|
||||
|
||||
> [!important] Exception:
|
||||
> Multioutlet branch circuits greater than 50 amperes
|
||||
> shall be permitted to supply nonlighting outlet loads on industrial premises
|
||||
> 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(A) Branch Circuits Not More Than 600 Volts.
|
||||
|
||||
##### 210.19(A)(1) General.
|
||||
|
||||
Branch-circuit conductors shall have an ampacity
|
||||
not less than the larger of 210.19(A)(1)(a) or (A)(1)(b)
|
||||
and comply with
|
||||
[[nfpa-70_article-110_requirements-for-electrical-installations#110.14(C) Temperature Limitations.|110.14(C)]]
|
||||
for equipment terminations.
|
||||
|
||||
* (a) Where a branch circuit supplies continuous loads
|
||||
or any combination of continuous and noncontinuous loads,
|
||||
the minimum branch-circuit conductor size
|
||||
shall have an ampacity not less than the noncontinuous load
|
||||
plus 125 percent of the continuous load in accordance with
|
||||
[[nfpa-70_article-310_conductors_for_general_wiring#310.14 Ampacities for Conductors Rated 0 Volts – 2000 Volts.|310.14]].
|
||||
|
||||
* (b) The minimum branch-circuit conductor size
|
||||
shall have an ampacity not less than the maximum load to be served
|
||||
after the application of any adjustment
|
||||
or correction factors in accordance with
|
||||
[[nfpa-70_article-310_conductors_for_general_wiring#310.15 Ampacity Tables.|310.15]].
|
||||
|
||||
##### 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 -->
|
||||
|
||||
### 210.21 Outlet Devices.
|
||||
|
||||
Outlet devices shall have an ampere rating
|
||||
that is not less than the load to be served
|
||||
and shall comply with 210.21(A) and (B).
|
||||
|
||||
#### 210.21(A) Lampholders.
|
||||
|
||||
Where connected to a branch circuit having a rating in excess of 20 amperes, lampholders
|
||||
shall be of the heavy-duty type. A heavy-duty lampholder
|
||||
shall have a rating of not less than 660 watts if of the admedium type,
|
||||
or not less than 750 watts if of any other type.
|
||||
|
||||
#### 210.21(B) Receptacles.
|
||||
|
||||
##### 210.21(B)(1) Single Receptacle on an Individual Branch Circuit.
|
||||
|
||||
A single receptacle installed on an individual branch circuit
|
||||
shall have an ampere rating
|
||||
not less than that of the branch circuit.
|
||||
|
||||
> [!important] Exception No. 1:
|
||||
> A receptacle installed in accordance with 430.81(B).
|
||||
|
||||
> [!important] Exception No. 2:
|
||||
> A receptacle installed exclusively for the use of a cord-and-plug-connected arc welder
|
||||
> shall be permitted to have an ampere rating
|
||||
> not less than the minimum branch-circuit conductor ampacity
|
||||
> determined by 630.11(A) for arc welders.
|
||||
|
||||
> [!info] Informational Note:
|
||||
> See the definition of receptacle in Article 100.
|
||||
|
||||
##### 210.21(B)(2) Total Cord-and-Plug-Connected Load.
|
||||
|
||||
Where connected to a branch circuit supplying two or more receptacles or outlets,
|
||||
a receptacle shall not supply a total cord-and-plug-connected load
|
||||
in excess of the maximum specified in Table 210.21(B)(2).
|
||||
|
||||
##### Table 210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle
|
||||
|
||||
| Circuit Rating (Amperes) | Receptacle Rating (Amperes) | Maximum Load (Amperes) |
|
||||
| ------------------------ | --------------------------- | ---------------------- |
|
||||
| 15 or 20 | 15 | 12 |
|
||||
| 20 | 20 | 16 |
|
||||
| 30 | 30 | 24 |
|
||||
|
||||
##### 210.21(B)(3) Receptacle Ratings.
|
||||
|
||||
Where connected to a branch circuit supplying two or more receptacles or outlets,
|
||||
receptacle ratings shall conform to the values listed in Table 210.21(B)(3),
|
||||
or, where rated higher than 50 amperes,
|
||||
the receptacle rating shall not be less than the branch-circuit rating.
|
||||
|
||||
> [!important] Exception No. 1:
|
||||
> Receptacles installed exclusively
|
||||
> for the use of one or more cord-and-plug-connected arc welders
|
||||
> shall be permitted to have ampere ratings
|
||||
> not less than the minimum branch-circuit conductor ampacity
|
||||
> determined by 630.11(A) or (B) for arc welders.
|
||||
|
||||
> [!important] Exception No. 2:
|
||||
> The ampere rating of a receptacle
|
||||
> installed for electric discharge lighting
|
||||
> shall be permitted to be based on 410.62(C).
|
||||
|
||||
##### Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits
|
||||
|
||||
| Circuit Rating (Amperes) | Receptacle Rating (Amperes) |
|
||||
| ------------------------ | --------------------------- |
|
||||
| 15 | Not over 15 |
|
||||
| 20 | 15 or 20 |
|
||||
| 30 | 30 |
|
||||
| 40 | 40 or 50 |
|
||||
| 50 | 50 |
|
||||
|
||||
##### 210.21(B)(4) Range Receptacle Rating.
|
||||
|
||||
The ampere rating of a range receptacle
|
||||
shall be permitted to be based on a single range demand load
|
||||
as specified in Table 220.55.
|
||||
|
||||
### 210.22 Permissible Loads, Individual Branch Circuits.
|
||||
|
||||
An individual branch circuit
|
||||
shall be permitted to supply any load for which it is rated,
|
||||
but in no case shall the load exceed the branch-circuit ampere rating.
|
||||
|
||||
### 210.23 Permissible Loads, Multiple-Outlet Branch Circuits.
|
||||
|
||||
In no case shall the load exceed the branch-circuit ampere rating.
|
||||
A branch circuit supplying two or more outlets or receptacles
|
||||
shall supply only the loads specified according to its size
|
||||
as specified in 210.23(A) through (D)
|
||||
and as summarized in 210.24 and Table 210.24.
|
||||
|
||||
#### 210.23(A) 15- and 20-Ampere Branch Circuits.
|
||||
|
||||
A 15- or 20-ampere branch circuit
|
||||
shall be permitted to supply lighting units
|
||||
or other utilization equipment,
|
||||
or a combination of both,
|
||||
and shall comply with 210.23(A)(1) and (A)(2).
|
||||
|
||||
> [!important] Exception:
|
||||
> The small-appliance branch circuits,
|
||||
> laundry branch circuits, and bathroom branch circuits
|
||||
> required in a dwelling unit(s) by 210.11(C)(1), (C)(2), and (C)(3)
|
||||
> shall supply only the receptacle outlets specified in that section.
|
||||
|
||||
##### 210.23(A)(1) Cord-and-Plug-Connected Equipment Not Fastened in Place.
|
||||
|
||||
The rating of any one cord-and-plug-connected utilization equipment not fastened in place
|
||||
shall not exceed 80 percent of the branch-circuit ampere rating.
|
||||
|
||||
##### 210.23(A)(2) Utilization Equipment Fastened in Place.
|
||||
|
||||
The total rating of utilization equipment fastened in place, other than luminaires,
|
||||
shall not exceed 50 percent of the branch-circuit ampere rating
|
||||
where lighting units, cord-and-plug-connected utilization equipment not fastened in place,
|
||||
or both, are also supplied.
|
||||
|
||||
#### 210.23(B) 30-Ampere Branch Circuits.
|
||||
|
||||
A 30-ampere branch circuit
|
||||
shall be permitted to supply fixed lighting units
|
||||
with heavy-duty lampholders in other than a dwelling unit(s)
|
||||
or utilization equipment in any occupancy.
|
||||
A rating of any one cord-and-plug-connected utilization equipment
|
||||
shall not exceed 80 percent of the branch-circuit ampere rating.
|
||||
|
||||
##### 210.23(C) 40and 50-Ampere Branch Circuits.
|
||||
|
||||
A 40- or 50-ampere branch circuit
|
||||
shall be permitted to supply cooking appliances
|
||||
that are fastened in place in any occupancy.
|
||||
In other than dwelling units,
|
||||
such circuits shall be permitted to supply
|
||||
fixed lighting units with heavy-duty lampholders,
|
||||
infrared heating units,
|
||||
or other utilization equipment.
|
||||
|
||||
#### 210.23(D) Branch Circuits Larger Than 50 Amperes.
|
||||
|
||||
Branch circuits larger than 50 amperes
|
||||
shall supply only nonlighting outlet loads.
|
||||
|
||||
<!-- TODO: TEXT OMITTED -->
|
||||
@@ -0,0 +1,86 @@
|
||||
---
|
||||
id:
|
||||
aliases:
|
||||
- nec-215
|
||||
tags:
|
||||
- authorship/other
|
||||
- destiny/uncertain
|
||||
- status/incomplete
|
||||
- topic/electrical
|
||||
- type/encyclopedia
|
||||
---
|
||||
# Article 215 Feeders
|
||||
|
||||
## 215.1 Scope.
|
||||
|
||||
This article covers the installation requirements, overcurrent protection requirements, minimum size, and ampacity of conductors for
|
||||
feeders.
|
||||
|
||||
Exception:
|
||||
Feeders for electrolytic cells as covered in 668.3(C)(1) and (C)(4).
|
||||
|
||||
#### 215.2 Minimum Rating and Size.
|
||||
|
||||
#### 215.2(A) Feeders Not More Than 1000 Volts.
|
||||
|
||||
#### 215.2(A)(1) General.
|
||||
|
||||
Feeder conductors shall have an ampacity
|
||||
not less than the larger of 215.2(A)(1)(a) or (A)(1)(b)
|
||||
and shall comply with 110.14(C).
|
||||
|
||||
- (a) Where a feeder supplies continuous loads
|
||||
or any combination of continuous and noncontinuous loads,
|
||||
the minimum feeder conductor size shall have an ampacity
|
||||
not less than the noncontinuous load plus 125 percent of the continuous load.
|
||||
|
||||
- (b) The minimum feeder conductor size
|
||||
shall have an ampacity not less than the maximum load to be served
|
||||
after the application of any adjustment or correction factors
|
||||
in accordance with
|
||||
[[nfpa-70_article-310_conductors_for_general_wiring#310.14 Ampacities for Conductors Rated 0 Volts – 2000 Volts.|310.14]].
|
||||
|
||||
Exception No. 1:
|
||||
If the assembly, including the overcurrent devices protecting the feeder(s),
|
||||
is listed for operation at 100 percent of its rating,
|
||||
the ampacity of the feeder conductors shall be permitted to be not less
|
||||
than the sum of the continuous load plus the noncontinuous load.
|
||||
|
||||
Exception No. 2:
|
||||
Where a portion of a feeder 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 ampacity
|
||||
not less than the sum of the continuous load plus the noncontinuous load.
|
||||
No portion of a feeder installed under this exception
|
||||
shall extend into an enclosure containing either the feeder supply
|
||||
or the feeder load terminations, as covered in 110.14(C)(1).
|
||||
|
||||
Exception No. 3:
|
||||
Grounded conductors that are not connected to an overcurrent device
|
||||
shall be permitted to be sized at 100 percent
|
||||
of the continuous and noncontinuous load.
|
||||
|
||||
Informational Note No. 1:
|
||||
See Examples D1 through D11 in Informative Annex D.
|
||||
|
||||
Informational Note No. 2:
|
||||
Conductors for feeders, as defined in Article 100,
|
||||
sized to prevent a voltage drop exceeding 3 percent
|
||||
at the farthest outlet of power, heating, and lighting loads,
|
||||
or combinations of such loads,
|
||||
and where the maximum total voltage drop on both feeders and branch circuits
|
||||
to the farthest outlet does not exceed 5 percent,
|
||||
will provide reasonable efficiency of operation.
|
||||
|
||||
Informational Note No. 3:
|
||||
See 210.19(A), Informational Note No. 4, for voltage drop for branch circuits.
|
||||
|
||||
#### 215.2(A)(2) Grounded Conductor.
|
||||
|
||||
The size of the feeder circuit grounded conductor
|
||||
shall not be smaller than that required by 250.122,
|
||||
except that 250.122(F) shall not apply
|
||||
where grounded conductors are run in parallel.
|
||||
|
||||
Additional minimum sizes shall be as specified in 215.2(A)(3)
|
||||
under the conditions stipulated.
|
||||
@@ -0,0 +1,154 @@
|
||||
---
|
||||
id:
|
||||
aliases:
|
||||
- nec-220
|
||||
tags:
|
||||
- authorship/other
|
||||
- destiny/uncertain
|
||||
- status/incomplete
|
||||
- topic/electrical
|
||||
- type/encyclopedia
|
||||
---
|
||||
# Article 220 Branch-Circuit, Feeder, and Service Load Calculations
|
||||
|
||||
## Part I. General
|
||||
|
||||
### 220.1 Scope.
|
||||
|
||||
This article provides requirements
|
||||
for calculating branch-circuit, feeder, and service loads.
|
||||
Part I provides general requirements for calculation methods.
|
||||
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.
|
||||
|
||||
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 -->
|
||||
|
||||
### 220.14 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 -->
|
||||
|
||||
#### 220.14(A) Specific Appliances or Loads.
|
||||
|
||||
An outlet for a specific appliance
|
||||
or other load not covered in 220.14(B) through (M)
|
||||
shall be calculated based on the ampere rating
|
||||
of the appliance or load served.
|
||||
|
||||
#### 220.14(B) Electric Dryers and Electric Cooking Appliances in Dwellings and Household Cooking Appliances Used in Instructional Programs.
|
||||
|
||||
Load calculations shall be permitted
|
||||
as specified in 220.54 for electric dryers
|
||||
and in 220.55 for electric ranges and other cooking appliances.
|
||||
|
||||
#### 220.14(C) Motor Outlets.
|
||||
|
||||
Loads for motor outlets shall be calculated
|
||||
in accordance with the requirements in 430.22, 430.24, and 440.6.
|
||||
|
||||
#### 220.14(D) Luminaires.
|
||||
|
||||
An outlet supplying luminaire(s) shall be calculated
|
||||
based on the maximum volt-ampere rating of the equipment
|
||||
and lamps for which the luminaire(s) is rated.
|
||||
|
||||
#### 220.14(E) Heavy-Duty Lampholders.
|
||||
|
||||
Outlets for heavy-duty lampholders
|
||||
shall be calculated at a minimum of 600 volt-amperes.
|
||||
|
||||
#### 220.14(F) Sign and Outline Lighting.
|
||||
|
||||
Sign and outline lighting outlets
|
||||
shall be calculated at a minimum of 1200 volt-amperes
|
||||
for each required branch circuit specified in 600.5(A).
|
||||
|
||||
#### 220.14(G) Show Windows.
|
||||
|
||||
Show windows shall be calculated
|
||||
in accordance with either of the following:
|
||||
|
||||
- (1) The unit load per outlet as required in other provisions of this section
|
||||
- (2) At 200 volt-amperes per linear 300 mm (1 ft) of show window
|
||||
|
||||
#### 220.14(H) Fixed Multioutlet Assemblies.
|
||||
|
||||
Fixed multioutlet assemblies used in other than dwelling units
|
||||
or the guest rooms or guest suites of hotels or motels
|
||||
shall be calculated in accordance with (H)(1) or (H)(2).
|
||||
For the purposes of this section,
|
||||
the calculation shall be permitted
|
||||
to be based on the portion that contains receptacle outlets.
|
||||
|
||||
- (1) Where appliances are unlikely to be used simultaneously,
|
||||
each 1.5 m (5 ft) or fraction thereof
|
||||
of each separate and continuous length
|
||||
shall be considered as one outlet of not less than 180 volt-amperes.
|
||||
|
||||
- (2) Where appliances are likely to be used simultaneously,
|
||||
each 300 mm (1 ft) or fraction thereof
|
||||
shall be considered as an outlet of not less than 180 volt-amperes.
|
||||
|
||||
#### 220.14(I) Receptacle Outlets.
|
||||
|
||||
Except as covered in 220.14(J) and (K),
|
||||
receptacle outlets shall be calculated at not less than 180 volt-amperes
|
||||
for each single or for each multiple receptacle on one yoke.
|
||||
A single piece of equipment consisting of a multiple receptacle
|
||||
comprised of four or more receptacles
|
||||
shall be calculated at not less than 90 volt-amperes per receptacle.
|
||||
This provision shall not be applicable to the receptacle outlets
|
||||
specified in [[nfpa-70_article-210_branch-circuits#210.11(C)(1) Small-Appliance Branch Circuits.|210.11(C)(1)]]
|
||||
and [[nfpa-70_article-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 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
|
||||
shall be considered part of the minimum lighting load.
|
||||
|
||||
- (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) and (G)
|
||||
- (3) The lighting outlets specified in 210.70
|
||||
|
||||
#### 220.14(K) Office Buildings.
|
||||
|
||||
In office buildings, the receptacle loads
|
||||
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$^2$
|
||||
|
||||
#### 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 -->
|
||||
@@ -0,0 +1,228 @@
|
||||
---
|
||||
id:
|
||||
aliases:
|
||||
- nec-310
|
||||
tags:
|
||||
- authorship/other
|
||||
- destiny/uncertain
|
||||
- status/incomplete
|
||||
- topic/electrical
|
||||
- type/encyclopedia
|
||||
---
|
||||
# Article 310 Conductors for General Wiring
|
||||
|
||||
## Part I. General
|
||||
|
||||
#### 310.1 Scope.
|
||||
|
||||
This article covers general requirements for conductors
|
||||
rated up to and including 2000 volts
|
||||
and their type designations, insulations, markings,
|
||||
mechanical strengths, ampacity ratings, and uses.
|
||||
These requirements do not apply to conductors that form an integral part of equipment,
|
||||
such as motors, motor controllers, and similar equipment,
|
||||
or to conductors specifically provided for elsewhere in this Code.
|
||||
|
||||
Informational Note:
|
||||
For flexible cords and cables, see Article 400.
|
||||
For fixture wires, see Article 402.
|
||||
|
||||
<!-- TODO: TEXT OMITTED -->
|
||||
|
||||
## Part II. Construction Specifications
|
||||
|
||||
### 310.4 Conductor Constructions and Applications.
|
||||
|
||||
Insulated conductors shall comply with [[#Table 310.4(A) Conductor Applications and Insulations Rated 600 Volts|Table 310.4(A)]]
|
||||
and [[#Table 310.4(B) Thickness of Insulation for Nonshielded Types RHH and RHW Solid Dielectric Insulated Conductors Rated 2000 Volts|Table 310.4(B)]].
|
||||
|
||||
Informational Note:
|
||||
Thermoplastic insulation may stiffen at temperatures lower than −10°C (+14°F).
|
||||
Thermoplastic insulation may also be deformed at normal temperatures
|
||||
where subjected to pressure, such as at points of support.
|
||||
|
||||
### Table 310.4(A) Conductor Applications and Insulations Rated 600 Volts
|
||||
|
||||
<!-- TABLE OMITTED -->
|
||||
|
||||
### Table 310.4(B) Thickness of Insulation for Nonshielded Types RHH and RHW Solid Dielectric Insulated Conductors Rated 2000 Volts
|
||||
|
||||
<!-- TABLE OMITTED -->
|
||||
|
||||
<!-- TODO: TEXT OMITTED -->
|
||||
|
||||
## Part III. Installation
|
||||
|
||||
### 310.10 Uses Permitted.
|
||||
|
||||
The conductors described in [[#310.4 Conductor Constructions and Applications.|310.4]]
|
||||
shall be permitted for use in any of the wiring methods covered in Chapter 3
|
||||
and as specified in their respective tables
|
||||
or as permitted elsewhere in this Code.
|
||||
|
||||
<!-- TODO: TEXT OMITTED -->
|
||||
|
||||
### 310.14 Ampacities for Conductors Rated 0 Volts – 2000 Volts.
|
||||
|
||||
#### 310.14(A) General.
|
||||
|
||||
##### 310.14(A)(1) Tables or Engineering Supervision.
|
||||
|
||||
Ampacities for conductors shall be permitted to be determined by tables as provided in 310.15 or under engineering supervision, as provided in 310.14(B).
|
||||
|
||||
Informational Note No. 1:
|
||||
Ampacities provided by this section
|
||||
do not take voltage drop into consideration.
|
||||
See 210.19(A), Informational Note No. 4, for branch circuits
|
||||
and 215.2(A), Informational Note No. 2, for feeders.
|
||||
|
||||
<!-- TODO: TEXT OMITTED -->
|
||||
|
||||
### 310.15 Ampacity Tables.
|
||||
|
||||
#### 310.15(A) General.
|
||||
|
||||
Ampacities for conductors rated 0 volts to 2000 volts
|
||||
shall be as specified in the Ampacity Table 310.16 through Table 310.21,
|
||||
as modified by 310.15(A) through (F) and 310.12.
|
||||
Under engineering supervision,
|
||||
ampacities of sizes not shown in ampacity tables
|
||||
for conductors meeting the general wiring requirements
|
||||
shall be permitted to be determined by interpolation of the adjacent conductors
|
||||
based on the conductor's area.
|
||||
The temperature correction and adjustment factors
|
||||
shall be permitted to be applied to the ampacity
|
||||
for the temperature rating of the conductor,
|
||||
if the corrected and adjusted ampacity does not exceed the ampacity
|
||||
for the temperature rating of the termination
|
||||
in accordance with the provisions of 110.14(C).
|
||||
|
||||
Informational Note No. 1:
|
||||
Table 310.16 through Table 310.19 are application tables
|
||||
for use in determining conductor sizes on loads
|
||||
calculated in accordance with Part II, Part III, Part IV, or Part V of Article 220.
|
||||
Ampacities result from consideration of one or more of the following:
|
||||
|
||||
* (1) Temperature compatibility with connected equipment, especially the connection points.
|
||||
* (2) Coordination with circuit and system overcurrent protection.
|
||||
* (3) Compliance with the requirements of product listings or certifications. See 110.3(B).
|
||||
* (4) Preservation of the safety benefits of established industry practices and standardized procedures.
|
||||
|
||||
Informational Note No. 2:
|
||||
For conductor area see Chapter 9, Table 8, Conductor Properties.
|
||||
Interpolation is based on the conductor area
|
||||
and not the conductor overall area.
|
||||
|
||||
<!-- Code terminology: **conductor area**, **conductor overall area** -->
|
||||
|
||||
Informational Note No. 3:
|
||||
For the ampacities of flexible cords and cables, see 400.5.
|
||||
For the ampacities of fixture wires, see 402.5.
|
||||
|
||||
Informational Note No. 4:
|
||||
For explanation of type letters used in tables
|
||||
and for recognized sizes of conductors for the various conductor insulations,
|
||||
see Table 310.4(A) and Table 310.4(B).
|
||||
For installation requirements,
|
||||
see 310.1 through 310.14 and the various articles of this Code.
|
||||
For flexible cords,
|
||||
see Table 400.4, Table 400.5(A)(1), and Table 400.5(A)(2).
|
||||
|
||||
#### 310.15(B) Ambient Temperature Correction Factors.
|
||||
|
||||
##### 310.15(B)(1) General.
|
||||
|
||||
Ampacities for ambient temperatures
|
||||
other than those shown in the ampacity tables
|
||||
shall be corrected in accordance with Table 310.15(B)(1) or Table 310.15(B)(2),
|
||||
or shall be permitted to be calculated using Equation 310.15(B).
|
||||
|
||||
<!-- TODO: fix prime notation -->
|
||||
|
||||
$$
|
||||
I\prime = I \sqrt{\frac{ T_c -T_{a}\prime }{ T_c - T_a }}
|
||||
$$
|
||||
|
||||
where:
|
||||
|
||||
* $I\prime$ = ampacity corrected for ambient temperature
|
||||
* $I$ = ampacity shown in the tables
|
||||
* $T_c$ = temperature rating of conductor (°C)
|
||||
* $T_{a}\prime$ = new ambient temperature (°C)
|
||||
* $T_a$ = ambient temperature used in the table (°C)
|
||||
|
||||
##### 310.15(B)(2) Rooftop.
|
||||
|
||||
For raceways or cables exposed to direct sunlight on or above rooftops
|
||||
where the distance above the roof
|
||||
to the bottom of the raceway or cable is less than 23 mm (7⁄8 in.),
|
||||
a temperature adder of 33°C (60°F) shall be added to the outdoor temperature
|
||||
to determine the applicable ambient temperature
|
||||
for application of the correction factors in Table 310.15(B)(1) or Table 310.15(B)(2).
|
||||
|
||||
Exception:
|
||||
Type XHHW-2 insulated conductors shall not be subject to this ampacity adjustment.
|
||||
|
||||
Informational Note:
|
||||
One source for the ambient temperatures in various locations
|
||||
is the ASHRAE Handbook -- Fundamentals.
|
||||
|
||||
##### Table 310.15(B)(1) Ambient Temperature Correction Factors Based on 30°C (86°F)
|
||||
|
||||
For ambient temperatures other than 30°C (86°F),
|
||||
multiply the ampacities specified in the ampacity tables
|
||||
by the appropriate correction factor shown below.
|
||||
|
||||
<!-- TODO: TABLE OMITTED -->
|
||||
|
||||
##### Table 310.15(B)(2) Ambient Temperature Correction Factors Based on 40°C (104°F)
|
||||
|
||||
For ambient temperatures other than 40°C (104°F),
|
||||
multiply the ampacities specified in the ampacity tables
|
||||
by the appropriate correction factor shown below.
|
||||
|
||||
<!-- TODO: TABLE OMITTED -->
|
||||
|
||||
#### 310.15(C) Adjustment Factors.
|
||||
|
||||
##### 310.15(C)(1) More than Three Current-Carrying Conductors.
|
||||
|
||||
The ampacity of each conductor shall be reduced as shown in Table 310.15(C)(1)
|
||||
where the number of current-carrying conductors in a raceway or cable exceeds three,
|
||||
or where single conductors or multiconductor cables not installed in raceways
|
||||
are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.).
|
||||
Each current-carrying conductor of a paralleled set of conductors
|
||||
shall be counted as a current-carrying conductor.
|
||||
|
||||
<!-- TODO: TEXT OMITTED -->
|
||||
|
||||
##### Table 310.15(C)(1) Adjustment Factors for More Than Three Current-Carrying Conductors
|
||||
|
||||
| Number of Conductors* | Percent of Values in Table 310.16 Through Table 310.19 as Adjusted for Ambient Temperature if Necessary |
|
||||
| --------------------- | ------------------------------------------------------------------------------------------------------- |
|
||||
| 4–6 | 80 |
|
||||
| 7–9 | 70 |
|
||||
| 10–20 | 50 |
|
||||
| 21–30 | 45 |
|
||||
| 31–40 | 40 |
|
||||
| 41 and above | 35 |
|
||||
|
||||
\*Number of conductors is the total number of conductors in the raceway or cable,
|
||||
including spare conductors.
|
||||
The count shall be adjusted in accordance with 310.15(E) and (F).
|
||||
The count shall not include conductors
|
||||
that are connected to electrical components
|
||||
that cannot be simultaneously energized.
|
||||
|
||||
##### 310.15(C)(2) Raceway Spacing.
|
||||
|
||||
Spacing between raceways shall be maintained.
|
||||
|
||||
#### 310.15(D) Bare or Covered Conductors.
|
||||
|
||||
Where bare or covered conductors are installed with insulated conductors,
|
||||
the temperature rating of the bare or covered conductor
|
||||
shall be equal to the lowest temperature rating of the insulated conductors
|
||||
for the purpose of determining ampacity.
|
||||
|
||||
<!-- TODO: TEXT OMITTED -->
|
||||
@@ -1,32 +0,0 @@
|
||||
---
|
||||
id:
|
||||
aliases: []
|
||||
tags:
|
||||
- destiny/fleeting
|
||||
- type/idea
|
||||
---
|
||||
# Voltage Drop
|
||||
|
||||
> [!info] Ohm's Law
|
||||
> $$
|
||||
> V = I \times R \quad R = \frac{ V }{ I }
|
||||
> $$
|
||||
|
||||
$$
|
||||
Vd = \frac{ I \times R \times L \times M }{ P }
|
||||
$$
|
||||
|
||||
$$
|
||||
L = \frac{ Vd }{ I \times M } \times \frac{ P }{ R }
|
||||
$$
|
||||
|
||||
where
|
||||
|
||||
- $Vd$ = Maximum Voltage Drop in volts
|
||||
- $I$ = Current in Amps
|
||||
- $R$ = Resistance in ohms per foot
|
||||
- $L$ = Length of wire one way in feet
|
||||
- $M$ = Multiplier
|
||||
- $2$ for 1-phase
|
||||
- $\sqrt{3}$ for 3-phase
|
||||
- $P$ = Number of parallel runs
|
||||
Reference in New Issue
Block a user