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nfpa-70_110_requirements-for-electrical-installations.md
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- status/incomplete
- topic/electrical
- type/media
title: Article 110 Requirements for Electrical Installations
title: "NEC Article 110: Requirements for Electrical Installations"
---
# Article 110 Requirements for Electrical Installations
# NEC Article 110: Requirements for Electrical Installations
## Part I. General
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### 110.8 Wiring Methods
Only wiring methods recognized as suitable
are included in this Code.
The recognized methods of wiring
shall be permitted to be installed
in any type of building or occupancy,
except as otherwise provided in this Code.
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### 110.14 Electrical Connections.
Because of different characteristics of dissimilar metals,
@@ -122,3 +133,115 @@ 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.
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## Part II. 1000 Volts, Nominal, or Less
### 110.26 Spaces About Electrical Equipment.
Access and working space shall be provided and maintained about all electrical equipment to permit ready and safe operation and
maintenance of such equipment.
#### 110.26(A) Working Space.
Working space for equipment operating at 1000 volts, nominal, or less to ground and likely to require examination, adjustment,
servicing, or maintenance while energized shall comply with the dimensions of 110.26(A)(1), (A)(2), (A)(3), and (A)(4) or as required or
permitted elsewhere in this Code.
Informational Note: NFPA 70E-2018, Standard for Electrical Safety in the Workplace, provides guidance, such as determining severity
of potential exposure, planning safe work practices including establishing an electrically safe work condition, arc flash labeling, and
selecting personal protective equipment.
### 110.26(A)(1) Depth of Working Space.
The depth of the working space in the direction of live parts shall not be less than that specified in Table 110.26(A)(1) unless the
requirements of 110.26(A)(1)(a), (A)(1)(b), or (A)(1)(c) are met. Distances shall be measured from the exposed live parts or from the
enclosure or opening if the live parts are enclosed.
### Table 110.26(A)(1) Working Spaces
Minimum Clear Distance
| Nominal Voltage to Ground | Condition 1 | Condition 2 | Condition 3 |
| ------------------------- | ------------- | ------------------ | ------------- |
| 0–150 | 900 mm (3 ft) | 900 mm (3 ft) | 900 mm (3 ft) |
| 151–600 | 900 mm (3 ft) | 1.0 m (3 ft 6 in.) | 1.2 m (4 ft) |
| 601–1000 | 900 mm (3 ft) | 1.2 m (4 ft) | 1.5 m (5 ft) |
Note: Where the conditions are as follows:
* 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
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.
(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.
(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.
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#### 110.26(C)(3) Personnel Doors.
Where equipment rated 800 amperes or more that contains overcurrent devices, switching devices, or control devices is installed and there is a personnel door(s) 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 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.
#### 110.26(D) Illumination.
Illumination shall be provided for all working spaces about service equipment, switchboards, switchgear, panelboards, or motor control centers installed indoors. Control by automatic means shall not be permitted to control all illumination within the working space. Additional lighting outlets shall not be required where the work space is illuminated by an adjacent light source or as permitted by 210.70(A)(1), Exception No. 1, for switched receptacles.
#### 110.26(E) Dedicated Equipment Space.
All switchboards, switchgear, panelboards, and motor control centers
shall be located in dedicated spaces and protected from damage.
Exception:
Control equipment that
by its very nature or because of other rules of the Code
must be adjacent to or within sight of its operating machinery
shall be permitted in those locations.
#### 110.26(E)(1) Indoor.
Indoor installations shall comply with 110.26(E)(1)(a) through (E)(1)(d).
* (a) _Dedicated Electrical Space._ The space equal to the width and depth of the equipment and extending from the floor to a height of 1.8 m (6 ft) above the equipment or to the structural ceiling, whichever is lower, shall be dedicated to the electrical installation. No piping, ducts, leak protection apparatus, or other equipment foreign to the electrical installation shall be located in this zone.
Exception: Suspended ceilings with removable panels shall be permitted within the 1.8 m (6-ft) zone.
* (b) _Foreign Systems._ The area above the dedicated space required by 110.26(E)(1)(a) shall be permitted to contain foreign
systems, provided protection is installed to avoid damage to the electrical equipment from condensation, leaks, or breaks in
such foreign systems.
* (c) _Sprinkler Protection._ Sprinkler protection shall be permitted for the dedicated space where the piping complies with this section.
* (d) _Suspended Ceilings._ A dropped, suspended, or similar ceiling that does not add strength to the building structure shall not be
considered a structural ceiling.
#### 110.26(E)(2) Outdoor.
Outdoor installations shall comply with 110.26(E)(2)(a) through (E)(2)(c).
* (a) Installation Requirements. Outdoor electrical equipment shall be the following:
1. Installed in identified enclosures
2. Protected from accidental contact by unauthorized personnel or by vehicular traffic
3. Protected from accidental spillage or leakage from piping systems
* (b) Work Space. The working clearance space shall include the zone described in 110.26(A). No architectural appurtenance or other equipment shall be located in this zone.
* (c) Dedicated Equipment Space. The space equal to the width and depth of the equipment, and extending from grade to a height of 1.8 m (6 ft) above the equipment, shall be dedicated to the electrical installation. No piping or other equipment foreign to the electrical installation shall be located in this zone.
Exception: Structural overhangs or roof extensions shall be permitted in this zone.
#### 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.