Article 110 Requirements for Electrical Installations

I. General

110.1

Scope

110.2

Approval

Only approved equipment and conductors are acceptable.

110.3

Examination, Identification, Installation, and Use of Equipment

The Code lists considerations for the examination of equipment such as mechanical strength, electrical insulation, etc.

110.4

Voltages

110.5

Conductors

Copper is to be used unless otherwise specified. Sizes given are for copper unless otherwise specified.

110.6

Conductor SizesExpressed in American Wire Gage (AWG) or in Circular Mils

110.7

Insulation Integrity

110.8

Wiring Methods

110.9

Interrupting Rating

110.10

Circuit Impedance and Other Characteristics

The entire electrical circuit, including all devices and wire, must be chosen and coordinated so that a fault will be cleared before extensive damage takes place.

110.11

Deteriorating Agents

110.12

Mechanical Execution of Work

110.13

Mounting and Cooling of Equipment

110.14

Electrical Connections

110.15

High-Leg Marking

110.16

Flash Protection

110.18

Arcing Parts

110.19

Light and Power from Railway Conductors

110.21

Marking

110.22

Identification of Disconnecting Means

110.23

Current Transformers

 

II. 600 Volts, Nominal, or Less

110.26

Spaces about Electrical Equipment

(A) Clearances for three conditions are noted. Condition 1 consists of live exposed parts on one side and no live or grounded parts on the other side of the working space or guarded live parts (wood or other insulating material used) on both sides of the working space. Condition 2 consists of exposed live parts on one side and grounded parts on the other side. Condition 3 consists of exposed live parts on both sides. For voltages to ground between 0 and 150 V, a minimum clear distance of 900 mm (3 ft.) is required in all cases. For voltages to ground between 151 and 600 V, Condition 1 requires 900 mm (3 ft.) clearance. Condition 2 requires 1.1 m (3½ ft.), and Condition 3 requires 1.2 m (4 ft.). No working space is required behind assemblies where no renewable parts are on the back and all wiring is accessible from the front (such as panelboards). A minimum of 762 mm (30 in.) in width is required in front of electrical equipment as well as room for a 90° opening of doors. There are requirements in the Code when the voltage is not greater than 30 volts rms, 42 volts peak, or 60 volts dc. There are also requirements in existing buildings where equipment is being replaced.

(E) Headroom of 2 m (6½ ft.) is required above service equipment, motor control centers, panelboards, or switchboards, with the exception of dwelling units not in excess of 200 A. If the equipment exceeds 2 m (6½ ft.), headroom shall be at least the height of the equipment.

110.27

Guarding Live Parts

 

III. Over 600 Volts, Nominal

110.30

General

110.31

Enclosure for Electrical Installations

110.32

Work Space about Equipment

110.33

Entrance and Access to Work Space

110.34

Work Space and Guarding

110.36

Circuit Conductors

110.40

Temperature Limitations at Terminations

 

IV. Tunnel Installations Over 600 Volts, Nominal

110.51

General

110.52

Overcurrent Protection

110.53

Conductors

110.54

Bonding and Equipment Grounding Conductors

110.55

Transformers, Switches, and Electrical Equipment

110.56

Energized Parts

110.57

Ventilation System Controls

110.58

Disconnecting Means

110.59

Enclosures

 

V. Manholes and Other Electric Enclosures Intended for Personnel, All Voltages

110.70

General

110.71

Strength

110.72

Cabling Work Space

110.73

Equipment Work Space

110.74

Bending Space for Conductors

110.75

Access to Manholes

110.76

Access to Vaults and Tunnels

110.77

Ventilation

110.78

Guarding

110.79

Fixed Ladders






Pocket Guide to the National Electrical Code 2005
Pocket Guide to the National Electrical Code(R), 2005 Edition (8th Edition)
ISBN: 0131480014
EAN: 2147483647
Year: 2004
Pages: 120
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