All questions and answers are based on the 2017 NEC.
Underlined text indicates a Code change.
Q. What does the Code require for overcurrent protection of flexible cords, flexible cables, and fixture wires?
A. Flexible cord and flexible cable must be protected by an overcurrent protection device in accordance with its ampacity as specified in Table 400.5(A)(1) or Table 400.5(A)(2). Fixture wires must be protected against overcurrent in accordance with their ampacity as specified in Table 402.5. Supplementary overcurrent protection, as discussed in Sec. 240.10, can provide this protection [240.5(A)].
Branch-circuit overcurrent protection must be provided for cords for listed appliances or luminaires. If flexible cord is used with a specific listed appliance or luminaire, the conductors are considered protected against overcurrent when used within the appliance or luminaire listing requirements [240.5(B)(1)].
Note: The NEC only applies to premises wiring, not to the supply cords of listed appliances and luminaires.
The branch circuit overcurrent protection device can be used to protect fixture wires when they are tapped to the following circuits [240.5(B)(2)]:
(1) 20A – 18 AWG, up to 50 ft of run length
(2) 20A – 16 AWG, up to 100 ft of run length
(3) 20A – 14 AWG and larger
(4) 30A – 14 AWG and larger
(5) 40A – 12 AWG and larger
(6) 50A – 12 AWG and larger
Flexible cord used in listed extension cord sets is considered protected against overcurrent when used within the extension cord’s listing requirements [240.5(B)(3)].
Q. When does the Code require ground-fault protection of equipment on electrical services?
A. Service disconnects and feeder circuits rated 1,000A or more, supplied from a 4-wire, 3-phase, 277/480V wye-connected system must be protected against ground faults in accordance with Sec. 230.95 [240.13].
The requirement for ground-fault protection of equipment doesn’t apply to:
(1) Continuous industrial processes where a nonorderly shutdown will introduce additional or increased hazards.
(2) Installations where ground-fault protection of equipment is already provided.
(3) Fire pumps [695.6(H)].
Note: Article 100 defines “Ground-Fault Protection of Equipment” as a system intended to provide overcurrent protection of equipment from ground faults by opening the overcurrent protection device at current levels less than those required to protect conductors from damage. This type of protective system isn’t intended to protect people, only connected equipment. See Sec. 215.10 and Sec. 230.95 for similar requirements for feeders and services. Ground-fault protection of equipment isn’t required for emergency power systems [700.26] or legally required standby power systems [701.17].
Q. What is the Code requirement for the physical location of overcurrent protection devices?
A. Circuit breakers and switches containing fuses must be readily accessible and installed so the center of the grip of the operating handle of the circuit breaker or switch, when in its highest position, isn’t more than 6 ft, 7 in. above the floor or working platform, except for [240.24(A)]:
(1) Busways, as provided in Sec. 368.17(C).
(2) Supplementary overcurrent protection devices per Sec. 240.10.
(3) For overcurrent protection devices, as described in Sec. 225.40 and Sec. 230.92.
(4) Circuit breakers and switches containing fuses are permitted above 6 ft, 7 in. where located next to equipment if accessible by portable means [404.8(A), Exception No. 2].
Exception: The use of a tool is permitted to access overcurrent protection devices located within listed industrial control panels or similar enclosures.
Overcurrent protection devices aren’t permitted to be exposed to physical damage [240.24(C)].
Informational Note: Electrical equipment must be suitable for the environment, and consideration must be given to the presence of corrosive gases, fumes, vapors, liquids, or chemicals that have a deteriorating effect on conductors or equipment [110.11].
Overcurrent protection devices aren’t permitted to be located near easily ignitable material, such as in clothes closets [240.24(D)].
Overcurrent protection devices aren’t permitted to be located in the bathrooms of dwelling units, dormitories, or guest rooms or guest suites of hotels or motels [240.24(D)].
Note: The service disconnect switch isn’t permitted to be located in a bathroom, even in commercial or industrial facilities [230.70(A)(2)].
Note: Overcurrent protection devices aren’t permitted to be located over the steps of a stairway [240.24(F)]. Clearly, it’s difficult for electricians to safely work on electrical equipment that’s located on uneven surfaces such as over stairways.
These materials are provided to us by Mike Holt Enterprises of Leesburg, Fla. To view additional Code training materials offered by this company, visit www.mikeholt.com.
