NEC Questions and Answers - April 2017

Q1. Where does the Code require the use of tamper-resistant receptacles?
A1. Nonlocking-type 15A and 20A, 125V and 250V receptacles in the following areas must be listed as tamper resistant [406.12]:

Author’s Comment:
On a tamper-resistant receptacle, inserting an object into one side of the receptacle doesn’t open the internal tamper-resistant shutter. Simultaneous pressure from a two or three pronged plug is required for insertion.

(1) Dwelling unit areas specified in 210.52 and 550.13
(2) Hotel and motel guest rooms and guest suites
(3) Child care facilities

Author’s Comment:
A child care facility is a building or portions thereof used for educational, supervision, or personal care services for five or more children seven years in age or less [406.2].

(4) Preschools and elementary education facilities
(5) Business offices, corridors, waiting rooms and the like in clinics, medical and dental offices, and outpatient facilities.
(6) Places of awaiting transportation, gymnasiums, skating rinks, and auditoriums
(7) Dormitories

Informational Note: Receptacle types covered by this requirement are identified as 5-15, 5-20, 6-15, and 6-20 in NEMA WD 6, Wiring Devices—Dimensional Specifications.

Ex to (1) through (7): Receptacles in the following locations aren’t required to be tamper resistant:
(1) Receptacles located more than 5½ ft above the floor.
(2) Receptacles that are part of a luminaire or appliance.
(3) A receptacle located within dedicated space for an appliance that in normal use isn’t easily moved from one place to another.
(4) Nongrounding receptacles used for replacements as permitted in 406.4(D)(2)(a).

Q2. What are the Code requirements for a dwelling unit garage branch circuit?
A2. In each attached garage and each detatched garage with electric power, at least one receptacle outlet, located not more than 5 ½ ft above the floor, is required in each vehicle bay [210.52]. At least one 20A, 120V branch circuit is required to supply the receptacle outlet(s) required by 210.52 in attached garages and detached garages with electric power. This 20A, 120V branch circuit isn’t permitted to serve any other outlet [210.11(C)(4)].

Ex: Readily accessible outdoor receptacle outlets (not lighting outlets) can be supplied by the 20A, 120V garage receptacle branch circuit.

Q3. What defines the rating of a branch circuit in the eyes of the NEC?
A3. The rating of a branch circuit is determined by the rating of the branch-circuit overcurrent protection device, not the conductor ampacity [210.18].

Author’s Comment:
For example, the branch-circuit rating of 10 THHN, rated 30A at 60ºC, protected by a 20A circuit breaker is 20A.

Q4. What are the working space and access requirements in the Code for equipment located above suspended ceilings or in a crawl space?
A4. Where equipment operating at 1000V or less is likely to require examination, adjustment, servicing, or maintenance while energized is located in a space with limited access, all of the following conditions apply [110.26(A)(4)]:

(a) Equipment installed above a suspended ceiling must have an access opening not smaller than 22 in. x 22 in. Equipment installed in a crawl space must have an accessible opening not smaller than 22 in. x 30 in.

(b) The width of the working space must be a minimum of 30 in., but in no case less than the width of the equipment.

(c) The working space must permit equipment doors to open 90 degrees.

(d) The working space in front of the equipment must comply with the depth requirements of Table 110.26(A)(1), the height is what is necessary to install the equipment. Horizontal ceiling structural members are permitted in this space.

Q5. Does the Code have any special requirements for grounding and bonding of roof-top air conditioning and refrigeration equipment?
A5. Where equipment is installed using a metal raceway run exposed on a roof for air-conditioning and refrigeration equipment, an equipment grounding conductor of the wire type must be installed within the outdoor portions of metal raceways that use non-threaded fittings [440.9].

Q6. Does the Code allow the use of swimming pool reinforcing steel as part of the grounding electrode system?
A6. Swimming pool reinforcing steel for equipotential bonding in accordance with 680.26(B)(1) and 680.26(B)(2) isn’t permitted to be used as a grounding electrode [250.52(B)(3)].

Q7. Does the NEC require the installation of a neutral conductor in switch boxes?
A7. Switches controlling line-to-neutral lighting loads must have a neutral conductor installed at a switch serving bathrooms, hallways, stairways, or rooms suitable for human habitation or occupancy as defined in the applicable building code [404.2(C)].

Where 3-way and 4-way switches are visible in a room, only one of the switches requires a neutral conductor.

A neutral conductor isn’t required under any of the following conditions:
(1) Where conductors enter the box through a raceway with sufficient cross-sectional area to accommodate a neutral conductor.
(2) Where the switch box can be accessed to add or replace a cable without damaging the building finish.
(3) Snap switches with integral enclosures [300.15(E)].
(4) Where the lighting is controlled by automatic means.
(5) Switches controlling receptacles.

The neutral conductor must be run to any replacement switch that requires line-to-neutral voltage [404.22] to operate the electronics of the switch in the standby mode.

Ex: A neutral conductor isn’t required for replacement switches installed in locations wired prior to the adoption of 404.2(C) where the neutral conductor can’t be extended without removing finish materials. The number of electronic lighting control switches without a neutral conductor on a branch circuit must not exceed five switches, and the number connected to any feeder must not exceed twenty-five switches.

Informational Note: The purpose of the neutral conductor at a switch is to complete a circuit path for electronic lighting control devices that require a neutral conductor.