Your most pressing National Electrical Code (NEC) questions
All questions and answers are based on the 2011 NEC.
Q. Are outdoor receptacles at a dwelling unit required to be tamper-resistant?
A. Yes. According to 406.12, all non-locking type 15A and 20A, 125V receptacles in the following areas of a dwelling unit [210.52] must be listed as tamper-resistant:
- Wall space — 210.52(A)
- Small-appliance circuit — 210.52(B)
- Countertop space — 210.52(C)
- Bathroom area — 210.52(D)
- Outdoors — 210.52(E)
- Laundry area — 210.52(F)
- Garage and outbuildings — 210.52(G)
- Hallways — 210.52(H)
An Exception to this rule notes that receptacles in the following locations aren’t required to be tamper-resistant:
- Receptacles located more than 5½ ft above the floor.
- Receptacles that are part of a luminaire or appliance.
- A receptacle located within dedicated space for an appliance that in normal use isn’t easily moved from one place to another.
- Nongrounding receptacles used for replacements as permitted in 406.4(D)(2)(a).
Q. If you replace a 2-wire receptacle with no equipment grounding conductor with a GFCI, is an equipment grounding conductor required for the GFCI?
A. If no equipment grounding conductor exists in the outlet box for the receptacle, such as old 2-wire Type NM cable without an equipment grounding conductor, existing nongrounding-type receptacles can be replaced using one of the following [406.4(D)(2)], as shown in the Figure (click here to see Figure).
a. Another nongrounding-type receptacle.
b. A GFCI-type receptacle marked “No Equipment Ground.”
c. A grounding-type receptacle, if GFCI protected and marked “GFCI Protected” and “No Equipment Ground.”
GFCI protection functions properly on a 2-wire circuit without an equipment grounding conductor because the circuit equipment grounding conductor serves no role in the operation of the GFCI-protection device. See the definition of “Ground-Fault Circuit Interrupter” for more information.
Caution: The permission to replace nongrounding-type receptacles with GFCI-protected grounding-type receptacles doesn’t apply to new receptacle outlets that extend from an existing outlet box that’s not connected to an equipment grounding conductor. Once you add a receptacle outlet (branch-circuit extension), the receptacle must be of the grounding type, and it must have its grounding terminal connected to an equipment grounding conductor of a type recognized in 250.118, in accordance with 250.130(C).
Q. Section 220.54 expresses electric clothes dryer loads in watts, and Table 220.55 provides wattage demands for ranges. Can watts be converted to VA for service calculations?
A. Yes. The feeder/service load for electric clothes dryers located in a dwelling unit must not be less than 5,000W (5,000VA), or the nameplate rating of the equipment if more than 5,000W (5,000VA). Kilovolt-amperes (kVA) are considered equivalent to kilowatts (kW) for loads calculated in this section [220.54].
When a building contains five or more dryers, it’s permissible to apply the demand factors listed in Table 220.54 to the total connected dryer load. A clothes dryer load isn’t required if the dwelling unit doesn’t have an electric clothes dryer circuit receptacle outlet.