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Stumped by the Code?

Nov 1, 2006 12:00 PM, By Mike Holt, NEC Consultant

All questions and answers are based on the 2005 NEC.

Q. How far away must I locate a receptacle outlet from a shower or bathtub?

A. Receptacles must not be installed within or directly over a bathtub or shower stall [406.8(C)], but they can be installed next to a bathtub or shower. Hydromassage bathtubs are treated like bathtubs [680.70].

Q. Can the sum of the ampere ratings of circuit breakers in a panel exceed the rating of the panelboard?

A. Yes. However, each panelboard with supply conductors that include a neutral, and having more than 10% of its overcurrent devices protecting branch circuits rated 30A or less, must be protected by an overcurrent protective device having a rating not greater than that of the panelboard [408.36].

Q. Can I use a different manufacturer's breaker in my panel as long as it fits?

A. Only if the circuit breaker is listed or classified to be used in the specific panelboard [110.3(B)].

Q. Can I use 12-3 NM cable to wire the bathroom and laundry circuits in a dwelling?

A. Yes. However, continuity of the grounded (neutral) conductor of a multiwire branch circuit must not be interrupted by the removal of a wiring device [300.13(B)]. Therefore, the grounded neutral conductors must be spliced together, and a pigtail must be provided for the wiring device.

Q. Can an AFCI-type receptacle be used to meet the AFCI requirements of the NEC?

A. Yes, if the AFCI is located within 6 feet of the branch-circuit overcurrent device as measured along the branch-circuit conductors, if the circuit conductors are installed in a metal raceway or a cable with a metallic sheath [210.12(B) Exception]. As of this writing, no manufacturer makes an AFCI receptacle.

Q. Do I need to bond the metal parts of a diving board and ladder of a fiberglass swimming pool?

A. Yes, all metal fittings within or attached to a permanently installed pool, outdoor spa, or outdoor hot tub structure, such as ladders, diving boards, and handrails must be bonded together, even if the pool is of fiberglass construction [680.26(B)(3)].

Q. I have two receptacles on two different circuits in the same outlet box. Am I required to use a two-pole breaker for these circuits?

A. No. However, a 2-pole breaker or two single breakers with handle ties identified for the purpose would be required if the two circuits terminated on equipment on the same yoke [210.4(B) and 210.7(B)].

Q. How many 12 AWG conductors can I install in 4-inch × 4-inch × 1¼-inch junction box if the enclosure has a plaster ring listed for 3.3 cubic inches, and there are no cable clamps or fixture support fittings in the enclosure?

A. According to Table 314.16(A), the box has a capacity of 21.0 cubic inches. Table 314.16(B) tells us that each 12 AWG conductor is considered as 2.25 cubic inches. So the calculation would be done as follows:

Step 1 Determine the total volume of the box assembly [314.16(A)].

21 cubic inch box + 3.3 cubic inch plaster ring = 24.3 cubic inches

Step 2 Determine the number of 12 AWG conductors permitted in the box.

24.3 cubic inches ÷ 2.25 cubic inches = 10.8

There is no permission to round up for box fill calculations, so the answer is ten 12 AWG conductors.

Q. What are the GFCI protection requirements for a receptacle supplying a water fountain?

A. GFCI protection is not required by the NEC for outlets supplying drinking water fountain equipment.

Q. Does an above-the-range combination microwave/hood fan require a dedicated circuit if it's cord-and-plug connected?

A. Yes [422.16(B)(4)(5)], and be sure to comply with the following as well [422.16(B)(4)]:

1. The flexible cord must terminate with a grounding-type attachment plug.

2. The length of the cord must not be less than 18 in. or longer than 36 in.

3. The range hood receptacle must be located to avoid physical damage to the flexible cord.

4. The range hood receptacle must be accessible.

Q. What are the rules on mixing emergency circuits in the same raceway or enclosure with nonemergency circuits?

A. To ensure that a fault on the normal wiring circuits will not affect the performance of emergency wiring or equipment, all wiring from an emergency source (or emergency source distribution overcurrent protection) to emergency loads must be kept entirely independent of all other wiring and equipment, except [700.9(B)]:

1. Wiring in transfer equipment enclosures.

2. Exit or emergency luminaires supplied from two sources of power.

3. A common junction box attached to luminaires supplied from two sources of power.

Q. Does the NEC require safety chains on high-bay lighting fixtures?

A. No, this is not an NEC requirement.

Q. Can AFCI-type receptacles be used to meet the requirements of the NEC?

A. Yes, if the AFCI is located within 6 feet of the branch-circuit overcurrent device, as measured along the branch-circuit conductors — and if the circuit conductors are installed in a metal raceway or a cable with a metallic sheath [210.12(B) Exception]. Because of the limited demand, AFCI protection devices of the receptacle type are not made. Therefore, this point is moot.

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