NEC Questions

By Mike Holt for EC&M Magazine

Q1. Is there any specific Code for an outside ceiling fan under a covered deck (opened sides)?

A1. Well, the NEC requires the box to be listed for the fan's weight [314.27(D)], the fan cannot be installed in a shower or bathtub space [410.4(D)], nor can it be installed within 5 ft of pool, spa or hot tub [680.22(B)]. Other than that, the NEC is silent.

The NEC does not require the ceiling fan to be listed, but if it is listed, then it must be installed in accordance with the listing instructions [110.3(B)]. The area under a covered deck would be a damp location [Article 100], so be sure to use a fan listed for this area.

Q2. Can I serve more than bathroom receptacle from the required 20A bathroom receptacle circuit in a dwelling unit? If yes, what is the maximum number of receptacles permitted to be supplied from a GFCI receptacle?

A2. There is no limit to the number of bathroom receptacles on the 20A dwelling unit bathroom circuit, nor is there a limit on the number of receptacle permitted to be supplied from a GFCI receptacle. See 210.11(C)(3) for additional details.

Q3. I have question concerning electric manholes that contains 4160V, 480V, and 120V circuits. If the manhole is 10 feet deep, does the NEC require a permanent ladder in the manhole?

A4. Nope.

Q4. Abandoned cable is a big problem in my plant. Where in the NEC does is specify that abandoned cables must be removed?

A4. Abandoned cable is identified as a cable that is not terminated at equipment and not identified for future use with a tag [725.2, 760.2, 770.2, 800.2, and 820.2] and the NEC does require the accessible portion of abandoned to be removed [725.3(B), 760.3(B), 770.3(A), 800.52(B), and 820.3(A)]

Q5. An electrician told me that I could not use nonmetallic sheath cable to wire a hot tub at my home. But the salesman at Home Depot said that I should use 6/2 NM cable. Could you please clarify this for me?

A5. If the hot tub is located indoors, then NM cable can be use as the wiring method [680.43]. However, if the hot tub is located outdoors of a one-family dwelling, then NM cable can be for the indoor portion [680.42(C)]. Outdoors, the most practical wiring method will be rigid nonmetallic conduit and liquid-tight flexible conduit [680.42 and 680.42(A)].

Q6. Is GFCI protection required for a receptacle next to a sink in a laundry room?

A6. Nope.

Q7. The lights in my house blink every time my new 5-ton Carrier AC unit starts (180 Amps on start). All conductor terminal connections are secured, so I know that's not the problem. The builder replaced the 6 AWG aluminum to the compressor with 1 AWG, carrier changed the compressor to ensure it was not sticking, the utility replaced the transformer from 25 kVA to 50 kVA, and they changed the service from 2/0 to 4/0 cable. Why do the lights still blink in the house?

A7. The lights blink because the start up inrush current (180A) of new more efficient air-conditioners causes a short-pulse voltage drop on the service conductors. What can be done? Nothing. This is part of the trade-off of higher efficient air conditioning equipment. Trust me I know, my lights blink as well, but you know you do get used to it!

Q8. Can wiring that is listed for low-voltage or limited-energy circuits according to the NEC be use for outdoor applications?

A8. The NEC requires low voltage and limited energy wiring within buildings to be listed as being resistant to the spread of fire [725.71,760.31, 760.71, 770.49, 800.50, and 820.49]. Because the NEC does not require low-voltage or limited energy wiring used outdoors to be listed, UL does not have a standard to list for this purpose. Therefore you can use any low-voltage or limited-energy wiring for outdoor application, even if it's not listed! But only if approved by the authority having jurisdiction [90.4 and 110.2]

Q9. I have been asked to assist in installing a baptismal in a church. The baptismal will be located inside of the building, permanently built into the stage. My problem is that I have yet to find anything in the NEC that directly addresses this topic. Should I treat this as a pool, spa, or therapeutic tub?

A9. The NEC does not specifically address this issue, so it's a judgment call by the authority having jurisdiction. I would consider it an indoor spa and apply the requirements of Article 680, Part IV.

Q10. Is the neutral conductor counted as a current carrying when derating circuits that are supplied by 120/240V single-phase?

A10. A neutral conductor that carries only the unbalanced current from other conductors of the same circuit is not be required to be counted when applying the conductor ampacity adjustments of 310.15(B)(2)(a) [310.15(B)(4)].

Mike Holt's Comment: If you disagree with any of my comments, please let me know, but be sure to give me a Code reference.

 

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