NEC Questions and Answers Based on 2008 NEC

April – Part 1

 

By Mike Holt for EC&M Magazine

 

Here’s the follow up to yesterday’s newsletter. This includes all of the answers to the questions sent yesterday so you can see how you did.

 

Q1. If we have receptacles that are within 20 feet of a swimming pool, but are located indoors, do we have to provide GFCI protection for them?

A1. No, only 15A and 20A, 125V receptacles located within 20 ft from the inside walls of a permanently installed pool, outdoor spa, or outdoor hot tub must be GFCI protected [680.22(A)(4) and (5)].

 

Q2. Do we still have to bond the deck of an outdoor swimming pool if the deck is constructed of pavers?

A2. Yes, an equipotential bonding grid must extend 3 ft horizon­tally beyond the inside walls of a pool, outdoor spa, or outdoor hot tub, including unpaved, paved, and poured concrete surfaces [680.26(B)(2)]. The bonding grid must comply with 680.26(B)(2)(a) or (b) and be at­tached to the conductive pool reinforcing steel at a minimum of four points uniformly spaced around the perimeter of the walls of a pool, outdoor spa, or outdoor hot tub.

 

Q3. Is the grounding conductor for a TV antenna sized the same as a grounding conductor for a satellite dish?

A3. Article 810 covers both VHF/UHF antennas, (which receive local television signals) and satellite antennas, which are often referred to as satellite dishes. The grounding conductor for either of these must not be smaller than 10 AWG copper or 17 AWG copper-clad steel or bronze [810.21(H)].

 

Q4. Is there is limit on how far the bathroom receptacle must be from a shower or bathtub?

A4. No, but receptacles must not be installed within or directly over a bathtub or shower stall [406.8(C].

 

Q5. We installed an equipment grounding conductor in our metal raceways even though the Code doesn’t require us to. Does the equipment grounding conductor have to meet be properly sized, even though it doesn’t have to be there in the first place?

A5. Yes, there are no exceptions to the rules found in article 250 that allows you to undersize the equipment grounding conductor. Equipment grounding conductors of the wire type must be sized not smaller than shown in Table 250.122 based on the rating of the circuit overcurrent device; however the circuit equipment grounding conductor is not required to be larger than the circuit conductors [250.122(A)].

 

Q6. Do we have to install a receptacle behind the swing of a door in a bedroom of a dwelling unit, even if the wall is only 30 inches long?

A6. Yes. In every kitchen, family room, dining room, living room, sunroom, parlor, library, den, bedroom, recreation room, and similar room, a receptacle outlet must be installed so that no point along the wall space is more than 6 ft, measured horizontally along the floor line, from a receptacle outlet [2105.52(A)(1)]. Remember that "wall space" includes any space 2 ft or more in width, unbroken along the floor line by doorways, fireplaces, and similar openings;    the space occupied by fixed panels in exterior walls; and the space occupied by fixed room dividers, such as freestanding bar-type counters or guard rails[210.52(A)(2)].

 

Q7. In an apartment building, do the common corridors, offices and exercise rooms have to be wired in accordance with the dwelling unit rules? For example, do we need a receptacle every twelve feet?

A7. No, because these areas do not meet the definition of dwelling unit in article 100: A space that provides independent living facilities, with space for eating, living, and sleeping; as well as permanent facilities for cooking and sanitation.

 

Q8. Where does the code require that all products must be listed by UL or equivalent?

A8. The NEC doesn’t require all electrical equipment to be listed, but some Code requirements do specifically require product listing. Organizations such as OSHA increasingly require that listed equipment be used when such equipment is available [90.7, 110.2, and 110.3].

 

Q9. We have a heat tape system installed on a metal roof. The heat tape has arced against the metal before, and we are concerned we will burn the place to the ground! Someone told us to use a GFCI on the circuit, and someone else told us not to. Please help us.

A9. Fixed outdoor electric deicing and snow-melting equipment must have ground-fault protection of equipment (GPE), unless the equipment uses mineral-insulated, metal-sheathed cable embedded in a noncombustible medium [426.28]. This GPE protection is different from a GFCI because it trips at a higher current value (30 mA as opposed to 5 mA).

 

Q10. We are having a lot of arguments about the requirements for vending machines. I know a Coke machine is a vending machine, but what about a fridge at the checkout line in the grocery store? Is this a “vending machine”?

A10. No. A “vending machine” is a self-service device that dispenses products or merchandise and requires coin, paper currency, token, card, key, or receipt of payment by other means.

 

Cord-and-plug-connected vending machines must include a GFCI as an integral part of the attachment plug, or within 12 in. of the attachment plug. Older machines that are not so equipped must be con­nected to a GFCI-protected outlet [422.51].

Q11. Can we install a plenum rated cable inside of an air duct to wire up the temperature sensor that is inside of the duct?

A11. No. Only type MI cable, Type MC cable that has a smooth or corrugated impervious metal sheath without an overall nonmetallic covering, electrical metallic tubing, flexible metallic tubing, intermediate metal conduit, or rigid metal conduit without an overall nonmetallic covering can be installed in ducts or plenums specifically fabricated to transport environmental air, and this is only allowed where the wiring is necessary for direct action upon, or sensing of, the contained air [300.22(B) and 725.3(C)].