ECM Questions
Q1 When wiring a circuit breaker, does the Code require the supply conductors to terminate to the top (line side) of the breaker?
A1 No, but if the breaker is marked with “line” and “load”, it must be installed in accordance with the manufactures instructions as per 110.3(B).
Q2 I want to run 3/0 AWG tri-plex to a transformer located outdoors. Am I required to include a ground wire with the tri-plex even though the transformer is grounded to two ground rods?
A2 Yes, an equipment grounding (bonding) conductor is required to be run to the transformer, because it is needed to provide the low-impedance path to the source that is necessary to clear a ground fault. Because the contact resistance to the earth via the ground rods is so high, very little ground-fault current would return to the electrical supply source via the earth. The result, the circuit overcurrent protection device will not open to clear a ground fault, and metal parts will remain energized.
Q3 When the NEC requires GFCI protection for receptacles, is the GFCI protection required to be supplied via a GFCI receptacle ?
A3 No. GFCI protection can be supplied by circuit breakers or receptacles.
Q4 When a vapor barrier has been installed under a footer, can the steel rebar above the vapor barrier be used as a grounding electrode?
A4 No. A concrete-encased electrode of the steel rebar type is only suitable to be used as a concrete encased electrode if it’s located within and near the bottom of a concrete foundation or footing that is in direct contact with the earth [250.52(A)(3)]. If a vapor barrier is installed between the footer and the earth, then the rebar can’t be use as an electrode.
Q5 Can recessed or surface mounted lighting fixture be supported by securing them to the suspended ceiling grid, or must they be independently supported to the building structure?
A5 The NEC does not specify that suspended ceilings can be used for the support of luminaires, it just specifies that if the suspended ceiling is used for support, then the luminaires must be attached to the suspended ceiling framing with screws, bolts, rivets, or clips listed and identified for such use [410.16(C)]. The building code must be consulted to determine if the suspended ceiling can be used to support the luminaires in question.
Q6 According to product instructions, a recessed lighting fixture is permitted to be installed in the ceiling above a shower if it’s GFCI protected. But my inspector insists that it’s not permitted to be installed above the shower space because it’s not listed for a wet location. Is this true?
A6 No, it is not true. Luminaires located in bathtub and shower zones must be listed for the location. Where subject to shower spray they must be listed for wet locations [410.4(D)].. Because you are installing the luminaire in the ceiling above the shower space, it will not be subject to shower spray, therefore it only needs to be listed for a damp location. Just be sure that’s the luminaire is GFCI protected in accordance with the instructions [110.3(B)].
Q7 I have six 18 ft metal poles to install in a parking lightning, is a ground rod required at each pole? If not, then why do some people insist that they are required?
A7 No, the grounding of a metal pose is not required by the NEC. I don’t know who started this, maybe a manufacture selling grounding fittings promoted this practice. Figure 250–26
Q8 If the feeder to a detached building contains a ground wire, is the detached building disconnect still required to be grounded to the earth?
A8 Metal parts of electrical equipment must be grounded to the earth to reduce transient voltage on the metal parts from lightning, thereby reducing fires from a surface arc within the building or structure from a lightning event [250.4(A)(2)]. The equipment grounding (bonding) conductor contained within the feeder conductor is intended to service as low-impedance fault current path to the source to assist in clearing a ground fault [250.2].
A9 Is there a Code rule that prohibits nonelectrical equipment in an electrical room?
A9 No, there is no such code rule, but 110.26(F) prohibits nonelectrical equipment above and below switchboards, panelboards, distribution boards and motor control centers. In addition, the minimum working space of 30 x 36 in. must also be kept clear at all times, and cannot be used for storage [110.26(B)].
Q10 Is plenum rated cable required in an equipment room, if the room is used as a return air space, via a grille on the equipment room door?
A10 The requirements for wiring in air handling spaces do not apply to rooms whose prime purpose isn’t air handling [300.22(C)], so no, plenum rated cabling would not be required.
Q11 How far away from the electric service must I locate a hot tub?
A11 Circuit breakers, time clocks, pool light switches, and other switching devices must be located not less than 5 ft horizontally from the inside walls of a permanently installed outdoor hot tub unless separated by a solid fence, wall, or other permanent barrier [680.22(C)].
Q12 What is the minimum burial depth requirement for residential service lateral conductors installed in rigid nonmetallic conduit?
A12 Cables and raceways run underground must have a minimum “cover” in accordance with Table 300.5. This table requires a minimum of 18 in. of cover. According to Note 1 to Table 300.5, “Cover” is defined as the distance from the top of the underground cable or raceway to the surface of finish grade.
Q13 I ran 14/3 NM cable to the bedrooms outlets and my boss says you can't put an AFCI breaker on a multiwire branch circuit. Is this true?
A13 Your boss is almost right. Two single pole AFCI breakers cannot be used on a 3-wire circuit, however 2-pole AFCI breaker can be used for this purpose.
Q14 Can energized power conductors be abandoned in place? If not, must I remove the conductors from the circuit protection device or must I remove the conductors completely?
A14 Abandoned power and lighting conductors are not required to be removed, but the free ends of all conductors must be covered with insulation that is equal to that of the conductor [110.14(B)].
However the accessible portions of audio, limited energy, signaling, fire alarm optical fiber and communications cables are required to be removed [640.3(A), 725.3(B), 760.760.3(A), 770.3(A), 800.3(C), 820.3(A) and 830.3(A)].
Q15 Can pneumatic control tubing be installed in the same raceway with electrical control or power conductors or cables?
A15 Raceways and cable trays are designed for the exclusive use of electrical conductors and cables, and cannot contain nonelectrical components, such as pipes or tubes for steam, water, air, gas, drainage, etc. [300.8].
Q16 Can we install coaxial cables inside the duct work of an existing building?
A16 No. The only time communications cables can be installed within ducts is if the wiring is necessary for the direct action upon, or sensing of the contained air, and the cables are installed in electrical metallic tubing, intermediate metal conduit, or rigid metal conduit as required by 300.22(B) [820.3(B].
Q17 What are the grounding requirements for a trailer that receives power via a portable generator that is mounted on the frame of the trailer.
A17 The frame of a portable generator isn’t required to be grounded to the earth if the generator only supplies equipment or receptacles mounted on the generator, and the metal parts of the generator and the receptacle grounding terminal are bonded to the generator frame [250.34(A)].
Q18 I have to move an outdoor post light and I was wondering if I could splice the UF cable underground without a junction box?
A18 Direct-buried conductors or cables can be spliced underground without a splice box [300.15(G)], if the splice or tap is listed for the purpose [300.5(E), 110.14(B)].
Q19 I thought that the Code had a limit of one wire per terminal, but some say that it’s okay to terminate two wires on some circuit breakers? Is this true?
A19 Maybe. Terminals for more than one wire must be identified for this purpose, either within the equipment instructions or on the terminal itself [110.14(A)]. Some equipment contains terminals that are listed for more than one conductor per terminal. For example, Square D and Cutler Hammer circuit breakers rated 30A or less are permitted to have two conductors under each lug.
