All questions and answers are based on the 2005 NEC.
Q. What are the requirements for installing 15A or 20A receptacles in wet locations?
A. All 15A and 20A receptacles in wet locations must be placed within an enclosure that's weatherproof and remains weatherproof when an attachment plug is inserted in the receptacle [406.8(B)] (Fig. 1). According to Art. 100, a wet location would be an area subject to saturation with water or an unprotected location exposed to weather.
Q. Must metal siding and metal framing members be grounded?
A. I think what you're trying to ask is whether the NEC requires metal siding and framing to be bonded to an effective ground-fault current path, and the answer is no, not specifically [250.4(A)(4)]. However, exposed structural metal that forms a metal building frame must be bonded to one of the following (effective ground-fault path) [250.104(C)] (Fig. 2):
Service equipment enclosure
Grounded neutral service conductor
Grounding electrode conductor sized in accordance with Table 250.66
One of the electrodes of the grounding electrode system
The bonding jumper for structural metal is sized to the conductors that supply the building or structure, in accordance with Table 250.66. In addition, the bonding jumper must be:
Copper, where within 18 inches of earth [250.64(A)].
Securely fastened and not exposed to physical damage [250.64(B)].
Installed without a splice or joint, unless spliced by compression connectors or by the exothermic welding process [250.64(C)].
Q. Where there are two service disconnects installed on one side of the meter, can I run the service conductors through one disconnect to feed the second?
A. You can if adequate space is provided in the first disconnect (312.8) (Fig. 3). In fact, this is the way I have my service installed.
Q. We installed access and security control equipment in a factory. The power source is in a breaker panel, and the employees have learned how to disable the system by turning the breaker off and waiting for the battery to discharge. Does the Code permit the use of a padlock on the panel door to restrict access?
A. The NEC doesn't prohibit you from locking panel doors or placing a padlock on a circuit breaker to restrict access.
Q. If a single 20A, 125V laundry receptacle is located within six feet of the laundry tub, is GFCI protection required?
A. Yes, GFCI protection is required for all 15A and 20A, 125V receptacles located within an arc measurement of 6 feet from the dwelling unit laundry, utility, and wet bar sink [210.8(A)(7)].
Q. Where in the Code can I find the requirements for locating smoke detectors in single-family dwelling units?
A. The requirements are in NFPA 72, National Fire Alarm Code, not the NEC.
Q. What size equipment grounding (bonding) conductor is required in each of four raceways for a 1,600A, 120/208V, 3-phase feeder?
A. 4/0 AWG. When circuit conductors are run in parallel [310.4, 250.122(F)], an equipment grounding (bonding) conductor must be installed with each parallel conductor set, and it must be sized to the ampere rating of the circuit-protection device in accordance with Table 250.122.
Got a Code question for Mike? E-mail him at firstname.lastname@example.org for help.