Q: Are nonmetallic boxes required at each outlet point when using nonmetallic cable?

A: No, they are permitted but not required. Metal boxes are also permitted and there are also provisions where no box is required. Section 300-15(e) of the NEC book permits the use of an identified wiring device in lieu of a box. If metal boxes are used with Type NM cable, the cable must be secured to the box. If Type NM cable is used with a nonmetallic box, the cable must be secured to the box.

Q: Does the NEC require two separate receptacles in the same box with a different circuit feeding each receptacle to be protected by a two-pole breaker?

A: No. Two circuits in the same box can have be protected by two different single-pole breakers. But two circuits to two devices on the same yoke (i.e., split-wired receptacles) is quite a different story. De-energizing a circuit to a receptacle with the tab removed leaving one circuit still energized is a very distinct possibility. When you take that receptacle yoke in your hand after shutting off one circuit and leaving one circuit "hot" inadvertently, it is comparatively easy to grasp the receptacle touching both the grounded and ungrounded terminals simultaneously.

Q: Is it required to drive a ground rod at every light pole in a parking lot?

A: No. A ground rod may be installed as a supplementary grounding electrode for connection to the equipment grounding conductor but the "earth shall not be used as the sole equipment grounding conductor," according to the NEC book. This means that a separate equipment grounding conductor must be run with the circuit conductors. The equipment grounding conductor shall be as permitted by Section 250-118 and sized in accordance with Section 250-122 of the book.

Q: How many twists per foot is the Fire Alarm Cable?

A: Conductor AWG 18 has 5 twists per foot, 14 AWG has approximately 4 twists per foot per U.L. More twists per foot are subject to inquiry.

Q: Why can't I use aluminum armored Type AC cables on a DC circuit?

A: U.L. has not approved aluminum armored Type AC cable for use on DC circuits. During the extreme testing procedures conducted by U.L., a conductor was energized to arc and caused the aluminum to burn. Normal usage would be 12DC or 24DC, but U.L. has not tested the cable under those conditions. Steel armored Type MC cable may be used on DC Circuits without exception.