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Code Quandaries

Feb 1, 2000 12:00 PM, By James Stallcup, Sr. and James Stallcup, Jr.

Here are the latest short answers to questions posted on our Web site, covering topics from Secs. 110-26(a)(3), 110-26(f)(1)(a), 250-32(b)(1) and (b)(2), 250-52(a), 250-104(b), 305-6(a) and (b), and 384-4 of the 1999 NEC.

Q. I know an electrical inspector who believes no one should use a metal gas pipe as a grounding electrode. Does Sec. 250-104(b) require the metal gas pipe to be bonded as a grounding electrode?

A. Sec. 250-104(b) does not require you to bond a metal gas pipe as a grounding electrode. However, you must bond the metal gas pipe into the grounding electrode system. Sec. 250-52(a) prohibits use the metal gas pipe as a grounding electrode. This requirement correlates with NFPA 54, Secs. 3.14(a) and (b). The 1999 NEC harmonizes these requirements.

Q. A competing contractor provides 7 ft of dedicated space above an electrical panelboard. I've always provided 25 ft or structural ceiling (whichever is lower) of dedicated space above an electrical panelboard. Sec. 384-4 doesn't list this requirement. Is there a new requirement regarding this?

A. You can now find the previous rules of Sec. 384-4 in Sec. 110-26(f)(1)(a). It requires an exclusive dedicated space for the width and depth of the equipment from the floor to a height of 6 ft or the structural ceiling, whichever is lower. (The 25 ft-or-structural-ceiling requirement no longer applies.)

Q. Must I run an equipment-grounding conductor with the supply conductors and connect it to the separate building or structure disconnecting means and then to the grounding electrode(s)?

A. Sec. 250-32(b)(2) does not require you to install an equipment-grounding conductor where there are no continuous metallic paths bonded to the grounding system in both the building and structures involved or where ground-fault protection hasn't been installed. Sec. 250-32(b)(1) requires you to install an equipment-grounding conductor where continuous metallic paths are present. The NEC addresses this issue to prevent neutral currents from returning to the source on parallel paths.

Q. Must you mount a panelboard and gutter so they are both of equal depths? One electrical inspector's interpretation is that the NEC requires electrical equipment located above or below other related equipment to be of equal depths.

A. Sec. 110-16(a) in the 1996 NEC has been renumbered as Sec. 110-26(a)(3) in the 1999 NEC to address the controversy that resulted from the equal depth rule. Sec. 110-16(a) permitted you to mount electrical equipment of equal depths above or below one another. This pertained to control equipment. Sec. 110-26(a)(3) now states electrical equipment located above or below other related equipment may extend not more than 6 in. beyond the front of such equipment. Because some authorities having jurisdiction (AHJs) didn't adopt this rule in the 1996 NEC, controversy resulted from the equal depth rule.

Q. An inspector requires all receptacles used on a construction site to be GFCI protected. Does this rule also require 30A, 40A, and 50A receptacles?

A. Sec. 305-6(a) requires GFCI protection for all 125V, single-phase, 15A, 20A, and 30A receptacles used for temporary wiring in a building or structure. Sec. 305-6(b) requires GFCI protection for all other receptacle outlets rated greater than 30A, or those rated 208V or 240V. Regardless of the ampere rating, Sec. 305-6(b) requires GFCI protection for personnel by either a GFCI protection device or by complying with the assured equipment grounding conductor program (AEGCP).