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Code Forum

Jan 1, 1999 12:00 PM, By Fred Hartwell, Senior Editor

Does the 1999 NEC disallow cord drops from boxes and wireways to a building surface to allow for vertical runs to portable or stationary equipment?

We have received several questions at seminars as to whether you can still make cord drops, with a building attachment, to portable and stationary equipment from overhead. This comes up in locations where you'd like to attach the drop to the wall from a wireway run overhead at a central point. The 1996 NEC allowed one building surface attachment; the 1999 NEC now refers only to Sec. 364-8 in the busway article. At least one leading national authority says you're only allowed to make such extensions from busways.

The EC&M Panel's Response. We think you can still make these drops, as long as you meet the installation rules in Sec. 364-8(b). At issue is the appropriate interpretation of "provisions" in Sec. 400-8(4) Ex.:

Exception: Flexible cord and cable shall be permitted to be attached to building surfaces in accordance with the provisions of Section 364-8.

Sec. 364-8(b), which follows, does indeed only apply to busways, which makes sense because we're dealing with the busway article:

(b) Suitable cord and cable assemblies approved for extra-hard usage or hard usage and listed bus drop cable shall be permitted as branches from busways for the connection of portable equipment or the connection of stationary equipment to facilitate their interchange in accordance with Sections 400-7 and 400-8 and the following conditions.

(1) The cord or cable shall be attached to the building by an approved means.

(2) The length of the cord or cable from a busway plug-in device to a suitable tension take-up support device shall not exceed 6 ft (1.83 m).

Exception: In industrial establishments only, where the conditions of maintenance and supervision ensure that only qualified persons will service the installation, lengths exceeding 6 ft. (1.83 m) shall be permitted between the busway plug-in device and the tension take-up support device where the cord or cable is supported at intervals not exceeding 8 ft (2.4 m).

(3) The cord or cable shall be installed as a vertical riser from the tension take-up support device to the equipment served.

(4) Strain relief cable grips shall be provided for the cord or cable at the busway plug-in device and equipment terminations.

We think the term "provisions" means to follow referenced installation requirements. Rather than reiterate a list of rules, the Code simply refers to the other location. We often see this throughout the Code. For example, Sec. 225-21 refers to provisions in Sec. 230-51, which only applies to service conductors. Nevertheless, no one would seriously suggest that you couldn't use Sec. 225-21 for outside feeders. Rather, you'd apply the appropriate installation conditions for your feeder similar to the way you'd run service wiring in this case.

This NEC change eliminated a conflict between the two articles, since in the 1996 NEC Sec. 364-8(b)(2) Ex. (involving more than one attachment to the building, and spaced at 8-ft intervals) allowed what Sec. 400-8 Ex. did not. No one submitted any technical substantiation to support a "busway-only" restriction. The final wording came from the Correlating Committee (TCC) to correct a style violation by the panel, and the TCC didn't discuss any such substantiation at their meeting either. Furthermore, Sec. 362-11 and Sec. 362-26 clearly permit such extensions.

We think that Sec. 400-8(4) Ex. could be clarified by adding the words "applicable installation" ahead of "provisions" in the next cycle. However, after reviewing the entire history of this change, as well as the overall Code context and widespread installation practice, we think you can go ahead and apply the rules in Sec. 364-8(b) without worrying about whether you originate at a busway. We can't think of any reason why a busway confers some special protective feature worthy of a special allowance in these cases.

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