National Electrical Installation Standards

Standards as High as Your Own

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Thursday, November 19, 2020

Question:

Charlie Trout Flashback Question:

Our company does quite a bit of work for "places of assembly." We often find that older structures were often wired by methods that the current NEC does not allow, most often nonmetallic sheathed cable. Generally, we will use Type NM cable when doing repair work or making small additions to such buildings. I have been told that such work is permissible, being “grandfathered” under the Code that existed when the building was constructed. Evidently, the inspectors agree because our work was never been turned down for improper wiring methods. Is there any wording in the NEC that allows this, or is this permission given through national or local building codes?

A

Answer:

Charlie Trout Flashback Answer:

Nonmetallic-sheathed cable is permitted in 518.4(B) to be used only in buildings or portions thereof that are not required to be of fire-rated construction by the applicable building code. The NEC has been consistent in this requirement prior to the acceptance of Article 518 into the 1975 NEC; this requirement was previously a part of Article 520, which at that time included Assembly Halls. The use of nonmetallic-sheathed cable has never been intended or permitted by the NEC in places of assembly except as shown above. Local requirements may differ from NEC requirements, but violations of the NEC should never be grandfathered in. See NEC Section 518.4(B).

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