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NEC Quiz: Article 376 Answers

by Mark Lamendola

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  1. In the prelude to the questions, we gave away the fact this is metal wireway. What we didn't give away is the detail that tells you its defining characteristics. Metal wireways are sheet metal troughs with covers that are either hinged or removable. It is this feature that makes them so efficient for installation purposes. You don't need to fish cables through them, as you do with (for example) metallic tubing. Instead, you lay the wires in the trough. Once you've run them all, you close or attach the cover. [376.1, 376.2].

  2. The NEC provides a list of four "Uses Permitted" for this wiring method [376.10]. You can use it for exposed work, in hazardous locations (where permitted by the relevant Chapter 5 Article), in wet locations (if it's listed for that use), and in concealed spaces. This last use has three conditions for it to be permissible: the wireway must be an extension that passes transversely through a wall, the length passing through the wall must be unbroken, and the conductors must be accessible on both sides of the wall.

  3. You can't use it in severe corrosive environments or (standard prohibition, here) where subject to physical damage [376.12].

  4. Typically, this question is answered in section 30 of an Article. But 376.30 does not specify the hardware. That's because the exact hardware isn't an electrical safety issue. Use something suitable, such as the mouting hardware that (usually) comes with the wireway or use screws of the appropriate size. What the NEC does say in 376.30 is you must provide support at minimum horizontal and vertical distances (which it specifies).
  5. This is kind of a trick question, as couplings and connectors generally aren't needed. You don't assemble lengths of this the way you do, say, Intermediate Rigid Conduit (IRC). In a typical application, you usually cut it to the lengths you need and screw those lengths onto a surface. That could be something like a building wall or the interior of a control panel. But it is common to use power distribution blocks with this type of wireway. If you use such blocks, make sure they are listed [376.56(B)].