NEC Quiz: Article 334 Answers

by Mark Lamendola

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  1. It addresses cables that have a sheath made of something other than metal. Thus, "Nonmetallic-sheathed cable" or Types NM, NMC, and NMS. The C stands for "corrosion-resistant" and the S stands for "Signal."

  2. You can use all three types of cable in five different defined applications [334.10(10-(5)]. Additionally, you can use:
    Type NM cable in two different defined applications [334.10(A)].
    Type NMC cable in three different defined applications [334.10(B)].
    Type NMS cable in two different defined applications [334.10(C)].

  3. You can't use it any of these in any of the ten applications listed in 334.12(A). Those are any structure not specifically permitted, exposed in dropped or suspended ceilings (except residential), as service entrance cable, in classified garages having hazardous locations defined in 511.3, and six other applications listed in that subsection.

    Additionally, you can't use Types NMC or NMS in any of the four conditions identified in 334.12(B).

  4. Generally, you must support the cable every 6ft (or less) using staples, straps, hangers, or similar fittings [334.30(A)]. But you don't have to support this cable if it's fished between access points in concealed spaces of finished structures, or supporting is impractical [334.30(B)].

  5. You can use any terminations suitable for the conductors. The NEC says almost nothing on this aspect of installation. But it very clearly says you can use only one conductor per screw terminal [334.40(B)].