NEC Quiz: Article 330 Answers

by Mark Lamendola

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  1. It addresses Metal-Clad Cable Type MC. This type of cable is a factory assembly of insulated circuit conductors inside an armor of interlocking metal tape or inside a metal sheath (smooth or corrugated) [330.2]
     

  2. You can use Type MC cable in a dozen different defined general applications [330.10(A)]. One of those, wet locations, is permissible only if the particular Type MC being considered meets one of three conditions. Article 330 lists four specific uses for Type MC Cable [330.10(B)]: Cable tray, direct buried, service entrance cable, and outdoor aerial cable.
     

  3. You can't use it where it's subject to physical damage or where exposed to corrosive factors it's not designed to handle [330.12]. Regarding the physical damage, Type MC Cable, while inherently very strong, is not as strong as a solid conduit such as RMC or IMC. But it is lighter and usually easier to install and has other benefits that make it suitable for many applications in place of RMC or IMC. It fills a niche between these stiff-walled conduits and lighter duty flexible conduits.
     

  4. Before answering that question, it's worth noting that the support issue is moot if you damage the cable during installation by exceeding its bend radius [330.24]. Generally, you must support the cable every 6ft (or less) using approved support methods that don't damage the cable [330.30(A), (B), (C)]. But you don't have to support this cable if it's fished between access points in concealed spaces of finished structures, supporting is impractical, or it's running to a luminaire (or other equipment) and is less than 6ft from the last support [330.30(D)].
     

  5. You can use any terminations suitable for the conductors. You must use fittings listed and identified for use with Type MC Cable [330.40].