NEC Quiz: Article 332 Answers

by Mark Lamendola

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  1. It addresses Mineral-Insulated, Metal-Sheathed Cable, which is Type MI [332.2]. This cable consists of copper conductors coated by inorganic magnesium oxide powder and run inside a copper sheath (it may be a steel alloy sheath).

    The reason to run this cable is you need to withstand the high temperatures involved in a fire; so, for example, you use it for your life safety systems. You can find out more about Type MI cable at www.micable.com.
     

  2. You can use Type MI cable in eleven different defined applications [332.10].
     

  3. You can't use it in underground runs, unless you ensure it's protected from physical damage. And you can't use it where it's exposed to conditions that may destroy or corrode the metal sheath, unless you provide additional protection to prevent said destruction or corrosion [332.12].
     

  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 [332.24]. Generally, you must support the cable every 6ft (or less) using staples, straps, hangers, or similar fittings [332.30(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 [332.30(B)].
     

  5. You can use any terminations suitable for the conductors. You must also use an end seal fitting where the cable terminates and you must install it immediately after stripping so moisture does not enter the insulation. You must also provide insulating material to each individual conductor. And, you must use fittings listed and identified for use with Type MC Cable [332.40].