Which two of the following types of metallic conduit REQUIRE threaded couplings? (Select two options.)

Question

Options

• AElectrical metallic tubing (EMT)
• BAluminum metal conduit (AMC)
• CFlexible metal conduit (FMC)
• DIntermediate metal conduit (IMC)
• ERigid metal conduit (RMC)

• A
  4% (1)
• B
  4% (1)
• C
  12% (3)
• D
  80% (20)

Explanation

IMC and RMC are both rigid steel conduits manufactured with walls thick enough to be threaded, so they connect using threaded couplings just like steel pipe - this is required by the NEC and is fundamental to their design. EMT (Choice A) is thin-walled and cannot be threaded; it uses set-screw or compression-type couplings instead. AMC (Choice B) is not a recognized NEC conduit type and serves as a distractor - aluminum versions of RMC or IMC still fall under those designations, not a separate "AMC" category. FMC (Choice C) is a flexible, spiral-wound conduit that uses snap-in or clamp-type connectors, not threaded couplings.

Memory tip: Think of the two correct answers as the "heavy hitters" - Rigid and Intermediate are the thickest, most pipe-like conduits, so they thread like pipe. If it bends (FMC) or has thin walls (EMT), it can't be threaded.

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