Wiring Methods and Materials Flashcards

When conductors of different systems share the same raceway, they must all be insulated for the:

Answer: Highest voltage present

NEC 300.3(C)(1) requires all conductors sharing a raceway to be insulated for the highest voltage present in that raceway.

What is the color code for the high-leg (wild leg) conductor in a 4-wire, 3-phase delta system?

Answer: Orange

NEC 230.56 and 408.3(F) require the high-leg conductor in a 3-phase delta system to be identified with orange color.

Electrical metallic tubing (EMT) is NOT permitted to be used in which condition?

Answer: Subject to severe physical damage

NEC 358.12 prohibits EMT where it will be subject to severe physical damage due to its thin-wall construction.

Type MC cable used for wiring in an accessible ceiling plenum space used for environmental air must be which type?

Answer: MC cable with a smooth or corrugated aluminum sheath or listed plenum cable

NEC 330.10(A)(11) and 300.22 require cables in air-handling plenums to be plenum-rated or have a metallic sheath that limits flame and smoke spread.

A 2-inch rigid metal conduit (RMC) must have a support within what distance of each box, cabinet, or conduit fitting?

Answer: 3 feet

NEC 344.30(B)(1) requires RMC to be supported within 3 feet of each outlet box, junction box, device box, cabinet, conduit body, or other conduit termination.

Which statement about aluminum conductors smaller than No. 8 AWG is correct under the NEC?

Answer: They are not permitted for branch circuit wiring

NEC 310.106(B) prohibits solid aluminum conductors smaller than No. 8 AWG for branch circuit wiring due to connection failure risks.

When pulling wire through conduit, the maximum pulling tension for copper conductors is based on a stress of:

Answer: 0.008 lb/circular mil

Industry practice limits conductor pulling tension to 0.008 lb per circular mil of cross-sectional area to avoid stretching or damaging copper conductors.