Wiring Methods and Materials Flashcards

What is the maximum number of 90-degree bends permitted in a single run of EMT between pull points?

Answer: Four 90-degree bends

NEC 358.26 limits EMT to a maximum of four quarter bends (360 degrees total) between pull points.

Which wiring method is specifically listed for use in concrete encasement?

Answer: Rigid Metal Conduit (RMC)

RMC (Rigid Metal Conduit) is permitted for direct burial and encasement in concrete per NEC 344.10.

Under NEC Article 330, Metal-Clad (MC) cable installed exposed in a commercial building must be supported at intervals not exceeding:

Answer: 6 feet

NEC 330.30 requires MC cable to be secured and supported at intervals not exceeding 6 feet.

When installing liquidtight flexible metal conduit (LFMC) in lengths exceeding 6 feet, the installer must:

Answer: Use a separate equipment grounding conductor inside

Per NEC 350.60, LFMC in lengths over 6 feet is not permitted to serve as the sole equipment grounding path — a separate EGC is required.

What is the minimum cover requirement for RMC installed directly in a concrete slab on grade?

Answer: 0 inches — no cover required

NEC Table 300.5 requires no additional cover for RMC encased in concrete above grade.

A commercial inspector finds Schedule 40 PVC conduit installed in a machinery area subject to physical damage. This installation is:

Answer: A code violation — Schedule 80 or RMC required

NEC 352.12(A) prohibits Schedule 40 PVC where subject to physical damage; Schedule 80 or a metal raceway must be used.

The NEC requires that all conductors of the same circuit, including the EGC, must be contained within the same raceway primarily to:

Answer: Prevent inductive heating of metallic raceways

NEC 300.3(B) requires all circuit conductors to be in the same raceway to prevent inductive heating caused by unbalanced magnetic fields in metal enclosures.