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Wiring Methods and Materials Flashcards

7 cards from real IEC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Wiring Methods and Materials flashcards as text

  1. Which conductor insulation type is rated for use in both dry and wet locations at 90°C?

    Answer: XHHW-2

    XHHW-2 is rated 90°C in both dry and wet locations, while THHN is 90°C dry/75°C wet and THW is 75°C in both.

  2. When installing conductors in parallel (per NEC 310.10(H)), what is the minimum size conductor permitted to be paralleled?

    Answer: No. 1/0 AWG

    NEC 310.10(H)(1) requires that conductors installed in parallel must be 1/0 AWG or larger.

  3. Armored cable (Type AC) differs from metal-clad cable (Type MC) primarily in that AC cable:

    Answer: Contains an internal bonding strip that serves as the EGC

    Type AC cable contains an internal aluminum bonding strip that, combined with the armor, provides the equipment grounding path per NEC 320.108.

  4. What is the purpose of an expansion fitting (expansion joint) installed in a PVC conduit run?

    Answer: To accommodate thermal expansion and contraction of the conduit

    PVC conduit expands and contracts significantly with temperature changes, and expansion fittings allow this movement without stressing the system.

  5. When must conductors be derated according to NEC 310.15(C) (adjustment factors)?

    Answer: When more than three current-carrying conductors are in a raceway or cable

    NEC 310.15(C) requires ampacity adjustment when more than three current-carrying conductors are bundled or installed in a raceway, because heat dissipation is reduced.

  6. What type of conduit fitting is required when terminating EMT into a weatherproof (rainproof) enclosure?

    Answer: A raintight or weatherproof connector listed for the application

    NEC 358.42 requires fittings for EMT used in wet locations to be listed for wet locations (raintight or weatherproof), maintaining the enclosure's environmental rating.

  7. Service entrance cable (Type SE) installed exposed on the exterior of a building must be supported at intervals not exceeding:

    Answer: 48 inches

    NEC 338.30(A) requires SE cable installed as a service-entrance conductor to be supported at intervals not exceeding 30 inches along the building exterior—but when used as branch-circuit or feeder wiring, it follows NEC 334.30 at 4.5-foot intervals; for service runs the standard is every 30 inches.