Wiring Methods and Protection Flashcards

Per NEC 310.15, what ambient temperature correction factor applies to THHN conductors when the ambient temperature is 50°C?

Answer: 0.58

THHN is rated for 90°C; at 50°C ambient, the correction factor from NEC Table 310.15(B)(1) is 0.58.

When installing PVC conduit above ground in an outdoor exposed location in a non-hazardous area, which schedule is required?

Answer: Schedule 80

NEC 352.10(B) requires Schedule 80 PVC conduit where subject to physical damage above ground.

What is the maximum number of 90° bends allowed in a single run of conduit between pull points per NEC 358.26?

Answer: 4

NEC 358.26 (and similar sections for other conduit types) limits conduit runs to a maximum of four 90° bends (360° total) between outlets or pull boxes.

Which conductor insulation type is rated for use in a wet location AND at 90°C?

Answer: THWN-2

THWN-2 is rated for wet locations at 90°C, while XHHW is only 90°C dry/75°C wet and THW is 75°C wet.

Type AC (armored cable) requires an internal bonding strip. What is its purpose?

Answer: To provide a low-impedance fault current path in addition to the armor

The aluminum bonding strip in Type AC cable works with the steel armor to provide a code-compliant equipment grounding path per NEC 320.108.

At what minimum voltage does the NEC require conductors to be separated from fire alarm circuit conductors that run in the same enclosure?

Answer: 150V

NEC 760.136 requires separation of power-limited fire alarm conductors from conductors of higher voltage circuits exceeding 150V.

When is a pull box required in a conduit system per NEC 314.28?

Answer: When the total bends exceed 360° or the straight distance exceeds 100 feet for trade sizes over 2 inches

NEC 314.28 requires pull or junction boxes when conduit runs exceed 360° total bends or certain straight distances based on trade size.