IEC Wiring Methods and Materials 5

Question 1

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

Accepted Answer

XHHW-2

Answer

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.

Question 2

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

Accepted Answer

No. 1/0 AWG

Answer

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

Question 3

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

Accepted Answer

Contains an internal bonding strip that serves as the EGC

Answer

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

Question 4

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

Accepted Answer

To accommodate thermal expansion and contraction of the conduit

Answer

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

Question 5

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

Accepted Answer

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

Answer

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.

IEC - Independent Electrical Contractors Practice Test

IEC - Independent Electrical Contractors Practice Test

IEC Wiring Methods and Materials 5