Electrical Systems & Wiring Installation Flashcards

When splicing conductors in a junction box, which connection method is NOT permitted by the NEC?

Answer: Soldering without mechanical connection

Splices must be mechanically secure before being soldered; soldering alone is not an acceptable splice method.

What is the minimum box fill volume required for each 12 AWG conductor entering a device box per NEC Table 314.16(B)?

Answer: 2.25 cubic inches

Each 12 AWG conductor counts as 2.25 cubic inches for box fill calculation per NEC Table 314.16(B).

A 240V, 30-amp dryer circuit requires which NEMA receptacle configuration?

Answer: NEMA 14-30R

NEMA 14-30R is the current NEC-required 4-wire receptacle for 240V, 30-amp dryer circuits.

What is the correct procedure when a breaker trips repeatedly on a newly installed circuit?

Answer: Check for overloaded circuit, short circuit, or ground fault before resetting

Repeated tripping indicates a fault condition that must be identified and corrected, not bypassed.

In a panel board, what is the purpose of the main bonding jumper (MBJ)?

Answer: To bond the neutral bus to the equipment grounding bus at the service entrance panel

The MBJ connects the neutral bus to the enclosure/ground bus at the service entrance, completing the fault current path.

Which conductor insulation type is rated for use in wet locations and direct burial without conduit?

Answer: UF-B

UF-B (Underground Feeder) cable is specifically rated for direct burial and wet location use without conduit.

What is the required minimum headroom clearance in front of a residential electrical panel for working space?

Answer: 6 feet

NEC 110.26(A)(3) requires a minimum of 6 feet of headroom in front of electrical equipment working spaces.