A metal device box has two 14 AWG conductors, one 14 AWG grounding conductor, two internal clamps, and a duplex receptacle.What is the minimum size metal device box you could use?

Question

Quizplus · Accepted Answer

According to NEC regulations, a metal device box must have at least 2.0 cubic inches of volume per #14 AWG conductor and 2.25 cubic inches for each internal clamp. The grounding conductor is counted as one #14 AWG conductor. The duplex receptacle counts as 4 conductor volumes. Therefore, the minimum size metal device box needed is:

2 (14 AWG conductors) x 2.0 cubic inches = 4.0 cubic inches
1 (14 AWG grounding conductor) x 2.0 cubic inches = 2.0 cubic inches
2 (internal clamps) x 2.25 cubic inches = 4.5 cubic inches
1 (duplex receptacle) x 4.0 cubic inches = 4.0 cubic inches
Total cubic inch volume needed = 14.5 cubic inches

The closest size metal device box that meets or exceeds this volume is 3" x 2" x 2-1/2", which has a volume of 15 cubic inches. Therefore, the best choice is C.

A Metal Device Box Has Two 14 AWG Conductors, One