A single-phase electrical device in a building draws 37 A and is supplied with two type THWN copper wires in a conduit. The conduit is run up through the cores of concrete blocks in a building. The wire ampacity is to be sized at 125% of the 37 A, which is 46.25 A. The minimum size of wire permitted is AWG number ____.
A) 4
B) 6
C) 8
D) 10

Question

Quizplus · Accepted Answer

To determine the minimum wire size needed, we will use the NEC ampacity chart for copper wire. Based on the given information, we need to find a wire size that can handle at least 46.25 A of current.

Looking at the chart, we see that a 10 AWG wire can handle up to 40 A, which is not enough for our application. However, an 8 AWG wire can handle up to 50 A, which is more than the required 46.25 A. Therefore, the minimum wire size permitted is AWG number 8.

A Single-Phase Electrical Device in a Building Draws 37 a and Is