In a metal junction box with 27 cubic inches containing six 12 AWG wires, how many additional 10 AWG conductors can be added?

To determine how many additional 10 AWG conductors can be added to the metal junction box, it’s important to first understand the fill capacity rules as outlined in the National Electrical Code (NEC).

A metal junction box is rated for a specific volume, and each type of wire has a specific cubic inch requirement. According to NEC guidelines, a 12 AWG conductor typically takes up 2 cubic inches of space, while a 10 AWG conductor takes up 2.25 cubic inches.

In this scenario, the junction box has a volume of 27 cubic inches and already contains six 12 AWG wires. Since each 12 AWG wire occupies 2 cubic inches, the total volume taken up by the six 12 AWG wires is:

6 wires x 2 cubic inches/wire = 12 cubic inches.

With 27 cubic inches total in the box, the remaining space is:

27 cubic inches - 12 cubic inches = 15 cubic inches available.

Now, considering the additional 10 AWG conductors, each will require 2.25 cubic inches. To find out how many 10 AWG conductors can fit into the remaining 15 cubic inches, we calculate:

15 cubic inches available