What is the minimum box volume requirement for two 12-2 NM-B cables and one 14-3 NM-B cable?

To determine the minimum box volume requirement for two 12-2 NM-B cables and one 14-3 NM-B cable, it's essential to understand how volume calculations work for electrical boxes.

First, we need to calculate the volume that each type of cable occupies. According to the National Electrical Code (NEC), we use a specific formula for calculating the allowances for conductors in a box. For NM-B cable, the volume for each cable is generally regulated based on their gauge (AWG) size.

For each 12-2 NM-B cable, it counts as two conductors plus one ground. Therefore, two 12-2 cables total six conductors (2 cables x 3 conductors each = 6 conductors). The volume requirement for 12 gauge conductors is typically four cubic inches each. Therefore, six 12-gauge conductors contribute 24 cubic inches (6 conductors x 4 cubic inches).

Next, the 14-3 NM-B cable consists of three conductors plus one ground. This results in four conductors. The volume requirement for each 14 gauge conductor is generally two cubic inches. Thus, the volume for one 14-3 NM-B cable is 8 cubic inches (