What is the minimum cubic inch volume required for a two-gang box containing two 12/2 AWG w/ground NM cables and two 14/2 AWG w/ground NM cables connected to devices?

To determine the minimum cubic inch volume required for a two-gang box containing the specified cables, it’s important to follow the National Electrical Code (NEC) guidelines for box fill calculations.

First, calculate the conductor fill. Each NM cable has two conductors and a ground, so for the cables mentioned:

• Each 12/2 NM cable contributes 3 conductors (2 hot and 1 ground).

• Each 14/2 NM cable also contributes 3 conductors.

Thus, for two 12/2 AWG cables and two 14/2 AWG cables, the total number of conductors is:

• 2 cables × 3 conductors = 6 for the 12/2 NM cables

• 2 cables × 3 conductors = 6 for the 14/2 NM cables

Adding these gives a total of 12 conductors. The NEC specifies that each conductor accounts for 2 cubic inches of fill in a box.

12 conductors × 2 cubic inches per conductor = 24 cubic inches for the conductors.

Next, additional space must be added for the devices. According to NEC requirements, each device (like a switch or outlet) typically counts as an additional 2