How many 12/2 AWG with ground, type NM cables can be installed in an 18 cubic inch outlet box with a duplex receptacle?

To determine how many 12/2 AWG with ground NM cables can fit in an 18 cubic inch outlet box with a duplex receptacle, we start by analyzing the volume allowance required per cable. According to the National Electrical Code (NEC), a standard 12/2 NM cable takes up a certain amount of cubic space within an outlet box.

For each 12/2 NM cable, we typically allocate about 2 cubic inches of space for the cable itself. In addition, we need to account for additional space for the receptacle and any conductors associated with it. A duplex receptacle typically requires additional cubic inch space as well.

Considering these factors, we convert the outlet box volume (18 cubic inches) into usable space:

1. Each 12/2 cable takes up approximately 2 cubic inches.

2. The duplex receptacle will require about 2 cubic inches for its installation.

Adding the cubic inch requirement for the receptacle to the total space required for the number of cables gives us a clear calculation.

If you have one duplex receptacle consuming 2 cubic inches, and allocate 2 cubic inches for each of the cables, you can fit multiple cables without exceeding the box's capacity. With this understanding