For an outlet box with no cable clamps, what is the minimum cubic inch capacity required when it contains a receptacle and four 12-2 NM cables?

To determine the correct minimum cubic inch capacity for an outlet box containing a receptacle and four 12-2 NM cables, it's essential to apply the code's fill calculations for electrical boxes.

Each 12-gauge NM cable (which consists of two insulated conductors and a ground) counts as two conductors for the purpose of box fill. Therefore, four 12-2 NM cables would contribute a total of eight conductors. Adding a receptacle typically adds one additional conductor count.

Now calculating the conductor fill:

• For cables, each 12-gauge conductor contributes 2 cubic inches when calculating box fill, so eight conductors would require 16 cubic inches.

• The single receptacle adds another 2 cubic inches.

This brings the total to 18 cubic inches. However, the National Electrical Code (NEC) requires additional space for the terminals, grounding conductors, and any clamps, if applicable. Without clamps in your scenario, a minimum factor is added based on the number of conductors (which often might lead to a minimum count multiplier).

In many cases, the best practice is to round up or use the NEC's standard volume when calculating, thus a box that holds slightly more than the calculated volume is