How many 12 AWG THHN conductors are permitted in a 4 in. x 1.5 in. square box?

To determine the number of 12 AWG THHN conductors permitted in a 4 in. x 1.5 in. square box, we need to apply the National Electrical Code (NEC) guidelines regarding box fill calculations.

First, we assess the volume of the box. A 4 in. x 1.5 in. square box has a volume of approximately 24 cubic inches. According to the NEC, every electrical conductor in a box takes up a certain amount of space. For conductors, the NEC allows for 2 cubic inches per 12 AWG conductor.

Calculating the space for the conductors:

• For 12 AWG conductors, 2 cubic inches multiplied by the number of conductors will give us the total volume used by the conductors.

If we take 9 as the number of conductors:

• 9 conductors x 2 cubic inches/conductor = 18 cubic inches, which fits within the box’s total volume of 24 cubic inches.

This means that there is still adequate volume left in the box for any additional requirements that may be specified by the NEC, such as the volume required for devices, fittings, or wire connectors.

Thus, 9