What is the minimum volume allowance required for conductor fill in a GFCI receptacle outlet box on a 20-ampere branch circuit with 12 AWG copper wire?

The minimum volume allowance required for conductor fill in a GFCI (Ground Fault Circuit Interrupter) receptacle outlet box is determined by the National Electrical Code (NEC), which provides guidelines for conductor fill based on the size and quantity of wires used.

For a 20-ampere branch circuit that utilizes 12 AWG copper wire, each conductor (including the hot and neutral wires) contributes to the total fill of the box. A standard rule of thumb from the NEC stipulates that each 12 AWG conductor requires a volume of 2.25 cubic inches.

In addition to the conductors, the box must also accommodate any device or equipment being installed, such as the GFCI receptacle, which adds to the volume calculation. Taking these requirements into consideration, the total volume needed for the outlet box that contains the GFCI receptacle and the conductors does indeed begin with the 2.25 cubic inches required for the conductors alone.

Therefore, while considering the base requirement for the conductors and typical provisions for GFCI devices, the minimum volume allowance required leading to the answer reflects the specific electrical code guidelines to ensure safety and adequate space for electrical connections.