In NEC box-fill calculations, what is the approximate volume assigned to a single 12 AWG conductor?

In NEC box-fill calculations, what is the approximate volume assigned to a single 12 AWG conductor?

• A. 2.00 cu in
• B. 2.20 cu in
• C. 2.30 cu in
• D. 2.25 cu in

Answer: (D)

For box-fill calculations, each conductor that originates outside the box and terminates inside (or passes through) counts as one unit of volume. The NEC specifies the volume per conductor by gauge, and for copper No. 12 the appropriate volume is 2.25 cubic inches. So a single 12 AWG conductor contributes 2.25 cu in toward the box’s required fill. (Grounding conductors, all together, count as one unit, and clamps or devices add their own allowances as applicable.) This is why 2.25 cu in is the standard per-conductor volume for a 12 AWG conductor.

For box-fill calculations, each conductor that originates outside the box and terminates inside (or passes through) counts as one unit of volume. The NEC specifies the volume per conductor by gauge, and for copper No. 12 the appropriate volume is 2.25 cubic inches. So a single 12 AWG conductor contributes 2.25 cu in toward the box’s required fill. (Grounding conductors, all together, count as one unit, and clamps or devices add their own allowances as applicable.) This is why 2.25 cu in is the standard per-conductor volume for a 12 AWG conductor.