In a 4 x 1 1/2 inch square box, how many 16 gauge conductors are permitted?

In a 4 x 1 1/2 inch square box, how many 16 gauge conductors are permitted?

• A. 10
• B. 8
• C. 14
• D. 12

Answer: (D)

Box-fill calculations determine how many conductors of a given gauge can fit in a box by comparing the box’s internal volume to the space each conductor requires. For 16-gauge conductors, the NEC tables assign 2.0 cubic inches of space per conductor. The box in question is a 4 by 4 by 1-1/2 inch square box, which yields about 24 cubic inches of internal volume. Dividing the box volume by the per-conductor allowance gives 24 ÷ 2.0 = 12. Therefore, up to 12 conductors of 16 AWG can be accommodated, assuming there are no additional allowances such as internal clamps or device yokes. If grounding conductors are present, all grounds together count as one conductor; an internal clamp would count as one more conductor, and a device on the box would add another conductor equivalent for the device’s yoke.

Box-fill calculations determine how many conductors of a given gauge can fit in a box by comparing the box’s internal volume to the space each conductor requires. For 16-gauge conductors, the NEC tables assign 2.0 cubic inches of space per conductor. The box in question is a 4 by 4 by 1-1/2 inch square box, which yields about 24 cubic inches of internal volume. Dividing the box volume by the per-conductor allowance gives 24 ÷ 2.0 = 12. Therefore, up to 12 conductors of 16 AWG can be accommodated, assuming there are no additional allowances such as internal clamps or device yokes. If grounding conductors are present, all grounds together count as one conductor; an internal clamp would count as one more conductor, and a device on the box would add another conductor equivalent for the device’s yoke.