Table 314.16(A) allows a maximum of ten wires in a certain box. If the box has two cable clamps and one fixture stud, how many conductors are allowed?

• A. 6 conductors
• B. 8 conductors
• C. 10 conductors
• D. 12 conductors

Answer: (B)

Box fill is all about how many conductors can physically fit inside the box based on its cubic inch capacity. Table 314.16(A) gives the maximum number of conductors the box can hold. In this case, the box can contain ten conductors.

Internal clamps also take up space and are counted as one conductor each. With two cable clamps inside, those consume two of the available conductor slots, leaving eight remaining.

A fixture stud, while a mounting device, is not a conductor and does not count toward the conductor total. So it doesn’t further reduce the allowance.

Therefore, eight conductors is the correct capacity for this box.