In box-fill calculations, beyond counting conductors, what is the additional volume required for one or more internal cable clamps?

• A. Single Volume Allowance
• B. Double Volume Allowance
• C. Triple Volume Allowance
• D. No Additional Volume

Answer: (A)

In box-fill calculations, you must account for every bit of space occupied inside the box, not just the wires and cables. Internal cable clamps inside the box also take up space, and the rule is to add a single volume allowance for them. This means you add the volume of one conductor (the largest size present in the box) once, even if there are multiple clamps. If there are no clamps, you add nothing. So the extra volume for one or more internal clamps is a single volume allowance.