A box with four internal cable clamps adds how many additional conductors to the fill allowance?

The correct answer is based on the National Electrical Code (NEC) guidelines regarding conduit fill calculations. When determining the fill allowance for a conduit or box, each internal cable clamp present in a box is counted as an additional conductor. This means that a box with four internal cable clamps will add one additional conductor to the fill calculation.

In practical terms, each clamp takes up space and should be accounted for when calculating the maximum number of conductors that can fit within the box without exceeding the fill limit. The fill limits are essential for ensuring safety, preventing overheating, and maintaining the integrity of the electrical system. Therefore, regardless of the number of clamps, it's always the case that each one contributes a single additional conductor count to the overall allowance, which is why the additional conductors added by the four clamps totals to one.