A continuous load must be multiplied by what factor to determine feeder ampacity?

A continuous load must be multiplied by what factor to determine feeder ampacity?

• A. 125%
• B. 100%
• C. 150%
• D. 200%

Answer: (A)

Continuous loads are those that run for 3 hours or more. To keep conductors from overheating when a load is sustained, the NEC requires sizing feeders and services at 125% of the continuous load. So when determining feeder ampacity, you multiply the continuous portion by 1.25. For example, a continuous load of 40 A becomes 40 × 1.25 = 50 A, so you’d size the feeder for at least 50 A (typically stepping up to the next standard size, like 60 A). Noncontinuous loads aren’t multiplied by this factor; they’re included at their actual values. This extra 25% margin ensures the system remains within temperature ratings under sustained operation.

Continuous loads are those that run for 3 hours or more. To keep conductors from overheating when a load is sustained, the NEC requires sizing feeders and services at 125% of the continuous load. So when determining feeder ampacity, you multiply the continuous portion by 1.25. For example, a continuous load of 40 A becomes 40 × 1.25 = 50 A, so you’d size the feeder for at least 50 A (typically stepping up to the next standard size, like 60 A). Noncontinuous loads aren’t multiplied by this factor; they’re included at their actual values. This extra 25% margin ensures the system remains within temperature ratings under sustained operation.