Which describes a continuous load under NEC guidelines for sizing overcurrent protective devices, and what is the applicable factor?

• A. A load that operates at variable voltage; factor 150%
• B. A load expected to run for 3 hours or more; factor 125%
• C. A load that never runs; factor 80%
• D. A load only during peak hours; factor 100%

Answer: (B)

Continuous loads are those that operate for three hours or more. For sizing overcurrent protective devices under NEC, you apply a 125% factor to the continuous load. This extra margin accounts for heat buildup and ensures the protection device won’t nuisance-trip during prolonged operation. So, if a load runs for at least three hours, multiply its current by 1.25 to determine the minimum OCPD rating. The other descriptions don’t describe a continuous load, and the factor for continuous loads is 125%, not 100% or any other percentage.