A continuous load of 30 A requires a minimum OCPD size based on the 125% rule.

• A. 30 A
• B. 35 A
• C. 40 A
• D. 50 A

Answer: (C)

Continuous loads must be protected by a device sized to handle 125% of the load current. For a 30 A continuous load, multiply by 1.25: 30 × 1.25 = 37.5 A. The overcurrent protection device must have a rating at least 37.5 A, and the smallest standard rating that meets or exceeds that value is 40 A. So the minimum appropriate OCPD is 40 A. A 30 A device is too small, and while a larger rating such as 50 A works, it isn’t the minimum; a 35 A rating, if available, would still be insufficient for 37.5 A.