An industrial facility has a 440-volt, three-phase, low-speed NEMA Design B squirrel-cage motor with a nameplate full-load current of 100 amperes. For this motor, 2026 NEC 430.6 requires the nameplate current as the sizing basis. It is not Design BE or CE. An inverse-time circuit breaker will provide branch-circuit short-circuit and ground-fault protection. Under the ordinary Table 430.52(C)(1) percentage, before any permitted increase for starting current and with no other exception, what is its maximum rating?

Where to look it up

https://www.elightinformation.com/post/motor-and-welding-machine-calculation-steps-2026-nec

Why D is correct

100 A × 250% = 250 A, D. The inverse-time breaker percentage establishes this ordinary branch short-circuit/ground-fault protection maximum, not a universal 125% minimum. Smaller ratings do not equal the requested maximum and still must carry starting current if selected. Separate motor overload protection uses a different rule; it cannot be replaced by this breaker-sizing calculation. Source: E Light Electric, Motor and Welding Machine Calculation Steps 2026 NEC, current-basis rule and Step 3: https://www.elightinformation.com/post/motor-and-welding-machine-calculation-steps-2026-nec