Motor Branch-Circuit Protection and Disconnect (NEC 430.52 / 430.110)

Sizes the maximum motor branch-circuit short-circuit and ground-fault protective device from the table FLC and device type per NEC Table 430.52 (250% inverse-time breaker, 175% dual-element fuse, 300% nontime-delay fuse, 800% instantaneous-trip), with the 430.52(C)(1) Exception 1 round-up to the next standard size (240.6), plus the 430.110 disconnect at 115% of FLC. Overload is sized separately (430.32); the AHJ governs.

max_ocpd = FLC x Table 430.52 multiplier (inverse-time breaker 250%, dual-element fuse 175%, nontime-delay fuse 300%, instantaneous-trip breaker 800%); round up to the next standard size (240.6) per 430.52(C)(1) Exception 1; min disconnect = 1.15 x FLC (430.110).

Motor branch-circuit short-circuit and ground-fault protection, NEC 2023 430.52 and Table 430.52, with the disconnect ampere rating 430.110, by name.

NEC is free to read at nfpa.org/freeaccess. The table value uses the table FLC (430.6(A)), not nameplate, and protects against short-circuit/ground-fault only; motor overload is sized separately (430.32).

Estimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.

Field names used by the API: flc_a, device_type, multiplier, max_ocpd_a, max_ocpd_std_a, min_disconnect_a

• Table 430.52 multipliers inverse-time breaker 250%, dual-element/time-delay fuse 175%, nontime-delay fuse 300%, instantaneous-trip breaker 800% (squirrel-cage/induction)NEC Table 430.52
• Round-up and disconnect 430.52(C)(1) Exception 1 permits the next standard size (240.6); the disconnect is rated at least 115% of FLC (430.110(A))NEC 430.52(C)(1), 430.110(A)