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.
Formula and source
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.
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