Full-load current, conductor, and overcurrent sizing for motors.
Inverse-time breaker (250%), continuous duty, SF ≥ 1.15, conductor at 125% FLC / 75°C Cu. Simplified — verify Table 430.52 for your device type.
NEC Article 430 governs motor branch circuits, feeders, and overcurrent protection. The starting point is always the full-load current (FLC) from the NEC tables — Table 430.248 for single-phase motors and Table 430.250 for three-phase motors. These table values, not the nameplate amperes, drive all downstream sizing for conductors, overcurrent protective devices, and overloads.
Branch-circuit conductors must be sized at a minimum of 125% of motor FLC per 430.22(A), accounting for continuous motor operation. The branch-circuit overcurrent protective device uses 250% of FLC for an inverse-time circuit breaker per 430.52(C)(1) and Table 430.52 — this higher multiple intentionally accommodates motor starting inrush without nuisance tripping. Overload protection is set at 125% of FLC for motors with a service factor of 1.15 or greater, per 430.32(A)(1).
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