Section 430.52/Motor Branch Circuit Protection
NEC 430.52 establishes maximum overcurrent device ratings for motor branch circuits using FLC tables rather than nameplate current.
Motor branch circuit short-circuit and ground-fault protective devices must be capable of carrying the starting current of the motor. The maximum rating is determined by Table 430.52, which specifies percentages of the motor full-load current (FLC) from Tables 430.248 through 430.250 based on the type of motor and the type of protective device. For an inverse time breaker protecting a standard AC motor, the maximum is 250% of the FLC. If 250% does not correspond to a standard rating, the next standard size up is permitted.
Why this section exists
Motors draw 5-8 times their full-load current during startup. A standard overcurrent device sized to the motor FLC would trip every time the motor starts. The elevated percentages in Table 430.52 allow the breaker to ride through the starting inrush without tripping while still providing short-circuit and ground-fault protection. Overload protection is provided separately by the motor overload relay per Part III of Article 430.
What plan reviewers look for
Plan reviewers verify that motor branch circuit breaker sizes on the panel schedule do not exceed the maximum percentage from Table 430.52. They check that the FLC is taken from the NEC tables (430.248-430.250), not from the motor nameplate. They also verify that the MOCP (Maximum Overcurrent Protective Device) on the mechanical equipment schedule matches the breaker size on the electrical panel schedule.
Common violations
Related NEC requirements
Section 430.6 requires using Table FLC values. Section 430.32 covers motor overload protection (separate from branch circuit protection). Section 430.24 covers conductor sizing for multiple motor circuits. Tables 430.248-430.250 provide the full-load current values.