When wiring a 20 amp FLA motor, what is the minimum amp fuse or circuit breaker that should be used?

When determining the minimum amp fuse or circuit breaker for a 20 amp full-load current (FLA) motor, it's important to consider the need for overload protection and the specifics of electrical codes.

In general, the National Electrical Code (NEC) allows for a fuse or circuit breaker size that is larger than the motor's FLA to handle the inrush current that occurs when the motor starts. For motors, the recommended approach is often to size the protection device at 125% of the full-load current. For a 20 amp FLA motor, 125% would be 25 amps.

By selecting a 25 amp fuse or circuit breaker, you are providing adequate protection for the motor during start-up while ensuring the circuit remains safe during normal operation. This sizing allows for the momentary surge in current that occurs when motors start, preventing nuisance tripping while still being adequately protected against overload or faults that could occur during regular operation.

Options that are lower than 25 amps would not meet the requirement for protecting the motor during start-up, and thus may lead to frequent tripping or inadequate protection. A 30 amp option is also larger than necessary, which may not align with the NEC guidelines directing adherence to the maximum allowable size