The largest motor circuit breaker that can be installed in the panel for a given motor is how many amps?

The largest motor circuit breaker that can be installed in a panel for a given motor is determined by the motor’s Full Load Amperage (FLA) as per the National Electrical Code (NEC) guidelines.

When sizing a motor circuit breaker, you typically want to ensure that the breaker can handle the maximum current drawn by the motor under full load conditions. The NEC provides specific ampacity tables and guidelines for motor branch circuits. For many standard commercial and residential applications, the most common practice is to size the motor circuit breaker at 250% of the motor's FLA for the short-circuit and ground-fault protection.

In this scenario, the correct answer suggests the maximum allowable breaker size is 70 amps, which could correlate to common FLA ratings for small to medium-sized motors. Therefore, if specific motor parameters adhere to this breaker size, it provides adequate short-circuit protection while also accommodating the motor's operational needs.

The other options represent either smaller or larger breaker ratings which may not comply with appropriate motor sizing rules, potentially resulting in inadequate protection or risk of nuisance tripping. The 70 amp rating specifically aligns with industry norms for maximum circuit breakers that can be effectively utilized within the constraints of typical motor loads.