Which could be used as a disconnecting means for a 2 horsepower, 240-volt, single-phase motor?

Which could be used as a disconnecting means for a 2 horsepower, 240-volt, single-phase motor?

• A. A manually operated switch
• B. A circuit breaker
• C. Either a manually operated switch or a circuit breaker
• D. Neither a manually operated switch nor a circuit breaker

Answer: (C)

The important point is that the disconnecting means for a motor must be able to disconnect all ungrounded conductors and be readily accessible. For motors, the NEC allows either a manually operated switch or a circuit breaker to serve as that disconnecting means, as long as it’s located where maintenance can safely shut the motor off. A manually operated switch provides the mechanical disconnection, while a circuit breaker provides both disconnection and overcurrent protection. If you use a manual switch, you still need a properly sized overcurrent protective device in the branch circuit. If you use a circuit breaker, it can serve as the disconnect as long as it’s installed correctly. So for a 2 HP, 240-volt, single-phase motor, either device could be used as the disconnecting means.

The important point is that the disconnecting means for a motor must be able to disconnect all ungrounded conductors and be readily accessible. For motors, the NEC allows either a manually operated switch or a circuit breaker to serve as that disconnecting means, as long as it’s located where maintenance can safely shut the motor off. A manually operated switch provides the mechanical disconnection, while a circuit breaker provides both disconnection and overcurrent protection. If you use a manual switch, you still need a properly sized overcurrent protective device in the branch circuit. If you use a circuit breaker, it can serve as the disconnect as long as it’s installed correctly. So for a 2 HP, 240-volt, single-phase motor, either device could be used as the disconnecting means.