For a 5 horsepower, 240-volt, single-phase motor, which of the following could be used as a disconnecting means?

For a 5 horsepower, 240-volt, single-phase motor, which of the following could be used as a disconnecting means?

• A. Neither I nor II
• B. Either I or II
• C. I only
• D. II only

Answer: (A)

A disconnecting means must be a listed device specifically rated to safely interrupt motor current and provide a means to lock it open. For a 5 HP, 240 V single‑phase motor, the disconnect must be sized for the motor’s full‑load current (which is about 15–16 A) and be located so it’s readily accessible and within sight of the motor. It also needs to be capable of interrupting the motor circuit and must allow lockout to ensure safe service. In this case, neither option shown satisfies those requirements because they do not provide a proper motor-rated disconnect or the necessary lockout capability, and they may not be suitable for interrupting the motor current. Therefore, neither can be used as the disconnecting means. The correct practice would be to use a motor-rated disconnect switch or a circuit breaker with a motor-rated ampacity, installed in the motor circuit, to meet the safety and code requirements.

A disconnecting means must be a listed device specifically rated to safely interrupt motor current and provide a means to lock it open. For a 5 HP, 240 V single‑phase motor, the disconnect must be sized for the motor’s full‑load current (which is about 15–16 A) and be located so it’s readily accessible and within sight of the motor. It also needs to be capable of interrupting the motor circuit and must allow lockout to ensure safe service.

In this case, neither option shown satisfies those requirements because they do not provide a proper motor-rated disconnect or the necessary lockout capability, and they may not be suitable for interrupting the motor current. Therefore, neither can be used as the disconnecting means. The correct practice would be to use a motor-rated disconnect switch or a circuit breaker with a motor-rated ampacity, installed in the motor circuit, to meet the safety and code requirements.