HOLT Electricians Practice Exam

A plug fuse may serve as the disconnecting means for a stationary motor of what horsepower or less?

1. 1/4 horsepower

2. 1/2 horsepower

3. 1/8 horsepower

4. 1 horsepower

The correct answer is: 1/8 horsepower

A plug fuse can indeed serve as the disconnecting means for a stationary motor, but it's essential to recognize the specific horsepower limit that is typically set for this application. In the context of electrical installations, particularly for stationary motors, the National Electrical Code (NEC) allows certain types of fuses to be used as both overcurrent protection and a means of disconnection. Specifically, for motors rated at 1/8 horsepower or lower, a plug fuse is permissible as the disconnecting means. This is based on safety and functionality, ensuring that the motor can be quickly de-energized for maintenance or in the event of a malfunction, while also providing protection against overcurrent situations. For higher horsepower ratings, other types of disconnecting means, such as disconnect switches or circuit breakers, are generally required to handle the increased current flow and provide the necessary safety measures. This is why the other choices, which indicate higher horsepower ratings, would not be correct in this instance.