What is the maximum size nontime-delay fuses permitted when a safety switch is installed adjacent to a motor?

The maximum size of nontime-delay fuses permissible when a safety switch is installed adjacent to a motor is determined primarily by the National Electrical Code (NEC) regulations, which provide guidelines for ensuring both safety and functionality in electrical systems.

In this context, a safety switch is typically used to provide local disconnection of a motor, and the fuses protect the circuit from overloads or short-circuits. The use of nontime-delay fuses limits the amount of current that can flow before the fuses blow, providing quick protection against overcurrent conditions, which is crucial to preventing damage to motors.

The prevailing rule under NEC guidelines designates the maximum size for nontime-delay fuses in this situation to be 175 amperes. This is based on the fact that nontime-delay fuses are meant to respond quickly to overcurrents, aligning with protective requirements for motor circuits. If the fuse size is too high, it might not provide adequate protection in case of an overload condition.

Consequently, while the other choices represent various sizes of fuses, 175 amperes aligns with the requirements outlined in the NEC for maximum protection in the circuits fed by safety switches proximate to motors. This is why the choice of