The largest non-time-delay fuses permitted to be installed in a disconnect switch for a motor is rated at what amperage?

The largest non-time-delay fuses permitted to be installed in a disconnect switch for a motor is rated at 50 amperes. This is based on the National Electrical Code (NEC) requirements which specify that for motor circuits, non-time-delay fuses may be rated higher than their time-delay counterparts. These fuses are designed to provide protection against overloads and short circuits, ensuring that equipment is safeguarded while allowing for normal operational inrush currents associated with motors.

The 50-amp rating aligns with the NEC guidelines for motor circuits, providing an ample level of protection while also taking into account potential brief overload conditions that motors may experience during operation. This balance is crucial in industrial and commercial electrical installations, where ensuring both safety and performance is key.