For a motor with a circuit line voltage of 480, the largest DETD fuses that can be installed in its safety switch are rated at:

To determine the largest DETD fuses that can be installed in the safety switch for a motor with a circuit line voltage of 480 volts, it is important to reference the National Electrical Code (NEC) and applicable tables for sizing overcurrent protection for motors.

The NEC specifies that the maximum fuse size for branch circuits supplying motors is based on the full-load current (FLC) of the motor. For three-phase motors, the FLC can be calculated from the motor horsepower and voltage. A rule of thumb is that the maximum fuse size should not exceed 250% of the full-load current for the specific motor.

In this case, if the maximum fuse size is determined to be 25 amps based on the full-load current, then this value aligns with the code requirements for overcurrent protection in a motor circuit at 480 volts. This would mean that 25 amps is the largest acceptable fuse size that complies with NEC standards, ensuring protection without exceeding the ratings that could lead to equipment damage or safety hazards.

Choosing this size also enhances the reliability of the motor’s operation and provides proper protection against potential overload conditions that the motor might encounter during normal operation, making it the appropriate choice in this scenario.