What is the minimum size EGC permitted for a 2 hp, 115/230-V motor fed from a 120/208-V panel where DETD fuses are installed?

The correct answer is based on the specific requirements outlined in the National Electrical Code (NEC) for equipment grounding conductors (EGC). For a 2 horsepower (hp) motor operating at 115/230 volts and fed from a 120/208-volt panel, the size of the EGC must be determined according to the NEC guidelines.

The NEC stipulates that the minimum size for an EGC is typically derived from the size of the circuit conductors feeding the motor. For a 2 hp motor, the full load current would be approximately 12 to 15 amps, depending on the voltage. According to NEC Table 250.122, the minimum size EGC for circuits rated up to 20 amps is usually 10 AWG copper or 8 AWG aluminum.

Choosing 10 AWG copper for the EGC provides suitable protection against ground faults for a motor of this capacity. This size is deemed appropriate for handling any fault currents that may occur, ensuring safety and compliance with the NEC guidelines. Specifically, the presence of DETD fuses, which are time-delay fuses designed to handle the inrush current of motors without nuisance tripping, does not affect the minimum size requirement for the EGC, which is