each 480-volt, three-phase, wye-connected feeder disconnect with a minimum rating of ___ amperes is required to be ground-fault protected.

Each 480-volt, three-phase, wye-connected feeder disconnect with a minimum rating of 1000 amperes is required to be ground-fault protected. This requirement applies to feeders and service disconnects rated 1000 amps or more on solidly grounded wye electrical systems with voltage over 150 volts to ground, but not exceeding 600 volts phase-to-phase. The ground-fault protection of equipment (GFPE) is intended to protect the equipment from damage due to low level ground faults that may not be detected by normal overcurrent devices. This is codified in NEC section 230.95 and related sections.