Section 230.95/Ground-Fault Protection of Equipment
NEC 230.95 requires ground-fault protection for solidly grounded wye services rated 1000 amps or more at voltages greater than 150V to ground.
Ground-fault protection of equipment (GFPE) must be provided for each service disconnect rated 1000 amperes or more on solidly grounded wye electrical services of more than 150 volts to ground but not exceeding 1000 volts (typically 480Y/277V services). The GFPE must operate to cause the service disconnect to open on ground-fault currents of 1200 amperes or more. The maximum time delay is specified to limit damage from arcing ground faults.
Why this section exists
Arcing ground faults on 480Y/277V systems can sustain at current levels too low to trip standard overcurrent devices but high enough to cause fires and equipment damage. At 277 volts to ground, an arcing fault through a loose connection or damaged insulation can generate enough heat to ignite surrounding materials while drawing only a fraction of the breaker's trip rating. GFPE detects these low-level ground faults and disconnects the service before the arc causes a fire.
What plan reviewers look for
Plan reviewers check the one-line diagram for GFPE on every service disconnect rated 1000 amps or more on 480Y/277V systems. They verify the trip setting (1200A maximum), verify GFPE is shown on the correct disconnect (the first in the system), and check that a performance testing requirement is noted in the specifications.
Common violations
Related NEC requirements
Section 215.10 covers GFPE on feeders. Section 700.26 prohibits GFPE on emergency systems (to prevent nuisance trips from disabling life safety equipment). Section 250.30 covers grounding of separately derived systems where additional GFPE may be required.