Master Electrician Exam (NEC)Overcurrent ProtectionHard
A commercial kitchen requires ground-fault protection for equipment (GFPE) on a 480Y/277V, 3-phase, 4-wire service rated at 1200 amperes. According to NEC 230.95(A), what is the maximum setting for the GFP device's instantaneous trip?
- A1000 amperes
- B1200 amperes
- C3000 amperes
- D2400 amperes
Show answer & explanationAnswer & explanation
Correct answer: B. 1200 amperes
NEC 230.95(A) specifies that ground-fault protection of equipment shall be provided for solidly grounded wye services of more than 150 volts to ground but not exceeding 1000 volts phase-to-phase for each service disconnect rated 1000 amperes or more. The maximum setting of the ground-fault protection shall be 1200 amperes.
Why the other options are wrong
- A. While 1000A is the threshold for requiring GFPE, it is not the maximum setting for the device.
- C. This value significantly exceeds the NEC requirement and would offer insufficient protection.
- D. This value significantly exceeds the NEC requirement for ground-fault protection settings.
Ground-Fault Protection of Equipment (GFPE)
GFPE is a system designed to protect equipment and property from damaging ground-fault currents, typically found on larger services, by opening the circuit before extensive damage occurs.
- Required for 480Y/277V, 3-phase, 4-wire services rated 1000A or more.
- Maximum setting for the ground-fault device is 1200A.
- Not intended for personnel protection.
Memory trick: Ground Faults need 'EQ'uipment 'P'rotection, 'E'veryone needs to know the '230.95' rule.