GFPE is required for a 1,000-ampere service disconnect with 800-ampere fuses for a 480/277-volt, 3-phase, 4-wire, solidly grounded wye system.

GFPE is required for a 1,000-ampere service disconnect with 800-ampere fuses for a 480/277-volt, 3-phase, 4-wire, solidly grounded wye system.

• A. True
• B. False
• C. Not applicable
• D. Unknown

Answer: (A)

Ground-Fault Protection of Equipment is required for service equipment on solidly grounded 480Y/277 V systems when the service disconnect rating is 1000 A or less. In this scenario, the service disconnect is rated at 1,000 A and is fed by 800 A fuses on a 480/277 V, 3-phase, 4-wire, solidly grounded wye system. The solid grounding and the relatively low service-rating trigger GFPE protection to quickly detect and interrupt ground faults, protecting both equipment insulation and personnel. The 800 A fuses don’t remove the requirement—the service equipment rating governs it. So this statement is correct.

Ground-Fault Protection of Equipment is required for service equipment on solidly grounded 480Y/277 V systems when the service disconnect rating is 1000 A or less. In this scenario, the service disconnect is rated at 1,000 A and is fed by 800 A fuses on a 480/277 V, 3-phase, 4-wire, solidly grounded wye system. The solid grounding and the relatively low service-rating trigger GFPE protection to quickly detect and interrupt ground faults, protecting both equipment insulation and personnel. The 800 A fuses don’t remove the requirement—the service equipment rating governs it. So this statement is correct.