Ground-fault protection of equipment shall be provided for solidly grounded wye electric services of more than 150 volts to ground, but not exceeding 1,000 volts phase-to-phase, for each service disconnect rated 1,000 amperes or more.

• A. True
• B. False
• C. Only for 600-volt systems
• D. Not required for this case

Answer: (A)

Ground-fault protection of equipment is required on solidly grounded wye services when the line-to-ground voltage is greater than 150 V and the line-to-line voltage does not exceed 1000 V, for each service disconnect rated at 1000 A or more. This protection is in place because large, solidly grounded systems can experience substantial fault currents from a ground fault, and GFPE helps remove power quickly to protect equipment and reduce fire and damage risk. The requirement targets large services within that voltage range, not smaller services or systems outside the range. So a large 480Y/277 V or similar service with a main disconnect of 1000 A or more would need GFPE, whereas smaller services or voltages outside the specified window do not.