A critical care area in a hospital requires ground-fault protection for its essential electrical system. According to NEC 517.17, which of the following statements is true regarding the ground-fault protection requirements for the essential electrical system in a hospital?
- AGround-fault protection is required for all feeders and branch circuits in the critical care area, regardless of voltage.
- BGround-fault protection is not permitted on the essential electrical system.
- CThe essential electrical system must have ground-fault protection, but it must be selectively coordinated with all supply-side overcurrent protective devices.
- DGround-fault protection is only required for the normal power source.
Show answer & explanationAnswer & explanation
Correct answer: C. The essential electrical system must have ground-fault protection, but it must be selectively coordinated with all supply-side overcurrent protective devices.
NEC 517.17(A) and (B) mandate that ground-fault protection of equipment (GFPE) shall be provided for the essential electrical system, and it must be selectively coordinated with all supply-side overcurrent protective devices. This ensures that a ground fault will only trip the nearest upstream device, maintaining power to other critical loads.
Why the other options are wrong
- A. GFPE is generally required for feeders at 1000 A or more, not necessarily all feeders and branch circuits, and the selective coordination is key.
- B. This is incorrect; ground-fault protection is required for the essential electrical system under specific conditions.
- D. NEC 517.17 specifically addresses the essential electrical system, not just the normal source.
Hospital Essential System GFPE
Ground-fault protection of equipment (GFPE) is required for the essential electrical system in hospitals and must be selectively coordinated with all supply-side overcurrent protective devices to ensure continuity of power.
- NEC 517.17 governs requirements.
- Applies to essential electrical systems.
- Requires selective coordination for GFPE.
Memory trick: Hospital 'essential' systems need 'alert' 'power' protection.