15.2 Health Care Facilities — NEC Article 517

Why Article 517 Matters for the TX Journeyman Exam

Health care facility wiring is one of the two topics the TX exam outline names explicitly under Area 9. Questions target the Essential Electrical System branches, the two-path equipment grounding rule, and the second level of ground-fault coordination — all pure section-number recall. Expect 2–4 questions.

Essential Electrical System (517.29)

A hospital (Category 1 patient care spaces) is supplied by a Type 1 Essential Electrical System (EES) consisting of:

• Life Safety Branch — illumination, exit/egress, alarm, and communications loads (517.33)
• Critical Branch — patient care-related loads, including receptacles and equipment in critical spaces (517.34)
• Equipment Branch — major electrical equipment that can be delayed (517.35)

Per 517.32, the Life Safety and Critical branches must be automatically connected to an alternate source (generator) so that all required functions are restored within 10 seconds of a normal power interruption. The Equipment Branch may be connected via timed-delay automatic or manual transfer.

Second Ground-Fault Coordination — 517.17

Where a health care facility is served by a solidly grounded wye system with more than 150 V to ground but not exceeding 1000 V phase-to-phase, and any disconnecting means is rated 1000 A or more (the classic 480Y/277 V service), 517.17 requires two levels of ground-fault protection of equipment (GFPE):

1. A main/service GFP device.
2. A downstream feeder GFP sized and set so a feeder ground fault opens only the feeder — not the main.

517.17(C) demands 100% selectivity between the two levels: the feeder device, not the service device, must operate for faults on the load side of the feeder, considering all manufacturer tolerances and disconnect operating time. The objective is that a single ground fault on a feeder cannot black out the entire facility — critical for a hospital. Maximum settings are 1200 A pickup and no longer than 1 second for fault currents of 3000 A or more. (General EES coordination under 517.31(G) only requires coordination for fault durations exceeding 0.1 second, which is less stringent.)

Equipment Grounding in Patient Care Spaces — 517.13

517.13 provides redundancy so a single installation error cannot leave patient-care equipment ungrounded. It requires two separate equipment grounding paths for branch circuits serving patient care spaces (including the homerun):

• 517.13(A) — Mechanical path: the wiring method itself must be a metal raceway or metal cable whose armor/sheath qualifies as an EGC per 250.118(A) — RMC, IMC, EMT, Type AC cable with internal bonding strip, or listed all-purpose Type MCAP. Traditional interlocked Type MC cable does not qualify under 250.118(A)(10)(a).
• 517.13(B) — Wire path: an insulated copper EGC (green insulation its entire length) installed inside the raceway and connected to receptacle grounding terminals, metal boxes/enclosures, and metal parts of fixed equipment operating at more than 100 V likely to become energized. Sized per 250.122.

The 2023 NEC changed the wording from "wiring in patient care spaces" to "wiring serving patient care spaces," so the two-path rule now applies to the entire branch circuit, not just the portion physically inside the space. Patient care spaces use the Category 1/2/3/4 risk-based system (Category 1 = critical care, Category 2 = general care) replacing the older critical/general/basic/support labels.

Isolated Ground Receptacles — 517.16

Where an isolated ground receptacle is installed in a patient care space, the isolated grounding terminal must be connected to the reference grounding point by an insulated copper equipment grounding conductor. The metal raceway required by 517.13(A) still provides the second path. Isolated ground receptacles are used to reduce electrical noise on sensitive medical equipment, but they do not eliminate the 517.13 two-path requirement.

Patient Bed Location Receptacles — 517.19

For Category 1 (critical care) patient bed locations, 517.19(B)(1) requires a minimum of 14 receptacles, which may be single, duplex, or quadruplex. At least one must be supplied by the normal system branch circuit or by a critical branch served by a different transfer switch than the other receptacles at that location (517.19(A) requires at least two branch circuits). All 14 receptacles must be listed hospital grade and identified as such (517.19(B)(2)), with the grounding terminal connected to the reference grounding point by an insulated copper EGC. Operating rooms under 517.19(C)(1) require a minimum of 36 receptacles, divided between at least two branch circuits.

For comparison, Category 2 (general care) patient bed locations under 517.18(B)(1) require a minimum of 8 receptacles, not all hospital grade.