Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Healthcare Essential Electrical Systems
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description: >
When to use: Design, specification, and installation of the Essential Electrical System (EES) in healthcare facilities governed by NEC Article 517 and NFPA 99 — hospitals, ambulatory surgical centers, outpatient clinics, and nursing homes containing patient care spaces. Covers all three EES branches (Life Safety, Critical, Equipment), the branch transfer switches, feeders, and distribution panelboards, and the Type 1 / Type 2 selection driven by NFPA 99 risk category.
− Not intended for: Generator set sizing, fuel systems, and paralleling (use [[sync/generators]]); automatic transfer switch hardware selection (use [[sync/automatic-transfer-switches]]); normal-mode overcurrent coordination and short-circuit study (use [[sync/protective-coordination-study]]); normal-service low-voltage panelboards (use [[sync/low-voltage-panelboards]]); non-healthcare NFPA 110 emergency and standby power (use [[sync/emergency-and-standby-power]]); the electrical safety program and arc-flash labeling (use [[sync/electrical-safety-program]]).
+ Not intended for: Generator set sizing, fuel systems, and paralleling (use [[sync/generators]]); automatic transfer switch hardware selection (use [[sync/automatic-transfer-switches]]); normal-mode overcurrent coordination and short-circuit study (use [[sync/protective-coordination-study]]); normal-service panelboards (use [[sync/panelboards]]); non-healthcare NFPA 110 emergency and standby power (use [[sync/emergency-and-standby-power]]); the electrical safety program and arc-flash labeling (use [[sync/electrical-safety-program]]).
---
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## The applicable NEC 517 sub-article (517.30 hospitals, 517.42 nursing homes, 517.45 limited care facilities, 517.80 ambulatory health care) shall be confirmed against the occupancy classification before branch loads are assigned.
−## Generator set sizing, fuel systems, and paralleling are specified in [[sync/generators]] and are outside this scope; this standard treats the on-site alternate power source as an interface and states only the performance it must deliver to the EES. {note}
+## Generator set sizing, fuel systems, and paralleling are specified in [[sync/generators]] and are outside this scope; this standard treats the on-site alternate power source as an interface and states only the performance it must deliver to the EES.
## Transfer switch hardware ratings and construction are specified in [[sync/automatic-transfer-switches]]; this standard states only the topology, branch assignment, and bypass requirements for switches serving the EES. {note}
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## The EES type shall be selected from the facility's highest patient-care-space risk category as established by the NFPA 99 risk assessment.
−## A Type 1 EES shall provide three branches: a Life Safety Branch, a Critical Branch, and an Equipment Branch.
−
−## A Type 2 EES shall provide a Life Safety Branch and a Critical Branch; a separate Equipment Branch is not required.
−
−## A facility containing a single Category 1 space cannot be downgraded to Type 2 by load count; the presence of the space, not its size, governs the classification. {note}
−
```datasheet
label: EES Type
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```
+## A Type 1 EES shall provide three branches: a Life Safety Branch, a Critical Branch, and an Equipment Branch.
+
+## A Type 2 EES shall provide a Life Safety Branch and a Critical Branch; a separate Equipment Branch is not required.
+
+## A facility containing a single Category 1 space cannot be downgraded to Type 2 by load count; the presence of the space, not its size, governs the classification. {note}
+
+## The facility's occupancy classification shall be specified so that the applicable NEC 517 sub-article governing the essential electrical system design is established.
+
```datasheet
label: Facility Occupancy Classification (governs applicable NEC 517 sub-article)
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## Patient bed receptacle quantities on the Critical Branch shall meet the minimums of NEC 517.18 for general care and 517.19 for critical care.
−## All receptacles connected to the Critical and Life Safety branches in patient care spaces shall be hospital-grade and identified by the listing mark and a distinctive color.
−
−## Only hospital-grade devices shall be used for receptacles in patient care spaces on Critical and Life Safety branch circuits.
−
−## Specifying standard commercial-grade receptacles on Critical or Life Safety branch circuits is a common coordination miss between the electrical and medical-equipment specifications. {note}
−
```datasheet
label: General Care Patient Bed Receptacles (NEC 517.18 minimum)
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```
+## All receptacles connected to the Critical and Life Safety branches in patient care spaces shall be hospital-grade and identified by the listing mark and a distinctive color.
+
+## Only hospital-grade devices shall be used for receptacles in patient care spaces on Critical and Life Safety branch circuits.
+
+## Specifying standard commercial-grade receptacles on Critical or Life Safety branch circuits is a common coordination miss between the electrical and medical-equipment specifications. {note}
+
## The Critical Branch shall be supplied by a dedicated transfer switch serving no other branch.
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## Branch transfer switches in a Type 1 EES shall be provided with bypass-isolation construction so the switch can be maintained or replaced without de-energizing the branch.
−## Specifying a non-bypass transfer switch for a hospital branch means the branch must be de-energized for switch maintenance, which can require patient relocation; bypass-isolation is the default for Type 1 EES branches. {note}
+## Specifying a non-bypass transfer switch for a hospital branch means the branch must be de-energized for switch maintenance, which can require patient relocation; bypass-isolation is the default for Type 1 EES branches.
## A closed-transition (make-before-break) transfer switch should be specified for the Equipment Branch where momentary interruption of motor-driven loads such as sterilizers or large air handlers is unacceptable.
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# Wiring Methods and Branch Separation {toc}
−## The Life Safety and Critical branch wiring is required to be mechanically protected and electrically separated from other wiring so that physical damage or a fault elsewhere cannot disable the branch. {note}
+## The Life Safety and Critical branch wiring is required to be mechanically protected and electrically separated from other wiring so that physical damage or a fault elsewhere cannot disable the branch.
## Life Safety and Critical branch conductors shall be installed in a metallic raceway — EMT, RMC, IMC, or listed metal wireway — or as Type MI cable, per NEC 517.30(C)(3).
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## EMT is acceptable for concealed Life Safety and Critical branch runs; RMC or IMC shall be used where the raceway is exposed and subject to physical damage.
−## Life Safety and Critical branch wiring shall be kept independent of all other wiring and equipment, and shall not occupy the same raceway, box, or cabinet as normal-service wiring except as permitted by NEC 517.30(C).
−
−## EES branch feeders shall be physically separated from each other and from normal-service feeders along their routing so that a single event cannot disable more than one branch.
−
−## Sharing a feeder or combined panelboard between two EES branches without separately identified sections is a code violation often missed on design-build projects; each branch requires separate transfer equipment, feeder, and panelboard identification. {note}
−
```datasheet
label: Concealed Life Safety / Critical Branch Raceway
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```
−# Panelboards and Feeders {toc}
+## Life Safety and Critical branch wiring shall be kept independent of all other wiring and equipment, and shall not occupy the same raceway, box, or cabinet as normal-service wiring except as permitted by NEC 517.30(C).
−## Each EES branch shall be served by a separate panelboard, or by a separately identified section of a panelboard, per NEC 517.30(E).
+## EES branch feeders shall be physically separated from each other and from normal-service feeders along their routing so that a single event cannot disable more than one branch.
−## Each branch panelboard and feeder shall be permanently marked to identify the branch it serves and that it is part of the Essential Electrical System.
+## Sharing a feeder or combined panelboard between two EES branches without separately identified sections is a code violation often missed on design-build projects; each branch requires separate transfer equipment, feeder, and panelboard identification. {note}
−## Life Safety and Critical branch feeders shall be sized for 100% of the connected load; no demand-factor reduction is permitted on these feeders per NEC 517.30(D).
+# Panelboards and Feeders {toc}
−## The EES feeder demand-factor prohibition is unique to the Life Safety and Critical branches; applying normal-service demand factors to these feeders undersizes them and is a frequent calculation error. {note}
+## Each EES branch shall be served by a separate panelboard, or by a separately identified section of a panelboard, per NEC 517.30(E).
```datasheet
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```
+## Each branch panelboard and feeder shall be permanently marked to identify the branch it serves and that it is part of the Essential Electrical System.
+
+## Life Safety and Critical branch feeders shall be sized for 100% of the connected load; no demand-factor reduction is permitted on these feeders per NEC 517.30(D).
+
```datasheet
label: Life Safety / Critical Feeder Demand Factor
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```
+## The EES feeder demand-factor prohibition is unique to the Life Safety and Critical branches; applying normal-service demand factors to these feeders undersizes them and is a frequent calculation error. {note}
+
# Ground-Fault Protection {toc}
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- Indicating lamps / LED modules
```