Article 517 asks for two ground paths where everywhere else in the code is satisfied with one. Then it takes the adjective it used to describe the second path and bans it on the receptacle.
Figure 1: Hospital-grade redundant grounding and insulation resistance testing per NEC Article 517.Both rules are in the same short stretch of text, and the pair is the reason hospital branch-circuit cable is built the way it is. Read together they describe a wiring method, not a grounding preference: you must provide a metal path, you must also provide an insulated copper conductor, and you may not use the receptacle that would isolate the conductor you just installed.
A patient care area is a wiring-method problem
517.13 opens by naming its scope precisely: "Wiring in patient care areas shall comply with 517.13(A) and (B)." That is a wiring-method sentence, not a protection sentence. It applies to the installation, and it applies because of where the installation is.
Which means the first question is not a cable question at all. Patient Care Area is defined in 517.2 as "any portion of a health care facility wherein patients are intended to be examined or treated," and the definition goes on to say that areas in which patient care is administered are classified as general care areas or critical care areas, with the facility’s governing body designating them in accordance with the type of patient care anticipated.
The informational note under that definition is the part worth reading before a quotation is priced: "Business offices, corridors, lounges, day rooms, dining rooms, or similar areas typically are not classified as patient care areas."
So the requirement attaches to a designation, and the facility makes it, not the electrical contractor. An examination room is in; the corridor outside it is typically out. Two runs of cable that look identical on a drawing can be governed by different rules.
Path one: the metal raceway, armor or sheath
517.13(A) requires that all branch circuits serving patient care areas "be provided with an effective ground-fault current path by installation in a metal raceway system, or a cable having a metallic armor or sheath assembly."
Then the sentence that makes the metal path a cable requirement rather than an installation nicety: "The metal raceway system, or metallic cable armor, or sheath assembly shall itself qualify as an equipment grounding conductor in accordance with 250.118."
Two consequences follow. A nonmetallic raceway cannot be the only path, because it is not a conductor. And the metal is not decoration over a ground conductor — it is expected to carry fault current, so its continuity end to end is the requirement, not its presence.
Path two: an insulated copper conductor
517.13(B) then adds the second path, and the wording is specific about the material: the items listed "shall be directly connected to an insulated copper equipment grounding conductor installed with the branch circuit conductors in the wiring methods as provided in 517.13(A)."
Three things in that sentence matter commercially.
Insulated, so a bare conductor does not satisfy it even though a bare conductor is an equipment grounding conductor everywhere else. Copper, so the material is fixed rather than left to the conductor family. And installed with the branch circuit conductors, so it is part of the cable or the raceway run, not a bonding jumper added at the ends.
That combination — a metal path plus an insulated copper conductor inside the same wiring method — is what a specifier is describing when they write a hospital-grade branch-circuit cable. The code never gives that combination a product name.
Requirement | Text |
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First path | Metal raceway system, or cable with metallic armor or sheath assembly, itself qualifying as an EGC per 250.118 |
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Second path | Insulated copper equipment grounding conductor installed with the branch circuit conductors |
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Both are required | 517.13 requires compliance with (A) and (B), not either |
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Two ground paths, both required
What has to connect to it, and the three exceptions
517.13(B)(1) lists what must be directly connected to the insulated conductor, and the list is short.
Item | What it covers |
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(1) | The grounding terminals of all receptacles |
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(2) | Metal boxes and enclosures containing receptacles |
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(3) | All non-current-carrying conductive surfaces of fixed electrical equipment likely to become energized that are subject to personal contact, operating at over 100 volts |
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Three exceptions cut the list back, and each is a place where a supplier gets asked for something that is not required.
The first is general: an insulated equipment bonding jumper that directly connects to the equipment grounding conductor may connect the box and receptacles to that conductor. The jumper stays insulated and must land on the conductor, not on the metal.
Exception No. 1 to item (3) permits metal faceplates to be connected to the equipment grounding conductor by means of metal mounting screw or screws securing the faceplate to a grounded outlet box or grounded wiring device. A faceplate does not need its own conductor.
Exception No. 2 to item (3) saves work: luminaires more than 2.3 m (7½ ft) above the floor and switches outside the patient care vicinity may connect to an equipment grounding return path complying with 517.13(A) — the metal path alone. A ceiling luminaire above the patient’s reach does not need the insulated conductor; the receptacle at the bedside does.
What connects to the insulated conductor
The adjective that reverses: insulated here, banned there
Here is the pair of provisions that makes this article worth writing.
517.13(B) requires an insulated copper equipment grounding conductor.
517.16 then states, in one sentence, that "receptacles with insulated grounding terminals, as described in 250.146(D), shall not be permitted."
Same adjective, opposite instruction, adjacent sections. The second one is the isolated-ground receptacle — the orange device that a designer reaches for when they hear the word "noise." In a patient care area it is prohibited outright.
The two requirements are not in conflict once you see what each isolates. In 517.13(B) the insulation runs along the conductor, keeping the return path separate from the metal raceway and the building steel for its whole length. In 517.16 the insulation is inside the device, isolating the receptacle’s grounding terminal from its mounting yoke. The first keeps a dedicated path intact between panelboard and outlet. The second breaks that continuity exactly where fault current has to move from the metal box onto the conductor.
One is a path requirement, the other a device prohibition, and a specification that confuses them is non-compliant in one direction and pointless in the other.
The adjective reverses
Panelboard bonding, and where the sizing comes from
517.14 ties the two systems together at the panelboard. The equipment grounding terminal buses of the normal and essential branch-circuit panelboards serving the same individual patient care vicinity shall be connected together with an insulated continuous copper conductor not smaller than 10 AWG. Where two or more panelboards serving the same vicinity are served from separate transfer switches on the emergency system, those buses shall also be connected together with an insulated continuous copper conductor not smaller than 10 AWG. The conductor is permitted to be broken in order to terminate on the equipment grounding terminal bus in each panelboard.
So the insulated conductor requirement is not confined to the branch circuit: it continues at the distribution level, between the normal and essential systems, in the same material with a floor of 10 AWG.
Sizing comes from elsewhere: 517.13(B)(2) sends the equipment grounding conductors and bonding jumpers to 250.122, where the size table lives. That is a separate subject.
Ground-fault protection comes in steps
517.17 is not a cable requirement, but it changes what the cable has to survive, and its applicability clause is broader than people assume. Under 517.17(A) the requirements apply to "hospitals and other buildings (including multiple-occupancy buildings) with critical care areas or utilizing electrical life-support equipment," and to buildings providing the essential utilities or services for those areas.
517.17(B) then requires a second step of ground-fault protection. Where ground-fault protection is provided for the service disconnecting means or feeder disconnecting means as specified by 230.95 or 215.10, an additional step of ground-fault protection shall be provided in all next-level feeder disconnecting means downstream toward the load, consisting of overcurrent devices and current transformers or equivalent equipment that will cause the feeder disconnecting means to open.
And the constraint that catches out coordination studies: "The additional levels of ground-fault protection shall not be installed on the load side of an essential electrical system transfer switch."
517.17(C) requires the protection to be fully selective, such that the feeder device and not the service device opens on a ground fault on the load side of the feeder device, with time-current separation achieving 100 percent selectivity. 517.17(D) requires each level to be performance tested when first installed.
Two levels in series only work if they are told apart, and the code says so rather than leaving it to the commissioning agent.
Patient bed circuits: two circuits, one panelboard, no shared neutral
517.18(A) adds three constraints to the circuit serving a patient bed location, and the third is the one that lands on cable selection.
Each patient bed location shall be supplied by at least two branch circuits, one from the emergency system and one from the normal system. All branch circuits from the normal system shall originate in the same panelboard. And "the branch circuit serving patient bed locations shall not be part of a multiwire branch circuit."
That last sentence removes the shared neutral — an ordinary way to save a conductor, and not permitted at the bed. Exception No. 1 carves out branch circuits serving only special-purpose outlets, such as portable X-ray outlets.
Two circuits from two systems, from one panelboard each, with no shared neutral — that is a cable count decision, and it is made before any cable is ordered.
FAQ
Question | Answer |
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What is a patient care area? | Any portion of a health care facility wherein patients are intended to be examined or treated, classified as general care or critical care and designated by the facility’s governing body. Business offices, corridors, lounges, day rooms and dining rooms typically are not |
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Why two ground paths? | 517.13(A) requires a metal raceway or metallic armor or sheath qualifying as an EGC per 250.118, and 517.13(B) requires an insulated copper equipment grounding conductor in addition |
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Can a bare equipment grounding conductor be used? | No. The conductor required by 517.13(B) must be insulated copper, installed with the branch circuit conductors |
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Are isolated ground receptacles allowed in a patient care area? | No. 517.16 prohibits receptacles with insulated grounding terminals, as described in 250.146(D) |
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Do ceiling luminaires need the insulated conductor? | Not where they are more than 2.3 m (7½ ft) above the floor; Exception No. 2 to 517.13(B)(1)(3) permits an equipment grounding return path complying with 517.13(A) |
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What to specify
The code decides that two paths are needed and what they must be made of. It leaves three things to the specification, and all three are cable decisions.
The first is the construction: a metal armor or sheath that qualifies as an equipment grounding conductor, with an insulated copper conductor inside the same assembly. That is a build, not an accessory, and it is the reason the two requirements cannot be met by adding a field-installed conductor.
The second is the jacket, because a hospital is a place where smoke performance and chemical resistance get written into the specification alongside the electrical requirement. The jacket selection guide covers the compound side, and the cable listing guide covers how the flame performance is evidenced.
The third is the quantity of conductors, because 517.18(A) removes the shared neutral at the bed and 517.14 adds an insulated copper conductor at the panelboard. Both are ordering questions rather than installation ones.
Where the ground path has to be measured rather than assumed, the TIA-607 grounding and bonding guide covers the testing side, and where the circuits are long enough that the conductor is upsized, the voltage-drop guide covers what that does to the grounding conductor. OEM and ODM projects are where a specific armored construction with a defined insulated conductor gets built, and our cable range is the product starting point.
Sources
- NFPA 70, National Electrical Code, 2011 edition — Article 517 (Health Care Facilities): 517.2 definitions of Patient Bed Location, Patient Care Area and General Care Areas with their informational note; 517.12; 517.13(A), 517.13(B)(1) and its exceptions, 517.13(B)(2); 517.14; 517.16; 517.17(A) through (D); 517.18(A) with Exception No. 1. These are the sections the article quotes or cites. Articles referenced by those sections and cited here only as cross-references: 250.118, 250.122, 250.146(D), 215.10 and 230.95. Public-domain copy consulted at Internet Archive, gov.law.nfpa.nec.2011.
