Healthcare Essential Electrical Systems

NOTE This standard governs the essential electrical system of a health care facility as one system: the risk categories that decide what the facility needs, the type of system those categories require, the branches the system is divided into and the loads each branch carries, the performance the alternate source owes the branches, the transfer switches that serve them, the wiring that keeps them independent, the circuits and receptacles at the patient bed, the ground-fault protection and the isolated power that protect the patient, the coordination requirement that applies to the whole system, and the tests and records that prove the system and keep it provable through its life. (1.1)

NOTE The essential electrical system is a layer over the emergency and standby power system, not a replacement for it: NFPA 70 Article 517 applies Article 700 to the life safety branch and amends it, and NFPA 99 adds the risk categories, the branch structure, the equipment branch sequence, and a testing regime of its own. The system-level decisions that are not specific to health care, including the alternate source redundancy, the transfer type, the neutral treatment, and the integrated acceptance test, are made under Emergency And Standby PowerEmergency and Standby Power SystemsResolves to the current adopted revision.sync/emergency-and-standby-power and are not repeated here. (1.2)

NOTE The following are governed elsewhere and are outside this standard: (1.3)

NOTE The Centers for Medicare and Medicaid Services adopt NFPA 99 and NFPA 101 by edition in the Conditions of Participation, and the edition they adopt is routinely older than the one the state has adopted, so a facility that bills Medicare answers to two editions at once; the more stringent of the two is the one a surveyor can cite. (2.3)

NOTE The branch load schedule is the submittal that decides whether the system passes its first survey, because a load on the wrong branch is a finding regardless of how well the equipment performs, and the schedule is the only document in which every load and its branch appear side by side with the provision that put it there. (3.1.3)

NOTE The integrated acceptance test record under NFPA 110 Chapter 7 is delivered under Emergency And Standby PowerEmergency and Standby Power SystemsResolves to the current adopted revision.sync/emergency-and-standby-power; the records this standard requires are the branch-level and patient-care-level records that the integrated record does not contain. (3.3.2)

NOTE The risk category of each patient care space is determined by the facility's governing body under NFPA 99 Chapter 4, not by the Engineer of Record, and the engineer records it and designs to it; a category the engineer assumed without a written determination behind it is the finding a surveyor writes first. (4.2)

NOTE A state health department or a state construction authority reviews the essential electrical system before construction in most states and inspects it before the facility is licensed, and the accrediting organization surveys the same records after occupancy; the reviews required on a project depend on the state and on whether the facility bills Medicare, so none is assumed beyond the witness every Authority Having Jurisdiction expects. (4.5)

NOTE Hospitals are Risk Category IV structures under the adopted building code, and the essential electrical system is the one system the building must still have when the event that cut the normal source is over, so the equipment that carries it is certified to keep working through the design earthquake rather than merely to stay anchored. (5.5)

NOTE The facility type decides which part of NFPA 70 Article 517 the system is built under. A hospital is built under the hospital provisions, which require the three-branch system whenever the facility has Category 1 spaces. A nursing home or a limited care facility is built under the provisions for those occupancies, which require a two-branch system, unless it admits residents who depend on electrical life support, in which case the hospital provisions apply. An ambulatory health care occupancy is built under NFPA 70 517.45, which requires an essential electrical system where the facility administers general anesthesia or uses electrical life support, and permits a battery system as the alternate source under the conditions it states. A medical office, a clinic, or an outpatient facility outside those occupancies is classified by the risk categories of its spaces alone. (6.2)

NOTE NFPA 99 categorizes a space by what a failure of the system does to the patient in it, not by the name of the room: Category 1 where failure is likely to cause major injury or death, Category 2 where it is likely to cause minor injury, Category 3 where it causes discomfort but no injury, and Category 4 where it has no effect on patient care. An operating room, an intensive care unit, and a dialysis station are Category 1 almost everywhere; a general inpatient bed is Category 2 in most facilities and Category 1 where ventilator-dependent patients are housed; an examination room in a clinic is Category 3 or 4. (6.4)

NOTE The presence of one Category 1 space makes the system Type 1; the type is set by the most demanding space the system serves and not by how much of the facility that space represents. (6.9)

NOTE Where every space the system serves is Category 4, the facility still needs the emergency illumination and the alarm power the adopted building code and NFPA 101 require, and those are specified under Emergency And Standby PowerEmergency and Standby Power SystemsResolves to the current adopted revision.sync/emergency-and-standby-power and Emergency And Egress LightingEmergency and Egress LightingResolves to the current adopted revision.sync/emergency-and-egress-lighting without the provisions of this standard. (6.10)

NOTE An engine-generator set on the premises is the alternate source of nearly every health care facility, because it is the one source that carries the whole system for the runtime the facility plans for and that NFPA 110 classifies directly, which is why it is the default. The second generating unit and the external utility service are the alternate sources of a facility whose normal source is its own generation, a cogeneration plant or a remote campus, and each is accepted only because the normal source is already a generator. A battery system is limited to the facility types and the loads the adopted edition of NFPA 70 permits it for, and its runtime is set by its capacity rather than by a fuel delivery. A fuel cell system is a recent addition to the permitted sources and is accepted where the adopted edition includes it and the Authority Having Jurisdiction accepts the fuel supply arrangement. (7.3)

NOTE NFPA 99 assigns Class X rather than a fixed class because the runtime is a planning decision of the facility: hospitals that plan to shelter in place through a regional event provision for 96 hours, which is the self-sufficiency period accrediting organizations ask a hospital to assess, while a facility that evacuates under its plan provisions for the time the evacuation takes. The runtime drives the fuel stored at the generator under GeneratorsEngine GeneratorsResolves to the current adopted revision.sync/generators and the fuel system beyond the skid under Fuel Oil SystemsFacility Fuel-Oil SystemsResolves to the current adopted revision.sync/fuel-oil-systems. (7.7)

NOTE The 10 seconds is a system figure and not a per-component allowance: a generator that reaches voltage in 8 seconds behind a transfer switch with a 3 second transfer delay restores the branch in 11, so the restoration time budget submitted under this standard is the document in which the allowances are reconciled. (7.9)

NOTE The connected load is the largest figure and the one a facility with no history uses when it would rather buy a larger set than defend a demand factor; the Article 220 feeder calculation applies the demand factors the code already grants and is the basis most new facilities use; prudent demand factors with historical data produce the smallest alternate source and are available only to an existing facility whose metered essential load over at least a year is in hand; and the combination lets each branch be calculated on the basis its data supports. The basis selected drives the alternate source capacity under Emergency And Standby PowerEmergency and Standby Power SystemsResolves to the current adopted revision.sync/emergency-and-standby-power and the set rating under GeneratorsEngine GeneratorsResolves to the current adopted revision.sync/generators. (7.11)

NOTE The branches exist so that the loads a patient's life depends on in the next ten seconds, the loads the clinical staff need to keep treating, and the building equipment that keeps the facility habitable are supplied through separate transfer switches and separate wiring, so that a fault, an overload, or a maintenance outage on one of them leaves the others energized. (8.2)

NOTE The life safety branch is the branch most often overloaded by design rather than by use, because a nurse station, a security desk, or a data closet reads as life safety to the people who work there and none of them is on the list; the list is exclusive, and a load that is not on it belongs on the critical or the equipment branch. (8.3.4)

NOTE The critical branch of a large hospital is routinely split by floor, by wing, or by service into several branches on separate transfer switches, because a single critical branch transfer switch becomes the one device whose failure darkens every patient care space at once, and because a split lets a floor be taken down for maintenance without touching the others. (8.4.4)

NOTE Delayed automatic connection is the manner nearly every facility selects for the heating, the ventilation, and the elevators 517.34(B) permits to be connected manually, because an operator who must walk to a transfer switch during an outage is an operator the clinical staff do not have, which is why it is the default; manual connection is selected where the equipment would overload the alternate source unless the operator first confirms the load it carries. (8.5.4)

NOTE The equipment branch is where the alternate source is sized and where it is overloaded: the chillers, the air handlers, and the elevators it carries are the large motors of the building, and the delay before they connect exists so that the life safety and critical branches are energized and the set is stable before the first of them starts. (8.5.10)

NOTE One transfer switch per branch is the arrangement NFPA 70 517.31(B) describes and the one a facility of moderate size builds; several transfer switches per branch is the arrangement of a hospital whose critical branch is split by floor or by service and whose equipment branch is sequenced across several switches with staggered delays; and one transfer switch for the whole system is permitted only to a facility whose essential electrical system demand does not exceed 150 kVA, which is a small nursing home or an ambulatory facility, and it buys one switch at the cost of every branch sharing one point of failure. (9.3)

NOTE Bypass-isolation on every switch lets any switch be inspected, tested, or replaced with its branch energized, which in a hospital is the difference between a maintenance task and a patient relocation, and it is the arrangement of most acute care facilities; bypass-isolation on the life safety and critical branch switches alone keeps that capability where an outage reaches the patient and accepts a scheduled outage of the building equipment; and no bypass-isolation is the arrangement of a facility that can take each branch down on a schedule, which a nursing home or an outpatient facility often can. Neither NFPA 70 nor NFPA 99 requires bypass-isolation, so the selection is the facility's, and the cost of every switch roughly doubles with it. (9.6)

NOTE One delayed step connects the whole equipment branch at one transfer switch after one delay, which suits a facility whose equipment branch is small relative to the set; sequenced steps on separate transfer switches, each with its own delay, bring the equipment branch on in increments the set can accept and are the arrangement of a hospital with a single set or a few sets on individual switches; and load added by the paralleling switchgear priority table hands the sequence to the lineup furnished under Generator Paralleling SwitchgearGenerator Paralleling SwitchgearResolves to the current adopted revision.sync/generator-paralleling-switchgear, which adds each block as capacity comes on line and sheds it in reverse when a set is lost. The sequence and the delays are the inputs to the step-load analysis the set manufacturer performs under GeneratorsEngine GeneratorsResolves to the current adopted revision.sync/generators. (9.8)

NOTE Nonflexible metal raceway, meaning rigid metal conduit, intermediate metal conduit, or electrical metallic tubing, is the method of nearly every life safety and critical branch run inside the building, because it is the one method that satisfies the mechanical protection rule and the redundant grounding rule of patient care spaces at once, which is why it is the only method selected by default; Type MI cable is selected where a feeder must survive fire exposure or where a raceway cannot be run; Schedule 80 PVC conduit is permitted for feeders and is the method of an exposed exterior run, and it is never permitted for a branch circuit that supplies a patient care space; and Schedule 40 PVC conduit encased in concrete is the method of the underground feeders between a generator building and the facility. (10.3)

NOTE The separation rule is the reason the branches survive: a critical branch feeder that shares a pull box with the normal feeder it parallels is a feeder that burns with it, and the inspector who opens the box after the fire is the one who finds the shared enclosure. (10.8)

NOTE One normal system circuit and one critical branch circuit at each bed is the arrangement NFPA 70 Article 517 states and the one nearly every facility builds, because the normal circuit stays energized through a failure of the essential electrical system itself, which is why it is the default; critical branch circuits from two separate transfer switches is the exception the article permits where the facility would rather have every bed on the essential system, and it is selected only where the two transfer switches are fed by separate feeders so that neither failure darkens the bed. (11.2)

NOTE The counts the datasheet defaults to are the floors NFPA 70 Article 517 sets, and a receptacle counts toward them whether it is a single, a duplex counted as two, or a quadruplex counted as four; a headwall or a boom in an intensive care room and an equipment-dense operating room both run well above the floor, and the count the facility wants is settled with the clinical planner against the equipment list, not against the code. (11.9)

NOTE A red face is the identification a clinician recognizes without reading, and it is the convention of nearly every facility in the country, which is why it is the default; a red cover plate on a general-color device is selected where the facility has standardized on one device color; the branch name on the plate tells the clinician which branch the outlet is on, which matters where both branches serve one room; and the panelboard and circuit number on the plate is what lets the staff and the electrician find the breaker for the outlet a device is plugged into without leaving the room, which is why it is in the default alongside the color. (11.16)

NOTE The second level exists so that a ground fault on one feeder opens that feeder and not the service: a hospital with a single level of ground-fault protection on a 2000 A service loses the whole building, essential system included until the transfer switches see the loss, to a fault in one panelboard. The requirement is triggered by the first level, which NFPA 70 230.95 requires on a solidly grounded wye service of 1000 A and more at more than 150 V to ground, so a facility served at 480Y/277 V above that size has it and a facility served at 208Y/120 V does not. (12.2)

NOTE NFPA 99 treats an operating room as a wet procedure location unless the governing body's risk assessment finds otherwise, and the two protections it allows answer different questions: ground-fault circuit-interrupter protection opens the circuit on the first fault, which protects the patient by de-energizing the equipment, and an isolated power system alarms on the first fault and keeps the circuit energized, which protects the patient by keeping the equipment running. The isolated power system is selected where the interruption would be worse than the fault, which is the case in a room where a device is keeping the patient alive, and ground-fault protection is selected where the interruption is tolerable. (13.2)

NOTE A 120 V single-phase secondary serves the receptacles and the equipment of nearly every operating room and procedure room, which is why it is the default; a 208 V or a 240 V single-phase secondary serves a specific device, an imaging unit, a laser, or a hyperbaric chamber, that needs it, and is furnished as a second isolated system rather than by converting the receptacle system; and a 208 V three-phase secondary serves a three-phase device, and its third conductor takes the third identification color. (13.7)

NOTE The indicator on the panel is integral to the monitor and the remote indicator is what the staff in the room actually see, because the panel is usually in the corridor or behind the control desk, which is why both are in the default; the alarm contact carries the alarm to the staff station through Nurse Call SystemsNurse Call SystemsResolves to the current adopted revision.sync/nurse-call-systems where the facility wants the alarm answered by someone outside the room; and the status point lets the facility trend hazard current and log alarms, at the cost of a controls interface at each panel. (13.13)

NOTE Type 1 is the enclosure of a panel installed in a finished procedure room, a corridor, or an equipment room, which is where nearly every panel is installed, which is why it is the default; Type 12 is selected in a sterile processing or a laboratory space where dust and dripping liquid reach the panel; and Type 4X in stainless steel is selected where the panel is in a space that is washed down. (13.15)

NOTE A flush panel sits in the wall of the operating room with its face in the finish, which is the installation of nearly every new operating room because the room is cleaned to the wall, which is why it is the default; a surface panel is selected in an existing wall that cannot be opened, in an equipment room, or where the room design places the panel outside the sterile field. (13.18)

NOTE NFPA 70 Article 517 amends the full-range coordination Article 700 requires of an emergency system to coordination beyond 0.1 second for the whole essential electrical system, so a pair of molded-case breakers that overlap in the instantaneous region, which would fail under Article 700, coordinates under Article 517; a project whose Authority Having Jurisdiction applies a different boundary records that boundary in the study under Emergency And Standby PowerEmergency and Standby Power SystemsResolves to the current adopted revision.sync/emergency-and-standby-power. (14.3)

NOTE The documents a state surveyor and an accrediting organization ask for at every survey are the same four: the one-line, the branch load schedule, the classification statement, and the test records; a facility that hands them over in one binder, or one folder, finishes the electrical portion of the survey in an hour, and a facility that has to assemble them from shop drawings does not. (15.5)

NOTE The retention force test is the one that fails most often, because a receptacle that has had a construction cord pulled from it a few hundred times no longer holds a plug, and a plug that falls out of a receptacle on the critical branch is the failure the branch cannot protect against. (16.1.8)

NOTE A permanently installed load bank lets the facility reach the loading NFPA 110 requires of every monthly test without bringing anything to the site, and it is selected where the building load on the essential system is a small fraction of the set rating, which is the case at a facility whose equipment branch is small or whose sets are redundant; a load bank connection accepts a rented load bank for the annual and the 36-month tests and costs a cabinet and a feeder, and it is the provision of most facilities whose monthly building load is adequate; and no provision is selected where the building load on the system reaches the required loading every month, which the facility proves from its own logs rather than assumes. The load bank, where permanent, is furnished under GeneratorsEngine GeneratorsResolves to the current adopted revision.sync/generators with the set it tests. (16.2.2)

NOTE The Owner performs the periodic tests, and the program the Contractor delivers is what the Owner's staff and the surveyor both read: a surveyor asks for the log of the last twelve generator tests and the last twelve transfer switch operations, and a facility whose program names the interval, the loading, and the form has a log to show. (16.3.4)

NOTE The interruption a renovation causes is the most common way an operating hospital loses its essential electrical system: not a utility failure, but an electrician opening a critical branch panelboard to add a circuit without knowing which beds it served. The schedule, the notice, and the written confirmation exist to make that impossible. (17.7)

NOTE The warranties of the transfer switches, the generator sets, and the paralleling switchgear are made under their own standards; this warranty covers the system work those standards do not, which is the work that decides whether the branches do what the classification statement says they do. (18.5)