Article 517 is your prescription for successful electrical installations
Article 517 provides the requirements for those parts of health care facilities involving examination and treatment of patients. This article covers both permanent and movable facilities.
Parts summary. Health care facilities differ from other types of facilities in many ways. Consequently, Art. 517 contains many specialized definitions that apply only to these types of buildings (see Key Definitions) and constitute nearly all of Part I. Not nearly as intuitive or obvious, the requirements in Parts II and III are highly detailed. However, if you understand the key concepts, you can understand and correctly apply these requirements. Parts II and III have three primary objectives:
- Maximize the physical and electromagnetic protection of wiring by requiring metal wiring methods.
- Minimize electrical hazards by minimizing the voltage potential between patients and medical equipment. This involves many specific steps, beginning with 517.11.
- Minimize the negative effects of power interruptions with specific requirements for essential electrical systems.
The main objective of Part IV is to prevent ignition of gases where flammable anesthetics are used. Part V addresses X-ray installations and has two main objectives:
- Provide adequate ampacity and protection for the branch circuits.
- Address the safety issues inherent in high-voltage equipment installations.
Please note that Art. 660 (X-Ray equipment) does not apply to X-Ray equipment used for medical purposes [660.1].
Part VI provides requirements for low-voltage communications systems, such as fire alarms and intercoms. Its main objective is to prevent compromising those systems with sources of interference. Part VII provides requirements for isolated power systems. Its main objective is to ensure they are isolated.
Application of requirements. The requirements contained in Part II of Art. 517 apply to patient care areas of all health care facilities [517.10(A)]. Part II requirements don't apply to:
- Business offices, corridors, waiting rooms, or similar areas in clinics, medical and dental offices, and outpatient facilities [517.10(B)(1)].
- Areas of nursing homes and limited-care facilities used exclusively for patient sleeping [517.10(B)(2)].
Requirements that don't apply to the areas specified in 517.10(B) include:
- 517.13 — Grounding and Bonding Requirements
- 517.18(B) — Hospital Grade Receptacles
- 517.18(D) — Emergency Wiring Methods
Wiring methods must comply with Chapters 1 through 4, except as modified in this Art. [517.12].
Equipment grounding. You have to provide each branch circuit serving a patient care area with an effective ground-fault current path [517.13, as described in 250.2]. But how? One way is to install those circuits in metal raceway. Alternatively, you can install those circuits in a cable having a metallic armor or sheath that qualifies as an equipment grounding conductor (EGC) per 250.118 (Fig. 1).
- The metal outer sheath of AC cable is listed as an EGC, because it contains an internal bonding strip in direct contact with the metal sheath of the cable [250.118(8)].
- The metal outer sheath of interlocked Type MC cable is not listed as an EGC, unless it contains a bare aluminum conductor that makes direct contact with the metal sheath of the cable [250.118(10)(a)].
In patient care areas, connect the grounding terminals of receptacles as well as any conductive surfaces of fixed electrical equipment to an insulated copper EGC [517.13(B)]. Size the circuit EGC per 250.122, and use a wiring method that meets the requirements of 517.13(A) (Fig. 2). Two exceptions exist:
- You can connect the metal faceplates for switches and receptacles to the EGC by the metal mounting screws that secure the faceplate to a metal outlet box or metal mounting yoke of switches [404.9(B)] and receptacles [406.3(C)].
- If luminaires are more than 7½ ft above the floor, you can connect them to the equipment grounding return path complying with 517.13(A), without connecting them to an insulated EGC.
Isolated ground receptacles. By definition, isolated ground receptacles have insulated grounding (IG) terminals. If you install An IG receptacle in a patient care area, it must have an insulated EGC that meets the requirements of 517.13(B). Install this EGC in a metal raceway or listed metal cable that meets the requirements of 517.13(A). Avoid IG receptacles if at all possible, because they circumvent the concept of having two equipment grounding conductors for all equipment in the patient care area [517.16 FPN]. The requirements for supplying an IG receptacle are location-dependent:
- Patient care areas. Use EMT, Type AC cable, or Type MC cable that meets the requirements of 250.118(10)(a).
- Nonpatient care areas. Use Type AC cable containing a single insulated EGC, traditional Type MC cable (where the metallic armor or sheath does not qualify as an EGC) with two EGCs, or Type MC cable with a single insulated EGC [250.118(8)] (Fig. 3).
Hospital-grade receptacles. Receptacles for inpatient sleeping beds or procedure table beds used in a critical care area (patient bed location — 517.2) must be listed as "hospital-grade" [517.18(B)]. Hospital-grade receptacles aren't required in treatment rooms of clinics, medical and dental offices, or outpatient facilities, because these locations don’t have a "patient bed location" as defined in 517.2.
Essential electrical systems for hospitals [Part III of Art. 517]. Emergency system circuits in hospitals must be mechanically protected by one of the following methods [517.30(C)(3)]:
- Nonflexible metal raceways or Schedule 80 PVC conduit, where not used to supply patient care area branch circuits [517.13(A)].
- Schedule 40 PVC conduit or flexible nonmetallic raceways encased in not less than 2 in. of concrete, where not used to supply patient care area branch circuits [517.13(A)].
- Listed flexible metal raceways or listed metal-sheathed cables when:
- Installed in listed prefabricated medical headwalls.
- Installed in listed office furnishings.
- Fished into existing walls or ceilings, and not subject to physical damage.
- Necessary for flexible connection to equipment.
- Flexible power cords of appliances or other utilization equipment in raceways, if the equipment is connected to the emergency system
- Secondary circuits of Class 2 or Class 3 communications or signaling circuits, with or without raceways.
You don't have to enclose the secondary circuits of transformer-powered communications or signaling systems in raceways, unless otherwise required in Chapter 7 or 8 [517.80].
Prescription for success. As you apply Art. 517, keep in mind the special requirements of health care facilities and why these requirements exist. For example, there's a lot of sophisticated equipment and a malfunction or power interruption of this equipment can result in tragedy. You'll also notice room after room of patients. In many of these rooms, patients' lives hang in the balance, because they depend on that sophisticated equipment.
These considerations are behind the thinking of Code Making Panel 15, which developed the requirements contained in Art. 517. Put these considerations behind your thinking when applying those requirements.
Sidebar: Key Definitions
Following is a summary of a few of the more important definitions in this Code article. You can find the full glossary in 517.2.
Health care facilities. Buildings or portions of buildings in which medical, dental, psychiatric, nursing, obstetrical, or surgical care is provided. Health care facilities include hospitals, nursing homes, limited-care facilities, supervisory care facilities, clinics, medical and dental offices, and ambulatory care facilities.
Hospital. An area (of a building) used for medical, psychiatric, obstetrical, or surgical care on a 24-hr basis of four or more inpatients.
Limited-care facility. An area of a building for housing (on a 24-hr basis) of four or more persons who are incapable of self-preservation.
Nursing home. An area (of a building) for the lodging, boarding, and nursing care (on a 24-hour basis) of four or more persons who may be unable to provide for their own needs and safety without assistance. This includes nursing and convalescent homes, skilled nursing facilities, intermediate care facilities, and infirmaries of homes for the aged.
Patient bed location. The location of an inpatient sleeping bed; or the bed or procedure table used in a critical care area.
Patient care area. The area (in a health care facility) designated for examining or treating patients. Business offices, corridors, lounges, day rooms, dining rooms, or similar areas aren’t classified as patient care areas. Areas where patient care is administered are classified as general care areas or critical care areas.
General care areas. Patient bedrooms, examining rooms, treatment rooms, clinics, and similar areas where patients come in contact with ordinary appliances.
Critical care areas. Special care units where patients are subjected to invasive procedures and are connected to electromedical devices. These areas include intensive care units, coronary care units, delivery rooms, and operating rooms.