shall be isolated from any distribution system by the use of

an isolated power system. (2) Isolated power system equipment shall be listed for the purpose and the system so designed and installed that it meets the provisions and is in accordance with Part G. (3)* In hazardous (classified) location(s) referred to in Section 517-60, all fixed wiring and equipment, and all portable equipment, including lamps and other utilization equipment, operating at more than 10 volts between conductors shall comply with the requirements of Sections 501-1 through 501-15 and Sections 501-16(a) and (b) for Class I, Division 1 locations. All such equipment shall be specifically approved for the hazardous atmospheres involved. ARTICLE 517 - HEALTH CARE FACILITIES 70-555 (4) Where a box, fitting, or enclosure is partially, but not entirely, within a hazardous (classified) location(s), the hazardous (classified) location(s) shall be considered to be extended to include the entire box, fitting, or enclosure. (5) Receptacles and attachment plugs in hazardous (classified) location(s) shall be listed for use in Class I, Group C hazardous (classified) locations and shall have provision for the connection of a grounding conductor. (6) Flexible cords used in hazardous areas for connection to portable utilization equipment, including lamps operating at more than 8 volts between conductors, shall be of a type approved for extra-hard usage in accordance with Table 400-4 and shall include an additional conductor for grounding. (7) A storage device for the flexible cord shall be provided and shall not subject the cord to bending at a radius of less than 3 inches (76 mm). (b) Above Hazardous Anesthetizing Locations. (1) Wiring above a hazardous area referred to in Section 517-60 shall be installed in rigid metal conduit, electrical metallic tubing, intermediate metal conduit, Type MI cable, or Type MC cable that employs a continuous, gas/vapor-tight metal sheath. (2) Installed equipment that may produce arcs, sparks, or particles of hot metal, such as lamps and lampholders for fixed lighting, cutouts, switches, generators, motors, or other equipment having make-and-break or sliding contacts, shall be of the totally enclosed type or so constructed as to prevent escape of sparks or hot metal particles. Exception: Wall-mounted receptacles installed above the hazardous area in flammable anesthetizing locations shall not be required to be totally enclosed or have openings guarded or screened to prevent dispersion of particles. (3) Surgical and other lighting fixtures shall conform to Section 501-9(b). Exception No. 1: The surface temperature limitations set forth in Section 501-9(b)(2) shall not apply. Exception No. 2: Integral or pendant switches that are located above and cannot be lowered into the hazardous (classified) location(s) shall not be required to be explosionproof. (4) Approved seals shall be provided in conformance with Section 501-5, and Section 501-5(a)(4) shall apply to horizontal as well as to vertical boundaries of the defined hazardous (classified) locations. (5) Receptacles and attachment plugs located above hazardous anesthetizing locations shall be listed for hospital use for services of prescribed voltage, frequency, rating, and number of conductors with provision for the connection of the grounding conductor. This requirement shall apply to attachment plugs and receptacles of the 2-pole, 3-wire grounding type for single-phase 120-volt, nominal, ac service. (6) Plugs and receptacles rated 250-volt, for connection of 50-ampere, and 60-ampere ac medical equipment for use above hazardous (classified) 70-556 NATIONAL ELECTRICAL CODE locations shall be so arranged that the 60-ampere receptacle will accept either the 50-ampere or the 60-ampere plug. Fifty-ampere receptacles shall be designed so as not to accept the 60-ampere attachment plug. The plugs shall be of the 2-pole, 3-wire design with a third contact connecting to the insulated (green or green with yellow stripe) equipment grounding conductor of the electrical system. (c) Other-than-Hazardous Anesthetizing Locations. (1) Wiring serving other-than-hazardous (classified) locations, as defined in Section 517-60, shall be installed in a metal raceway system or cable assembly. The metal raceway system, or cable armor or sheath assembly, shall qualify as an equipment grounding return path in accordance with Section 250-91(b). Type MC and Type MI cable shall have an outer metal armor or sheath that is identified as an acceptable grounding return path. Exception: Pendant receptacle constructions employing at least Type SJO or equivalent flexible cords suspended not less than 6 feet (1.83 m) from the floor. (2) Receptacles and attachment plugs installed and used in other-thanhazardous (classified) locations shall be listed for hospital use for services of prescribed voltage, frequency, rating, and number of conductors with provision for connection of the grounding conductor. This requirement shall apply to 2-pole, 3-wire grounding type for single-phase 120-, 208-, or 240-volt, nominal, ac service. (3) Plugs and receptacles rated 250-volt, for connection of 50-ampere, and 60-ampere ac medical equipment for use in other-than-hazardous (classified) locations shall be so arranged that the 60-ampere receptacle will accept either the 50-ampere or the 60-ampere plug. Fifty-ampere receptacles shall be designed so as not to accept the 60-ampere attachment plug. The plugs shall be of the 2-pole, 3-wire design with a third contact connecting to the insulated (green or green with yellow stripe) equipment grounding conductor of the electrical system. 517-62. Grounding. In any anesthetizing area, all metal raceways and metal-sheathed cables, and all noncurrent-carrying conductive portions of fixed electric equipment, shall be grounded. Exception: Equipment operating at not more than 10 volts between conductors shall not be required to be grounded. 517-63. Grounded Power Systems in Anesthetizing Locations. (a) General-Purpose Lighting Circuit. A general-purpose lighting circuit connected to the normal grounded service shall be installed in each operating room. Exception: Where connected to any alternate source permitted in Section 700-12 that is separate from the source serving the emergency system. (b) Branch-Circuit Wiring. Branch circuits supplying only listed, fixed, therapeutic and diagnostic equipment, permanently installed above the hazardous (classified) location and in other-than-hazardous (classified) ARTICLE 517 - HEALTH CARE FACILITIES 70-557 locations, shall be permitted to be supplied from a normal grounded service, single- or three-phase system, provided: (1) Wiring for grounded and isolated circuits does not occupy the same raceway, (2) All conductive surfaces of the equipment are grounded, (3) Equipment (except enclosed X-ray tubes and the leads to the tubes) are located at least 8 feet (2.44 m) above the floor or outside the anesthetizing location, and (4) Switches for the grounded branch circuit are located outside the hazardous (classified) location. Exception: Sections 517-63 (b)(3) and (b)(4) shall not apply in other- I than-hazardous (classified) locations. (c) Fixed Lighting Branch Circuits. Branch circuits supplying only fixed lighting shall be permitted to be supplied by a normal grounded service, provided: (1) Such fixtures are located at least 8 feet (2.44 m) above the floor, (2) All conductive surfaces of fixtures are grounded, (3) Wiring for circuits supplying power to fixtures does not occupy the same raceway for circuits supplying isolated power, and (4) Switches are wall-mounted and located above hazardous (classified) locations. (d) Remote-Control Stations. Wall-mounted remote-control stations for remote-control switches operating at 24 volts or less shall be permitted to be installed in any anesthetizing location. (e) Location of Isolated Power Systems. An isolated power center listed for the purpose and its grounded primary feeder shall be permitted to be located in an anesthetizing location, provided it is installed above a hazardous (classified) location or in an other-than-hazardous (classified) location. (f) Circuits in Anesthetizing Locations. Except as permitted above, each power circuit within, or partially within, a flammable anesthetizing location as referred to in Section 517-60 shall be isolated from any distribution system supplying other-than-anesthetizing locations. 517-64.* Low-Voltage Equipment and Instruments. (a) Equipment Requirements. Low-voltage equipment that is frequently in contact with the bodies of persons or has exposed current-carrying elements shall: (1) Operate on an electrical potential of 10 volts or less, or (2) Be approved as intrinsically safe or double-insulated equipment. (3) Be moisture-resistant. (b) Power Supplies. Power shall be supplied to low-voltage equipment from: (1) An individual portable isolating transformer (autotransformers shall not be used) connected to an isolated power circuit receptacle by means of an appropriate cord and attachment plug, or 70-558 NATIONAL ELECTRICAL CODE (2) A common low-voltage isolating transformer installed in a nonhazardous location, or (3) Individual dry-cell batteries, or (4) Common batteries made up of storage cells located in a nonhazardous location. (c) Isolated Circuits. Isolating-type transformers for supplying lowvoltage circuits shall: (1) Have approved means for insulating the secondary circuit from the primary circuit, and (2) Have the core and case grounded. (d) Controls. Resistance or impedance devices shall be permitted to control low-voltage equipment but shall not be used to limit the maximum available voltage to the equipment. (e) Battery-Powered Appliances. Battery-powered appliances shall not be capable of being charged while in operation unless their charging circuitry incorporates an integral isolating-type transformer. (f) Receptacles or Attachment Plugs. Any receptacle or attachment plug used on low-voltage circuits shall be of a type that does not permit interchangeable connection with circuits of higher voltage. (FPN): Any interruption of the circuit, even circuits as low as 10 volts, either by any switch, or loose or defective connections anywhere in the circuit, may produce a spark sufficient to ignite flammable anesthetic agents. See Section 7-5.1.2.3 of Health Care Facilities, NFPA 99-1990 (ANSI). E. X-Ray Installations Nothing in this part shall be construed as specifying safeguards against the useful beam or stray X-ray radiation. (FPN No. 1): Radiation safety and performance requirements of several classes of X-ray equipment are regulated under Public Law 90-602 and are enforced by the Department of Health and Human Services. (FPN No. 2): In addition, information on radiation protection by the National Council on Radiation Protection and Measurements is published as Reports of the National Council on Radiation Protection and Measurement. These reports are obtainable from NCRP Publications, P.O. Box 30175, Washington, D.C. 20014. 517-71. Connection to Supply Circuit. (a) Fixed and Stationary Equipment. Fixed and stationary X-ray equipment shall be connected to the power supply by means of a wiring method meeting the general requirements of this Code. Exception: Equipment properly supplied by a branch circuit rated at not over 30 amperes shall be permitted to be supplied through a suitable attachment plug and hard-service cable or cord. (b) Portable, Mobile, and Transportable Equipment. Individual branch circuits shall not be required for portable, mobile, and transportable medical X-ray equipment requiring a capacity of not over 60 amperes. (c) Over 600-Volt Supply. Circuits and equipment operated on a supply circuit of over 600 volts shall comply with Article 710. ARTICLE 517 - HEALTH CARE FACILITIES 70-559 517-72. Disconnecting Means. (a) Capacity. A disconnecting means of adequate capacity for at least 50 percent of the input required for the momentary rating or 100 percent of the input required for the long-time rating of the X-ray equipment, whichever is greater, shall be provided in the supply circuit. (b) Location. The disconnecting means shall be operable from a location readily accessible from the X-ray control. (c) Portable Equipment. For equipment connected to a 120-volt branch circuit of 30 amperes or less, a grounding-type attachment plug and receptacle of proper rating shall be permitted to serve as a disconnecting means. 517-73. Rating of Supply Conductors and Overcurrent Protection. (a) Diagnostic Equipment. (1) The ampacity of supply branch-circuit conductors and the current rating of overcurrent protective devices shall not be less than 50 percent of the momentary rating or 100 percent of the long-time rating, whichever is greater. (2) The ampacity of supply feeders and the current rating of overcurrent protective devices supplying two or more branch circuits supplying X-ray units shall not be less than 50 percent of the momentary demand rating of the largest unit plus 25 percent of the momentary demand rating of the next largest unit plus 10 percent of the momentary demand rating of each additional unit. Where simultaneous biplane examinations are undertaken with the X-ray units, the supply conductors and overcurrent protective devices shall be 100 percent of the momentary demand rating of each X-ray unit. (FPN): The minimum conductor size for branch and feeder circuits is also governed by voltage regulation requirements. For a specific installation, the manufacturer usually specifies minimum distribution transformer and conductor sizes, rating of disconnecting means, and overcurrent protection. (b) Therapeutic Equipment. The ampacity of conductors and rating of overcurrent protective devices shall not be less than 100 percent of the current rating of medical X-ray therapy equipment. (FPN): The ampacity of the branch-circuit conductors and the ratings of disconnecting means and overcurrent protection for X-ray equipment are usually designated by the manufacturer for the specific installation. 517-74. Control Circuit Conductors. (a) Number of Conductors in Raceway. The number of control circuit conductors installed in a raceway shall be determined in accordance with