Resolución 2535: adopta el Código Eléctrico Nacional, versión 1993. (Sustituye el Anejo A del Reglamento 4435)

(b) Minimum Size of Conductors. Size No. 18 or No. 16 fixture wires as specified in Section 725-16 and flexible cords shall be permitted for the control and operating circuits of X-ray and auxiliary equipment where protected by not larger than 20-ampere overcurrent devices. 517-75. Equipment Installations. All equipment for new X-ray installations and all used or reconditioned X-ray equipment moved to and reinstalled at a new location shall be of an approved type. 70-560 NATIONAL ELECTRICAL CODE 517-76. Transformers and Capacitors. Transformers and capacitors that are part of an X-ray equipment shall not be required to comply with Articles 450 and 460. Capacitors shall be mounted within enclosures of insulating material or grounded metal. 517-77. Installation of High Tension X-Ray Cables. Cables with grounded shields connecting X-ray tubes and image intensifiers shall be permitted to be installed in cable trays or cable troughs along with X-ray equipment control and power supply conductors without the need for barriers to separate the wiring. 517-78. Guarding and Grounding. (a) High-Voltage Parts. All high-voltage parts, including X-ray tubes, shall be mounted within grounded enclosures. Air, oil, gas, or other suitable insulating media shall be used to insulate the high-voltage from the grounded enclosure. The connection from the high-voltage equipment to X-ray tubes and other high-voltage components shall be made with highvoltage shielded cables. (b) Low-Voltage Cables. Low-voltage cables connecting to oil-filled units that are not completely sealed, such as transformers, condensers, oil coolers, and high-voltage switches, shall have insulation of the oil-resistant type. (c) Noncurrent-Carrying Metal Parts. Noncurrent-carrying metal parts of X-ray and associated equipment (controls, tables, X-ray tube supports, transformer tanks, shielded cables, X-ray tube heads, etc.) shall be grounded in the manner specified in Article 250, as modified by Sections 517-13(a) and (b). Exception: Battery-operated equipment. F. Communications, Signaling Systems, Data Systems, Fire Protective Signaling Systems, and Systems Less than 120 Volts, Nominal 517-80. Patient Care Areas. Equivalent insulation and isolation to that required for the electrical distribution systems in patient care areas shall be provided for communications, signaling systems, data system circuits, fire protective signaling systems, and systems less than 120 volts, nominal. (FPN): An acceptable alternate means of providing isolation for patient/nurse call systems is by the use of nonelectrified signaling, communication, or control devices held by the patient or within reach of the patient. 517-81. Other-than-Patient-Care Areas. In other than patient care areas, installations shall be in accordance with the appropriate provisions of Articles 725, 760, and 800. 517-82. Signal Transmission Between Appliances. (a) General. Permanently installed signal cabling from an appliance in a patient location to remote appliances shall employ a signal transmission system that prevents hazardous grounding interconnection of the appliances. ARTICLE 517 - HEALTH CARE FACILITIES 70-561 (FPN): See Sections 517-13(b) and 517-15. (b) Common Signal Grounding Wire. Common signal grounding wires (i.e., the chassis ground for single-ended transmission) shall be permitted to be used between appliances all located within the patient vicinity, provided the appliances are served from the same reference grounding point. G. Isolated Power Systems 517-160. Isolated Power Systems. (a) Installations. (1) Each isolated power circuit shall be controlled by a switch having a disconnecting pole in each isolated circuit conductor to simultaneously disconnect all power. Such isolation shall be accomplished by means of one or more transformers having no electrical connection between primary and secondary windings, by means of motor generator sets, or by means of suitably isolated batteries. (2)* Circuits supplying primaries of isolating transformers shall operate at not more than 600 volts between conductors and shall be provided with proper overcurrent protection. The secondary voltage of such transformers shall not exceed 600 volts between conductors of each circuit. All circuits supplied from such secondaries shall be ungrounded, and shall have an approved overcurrent device of proper ratings in each conductor. Circuits supplied directly from batteries or from motor generator sets shall be ungrounded, and shall be protected against overcurrent in the same manner as transformer-fed secondary circuits. If an electrostatic shield is present, it shall be connected to the reference grounding point. (3) The isolating transformers, motor generator sets, batteries and battery chargers, and associated primary or secondary overcurrent devices shall not be installed in hazardous (classified) locations. The isolated secondary circuit wiring extending into a hazardous anesthetizing location shall be installed in accordance with Section 501-4. (4) An isolated branch circuit supplying an anesthetizing location shall supply no other location. (5) The isolated circuit conductors shall be identified as follows: Isolated Conductor No. 1 - Orange Isolated Conductor No. 2 - Brown For 3-phase systems, the third conductor shall be identified as yellow. (6) Wire-pulling compounds that increase the dielectric constant shall not be used on the secondary conductors of the isolated power supply. (FPN No. 1): It is desirable to limit the size of the isolation transformer to 10 kVA or less and to use conductor insulation with low leakage to meet impedance requirements. (FPN No. 2): Minimizing the length of branch-circuit conductors and utilizing conductor insulations with a dielectric constant less than 3.5 and insulation resistance constant greater than 6100 megohm-meters (20,000 megohm-feet) at 60°F (16°C) reduces leakage from line to ground reducing the monitor hazard current. (b)* Line Isolation Monitor. (1) In addition to the usual control and overcurrent protective devices, each isolated power system shall be provided with a continually operating 70-562 NATIONAL ELECTRICAL CODE line isolation monitor that indicates possible leakage or fault currents from either isolated conductor to ground. The monitor shall be designed so that a green signal lamp, conspicuously visible to persons in the anesthetizing location, remains lighted when the system is adequately isolated from ground; an adjacent red signal lamp and an audible warning signal (remote if desired) shall be energized when the total hazard current (consisting of possible resistive and capacitive leakage currents) from either isolated conductor to ground reaches a threshold value of 5 milliamperes under nominal line voltage conditions. The line monitor shall not alarm for a fault hazard of less than 3.7 milliamperes or for a total hazard current of less than 5.0 milliamperes. Exception: A system shall be permitted to be designed to operate at a lower threshold value of total hazard current. A line isolation monitor for such a system shall be permitted to be approved with the provision that the fault hazard current shall be permitted to be reduced but not to less than 35 percent of the corresponding threshold value of the total hazard current, and the monitor hazard current is to be correspondingly reduced to no more than 50 percent of the alarm threshold value of the total hazard current. (2) The line isolation monitor shall be designed to have sufficient internal impedance such that, when properly connected to the isolated system, the maximum internal current that can flow through the line isolation monitor, when any point of the isolated system is grounded, shall be 1 milliampere. Exception: The line isolation monitor shall be permitted to be of the low-impedance type such that the current through the line isolation monitor, when any point of the isolated system is grounded, will not exceed twice the alarm threshold value for a period not exceeding 5 milliseconds. (FPN): Reduction of the monitor hazard current, provided this reduction results in an increased "not alarm" threshold value for the fault hazard current, will increase circuit capacity. (3) An ammeter calibrated in the total hazard current of the system (contribution of the fault hazard current plus monitor hazard current) shall be mounted in a plainly visible place on the line isolation monitor with the "alarm on" zone at approximately the center of the scale. Exception: The line isolation monitor may be a composite unit, with a sensing section cabled to a separate display panel section on which the alarm or test functions are located. (FPN): It is desirable to locate the ammeter so that it is conspicuously visible to persons in the anesthetizing location.