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

(FPN): See Section 250-21 for objectionable current over grounding conductors. Exception No. 1: The main bonding jumper shall not be required at the distribution panelboard in or on buildings housing livestock or poultry where all the following conditions are met: a. All buildings and premises wiring are under the same ownership. b. An equipment grounding conductor is run with the supply conductors and is of the same size as the largest supply conductor, if of the same material, or is adjusted in size in accordance with the equivalent size columns of Table 250-95 if of different materials. c. Service disconnecting means is provided at the distribution point for supply to those buildings. d. The equipment grounding conductor is bonded to the grounded circuit conductor at the service equipment or the source of a separately derived system. e. A grounding electrode is provided and connected to the equipment grounding conductor in the distribution panelboard. Exception No. 2: A metal interior water piping system or other interior metal or metallic piping system of an agricultural building to which electrical equipment requiring grounding is not attached or in electrical contact shall be permitted to be bonded to the service equipment enclosure, the grounded conductor at the service, or to the equipment grounding terminal bar in a panelboard that serves the building by means of an impedance device listed for the purpose, provided that all the following conditions are complied with: a. The device shall have the short-circuit withstand rating identified where other than the minimum of 10,000 amperes. b. The bonding conductor shall be an insulated copper conductor not smaller than No. 8 and shall be installed without splice other than where connected to the impedance device. C. The bonding conductor shall be installed in a raceway suitable for the conditions. d. The bonding conductor shall be connected to the metal piping system or other metal by means of a listed pressure connector suitable for the conditions or by exothermic welding. (b) Concrete Embedded Elements. Wire mesh or other conductive elements where provided in the concrete floor of animal confinement areas to provide an equipotential plane shall be bonded to the building grounding electrode system. The bonding conductor shall be copper, insulated, covered or bare, and not smaller than No. 8. The means of bonding to wire 70-588 NATIONAL ELECTRICAL CODE mesh or conductive elements shall be by pressure connectors or clamps of brass, copper, copper alloy, or an equally substantial approved means. Equipotential Plane: An equipotential plane is an area where a wire mesh or other conductive elements are embedded in concrete, bonded to all adjacent conductive equipment, structures, or surfaces, and connected to the electrical grounding system to prevent a difference in voltage from developing within the plane. (FPN): If a wire mesh or other conductive grid is embedded in a concrete floor or platform, and, if this grid is bonded to the electrical system grounding bus, livestock making contact between the concrete floor or platform and the equipment or metal structure will be less likely to be exposed to a level of voltage that may alter animal behavior or productivity. (c) Separate Equipment Grounding Conductor. In agricultural buildings as described in Sections 547-1(a) and (b), noncurrent-carrying metal parts of equipment, raceways, and other enclosures, where required to be grounded, shall be grounded by a copper equipment grounding conductor installed between the equipment and the building disconnecting means. If installed underground, the equipment grounding conductor shall be insulated or covered. (FPN): Grounding electrode system resistances lower than required by Article 250, Part H, may reduce potential differences in livestock facilities. (d) Water Pumps and Metal Well Casings. The frame of the motor of any water pump shall be grounded as required for Section 430-142. Where a submersible pump is used in metal well casing, the well casing shall be bonded to the pump circuit equipment grounding conductor, or to the equipment grounding bus of the panelboard supplying the submersible pump.