STORAGE BATTERIES

480-1. Scope. The provisions of this article shall apply to all stationary installations of storage batteries. 480-2. Definitions. Storage Battery: A battery comprised of one or more rechargeable cells of the lead-acid, nickel-cadmium, or other rechargeable electrochemical types. Sealed Cell or Battery: A sealed cell or battery is one that has no provision for the addition of water or electrolyte or for external measurement of electrolyte specific gravity. The individual cells shall be permitted to contain a venting arrangement as described in Section 480-9(b). Nominal Battery Voltage: The voltage computed on the basis of 2.0 volts per cell for the lead-acid type and 1.2 volts per cell for the alkali type. 480-3. Wiring and Equipment Supplied from Batteries. Wiring and equipment supplied from storage batteries shall be subject to the requirements of this Code applying to wiring and equipment operating at the same voltage. Exception: As otherwise provided for communication systems in Article 800. 480-4. Grounding. The requirements of Article 250 shall apply. 480-5. Insulation of Batteries of Not Over 250 Volts. This section shall apply to storage batteries having cells so connected as to operate at a nominal battery voltage of not over 250 volts. (a) Vented Lead-Acid Batteries. Cells and multicompartment batteries with covers sealed to containers of nonconductive, heat-resistant material shall not require additional insulating support. (b) Vented Alkaline-type Batteries. Cells with covers sealed to jars of nonconductive, heat-resistant material shall require no additional insulation support. Cells in jars of conductive material shall be installed in trays of nonconductive material with not more than 20 cells (24 volts, nominal) in the series circuit in any one tray. (c) Rubber Jars. Cells in rubber or composition containers shall require no additional insulating support where the total nominal voltage of all cells in series does not exceed 150 volts. Where the total voltage exceeds 150 volts, batteries shall be sectionalized into groups of 150 volts or less, and each group shall have the individual cells installed in trays or on racks. (d) Sealed Cells or Batteries. Sealed cells and multicompartment sealed batteries constructed of nonconductive, heat-resistant material shall not 70-464 NATIONAL ELECTRICAL CODE require additional insulating support. Batteries constructed of a conducting container shall have insulating support if a voltage is present between the container and ground. 480-6. Insulation of Batteries of Over 250 Volts. The provisions of Section 480-5 shall apply to storage batteries having the cells so connected as to operate at a nominal voltage exceeding 250 volts, and, in addition, the provisions of this section shall also apply to such batteries. Cells shall be installed in groups having a total nominal voltage of not over 250 volts. Insulation, which can be air, shall be provided between groups and shall have a minimum separation between live battery parts of opposite polarity of 2 inches (50.8 mm) for battery voltages not exceeding 600 volts. 480-7. Racks and Trays. Racks and trays shall comply with (a) and (b) below. (a) Racks. Racks, as required in this article, are rigid frames designed to support cells or trays. They shall be substantial and made of: (1) Metal, so treated as to be resistant to deteriorating action by the electrolyte and provided with nonconducting members directly supporting the cells or with continuous insulating material other than paint or conducting members; or (2) Other construction such as fiberglass or other suitable nonconductive materials. (b) Trays. Trays are frames, such as crates or shallow boxes usually of wood or other nonconductive material, so constructed or treated as to be resistant to deteriorating action by the electrolyte. 480-8. Battery Locations. Battery locations shall conform to (a) and (b) below. (a) Ventilation. Provisions shall be made for sufficient diffusion and ventilation of the gases from the battery to prevent the accumulation of an explosive mixture. (b) Live Parts. Guarding of live parts shall comply with Section 110-17. 480-9. Vents. (a) Vented Cells. Each vented cell shall be equipped with a flame arrestor designed to prevent destruction of the cell due to ignition of gases within conditions. the cell by an external spark or flame under normal operating (b) Sealed Cells. Sealed battery/cells shall be equipped with a pressurerelease vent to prevent excessive accumulation of gas pressure, or the battery/cell shall be designed to prevent scatter of cell parts in event of a cell explosion. 70-465 Chapter 5. Special Occupancies