ELECTROLYTIC CELLS

70-683 665-68. Remote Control. (a) Selector Switch. Where remote controls are used for applying power, a selector switch shall be provided and interlocked to provide power from only one control point at a time. (b) Foot Switches. Switches operated by foot pressure shall be provided with a shield over the contact button to avoid accidental closing of the switch. ARTICLE 668 - ELECTROLYTIC CELLS 668-1. Scope. The provisions of this article apply to the installation of the electrical components and accessory equipment of electrolytic cells, electrolytic cell lines and process power supply for the production of aluminum, cadmium, chlorine, copper, fluorine, hydrogen peroxide, magnesium, sodium, sodium chlorate, and zinc. Not covered by this article are cells used as a source of electric energy and for electroplating processes and cells used for the production of hydrogen. (FPN No. 1): In general, any cell line or group of cell lines operated as a unit for the production of a particular metal, gas, or chemical compound may differ from any other cell lines producing the same product because of variations in the particular raw materials used, output capacity, use of proprietary methods or process practices, or other modifying factors to the extent that detailed Code requirements become overly restrictive and do not accomplish the stated purpose of this Code. (FPN No. 2): For further information, see IEEE Standard for Electrical Safety Practices in Electrolytic Cell Line Working Zones: IEEE Std. 463-1977. 668-2. Definitions. Cell Line: An assembly of electrically interconnected electrolytic cells supplied by a source of direct-current power. Cell Line Attachments and Auxiliary Equipment: As applied to Article 668, cell line attachments and auxiliary equipment include, but are not limited to, auxiliary tanks; process piping; duct work; structural supports; exposed cell line conductors; conduits and other raceways; pumps, positioning equipment, and cell cutout or bypass electrical devices. Auxiliary equipment includes tools, welding machines, crucibles, and other portable equipment used for operation and maintenance within the electrolytic cell line working zone. In the cell line working zone, auxiliary equipment includes the exposed conductive surfaces of ungrounded cranes and crane-mounted cellservicing equipment. Electrolytic Cell: A receptacle or vessel in which electrochemical reactions are caused by applying electrical energy for the purpose of refining or producing usable materials. Electrolytic Cell Line Working Zone: The cell line working zone is the space envelope wherein operation or maintenance is normally performed on or in the vicinity of exposed energized surfaces of electrolytic cell lines or their attachments. 70-684 NATIONAL ELECTRICAL CODE 668-3. Other Articles. (a) Lighting, Ventilating, Material Handling. Chapters 1 through 4 shall apply to services, feeders, branch circuits, and apparatus for supplying lighting, ventilating, material handling, and the like, that are outside the electrolytic cell line working zone. (b) Systems Not Electrically Connected. Those elements of a cell line power-supply system that are not electrically connected to the cell supply system, such as the primary winding of a two-winding transformer, the motor of a motor-generator set, feeders, branch circuits, disconnecting means, motor controllers, and overload protective equipment shall be required to comply with all applicable provisions of this Code. (FPN): For the purpose of this section, "electrically connected" means connection capable of carrying current as distinguished from connection through electromagnetic induction. (c) Electrolytic Cell Lines. Electrolytic cell lines shall comply with the provisions of Chapters 1, 2, 3, and 4. Exception No. 1: The electrolytic cell line conductors shall not be required to comply with the provisions of Articles 110, 210, 215, 220, and 225. See Section 668-11. Exception No. 2: Overcurrent protection of electrolytic cell dc process power circuits shall not be required to comply with the requirements of