REQUIREMENTS FOR

ELECTRICAL INSTALLATIONS A. General 110-2. Approval. The conductors and equipment required or permitted by this Code shall be acceptable only if approved. (FPN): See Examination of Equipment for Safety, Section 90-7 and Examina- I tion, Identification, Installation, and Use of Equipment, Section 110-3. See definitions of "Approved," "Identified," "Labeled," and "Listed." 110-3. Examination, Identification, Installation, and Use of Equipment. (a) Examination. In judging equipment, considerations such as the following shall be evaluated: (1) Suitability for installation and use in conformity with the provisions of this Code. (FPN): Suitability of equipment use may be identified by a description marked I on or provided with a product to identify the suitability of the product for a specific purpose, environment, or application. Suitability of equipment may be evidenced by listing or labeling. (2) Mechanical strength and durability, including, for parts designed to enclose and protect other equipment, the adequacy of the protection thus provided. (3) Wire-bending and connection space. (4) Electrical insulation. (5) Heating effects under normal conditions of use and also under abnormal conditions likely to arise in service. (6) Arcing effects. (7) Classification by type, size, voltage, current capacity, and specific use. (8) Other factors that contribute to the practical safeguarding of persons using or likely to come in contact with the equipment. (b) Installation and Use. Listed or labeled equipment shall be used or labeling. installed in accordance with any instructions included in the listing or 110-4. Voltages. Throughout this Code, the voltage considered shall be that at which the circuit operates. 110-5. Conductors. Conductors normally used to carry current shall be of copper unless otherwise provided in this Code. Where the conductor material is not specified, the material and the sizes given in this Code shall apply to copper conductors. Where other materials are used, the size shall I be changed accordingly. (FPN): For aluminum and copper-clad aluminum conductors, see Section 310-15. 110-6. Conductor Sizes. Conductor sizes are expressed in American Wire Gage (AWG) or in circular mils. 70-20 NATIONAL ELECTRICAL CODE 110-7. Insulation Integrity. All wiring shall be so installed that, when completed, the system will be free from short circuits and from grounds other than as required or permitted in Article 250. 110-8. Wiring Methods. Only wiring methods recognized as suitable are included in this Code. The recognized methods of wiring shall be permitted to be installed in any type of building or occupancy, except as otherwise provided in this Code. 110-9. Interrupting Rating. Equipment intended to break current at fault levels shall have an interrupting rating sufficient for the nominal circuit voltage and the current that is available at the line terminals of the equipment. Equipment intended to break current at other than fault levels shall have an interrupting rating at nominal circuit voltage sufficient for the current that must be interrupted. 110-10. Circuit Impedance and Other Characteristics. The overcurrent protective devices, the total impedance, the component short-circuit withstand ratings, and other characteristics of the circuit to be protected shall be so selected and coordinated as to permit the circuit protective devices that are used to clear a fault without the occurrence of extensive damage to the electrical components of the circuit. This fault shall be assumed to be either between two or more of the circuit conductors, or between any circuit conductor and the grounding conductor or enclosing metal raceway. (FPN): For circuit breakers, see Section 240-83(c). 110-11. Deteriorating Agents. Unless identified for use in the operating environment, no conductors or equipment shall be located in damp or wet locations; where exposed to gases, fumes, vapors, liquids, or other agents having a deteriorating effect on the conductors or equipment; nor where exposed to excessive temperatures. (FPN No. 1): See Section 300-6 for protection against corrosion. (FPN No. 2): Some cleaning and lubricating compounds can cause severe deterioration of many plastic materials used for insulating and structural applications in equipment. Equipment approved for use in dry locations only shall be protected against permanent damage from the weather during building construction. 110-12. Mechanical Execution of Work. Electric equipment shall be installed in a neat and workmanlike manner. (a) Unused Openings. Unused openings in boxes, raceways, auxiliary gutters, cabinets, equipment cases, or housings shall be effectively closed to afford protection substantially equivalent to the wall of the equipment. (b) Subsurface Enclosures. Conductors shall be racked to provide ready and safe access in underground and subsurface enclosures, into which persons enter for installation and maintenance. (c) Integrity of Electrical Equipment and Connections. Internal parts of electrical equipment, including busbars, wiring terminals, insulators, and other surfaces shall not be damaged or contaminated by foreign materials such as paint, plaster, cleaners, or abrasives.