CABLEBUS

365-1. Definition. Cablebus is an approved assembly of insulated conductors with fittings and conductor terminations in a completely enclosed, ventilated protective metal housing. The assembly is designed to carry fault current and to withstand the magnetic forces of such current. (FPN): Cablebus is ordinarily assembled at the point of installation from components furnished or specified by the manufacturer in accordance with instructions for the specific job. 365-2. Use. (a) 600 Volts or Less. Cablebus shall be permitted at any voltage or current for which spaced conductors are rated and shall be installed for exposed work only. Cablebus installed outdoors or in corrosive, wet, or damp locations shall be identified for such use. Cablebus shall not be installed in hoistways or hazardous (classified) locations unless specifically approved for such use. Cablebus shall be permitted to be used for branch circuits, feeders, and services. Cablebus framework, where adequately bonded, shall be permitted as the equipment grounding conductor for branch circuits and feeders. (b) Over 600 Volts. Cablebus shall be permitted for systems in excess of 600 volts, nominal. See Section 710-4(a). 365-3. Conductors. (a) Types of Conductors. The current-carrying conductors in cablebus shall have an insulation rating of 75°C or higher of an approved type and suitable for the application in accordance with Articles 310 and 710. (b) Ampacity of Conductors. The ampacity of conductors in cablebus shall be in accordance with Tables 310-17 and 310-19. (c) Size and Number of Conductors. The size and number of conductors shall be that for which the cablebus is designed, and in no case smaller than No. 1/0. (d) Conductor Supports. The insulated conductors shall be supported on blocks or other mounting means designed for the purpose. The individual conductors in a cablebus shall be supported at intervals not greater than 3 feet (914 mm) for horizontal runs and 1½ feet (457 mm) for vertical runs. Vertical and horizontal spacing between supported conductors shall not be less than one conductor diameter at the points of support. 365-5. Overcurrent Protection. Where the allowable ampacity of cablebus conductors does not correspond to a standard rating of an overcurrent device, the next higher ampere-rated overcurrent device shall be permitted. 70-278 NATIONAL ELECTRICAL CODE 365-6. Support and Extension Through Walls and Floors. (a) Support. Cablebus shall be securely supported at intervals not exceeding 12 feet (3.66 m). Exception: Where spans longer than 12 feet (3.66 m) are required, the structure shall be specifically designed for the required span length. (b) Transversely Routed. It shall be permissible to extend cablebus transversely through partitions or walls, other than fire walls, provided the section within the wall is continuous, protected against physical damage, and unventilated. (c) Through Dry Floors and Platforms. Except where fire stops are required, it shall be permissible to extend cablebus vertically through dry floors and platforms, provided the cablebus is totally enclosed at the point where it passes through the floor or platform and for a distance of 6 feet (1.83 m) above the floor or platform. (d) Through Floors and Platforms in Wet Locations. Except where fire stops are required, it shall be permissible to extend cablebus vertically through floors and platforms in wet locations where (1) there are curbs or other suitable means to prevent water flow through the floor or platform opening, and (2) where the cablebus is totally enclosed at the point where it passes through the floor or platform and for a distance of 6 feet (1.83 m) above the floor or platform. 365-7. Fittings. A cablebus system shall include approved fittings for (1) changes in horizontal or vertical direction of the run; (2) dead ends; (3) terminations in or on connected apparatus or equipment or the enclosures for such equipment; and (4) additional physical protection where required, such as guards for severe mechanical exposure. 365-8. Conductor Terminations. Approved terminating means shall be used for connections to cablebus conductors. 365-9. Grounding. Sections of cablebus shall be electrically bonded either by inherent design of the mechanical joints or by applied bonding means. (FPN): See Section 250-75 for bonding of metal noncurrent-carrying parts. A cablebus installation shall be grounded in accordance with Sections 250-32 and 250-33. 365-10. Marking. Each section of cablebus shall be marked with the manufacturer's name or trade designation and the maximum diameter, number, voltage rating, and ampacity of the conductors to be installed. Markings shall be so located as to be visible after installation.