370.1 Scope. This article covers the use and installation requirements of cablebus and associated fittings.
370.2 Definition.
Cablebus. An assembly of insulated conductors with fit- tings and conductor terminations in a completely enclosed, ventilated protective metal housing. Cablebus is ordinarily assembled at the point of installation from the components furnished or specified by the manufacturer in accordance with instructions for the specific job. This assembly is designed to carry fault current and to withstand the magnetic forces of such current.
370.3 Use. Approved cablebus shall be permitted at any voltage or current for which spaced conductors are ratedand shall be installed only for exposed work, except as permitted in 370.6. 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 bonded, shall be permitted to be used as the equipment grounding conductor for branch circuits and feeders.
370.4 Conductors.
(A) T^pes of Conductors. The current-carrying conduc- tors in cablebus shall have an insulation rating of 75 °C (167°F) or higher and be an approved type suitable for the application.
(B) Ampacity of Conductors. The ampacity of conduc- tors in cablebus shall be in accordance with Table
310.17 and Table 310.19, or with Table 310.69 and
Table 310.70 for installations over 600 volts.
(C) Size and Number of Conductors. The size and num- ber of conductors shall be that for which the cablebus is designed, and in no case smaller than 1/0 AWG.
(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 sup- ported at intervals not greater than 900 mm (3 ft) for horizontal runs and 450 mm (II/2 ft) for vertical runs. Vertical and horizontal spacing between supported
conductors shall not be less than one conductor diameter at the points of support.
370.5 Overcurrent Protection. Cablebus shall be pro tected against overcurrent in accordance with the allowable ampacity of the cablebus conductors in accordance with 240.4.
Exception: Overcurrent protection shall be permitted in accordance with 240.100 and 240.101 for over 600 volts, nominal.
370.6 Support and Extension Through Walls and
Floors.
(A) Support. Cablebus shall be securely supported at in tervals not exceeding 3.7 m (12 ft).
Exception: Where spans longer than 3.7 m (12 ft) are re- quired, the structure shall be specifically designed for the required span length.
(B) Transversely Routed. Cablebus shall be permitted to extend 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 firestops are required, cablebus shall be permitted to extend 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 1.8 m (6 ft) above the floor