ft) at each end or joint, unless listed for other support intervals. The distance between supports shall not exceed 3 m (10 ft).
(B) Vertical Support. Vertical runs of wireways shall be securely supported at intervals not exceeding 4.5 m (15 ft) and shall not have more than one joint between supports. Adjoining wireway sections shall be securely fastened together to provide a rigid joint.
376.56 Splices, Taps, and Power Distribution Blocks.
(A) Splices and Taps. Splices and taps shall be permitted within a wireway, provided they are accessible. The conductors, including splices and taps, shall not fill the wire-way to more than 75 percent of its area at that point.
(B) Power Distribution Blocks.
(1) Installation. Power distribution blocks installed in
metal wireways shall be listed.
(2) Size of Enclosure. In addition to the wiring space re- quirement in 376.56(A), the power distribution block shall be installed in a wireway with dimensions not smaller than specified in the installation instructions of the power distribution block.
(3) Wire Bending Space. Wire bending space at the ter- minals of power distribution blocks shall comply with
312.6(B).
(4) Live Parts. Power distribution blocks shall not have uninsulated live parts exposed within a wireway, whether or not the wireway cover is installed.
376.58 Dead Ends. Dead ends of metal wireways shall be closed.
376.70 Extensions from Metal Wireways. Extensions from wireways shall be made with cord pendants installed in accordance with 400.10 or with any wiring method in Chapter 3 that includes a means for equipment grounding. Where a separate equipment grounding conductor is employed, connection of the equipment grounding conductors in the wiring method to the wireway shall comply with 250.8 and 250.12.
III. Construction Specifications
376.100 Construction.
(A) Electrical and Mechanical Continuity. Wireways shall be constructed and installed so that adequate electrical and mechanical continuity of the complete system is secured
(B) Substantial Construction. Wireways shall be of sub- stantial construction and shall provide a complete enclosure for the contained conductors. All surfaces, both interior and exterior, shall be suitably protected from corrosion. Corner joints shall be made tight, and where the assembly is held together by rivets, bolts, or screws, such fasteners shall be spaced not more than
300 mm (12 in.) apart
(C) Smooth Rounded Edges. Suitable bushings, shields, or fittings having smooth, rounded edges shall be provided where conductors pass between wireways, through partitions, around bends, between wireways and cabinets or junction boxes, and at other locations where necessary to prevent abrasion of the insulation of the conductors.
(D) Covers. Covers shall be securely fastened to the wireway.