UL-870:2016 pdf free download – STANDARD FOR SAFETY Wireways, Auxiliary Gutters, and Associated Fittings.
12.5 A flat, unhinged cover may be used if:
a) Each side wall of the trough is flanged at right angles to the wall to overlap the cover not less than 1/2 in (12.7 mm),
b) Each end of the cover forms a 1/4-in (6.4-mm) rabbet with the adjoining cover, and
c) The cover is fastened to the trough as required by 12.2.
13 Hinges and Latches — Metal Wireways, Auxiliary Gutters, and Associated Fittings
13.1 A hinge for a door or cover shall be of metal not less than 0.054-in (1 .37-mm) thick it made of steel, and not less than 0.077-in (1 .96-mm) thick if made of copper or aluminum.
Exception: A wireway cover may employ a continuous piano-type hinge made of steel not less than 0.04 7-in (1.2-mm) thick.
13.2 Hinges shall not be spaced more than 24 in (610 mm) apart, measured center to center, and not more than 15 in (381 mm) from each end of the cover. At least two hinges shall be used for each cover.
Exception: A single hinge that extends the full length of the cover may be used.
13.3 A hinged door or cover shall be provided with at least one latch or the equivalent for each 30 in (762 mm) or less of cover length. Latches shall not be located more than 12 in (305 mm) from each end of the cover and shall be evenly spaced not more than 36 in (914 mm) apart at points between the end latches.
13.4 Latches shall be positive in action.
13.5 A screw fastening is considered to be equivalent to a latch.
13.6 A button latch consisting of a projection stamped on the edge of the trough and engaging a corresponding indentation in the cover flange is not acceptable.
13.7 A spring latch consisting of a strip of steel fastened to the wall of a trough and cooperating with a slot in the cover shall be formed and attached so that the latch engages the edge of the cover slot away from the trough wall.
13.8 An arrangement of hinges or latches, or both, that does not fully comply with the requirements in 13.1 — 13.5, may be acceptable if, when subjected to an appropriate investigation, it is found to provide the necessary mechanical strength and rigidity of the complete assembly.
14 Expansion Joints and Telescoping Sections — Metal Wireways, Auxiliary Gutters, and Associated Fittings
14.1 An expansion joint or telescoping section shall have the necessary mechanical strength to support the conductors that may be installed in it and shall be provided with one or more bonding conductors to provide electrical continuity.
Exception: A telescoping section that can be made immovable at the time of installation by bolted fastenings equivalent to the fastenings required between straight lengths of wireway need not be provided with a bonding conductor.
14.2 The size of the bonding conductors, or the total cross section of the conductors if two or more are in parallel, shall be in compliance with Table 14.1.
Exception: A smaller conductor may be used lithe expansion joint or telescoping section is marked to indicate a maximum circuit ampere rating for which the smaller conductor is adequate in accordance with Table 14.2. See 25.7.