UL 870-2016 pdf download – Wireways, Auxiliary Gutters, and Associated Fittings.
8.2 Nonmetallic wireways, auxiliary gutters, and associated fittings 8.2.1 The material used for nonmetallic wireways, auxiliary gutters, and associated fittings shall comply with the Standard for Nonmetallic Surface Raceways and Fittings, UL 5A. 8.2.2 In an auxiliary gutter, the use of insulating material to replace a portion of one wall of the auxiliary gutter where the wiring goes through meets the intent of the requirement in 8.2.1 when the insulating material and the assembly of the material to the auxiliary gutter supplies strength and rigidity equivalent to that of the auxiliary gutter without the substitution. 9 Thickness of Metal – Metal Wireways, Auxiliary Gutters, and Associated Fittings 9.1 A sheet-metal enclosure shall have a thickness not less than that specified in Table 9.1 . If a metal other than steel, aluminum, or copper is used, it shall be of sufficient thickness to provide strength and rigidity equivalent to that of steel in the thickness specified.
11 Openings in Enclosure – Metal Wireways, Auxiliary Gutters, and Associated Fittings 11.1 Connections for wiring systems 1 1 .1 .1 An opening for connection of a wiring system in a wireway intended for stock and not for a particular installation shall be closed with a knockout, cover, or plug having a thickness not less than 0.053 in (1 .35 mm) if of uncoated steel, 0.056 in (1 .42 mm) if of galvanized steel, and no less than 0.077 in (1 .96 mm) if of aluminum or copper. The knockout, cover, or plug shall be so secured in place that it can be readily removed but will not be displaced with ordinary handling. For a raintight wireway see 1 7.2. 1 1 .1 .2 A hole or a knockout shall be located so that adequate space will be provided for the installation of a locknut, a conduit bushing, an armored-cable connector, or other similar fitting. 11.2 Other openings 1 1 .2.1 An open hole or a slot shall not be provided unless it will be closed in the final assembly and installation of the wireway. Exception: See 1 7.2 and 1 7.3. 12 Covers – Metal Wireways, Auxiliary Gutters, and Associated Fittings 1 2.1 A cover shall be provided with means for securely holding it in place on the trough. 1 2.2 Fastenings for a flat or flanged cover shall comply with the requirements in 1 0.7 and 1 0.8 for screws and tapped holes or nuts, and with the requirements in 1 2.3 for other types of fastenings. The fastenings shall be located not more than 6 in (1 52 mm) from each end of the cover and spaced not more than 1 2 in (305 mm) apart at points between the end fastenings. Exception: If the straps or rods mentioned in 6.8 are spaced not more than 30 in (762 mm) apart along the length of the wireway after assembly, a flat or flanged cover may be held by fastenings located not more than 6 in (1 52 mm) from each end of the cover and spaced not more than 24 in (1 60 mm) apart at points between these end fastenings.