UL 870:2008 pdf download.Wireways,Auxiliary Gutters,and Associated Fittings.
5.5 Nonmetallic wireways，auxiliary gutters and fittings shall additionally comply with constructionrequirements in the Standard for Nonmetallic Surface Raceways and Fittings,UL 5A.
5.6 Wireways，auxiliary gutters and fittings marked for use with an environmental rating，includingenclosure types, shall comply with the applicable requirements specified in the Standard for Enclosuresfor Electrical Equipment,Environmental Considerations,UL 5OE.
6 Design
6.1 A metal wireway shall be constructed,such that the interconnection of sections and fittings willprovide a rigid mechanical assembly and provide electrical conductivity complying with the requirementsfor the Electrical Continuity Test -Metal Wireways,Auxiliary Gutters, and Associated Fittings, Section 17.
6.2 A wireway shall be formed and assembled so that it will have the strength and rigidity necessary toresist the abuses to which it is likely to be subjected, without resulting in a risk of fire,electric shock,orinjury to persons due to total or partial collapse with resulting damage to conductors，loosening ordisplacement of parts, or other serious defects.
6.2 A wireway shall be formed and assembled so that it will have the strength and rigidity necessary toresist the abuses to which it is likely to be subjected, without resulting in a risk of fire,electric shock,orinjury to persons due to total or partial collapse with resulting damage to conductors，loosening ordisplacement of parts, or other serious defects.
6.3 The interior of the wireway shall be free from burrs and sharp corners or edges that may abrade theinsulation on conductors or otherwise damage wiring. Screws and bolts, however used, shall not projectinto the wireway unless sharp ends and threaded sections are covered or otherwise prevented fromcoming in contact with wires.
Exception: A threaded section of a screw or bolft not having a sharp point need not be prevented fromcoming in contact with wires provided the screw or bolt does not project more than 1/32 in (0.8 mm) intothe wireway.
