UL 884:2016 pdf free download – STANDARD FOR SAFETY Underfloor Raceways and Fittings.
6.2 Outlet boxes and fittings
6.2.1 A junction box or duct fitting, if made of iron or steel, shall be protected against corrosion by enameling, galvanizing, cementation, plating, or other equivalent means. If constructed of aluminum, it shall have a protective coating of asphalt, varnish, or enamel.
6.2.2 An outlet fitting, if made of iron or steel, shall be protected against corrosion by means of a zinc coating specified in 6.1.1(a) or an equivalently protective coating of another metal.
6.2.3 At any time up to one year from the time of manufacture, an enamel coating on a junction box or fitting shall comply with the requirements in 15.2.
6.2.4 At any time up to one year from the time of manufacture, an epoxy coating on a junction box or fitting shall comply with the requirements in 15.3.
7 Duct
7.1 Duct shall be made of sheet steel. Both inside and outside surfaces of each length of duct shall be cleaned of all scale and rust. The cleaning process shall leave the surface of the duct in a condition that results in the protective coating adhering firmly and having a smooth surface.
7.2 The partitions between cells of a multicellular duct shall not have any openings through which wires or cables are likely to be passed from one cell to another in normal use.
7.3 After cleaning and before the protective coating is applied, the interior surface of each length of duct shall be examined to determine the absence or presence of scale.
7.4 Ordinarily, scale can be identified as a sharply defined edge or a rough surface extending for some distance along the duct, causing a slight but noticeable decrease in the internal dimensions. At the ends of the duct, scale may be identified by scraping the surface of the duct and thus removing the hard, brittle film of the scale.
7.5 Welded seams shall be made so that each length of duct has strength for the conditions of use.
7.6 Duct shall be of dimensions applicable to the size and quantity of wires to be installed in the raceway. Upper corners shall be rounded to a radius (outside) of not less than 3/16 inch (5 mm), except that flush duct need not have its upper corners rounded. See 21.2.
7.7 Duct shall provide a smooth wireway for pulling in wires and cables and shall not have any burrs, fins, or other projections that can damage wiring.
7.8 The thickness of single-celled and multicellular sheet-steel duct and of the sheet-steel partitions between the cells of multicellular duct shall not be less than indicated in Table 7.1.
8 Preset Inserts
8.1 Each insert shall be made of metal and shall not be less than 0.067 inch (1.70 mm) thick if
constructed of uncoated sheet steel — 0.070 inch (1.78 mm) if zinc-coated — or shall be formed from the metal of the duct. If a separate insert is attached to the duct, the joint shall be mechanically strong and shall block the entry of fresh concrete. An insert shall be capable of withstanding the Pull Test, Section 17.
8.2 Each insert shall provide a continuous metal passage from the duct or raceway to the underside of the floor covering and shall be constructed to provide a smooth wire-pulling radius without any obstruction(s) within the duct or the outlet.
8.3 Visual inspection is to be made to determine whether an insert complies with the requirements in 8.2.
8.4 Each insert shall be capable of accommodating fittings designed for use with the raceway system in a manner that establishes and maintains continuity of the metal grounding connection between the fitting and the duct.
8.5 If compliance of an insert with the requirement in 8.4 cannot be determined by visual inspection, the bonding in question is to be investigated with particular attention to the reliability and the resistance of joints. See the Grounding Continuity Test, Section 14.