UL-1484:2016 pdf free download – STANDARD FOR SAFETY Residential Gas Detectors.
14.6 Product mounting
14.6.1 The enclosure of a detector shall be provided with means for mounting in the intended manner. Any fittings, such as brackets, hangers, or the like, necessary for intended mounting shall be furnished with the detector. The mounting means shall be accessible without disassembling any operating part of the detector. A detector cover is not to be considered an operating part if its removal does not expose the installer to a risk of electric shock.
14.6.2 If the detector is intended for permanent connection, the enclosure shall either have provision for the connection of metal-clad cable, conduit, or nonmetallic sheathed cable or have provision for mounting on an outlet box.
14.7 Ventilating openings
14.7.1 Ventilating openings in an enclosure for high-voltage circuits including perforated holes, louvers, and openings protected by means of wire screening, expanded metal, or perforated covers, shall be of such size or shape that no openings will permit passage of a rod having a diameter of 9/64 inch (3.6 mm). An enclosure for a fuse or other overload protective device provided with ventilating openings shall afford protection against the emission of flame or molten metal.
14.8 Screens and expanded metal
14.8.1 Perforated sheet metal used for expanded metal mesh shall not be less than 0.042 inch (1.07 mm) thick, 0.046 inch (1.17 mm) thick if zinc coated.
Exception: lithe indentation of the guard or enclosure will not alter the clearance between uninsulated live parts and grounded metal so as to reduce spacings below the minimum values required, 0.02 1 inch (0.53 mm) expanded metal mesh or perforated sheet metal, 0.024 inch (0.61 mm) if zinc coated, may be employed under the following conditions:
a) The exposed mesh on any one side or surface of the product has an area of not more than 72 square inches (465 cm2) and has no dimension greater than 12 inches (305 mm) or
b) The width of an opening so protected is not greater than 3-1/2 inches (88.9 mm).
14.8.2 The wires forming a screen protecting high-voltage current-carrying parts shall not be smaller than 16 AWG (1.3 mm2) and the screen openings shall not be greater than 1/2 square inch (3.2 cm2) in area.
14.8.3 Openings provided to permit cleaning or openings which may be used to clean internal parts shall be constructed to reduce the risk of damage to functional internal components during such cleaning operations.
14.8.4 A ferrous plate or plug closure for an unused conduit opening or other hole in the enclosure shall not be less than 0.027 inch (0.69 mm) thick, and a nonferrous metal plate or plug closure shall not be less than 0.032 inch (0.81 mm) thick, for a hole having a diameter not larger than 1-3/8 inch (34.9 mm).