UL 1917-2013 pdf download – Solid-State Fan Speed Controls.
4 Units of Measurement 4.1 Values stated without parentheses are the requirement. Values in parentheses are explanatory or approximate information. 5 Undated References 5.1 Any undated reference to a code or standard appearing in the requirements of this standard shall be interpreted as referring to the latest edition of that code or standard. 6 General 6.1 The term ″speed control″ as used in this standard refers to a solid-state speed control used with electric fans for non-industrial applications. CONSTRUCTION 7 Enclosure 7.1 General 7.1 .1 A speed control shall be provided with a complete enclosure for all live parts and all operating parts other than necessarily exposed operating parts, such as an actuating member. Exception: An open speed control (see 20.4) intended for installation in a wall box is not required to be provided with a complete enclosure of the field wiring terminals. 7.1 .2 An enclosure of a speed control shall be constructed and assembled so that it has the strength and rigidity necessary to resist the abuses to which it is likely to be subjected, without total or partial collapse resulting in a risk of fire, electric shock, or injury to persons due to reduction of spacings, loosening or displacement of parts, or other serious defects. 7.1 .3 An enclosure shall be constructed so as to reduce the risk of unintentional contact with enclosed electrical devices, and to provide internal devices with protection from specified external conditions. 7.1 .4 The enclosure shall be constructed such that the switchplate cover mounting means, such as mounting screws, shall not enter the interior of the speed control. Exception: The mounting means may penetrate the interior of the speed control if the applicable evaluations defined in Sections 7 – 36 are performed with a screw having a length of 3/8 inch (9.5 mm) in place. 7.1 .5 Mechanical protection shall be provided to protect components during and after installation. See Crush Test, Section 28.