UL 464A-2021 pdf download

UL 464A-2021 pdf download.Audible Signal Appliances for General Signaling Use.
2.3 Undated references 2.3.1 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. 2.4 Electrical circuits terminology 2.4.1 For the purpose of these requirements, electrical circuit characteristics are defined as follows: a) Low-Voltage Circuit – A circuit involving a potential of not more than 30 volts alternating current, [42.4 volts (AC) peak or direct current (DC)], and supplied from a circuit whose power is limited to a maximum of 100 volt-amperes. b) High-Voltage Circuit – A circuit having circuit characteristics in excess of those of a low-voltage circuit. 2.4.2 The term “appliance” as used in this standard refers to any equipment covered by this standard. 3 Enclosures 3.1 General 3.1.1 Electrical parts of an appliance shall be located or enclosed so that protection against contact with uninsulated live parts is provided. 3.1.2 An appliance intended to be installed on a flush-device box, cutout box, one provided for outdoor use, or similar device, is to be judged with respect to compliance of the combination with the requirements of 3.1.1.
3.1.3 An operating part, such as a gear mechanism, light-duty relay, or similar device, shall be protected against mechanical damage and fouling by dust or other material which impairs its intended operation. 3.1.4 The enclosure of an appliance shall be provided with means for mounting in the intended manner. Any fittings, such as brackets, hangers, or similar hardware required for mounting shall be furnished with the appliance. The mounting means shall be accessible without disassembly of any operating part of the appliance. The removal of a completely assembled panel, cover, or similar part, to mount the appliance is not considered to be disassembly of an operating part. 3.1.5 An enclosure shall have provision for the connection of metal-clad cable, conduit, or nonmetallic sheathed cable. An enclosure without such provision is permitted when: a) It is furnished with definite instructions indicating the sections of the enclosure which are intended to be drilled in the field for the connection of raceways, b) The appliance is intended for mounting on an outlet box, or c) The enclosure is intended for use with a low-voltage rated appliance for general signaling use. 3.1.6 A cover or other detachable part of the enclosure shall be secured in place with means not requiring use of a tool for removal. Using only snap-catch fastenings to secure this part is not permitted.
3.2.2 Die-cast metal for other than flush boxes is permitted when it complies with one of the alloy specifications given in Standard Specification for Zinc and Zinc-Aluminum (ZA) Alloy Foundry and Die Castings, ASTM B86. 3.2.3 Compliance of a zinc-base alloy die casting with the requirement of 3.2.2 is to be determined by the Standard Specification for Master Alloys Used in Making Zinc Die Casting Alloys, ASTM B327. 3.2.4 If threads for the connection of conduit are tapped all the way through a hole in an enclosure wall, there shall be not less than 3-1/2 nor more than five threads in the metal, and the construction shall be such that a standard conduit bushing is capable of being attached. 3.2.5 If threads for the connection of conduit are tapped only part of the way through a hole in an enclosure wall, there shall be not less than five full threads in the metal, and there shall be a smooth, rounded inlet hole which shall afford protection to the conductors equivalent to that provided by a standard conduit bushing. 3.3 Sheet metal 3.3.1 The thickness of sheet metal employed for the enclosure or mechanism cover of an appliance shall be not less than the applicable value specified in Table 3.1. 3.3.2 At any point where conduit or metal-clad cable is to be attached, sheet metal shall be of such thickness or shall be so formed or reinforced that it has a stiffness at least equivalent to that of an uncoated flat steel sheet having a minimum thickness of 0.053 inch (1.35 mm).UL 464A-2021 pdf download.