UL 753:2018-07 Alarm Accessories for Automatic Water-Supply Control Valves for Fire Protection Service.
1.1 These requirements cover alarm accessories for automatic water-supply control valves for use in automatic sprinkler equipment for fire protection service. Accessories may include water motors and gongs, pressure-operated switches, and other electrical and nonelectrical attachments, components, or units commonly used with alarm, dry-pipe and pre-action valves.
1.2 Requirements for the installation and use of alarm accessories with automatic water-supply control valves are included in the Standard for Installation of Sprinkler Systems, NFPA 13.
1.3 The electrical alarm accessories for automatic water-supply control valves are intended for fire-protective signaling use in ordinary locations in accordance with the National Electrical Code, ANSI/NFPA 70.
2 Components
2.1 Except as indicated in 2.2, a component of a product covered by this standard shall comply with the requirements for that component. See Appendix A for a list of standards covering components generally used in the products covered by this standard.
2.2 A component is not required to comply with a specific requirement that:
a) Involves a feature or characteristic not required in the application of the component in the product covered by this standard, or
b) Is superseded by a requirement in this standard.
2.3 A component shall be used in accordance with its rating established for the intended conditions of use.
2.4 Specific components are incomplete in construction features or restricted in performance capabilities. Such components are intended for use only under limited conditions, such as certain temperatures not exceeding specified limits, and shall be used only under those specific conditions.
3 Units of Measurement
3.1 Values stated without parentheses are the requirement. Values in parentheses are explanatory or
approximate information.
4 Undated References
4.1 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.
5 Glossary
5.1 For the purpose of this standard, the following definitions apply.
5.2 HIGH-VOLTAGE ELECTRIC CIRCUIT— A circuit involving a potential of not more than 600 volts and having circuit characteristics in excess of those of a low-voltage (or Class 2) circuit (or power limited circuit).
5.3 LOW-VOLTAGE ELECTRIC CIRCUIT— A circuit involving a potential of not more than 30 volts rms alternating current (ac) [42.4 volts peak or direct current (dc)] and supplied by:
a) A Class 2 transformer; or by a battery, by a battery and fixed impedance, or by a transformer and fixed impedance, each of which, as a unit, complies with all the performance requirements for a Class 2 transformer; or
b) Is limited to a maximum of 100 volt-amperes (va).
A circuit derived from a source of supply classified as high-voltage circuit, using resistance in series with the supply circuit as a means of limiting the voltage and current, is not considered to be a low-voltage or an isolated limited secondary circuit.UL 753 pdf download.