1.1 This Standard applies to visual signaling devices intended for indoor and/or outdoor installation:
a) In Canada only: in accordance with CSA C22.1, Canadian Electrical Code, Part I, Safety Standard for Electrical Installations; and with ULC 524, Standard for Installation of Fire Alarm Systems.
b) In the United States only: in accordance with the National Electrical Code, NFPA 70, and the National Fire Alarm and Signaling Code, NFPA 72.
1.2 These requirements cover visible signal devices for use in ordinary (non-hazardous) indoor locations and outdoor locations. This includes:
a) Flashing visual devices used for fire alarm or emergency signaling in both public mode and private mode as defined in the glossary;
b) Emergency warning used to notify occupants that an emergency exists; and
c) Informative type visual signaling devices connected to or controlled by fire alarm or other emergency signaling system equipment, or both.
1.3 This Standard also applies to protective covers and accessories used with visible signals.
1.4 This Standard does not apply to visual signaling devices not intended for emergency signaling applications and intended for operation on Class 2 signal circuits as defined in:
a) In Canada only: CSA C22.1, Canadian Electrical Code, Part I, Safety Standard for Electrical Installations.
b) In the United States only: the National Electrical Code, NFPA 70.
1.5 Visible signaling devices for use in hazardous or corrosive locations shall comply with the requirements of this Standard and the applicable requirements of:
a) In Canada only: CSA C22.1, Canadian Electrical Code, Part I, Safety Standard for Electrical Installations, with respect to the location hazard.
NOTE: In the United States, general signaling appliances are covered by UL 464A.
1.6 A supplementary audible signal incorporated as part of a visible signaling device which is intended for fire alarm application shall comply with the requirements of this Standard and the applicable requirements of:
a) The Standard for Audible Signaling Devices for Fire Alarm and Signaling Systems, Including Accessories, ULC 525 and UL 464; and
b) The Standard for Speakers for Fire Alarm and Signaling Systems, Including Accessories, ULC 541 and UL 1480.
This revision of ANSI/UL 1638 dated May 14, 2026 includes changes in requirements for Black Box Test Procedure Clarification, 20.3.6.
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Referenced Standards (23)
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