UL 924 Self Luminous Exit Signs
Comply With the Code
The Underwriters Laboratories (UL) is an internationally recognized non-profit organization that has been certifying public safety appliances for over a century. Their proven brand is one of the most trusted qualifiers for all self luminous exit signs.
UL has standards for over 1000 different classifications of safety and electronic devices. UL 924 covers all emergency lighting that uses 600 volts or less. Such life-saving equipment must automatically illuminate or power critical areas and equipment during a major power outage.
UL 924 is a nationally recognized exit sign standard in the United States and Canada. These standards are independent of state and city codes, which you should also familiarize yourself when installing your self powered exit sign.
UL 924-Listed Self Luminous Exit Signs
Though SL fixtures have a self-contained lighting source that requires no electricity, they still fall under UL 924 guidelines. These guidelines include the legal lettering size, color, viewing distance and emergency runtime required of all emergency fixtures.
UL Emergency Runtime
All exit signs must maintain illumination for a minimum of 90 minutes following a power outage. They must automatically come on the second a loss in power is detected.
Self-luminous signs, however, are always on if there is power or not. This allows SL models to last longer than any exit sign on the market.
The standard used to be red exit lettering. Though tritium exit signs can only glow green, you can order them with red 'exit' stencils that comply with this standard.
Since 2000, green has become increasingly utilized on the west coast and other states. Green is an internationally recognized color and is used exclusively throughout Canada, the European Union and Asia.
UL Exit Sign Displays
Since 1970, UL has used the NFPA 101's minimum light output of 0.06 ft. lamberts as the national standard. This is accomplished through a 100-ft viewing distance test using a photometer. The distance is then stamped on each individual sign.
Lettering must have:
- Stroke width - 3/4 inch
- Spacing between letters - 3/8
Required on all self luminous exit sign fixtures, this stamped date will tell you when it is time to schedule tritium disposal and sign replacement.