The UL 924 standard is applicable for emergency lighting and power equipment circuits of 600 volts or less, which is intended to supply power and illumination in critical locations when the regular power fails.
A brief history of Underwriters Laboratories
The history of the Underwriters Laboratories can be traced back to the 1893 World’s Fair in Chicago. Notably, the first Ferris Wheel was also introduced at the same event. The event’s organizers wanted an attraction that would exceed the Eiffel Tower’s magnificence, which had been unveiled four years earlier at the 1889 World Fair in Paris. Gustave Eiffel even offered to build a more prominent tower for the Chicago event, but it was determined an American should have the honor. The design of George Washington Ferris was selected, and the more than twenty-seven million who attended the fair were delighted.
Also at the fair was William Henry Merrill, Jr., a Massachusetts Institute of Technology (MIT) graduate and employee of the Boston Board of Fire Underwriters. He proposes creating a testing lab for electrical equipment that would benefit the insurance industry. In 1894, the Electrical Bureau of the National Board of Fire Underwriters was officially formed and would become the Underwriters Laboratories we know today.
Less than ten years later, a Chicago theater fire killed 600 people. One of the many reforms after that tragedy was the requirement for exit signs and emergency lighting.
What equipment is impacted by UL 924?
The standard applies to emergency lighting and power equipment that provide critical safety support when standard power fails, and building occupants need lighting and wayfinding guidance to egress a structure safely. Examples of this equipment include:
- Inverters
- Exit Signs
- Auxiliary Lighting
- Emergency Luminaires
- Battery Banks
- Automatic Battery Charging and Control Equipment
- Emergency Lighting Control Devices
UL 924 is designed to validate compliance with emergency system functionality and expectations.
Requirements of UL 924
When tested, the equipment and system must meet the following sample of standards:
- An emergency or auxiliary light fixture must illuminate for a minimum of 90 minutes if the power fails
- An emergency light fixture must immediately illuminate after power loss and provide sufficient light output to assist with the safe navigation of building occupants and emergency personnel
- An emergency exit sign must provide 90 minutes of illumination, whether powered by battery or the wired emergency power supply
- The letters of an exit sign must be either green or red and must be 6” tall with 3/8 of an inch font thickness and 3/8 of an inch in space between letters
- Exit signs are required to have a minimum of 0.06 feet per lamberts in luminance and be visible from at least 100 feet
The Isolite family of products is designed to comply with and support UL 924 standards. Learn more about UL 924 here.
