Most emergency lights installed in businesses are simple lighting devices that contain a small battery. The device is connected to the building’s electrical supply, which provides a constant charge to the battery. In the event of a power failure, circuitry in the fixture activates the lights so that the occupants can see to exit the building. Emergency lights are only designed to work from the code’s required minimum of 30 minutes to as long as 90 minutes on battery power.

The lights are usually located along hallways, which can light a path to an exit. They come in either a lighting unit only or emergency light-exit sign combo. The lighting only units can be low profile, which only sticks out from the wall a few inches to larger models that can be hung from the ceiling.