Emergency lighting is used to reduce the number of injuries and deaths caused by fire and other emergencies. A variety of light fixtures are installed in buildings that allow occupants to find exit routes and doors more quickly. These include flood lamps, exit signs and escape path lighting, as well as a number of other fixtures. In Britain, emergency lighting standards are set by the British Standards Institute. British Standard 5588 addresses emergency lighting in both residential and commercial applications.
In Britain, maintained emergency lighting systems are only required in areas with dim lighting, or in facilities that serve alcohol. This primarily includes theatres, bars and nightclubs, though other facilities may also be subject to this standard. In a maintained system, all emergency light fixtures must always be illuminated, both during an emergency and during normal operation. These fixtures are powered by battery supplies, which are continuously charged off of the main power system.
Non-maintained systems are required in commercial settings that do not feature dim lighting or serve alcohol. This includes the majority of stores, offices and medical facilities. In a non-maintained system, emergency lights are only illuminated when there is a power failure. Emergency lights are powered by a backup battery system, which is not linked to the main power supply. Non-maintained systems are typically subject to a duration depending on the facility. For example, a building with a NM/3 rating must be equipped with emergency lights that will operate for three hours after the power fails.
Escape lighting includes those fixtures in place near ground level to light the exit path. These lights must always be placed in windowless or underground areas, regardless of whether the setting is residential or commercial. In homes, they should also be placed in corridors longer than 30 meters, stairs higher than 18 meters, and along roof escapes paths. In retail establishments, escape lights must be installed in all areas that are farther than 15 meters from an exit.
Escape route lighting levels are measured along the centre line of the route and should be inspected at floor level. Luminance levels from these lights must be at least 0.2 lux in residential and commercial areas. In anti-panic settings, such as schools, stadiums or theatres, these lights should measure at least 0.5 lux. Escape paths wider than 2 meters should display at least 0.1 lux at the centre of each 2 meter wide band of floor space.
All emergency exit lighting should be tested monthly to ensure adequate operation. These tests should be performed after hours to avoid panic among occupants. In facilities that are in use around the clock, testing may be done in phases or on alternating fixtures. During testing, the main power supply should be switched off to ensure that backup power supplies are functioning properly. Once the main power is restored, battery charging supplies must be inspected to ensure they are charging as designed.