Emergency lighting is lighting for an emergency when the main power supply is cut and any normal illumination fails. The loss of mains electricity could be the result of a fire or a power cut and the normal lighting supplies fail. This may lead to sudden darkness and a possible danger to the occupants, through either physical danger or panic.
Emergency lighting is normally required to operate fully automatically and give illumination of a sufficiently high level to enable all occupants to evacuate the premises safely. Most new buildings now have emergency lighting installed during construction; the design and type of equipment being specified by the consultant in accordance with current Building Regulations and any local authority requirements.