See the way through practicalities and safety standards
This requires that, as well as escape routes, all open areas larger than 60m2 must have emergency lights in case the normal lighting fails. Building Regulations 2000
Emergency lighting is a back–up for when the main power supply cuts out, resulting in darkness which could present a danger to the occupants of a building.
Therefore emergency lights must operate automatically in all common areas and escape routes, and must be adequate for people to see clearly enough to navigate obstacles and find a way out safely.
New buildings usually have these installed already, having been agreed between the local authority, fire authority, architect, building control officer, and system designer and installer. The installer of an emergency lighting system must supply a completion certificate to the owner/occupier of the building, and the Building Control Department should retain a copy within the Building Regulations application.