Emergency lighting is a self-descriptive term and is lighting for an emergency situation when the main power supply 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, either through physical danger or panic.
Emergency lighting is normally required to operate
fully automatically and give illumination of a sufficiently high level to
enable persons of all ages to evacuate the premises safely. Most new buildings
now have emergency lighting installed during construction, the design and type
of equipment is normally specified by the relevant local authority, architect
or consultant.
The British Standard provides the emergency
lighting designer with laid down guide lines which form the general basis for
the designer to work to. British Standard BS 5266: Part 1: 2005 includes in its
scope residential hotels, clubs, hospitals, nursing homes, schools and
colleges, licensed premises, offices, museums, shops, multi-storey dwellings
etc. Although this standard recommends the types and durations of emergency
lighting systems relating to each category of premise it should be remembered
that the standards are minimum safe standards for the types of premises and
that a higher standard may be needed for a particular installation.
Type of system
Most emergency lighting schemes fall into one of the following categories :
Most emergency lighting schemes fall into one of the following categories :
- Non-maintained - The emergency light units only illuminate in the event of a mains failure
- Maintained - The emergency light units are illuminated at all times using the same lamps for both normal and emergency operation
- Sustained - The emergency light units are fitted with two lamps or two sets of lamps. One of which operates on mains 240V AC supply, the other which operates from the battery supply in the event of mains failure. It is basically a non-maintained system with the addition of mains lamps which should be illuminated whenever the premises are occupied
