Simply, it is lighting that will remain in operation when the normal functional lighting fails. Lighting is essential to us to enable us to escape from a property should we need to just to exit a property because the lighting has failed or indeed to escape from a property in an emergency situation.
There are 2 main ways for creating an emergency light, a central battery system and a self contained system.
A central battery system in generally installed in large properties as they involved complicated and expensive hardware to ensure they work when required such a large battery banks, change over panels, UPS panels, switchgear all of which would normally be installed in a large plant rooms.
A dedicated circuit could then wired around the building with no switches anywhere on the circuit to ensure that there was no break in the circuit. Any light fitting wired to the emergency circuit would become an emergency light, normally wired in a fire resistant cable to ensure the integrity of circuit is maintained.
The second method and much more common way of completing an emergency lighting project is using self contained emergency light fittings where the battery to keep the light fitting on is fitted inside the light fitting itself.
This method is a much more cost effective way of installing an emergency lighting system and there are several options to consider when looking at this type of fitting.
Many light fitting manufactures have an emergency option for their products where they will build a battery and charging circuit into their fittings.
If an integrated emergency fitting is not available from the lighting manufacturer then a emergency bulkhead or small LED downlight can be installed either adjacent to a light fittings or directly into the escape route. The bulkhead and LED downlight options are often much cheaper than the integrated emergency light fittings supplied by the light fitting manufacture.
The risk assessment process will determine the best method to be selected and should always be conducted with all interested parties.