It is not necessary to provide individual lights (luminaires) for each item above, but there should be a sufficient overall level of light to allow them to be visible and usable. The FPA handbook, referenced above, contains a useful table highlighting the pros and cons of slave versus self-contained luminaires (p 21):
|Central power sources||Self-contained|
|Less expensive||Separate wiring||Ease / speed of installation||Limited lamp power|
|Long battery life if maintained||Regular battery maintenance||Flexible, extendibility||Operation limit to battery operation temperature|
|Few temperature effects||Loss when central system in fire||No battery room required||Shorter life batteries|
|Easier / automatic testing||Battery cabinet often required||No regular battery maintenance||Not suited to harsh or hazardous environments|
|Real time monitoring||Limited flexibility||No loss of total system||Cost of periodic testing greater|
All the lamps will be lit under normal circumstances, but if the electricity supply should fail just the emergency lamp(s) will come on, powered by the battery.
Maintenance and testing of emergency escape lighting
Government guidelines (Fire safety risk assessment: offices and shops, p 101) state that all emergency escape lighting systems should be regularly tested and properly maintained to an appropriate standard (i.e. BS 5266 – Code of practice for the emergency lighting of premises). This testing has traditionally been undertaken manually although, as noted above, emergency luminaires are available with a self-test facility. Depending on the type of installation, trained members of staff should be able to carry out most of the routine tests by themselves. As the test methods will vary, there may be some doubt, in which case it is recommended that advice is sought from the supplier or another competent person.
A typical test is via a key operated switch that is located either near the main fuse board or adjacent to relevant light switches. This is also known as a ‘secret key’ switch, as it designed to allow testing of emergency lights while preventing non-authorised operation of the test switch.
Testing would usually include the following:
- A daily visual check of any central controls if a centrally powered system with slave luminaires is installed
- A monthly function test by operating the test facility for a period sufficient to ensure that each emergency lamp illuminates
- An annual full discharge test to ensure that the lamps are lit for the full discharge period
(usually 3 hours) and that the batteries are re-charging
Particular care needs to be taken following a full discharge test. Batteries typically take 24 hours to re-charge and the premises should not be re-occupied until the emergency lighting system is fully functioning, unless alternative arrangements have been made. It is best practice to keep a record of all tests in the which you can download here fire safety logbook.