Sam asks this question about an apparent conflict in the regulations concerning emergency lighting testing. It has been answered by Lux Magazine’s Ray Molony (Theme – Lighting):
This Q & A is one of thousands posted in our Technical Expertise area, and answered on a daily basis by our Voltimum Experts.
Question: An electrical contractor undertook an emergency lighting test on a site that has just passed its 12 months defect period. When tested, all the normal lights went out and the emergency fittings came on.
It was stated that this is not correct under BS 5266-1-2011 8.3.3 test facility – ‘Each emergency lighting system should have suitable means for simulating failure of the normal supply for test purposes (i.e. without interruption of the normal supply)’.
Yet, BS 5266 -1-1999 recommends that all the lights should go out under test procedure 5266 -1-1999 8.3.3 test facility - ‘Each emergency lighting system should have suitable means for simulating failure of the normal supply for test purposes’.
The electrical contractor has suggested that the installation be changed to BS 5266 -1-2011, so the original contractor was contacted and asked to change the wiring so that the lights would stay on while under testing procedures.
The original electrical contractor firm responded and stated that their installation fully complies with British Standards, and NICEIC regulations.
They also stated that the interruption of the normal supply in effect relates to operation / tampering with the main supply; and that this can be verified by NICEIC technical support.
Can anyone please confirm which is correct?
Answer: I had to consult with my friend and expert David Wright of ELP who is very knowledgeable on this area and sits on some of the technical committees. His view is that we try to consider the ‘intent’ of the standard.
'It is of course technically essential to ‘interrupt the normal (un-switched) mains supply’ to create a test - whether this is done locally by a test switch or self-test device within the luminaire or back in the plant room by a keyswitch.'
The intent of the standard, believes David, was that no additional risk be created by conducting a test, e.g. plunging an escape route into total darkness. Therefore, it is better that only the supply to the emergency luminaires is interrupted during a test. I cannot think of any installation method that would not have an un-switched mains supply feeding the emergency lighting luminaires that is completely separate from the normal switched supply feeding the general lighting.
David believes the standard still allows the most basic form of initiating a test to be interrupting the mains supply (hopefully via an appropriate keyswitch or the like).
'I personally believe that the note in parenthesis in BS 5266-1:2011 Clause 8.3.3 refers to the normal lighting supply but it is misleading and I will personally take this up with the appropriate BSI representatives,' says David.
We hope this helps!
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