Emergency key switch

snipersmith87 · Mar 4, 2017

Hi all. Having a debate with another sparks regarding the set up for operating emergency lighting via key switch. I've always been under the impression it's to isolate every light on that switch bringing on just the emergencies. Obviously to mimic as close as an emergency situation. However he seems to think the non emergencies still need to be functional. Is there a set reg?? Is it preference?? I get some environments this would apply. Maybe hospitals etc or if an emergency test can't be done out of hours. But even then surely the emergency lighting is sufficient. If you can't rely on it safely for a test what chance do you have for an emergency!!

The Ghost · Mar 4, 2017

Normally it is preferable to make sure main lights stay on as it presents a hazard with no light in corridors and offices etc. as well as inconvenience to workers etc. It helps the tester as well with writing the results.

Rpa07 · Mar 4, 2017

Try find this thread from 23feb from bottom of this thread page. Vortigern has good views being a learned gentleman that he is.

Mark.W said:
Hey guys,

How do you all wire your emergency lighting?

Option 1. When the key switch is switched, ALL lights go off and the emergencies stay on.
Option 2. The lights operate as normal when the key switch is switched but the emergencies switch to emergency mode.

With option 2, am I correct in thinking there are 2 permanent lives from the DB (brown & black), the black is the PL to the fitting (via a key switch) and the brown is the SL via a switch, PIR etc? What I cant understand is how the fitting goes into emergency mode when the key switch is switched if the fitting also has a SL from a PIR etc. Do I have to switch both via a double pole key switch???

I am probably overthinking this TBH.

Thanks in advance.

snowhead · Mar 4, 2017

The test is more likely to be done if the non EMs stay on.
The test isn't to see the EM light coverage, that should already have been checked, it's only testing that they come on and stay on.

EM lighting is to allow a safe escape, not to allow normal working to carry on.

westward10 · Mar 4, 2017

I don't have a recent copy of BS5266-1 to hand but Reg 8.3.3 gives guidance, interpret this as you will. Your intention when fitting test facilities is not to create a hazard and isolating the general lighting may well do this. Test facilities are not there to mimic an emergency situation but to carry out routine and duration tests.

Risteard · Mar 4, 2017

snipersmith87 said:
Hi all. Having a debate with another sparks regarding the set up for operating emergency lighting via key switch. I've always been under the impression it's to isolate every light on that switch bringing on just the emergencies. Obviously to mimic as close as an emergency situation. However he seems to think the non emergencies still need to be functional. Is there a set reg?? Is it preference?? I get some environments this would apply. Maybe hospitals etc or if an emergency test can't be done out of hours. But even then surely the emergency lighting is sufficient. If you can't rely on it safely for a test what chance do you have for an emergency!!

BS 5266-1 up until the most recent (2016) version specifically stated that they should not cause interruption of the normal lighting.