Emergency Lighting with key switch

[whu1990]

Hi im currently in my 1st year of my apprenticeship and i have a question.
i would like to know how to wire/connect a emergency lighting circuit including a key switch.
a electrician did try to explain but it didnt sink in.
where im working they is a row of lights in corridor, some emergency some regular and a key switch with brown and black cables.
any help would be good
Thanks

 

[needasparks]

You will find each lighting circuit will have a switched live (normally brown) and a maintained supply (normally black), the keyswitch will control the maintained supply for testing purposes and when opened the lighting will run on their internal batteries as simulating a power failure. There are loads of different types and formats of emergency lighting but hopefully that answers your question.

 

[telectrix]

basically, the keyswitch is there to interrupt the permanent live feed to the em's without losing the supply to the "normal" lights, which could cause a hazard.

 

[Adam W]

Alternatively you can use the keyswitch to interrupt the switched supply to the lights as well, so when the key is operated only the emergency lights should be on, running from the battery. This makes it easier to see what's working and what isn't, although as tel says it could cause safety issues in a room (or corridor) with no windows.

So from the CU you go straight to the keyswitch, then on the switched side you go out to the permanent feed on the emergency lights and also loop round to supply the switch. This way the keyswitch kills the whole circuit and has the same effect as just turning off the breaker.

To leave the 'ordinary' lights on when you do the test all you do is take the link to the switch from the feed side of the keyswitch instead.