Emergency lighting key switch

[dodge26]

Is there any reg on emergency lighting should be on a key switch in bs7671, I know of it coming up in bs5266.

 

[telectrix]

not that i know of. the keyswitch method of interrupting the feed to the em's is basically so you can test them without interrupting the feed to the "normal" lights. a matter of safety and convenience. nobody likes to work in the dark if possible.

 

[dodge26]

So could the isolation of an mcb, be a suitable test method as highlighted in bs5266?

 

[telectrix]

problem there is that either the MCB will switch off the "normal" lights, or, if you feed the permanent em line from a different MCB, you would have 2 line feeds into fittings, which is not good.

a different story if the em's are independent of the "normal" lights. but that would bring up the problem of the em's not activating when the lighting failed.

so, we're back to keyswitches being the best way to meet all requirements and regulations.

 

[dodge26]

Regrdless of the darkness issue, on the 3 hour emg test, on the tick sheet there is the question, does the system have a suitable test facility. MCB suitable or not.

 

[telectrix]

all boils down to whether or not it is acceptable to switch off the lights for 3 hours. i would not call that a suitable test facility. a keyswitch or even an unswitched spur ( supplying the permanent line) would do.

 

[mogga]

some commercials have a LMO switch on contactors so Iv seen feed from mcb to 2 contactors no1 LMO switching no2 Emlighting bank of contactors from different phases

 

[dodge26]

Are we saying there is no requirement for a key switch, if they are happy sitting in darkness for 3 hours?

 

[telectrix]

till someone falls over the cat, breaks a bone or 2, then sues you

 

[dodge26]

Love this forum, you never seem to get a straight answer, bit like the regs....

 

[Spudnik]

There is no real answer, although the key switch method mentioned is a valid way of providing suitable testing facilities for em's.

You dont have to use them, but as you are the installer, any issues arising from them not being fitted is down to you.

What answer were you hoping for?

 

[netblindpaul]

Look at your state law duties as a designer under CDM then you will have your answer I think.

 

[Engineer54]

Love this forum, you never seem to get a straight answer, bit like the regs....

How many straight answers do you need then, before the penny drops??

If your looking for some sort of get out clause, there isn't one. The key switch method is generally accepted as the way to isolate the EM/lighting side of things. You can use other methods as others here have stated, such as unswitched FCU and the like, but the key switch method best meets all the requirements for testing and isolation.... Yep, it's that simple!!

 

[Andy 7671]

P4 is it...? cant remember.

Data cable that monitors state of battery via computer interface. No need for keyswitch

I asked the commissioning engineer if there was any need for a visual check when testing EMs, "Nope" he replied just trust computer.

I didnt like that answer.

 

[Tosh]

an m.c.b is suitable yes.. and depending on how its wired all lights on that circuit would go out anyway.. an m.c.b can also be used as a functional switch too..

 

[i=p/u]

depends on the actual building and its use aswell, im only little fish in big pond and any ive tested 2 restaurants, the key switch didnt work so i knocked off mcbs. but because the chinnese start early i was there at 9am as soon as doors open as this was appropiate time for full duration test.. so no you dont need it but if you bigger building maybe you do and if you in biger important building you might need the computer controlled version...

 

[ezzzekiel]

Do people tend to run two lives back from switch and continue the em light feed through whole circuit then

 

[i=p/u]

the ones i tested were just tapped off lighting circuits, non maintained and maintained ones near doors and stuff just had perm feed,

the other ones i tested in block of flats were maintained and running off a sensor when it gets dark....

 

[ezzzekiel]

Just figured if fed through single key switch to all lights then no reason not to fit one just one extra core run through

 

[mogga]

there are Em lights with built in test buttons ones with remote control testing buttons i
the answer to the question is realy "what is suitable and most appropriate for the job Im doing?"