Emergency Test Switches

[seawead]

Hi,

I don't have a load of experience with emergency lighting.
Can anyone tell me if in an environment with maintained emergency lights it is normal for the key switch to only cut the permanent live, leaving the switched lives on??
I thought it should cut both, but today was working on an installation where the switched stayed on.
Is there any reason to install this way?

If it's an obvious answer don't shoot me down I normally work on domestic & thought this was a fair enough question!

Dave

 

[bigdavs83]

Looks like it has wiring mixed up somewhere along the lines as by definition if you kill the mains the switch wire should be killed as well. however the emergency light test switch shouldn't ever be used as a means of safe isolation and all feeds either switched or mains should be tested before any work is carried out.

 

[seawead]

Yep, I thought the key switch should switch off both lives.
But I don't mean for working on the circuits, just for a battery test.
Just thought it was unusual the non emergencies stayed on here (i.e the switched live cct)
& wondered how common this was & why it might be designed this way

 

[bigdavs83]

As is say I don't think it's been wired properly. Most of the stuff that we work on is with banks of grid switches that kill the lcm's above the ceilings but a lot of installs are different. I've never came across any of what you've encountered though. It may just be that specific system and as long as it does what it says and tests the emergency part of the fitting then fair enough. Also I wasn't implying you were using that as safe isolation. I just jumped on my high horse so apologies!! Lol

 

[iamelectric]

sounds like its wired perfectly fine

 

[seawead]

cheers iamelectric so is there no standard as to whether the key switches both lives or just the perm?

 

[iamelectric]

lets say supply to switch and then looped to key switch in same grid bank then 3 core to klik box SW L from switch plus perm live from key switch , normal fitting will have a 3 pin plug and emgs will have a 4 pin plug , so when you thro the key switch it will cut power to only emgs inverter kicks in and puts them in emg mode doesnt effect the standard fittings , seen it wired like this a lot , suppose its more convenient for testing during working hours

 

[johnboy6083]

I personally like to wire the key switches, so that they kill the feed to the standard switches. This allows for a proper test of the system, and lux levels can be checked. I understand however for large office blocks ect, this isn't practical, and they have to be wired so that the standard lighting can stay energised whilst the EM lights are in test mode.

 

[Brightspark2]

Operating the key switch and testing the emergency lights should have no effect on the standard lighting...

There is wording to that effect in the British standard...

 

[guest119]

I personally like to wire the key switches, so that they kill the feed to the standard switches. This allows for a proper test of the system, and lux levels can be checked. I understand however for large office blocks ect, this isn't practical, and they have to be wired so that the standard lighting can stay energised whilst the EM lights are in test mode.

Pointless, you can do this from the breaker.

What are you going to do when carrying out a 3 hour discharge test, put the place in darkness?

What does it say on the test switch? Emergency test!

Boydy

 

[snowhead]

If all the lights go out, the emergencies are less likely to get tested regularly.
It will need an out of hours test, assuming the office or room doesn't have full glazing and or Sun tubes.

 

[tazz]

Would never shoot anyone down for a sensible question....answer, to prevent putting complete lighting system out, whilst conducting a periodic test. Most em maintained lighting, will switch into sections, ie a 4 tube system, will only light 2 tubes at 50%, whilst the other 2 are powered by the sw circuit, 8w bulkheads, are manufactured to ignore sw line, when permanent line is disconnected.

 

[iamelectric]

the emgs i have been fitting lately are wired independently from the standard lights , they are mini led down lights about the size of a £2 coin and led maintained bulkheads , i wire them back to key switches at the db and dip them into the relevant mcb , ie office emg dipped into office mcb , i have seen it done the other way i mentioned with key switches next to light switch but as the places i install them have a high turnover of staff its easier to have the key switches all in the same place , i am assuming this is ok? please tell me it is or the last 2 weeks work will be a write-off

 

[itselectric]

So long as the em lights are operational on relevant failure of lighting circuit. ie the lights in one room go out then the em lights in that room come on then there should be no problem. But make sure the em switches are identified so the person testing them can go to the area that's being tested

 

[iamelectric]

every manager gets plans of the building with every emg light marked on it and relevant key switch is numbered and marked on plans

 

[itselectric]

every manager gets plans of the building with every emg light marked on it and relevant key switch is numbered and marked on plans

Not in the real world he doesn't. In the past if I have ad to test, and gone to the person in charge tey haven't a clue what you're on about.

 

[iamelectric]

Not in the real world he doesn't. In the past if I have ad to test, and gone to the person in charge tey haven't a clue what you're on about.

yip but as long as i hand him it and show him what to do , my job is done

 

[guest119]

every manager gets plans of the building with every emg light marked on it and relevant key switch is numbered and marked on plans

In your world maybe!

Boydy

 

[tazz]

If you have the service contract to undertake periodic testing, then its now your job to number fittings a switches if they have not been done.

 

[johnboy6083]

Pointless, you can do this from the breaker.

What are you going to do when carrying out a 3 hour discharge test, put the place in darkness?

What does it say on the test switch? Emergency test!

Boydy

Thats a fair point. It's just the way I like to do it.
3 hours? If a system requires 3 hours worth of lighting, then it's bloody massive. The system should be capable of operation for the expected time of evacuation (worst case scenario of course).