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arashabb

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Good morning everyone,
I have been asked to do the initial verification on a newly completed building. so all the light fittings have been installed, false ceilings have been closed off,..etc.
what is your suggestion for testing the lighting circuits?( continuity, IR tests) some of them are at very high level ( 8 meters), some are installed on the false ceiling so even if I remove the lights, wont be able to reach the connectors at ceiling rose.flexible wire has been used from light up to connection point near slab) .
any suggestion?
 
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pc1966

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Ideally you would not be in this position, but as you are there is not much gain by discussing it.

I don't know what the UAE regulations are, but assuming they are similar to the UK regs then your IR test is the easiest to do - make sure the CPC (E) is connected to the supply earth and then check L+N together to E.

For anything else you will need access to the lights, at the very least to the furthest ones, and at that sort of height you are looking at a platform being hired. Presumably they have some plan for this for the inevitable maintenance/replacement of lights in a couple of year's time?

If you can get to the lights flexible cables then you ought to be able to do a R1+R2 measurement on L to E with them temporarily shorted at one end (and N open) to confirm the CPC is complete and that impedance is low enough for the chosen OCPD.

The presence of fitted lights should make no little difference if N is open at the supply end, even if it were connected to E via the supply then the low test voltage for low-ohm measurement would not be impacted by the lights to any significant degree.

Finally I would do a live Zs measurement on the furthest light (non-trip, as I guess it is on a RCBO / RCD protected supply?) to really verify that it is all OK, but if that is too much trouble then the dead test of R1+R2 and a measurement of the board's Zs/Ze should allow you to confirm by calculation that it would disconnect rapidly enough on a fault.
 
A

arashabb

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  • Thread Starter Thread Starter
  • #3
Ideally you would not be in this position, but as you are there is not much gain by discussing it.

I don't know what the UAE regulations are, but assuming they are similar to the UK regs then your IR test is the easiest to do - make sure the CPC (E) is connected to the supply earth and then check L+N together to E.

For anything else you will need access to the lights, at the very least to the furthest ones, and at that sort of height you are looking at a platform being hired. Presumably they have some plan for this for the inevitable maintenance/replacement of lights in a couple of year's time?

If you can get to the lights flexible cables then you ought to be able to do a R1+R2 measurement on L to E with them temporarily shorted at one end (and N open) to confirm the CPC is complete and that impedance is low enough for the chosen OCPD.

The presence of fitted lights should make no little difference if N is open at the supply end, even if it were connected to E via the supply then the low test voltage for low-ohm measurement would not be impacted by the lights to any significant degree.

Finally I would do a live Zs measurement on the furthest light (non-trip, as I guess it is on a RCBO / RCD protected supply?) to really verify that it is all OK, but if that is too much trouble then the dead test of R1+R2 and a measurement of the board's Zs/Ze should allow you to confirm by calculation that it would disconnect rapidly enough on a fault.
Thank you so much for your reply and advice.
Yes, the consultant requires an inspection by a 3rd party but contractor has delayed it till now to try to get away with that as this is additional expense for them. Having all the lights being installed ( and they are all LED), makes the work more difficult. I probably need to disconnect them before carrying IR test?(to avoid damaging them)
We are following BS regulation here and all circuits are RCD protected.
Appreciate your comment again.
 
Vortigern

Vortigern

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How many lights? When you say false ceiling are you meaning suspended ceiling or plasterboard? Any photos?
 
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pc1966

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Ideally you would test the wiring before the lights were installed, but if it is too late for that and you can't (sensibly) disconnect them for testing, then do the L+N shorted together to E test. That way you are not trying to subject the LED electronics to a 500V test voltage, as they should be fully insulated from earth. Typically that is how you would do an inspection after installation on fixed electronic equipment anyway.
 
A

arashabb

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  • Thread Starter Thread Starter
  • #6
How many lights? When you say false ceiling are you meaning suspended ceiling or plasterboard? Any photos?
Hundreds of lights. they are installed on gypsom board. unfortunately do not have any photo
 
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