Strange Lighting Fault

[welshsparky82]

Was carrying out a periodic inspection today on a accomadation block....

testing the corridor lighting, which is made up of 28w 2D fittings, and Emergency bulkheads.

Went to carry out an earth loop test on the circuit, and wasnt able to.

checked supply at a fitting.

and was getting these voltages

L - N - 230v

L - E - 70v

N - E - 50V



Wandering, if anyone has come across something like this before, and could point me in the right direction..


cheers!

 

[bugsy]

Switchgear could effect you test results ,It's going to be a pain but I would do an Zs and R1 R2

 

[eddielarge]

Switchgear could effect you test results ,It's going to be a pain but I would do an Zs and R1 R2

surely he has done these as part of the test.

have you disconnected all fitting out of the circuit...

 

[welshsparky82]

Hi

Ye was about to start disconnecting fittings tomorrow.. its quite a large circuit, possibly 20-25 fittings on it.

so just wanted to see if anyone had come across this problem before...

was thinking dodgy fitting perhaps.

 

[pevvers]

Hi

Ye was about to start disconnecting fittings tomorrow.. its quite a large circuit, possibly 20-25 fittings on it.

so just wanted to see if anyone had come across this problem before...

was thinking dodgy fitting perhaps.

No earth continuity at the fitting, guaranteed.

Mine's a pint for solving the problem...

(Only being so certain because it's come up quite a few times in the last couple of months, and there's no other way you would get readings like that apart from a floating earth)

Best way to find it would be to halve the circuit, check halfway if there is an earth. If there is, then check half again further along, and so on and so forth. If there is still no earth half way, check half back. It's the easiest way to check stuff like this, used to call it the split half technique back when I was doing electronic fault finding....

Of course, I would check you have an adequate earth reading at the board first, and also that the CPC for the circuit you are working on is terminated properly.

 

[Mr Mark Sparks]

No earth continuity at the fitting, guaranteed.

Mine's a pint for solving the problem...

(Only being so certain because it's come up quite a few times in the last couple of months, and there's no other way you would get readings like that apart from a floating earth)

Best way to find it would be to halve the circuit, check halfway if there is an earth. If there is, then check half again further along, and so on and so forth. If there is still no earth half way, check half back. It's the easiest way to check stuff like this, used to call it the split half technique back when I was doing electronic fault finding....

Of course, I would check you have an adequate earth reading at the board first, and also that the CPC for the circuit you are working on is terminated properly.

what he said

 

[Sintra]

Most probably a loose or disconected cpc.

Isolate circuit and test R2 with wander lead between cu and fittings.

 

[pevvers]

Most probably a loose or disconected cpc.

Isolate circuit and test R2 with wander lead between cu and fittings.

Ah, but wander leads take all the fun out of fault finding!!