Voltage reading puzzle

[toast]

230V single phase supply.
6amp Lighting circuit, T&E 1.0/1.0
Readings
Highest r1+r2=1.72
IR: L-N, L-E, N-E all >299 Mohms
But when energised there is voltage reading across the conductors at the board as follows:
N-E 112V
L-N 107V
L-E 107V
Then at the light fittings:
N-E 127V
L-N 240V (closed circuit)
L-E 7V

The voltage readigns were taken with Line and neutral terminated at MCB and neutral bar respectively but with CPC/Earth not connected at Earth bar.
The circuit does not trip when energised.
Any thoughts of why this is occurring?

 

[SirKit Breaker]

Firstly why did you test the voltage with the CPC disconnected?
Secondly, think about what you havent done, and why you are experiencing the problems that you are.
Thirdly think about what you have done again, and why this might stop the circuit from tripping if there is an earth fault!

You should be able to answer your own questions if you think about it.

Cheers..........Howard

 

[trev]

A voltage L-E when E isn't connected to anything??

 

[ste77]

Is this a wind-up? Especially since its called a "puzzle".

 

[Octopus]

Puzzle my foot. Readings like that mean no earth or no neutral.

 

[toast]

There had been a unit swap (not by me) and the installer called me as they had got a belt of the CPC. that is why I tested as I did.
I can only think that it is a polarity problem as I get continuity with earth and IR readings are really good.
But I tested all Perm lives at fittings, so if it polarity must be connected incorrectly within voids or walls.

All other circuits test off fine.

I know without earth connected there will be no earth fault.

 

[ste77]

where did he get a belt off the cpc? consumer unit end or at the light? if hes changed the CU and the lighting circuit worked fine previously then its something hes done, maybe nicked a cable when screwing the CU up?

 

[toast]

Con unit
I was informed reason for unit change was that there had been fusing issues. But the information I have received regarding this, so far is vague.
But if cable nicked, I would expect IR issues!

 

[ste77]

so he had the power on and the cpc disconnected??? why????

 

[toast]

so he had the power on and the cpc disconnected??? why????

TBH I don't know why, just told me he did.
I wouldn't expect to get a belt though regardless, of this!

 

[ste77]

he sounds like he doesnt have a clue. id be checking everything again, if hes stupid enough to do that god knows what else hes done.

 

[plugsandsparks]

so he had the power on and the cpc disconnected??? why????

Sounds scary, .....

 

[toast]

May sound scary but I wasn't there at the time. So don't know the reason behind this, just know that he got a belt, which then led me to testing as I did.

 

[ste77]

Sounds scary, .....

lucky guy considering the fault, nice that he left the job for someone else though......

 

[toast]

he sounds like he doesnt have a clue. id be checking everything again, if hes stupid enough to do that god knows what else hes done.

Well that is a fair assumption, I did disconnect all the circuits and reinstalled, without the aid of any pre-planned EIRC and a young family with pregnant mother complaining about the heating and Jeremy Kyle being off.
All other circuits tested off fine.
This is genuinely not a wind up.

 

[ste77]

is it loop in?

 

[toast]

is it loop in?

It's mixed bag some fittings are looped-in at ceiling and others are junction/jointed in void.

 

[ste77]

It's mixed bag some fittings are looped-in at ceiling and others are junction/jointed in void.

id be trying to break the circuit down and find what leg your fault is on.

 

[Octopus]

id be trying to break the circuit down and find what leg your fault is on.

I'd be doing dead tests at different fittings!

 

[toast]

id be trying to break the circuit down and find what leg your fault is on.

That is my next move, just a little puzzled why this fault could occur. Never come across it before.