ODD ELECTRIC RESULTS ON REWIRE

[houserenovator]

Please help. Having just completed a full rewire on a 1970s bungalow, it has weird results on the final tests. I am not very technical, but our electrician mate (long time served) who's done the rewire - and his sparky pals - are all at a frustrated loss.
Basically, although individual stretches of wiring are testing fine, once they are linked together the results are failing. Even though EVERYTHING (including gas and water mains) are disconnected - it is still showing live electricity on the circuits. Why? Where can it be coming from?
Also, they tested a bit of the house wall and it was showing a reading of three volts. Surely this should be completely neutral if everything's disconnected.
The earth around the house has tested fine, and the socket components are testing fine. The only thing that hasn't been rewired is the existing burglar alarm. This is disconnected at mains and has reverted to its internal battery back-up.
What's causing this "leakage" of electricity into circuits (it's happening across several) where nothing is connected? Thankyou.

 

[ColJack]

it might be the suppliers earth since the house is reading some voltage to earth ( presumably that's where you're taking your reference to? )

 

[RF Lighting]

What sort of meter are you using, what setting is it on, and what are you connecting each probe of the meter to when a voltage is showing?

 

[1john]

you haven't got a lot of cables bunched together perhaps neat the main supply tails or cable have you?

 

[houserenovator]

I am really sorry, I do not know all the technical stuff (just a useless girl!!). They were testing two wires at a time at 1000 volts for resistance on a Fluke meter at one point.

The earth around the house has been tested separately and is fine, so they don't think it's a supplier issue. Also the fault is not bad enough to trip the RCDs, so it's not dangerous at the moment. However, it is still not right, as there should not be any electricity showing when it's all disconnected.

Is there any possibility that electricity could be leaking into the house from the burglar alarm?

The electricians have tested ever bit of the wire and scratched their heads for ages over this - it appears to defy logic for them. Any suggestions that I could feed back would be greatly appreciated.

 

[ColJack]

no it's not leaking from the burglr alarm.

have they checked the main earth?
what does the sheet say the Ze is ( should be written somewhere at the top of the test sheet.. )..

 

[houserenovator]

Thanks for your reassurance that it can't be coming from the alarm. I don't know what they've written on the test sheet.

For some reason the problem is showing on both lighting and socket circuits. Individual stretches of wire are testing fine, but when put back together and tested as a whole, fail as the resistance is too low.
At first they thought it was dodgy sockets, but it does the same with connector blocks on the wires. If a wire had been grazed by something (some were fed through old existing ducts), surely the problem would not show on all circuits or the RCDs would trip?
The problem seems to be showing itself in two ways, which must surely be linked? Firstly, the earth resistance is slightly failing when circuits are tested as whole (although fine as individual stretches). Secondly, there is some "live" electricity showing when everything is disconnected.
Apologies I can't be more technical.

 

[Spark123]

Why are they using 1000v, presumably for an insulation resistance test?
Normally it is done at 500v.

 

[houserenovator]

Yes, they were testing at both 500v and 1000v for insulation resistance. Maybe because they were getting odd results, they tested at higher figure to see what happened.

 

[houserenovator]

you haven't got a lot of cables bunched together perhaps neat the main supply tails or cable have you?

Thanks for that idea, but they've checked for bunching.

 

[Spark123]

You don't need to use the 1000v setting on a 240v circuit.
Can you post up the test results?

 

[houserenovator]

I don't have results sheet yet, but I will certainly ask them why they were testing at such a high figure if it wasn't necessary.

 

[Steve]

but I will certainly ask them why they were testing at such a high figure if it wasn't necessary.

ooh, ooh, I know!! Its because they just got a new meter and it goes up to 1000v. 1000v is bigger than 500v, so it must be better!!!

 

[GaryMo]

Yes, they were testing at both 500v and 1000v for insulation resistance. Maybe because they were getting odd results, they tested at higher figure to see what happened.

It's like saying "look what damage I can do when I hit this wall at 30mph" then wonder what it would be like to hit it at 60mph!

Insulation tests will be carried out whilst the installation is dead. If it's failing an insulation resistance test and tester (and constructor?) can't pinpoint why or where it's failing nor know the correct volatge range to carry out an IR test then I don't think much of their ability.
I'm another one who would love to see a copy of the Electrical Installation Certificate.

 

[1john]

I dont think there is going to be a certificate and I am expecting that these chaps havent got a clue about what they are doing, 1000V test on domestic 230 install ?? WTF ?? 5 day course sparkys I am guessings, they must have been cheap too. I stand to be corrected and for the OP's sake I hope I am.