Voltage up to 100v on CPC even when disconnected

[chrisses]

Oh and to clarify as well when I switch off the breaker to this circuit only the earth voltage disappears

 

[Tiny Spark]

Have you dont IR tests on all circuits?

 

[spark 68]

i have spoken to the second man and he has admitted to me that he tried to take an earth loop but the tester wouldn't let him

Oh dear!, so instead of investigating this issue (above 50V touch ?), the installation was put into service with a possible inherent defect.

 

[telectrix]

Oh and to clarify as well when I switch off the breaker to this circuit only the earth voltage disappears

so, the stray voltage must be coming from that MCB. dis all that circuit's cables from CU. do continuity and then IR tests on that circuit with all loads disconnected. bet you the IR tests will show a L-E fault on that circuit.

 

[spark 68]

It does look as though there are two faults, the initial one (earthing) not picked up, and whatever is leaking back to the CPC.

 

[chrisses]

Oh dear!, so instead of investigating this issue (above 50V touch ?), the installation was put into service with a possible inherent defect.

Yes oh dear I have dealt with the issue accordingly

 

[chrisses]

so, the stray voltage must be coming from that MCB. dis all that circuit's cables from CU. do continuity and then IR tests on that circuit with all loads disconnected. bet you the IR tests will show a L-E fault on that circuit.

Yeah I think your right but am I not right in thinking if that was the case then I would be able to disconnect the earths and only one would still be live?

 

[telectrix]

not if the fault is transmitting through a load to N and then onto the earth via the TNC-S.

 

[Octopus]

Oh and to clarify as well when I switch off the breaker to this circuit only the earth voltage disappears

In which case I'd be back with a copy of the EIC you did for the rewire and comparing the results with what you find now.

 

[Octopus]

so, the stray voltage must be coming from that MCB. dis all that circuit's cables from CU. do continuity and then IR tests on that circuit with all loads disconnected. bet you the IR tests will show a L-E fault on that circuit.

But wouldn't the rcd trip?

 

[spark 68]

I would be more concerned about how the Earth is rising above 50V, and why the ELI test could not be performed first and foremost, then try to find the other fault.

Something doesn't add up here, I would be inclined to start re-testing from the beginning.

 

[chrisses]

not if the fault is transmitting through a load to N and then onto the earth via the TNC-S.

I've arranged to go there tomorrow I'll let you know how I get on.

- - - Updated - - -

Thanks to everyone who has taken the time to give advice on this I will let you know how I get on

 

[Des 56]

You need to clear your head with the confused state you are at


Approach the job with a fresh mind as if it was the initial verification,do the appropriate tests and in the correct sequence
The fault or faults can and should become apparent

Personally I would find faffing around taking voltage readings a waste of time and effort and it will likely confuse ( as it has done with your investigating)

Ignore these voltage readings that you seem fixated on,clear the system using insulation.continuity and loop impedance tests
Get those done correctly with acceptable results and you will sort the problem yourself

 

[Marvo]

I would be more concerned about how the Earth is rising above 50V, and why the ELI test could not be performed first and foremost, then try to find the other fault.

Something doesn't add up here, I would be inclined to start re-testing from the beginning.

I agree, start from scratch and be methodical. Test the incoming supply to prove all the faults are on the premises, find out why the earthing is high impedance hance allowing a rise in touch voltage and find the IR fault(s). Finally test the RCD to make sure it's still functional.

 

[HandySparks]

TN what though ? TN-S or TNC-S...

I may have missed it, but have we got an answer to this?