Live pipework in flat no power

[Stevesplatto]

Called out to a 1st floor flat in 3 storey 9 flat council block.
Leaseholder was getting shocks of the shower and the shower room floor.
Suspected either static or insulation fault. Lifted saniflo cable and got a shock (just a nip but definitely not static!) when my hand brushed against the pipework and the wall.
Checked with megger and getting extraneous voltages of 50v - 110v between pipework and brickwork/concrete.
Turned of main switch on CU, still getting voltages.
Pulled main 1361 in ground floor plant room.
Still getting voltage readings.
Flat has poor main earth and needs supplementary bonding. Client called the council who sent their own electricians but though they agree there must be some kind of earth fault somewhere in the building arent really helping.
Any ideas? The extraneous voltages with the 1361 pulled has thrown me!
Steve

 

[Darkwood]

It could be a few things here but I would consider getting the DNO involved as it could be a network fault or a fault in a neighbouring premises.

What is the nature of the supply TNS, TNCS etc etc

 

[Stevesplatto]

It could be a few things here but I would consider getting the DNO involved as it could be a network fault or a fault in a neighbouring premises.

What is the nature of the supply TNS, TNCS etc etc

I'm thinking it's a fault in a neighbouring property as well.
How else could a potential exist with all power cut!
The supply is a PME.

A supervisor from the council is coming today....

 

[Marvo]

I'd start with the main supply to the building. Establish what the buildings earthing arrangement is and test it. Also check any bonding of services.

 

[Darkwood]

When you say you withdrew the main fuse - is that to the flat or the DNO fuse to the premises when this issue remained.

 

[IzzyS]

Flat has poor main earth and needs supplementary bonding.

Sort out the earthing, main equipotential & supplementary bonding then wait for the call from one of the neighbours...

 

[Stevesplatto]

Client put me on the phone with the council electrician. He said the bonding and etc needed sorting which I agreed but pointed out that carrying out that work wouldnt stop extraneous voltage readings in pipework that persists when the main incomer for the flat is pulled. He agreed.
I suggested pulling the fuses on the bolck one at a time until the reading dropped away.
luckily the 1st fuse he pulled dropped the reading to zero. Tenants said theyd had problems with flickering lights. Electrician found a couple of fittings full of water. Cleared it. Sorted. Council electrician to his credit stayed with it (unlike the previous two!)
Both flats only had MCBs. RCDs would obviously have tripped.
Landed a CU change, possibly 2...

Thanks for suggestions
Regards
Steve