I am currently doing an EICR in a large thatched cottage that has been split on to a main house and small rental.
They share one supply but have separate DB's and are on a single TT earth,
They also have a single 30mA RCD protecting both properties, not great for selectivity but at least there is RCD protection.
Main bonding is in place to the oil feed for both properties.
The properties share a single water supply that's bonded when it enters the main property but all the pipework in the second property is giving me a reading of 0.54 ohms. My working assumption is some plastic pipe somewhere along with supplementary bonding to a lighting or power circuit. I believe the pipes just run through the fabric of the building rather than going in the ground but the outer walls of the property are damp, quite a bit of corrosion in back boxes etc, and the pipework is partially buried in the walls in places.
In my mind at least if the walls are damp they are probably also conductive to some extent and providing a path to earth, I would love to be able to run an insulation test on the pipes but so far I cant find the supplementary bonding to disconnect it.
Ze 47 ohms, Zs at DB 22 ohms.
The MET is more or less diagonally opposite where I would need to make a bonding connection, therefore getting a bond in place is far from trivial.
Would you agree that I probably have no choice and need to find a way to get bonding in place
Is it worthwhile me spending more time trying to locate and isolate the supplementary bonding or is it very likely that an insulation test between the pipes and MET will come back below 22K because of the damp walls.
If I was to make a crimp connection to an existing 10mm earth bonding cable outside and protect it with amalgamating tape would this be acceptable or would I need to give it better protection?
Thanks
