testing earth bonding


Postby chris_on_tour2002 » Mon Apr 28, 2008 3:58 pm

also posted on plumbing thread.

can anybody tell me the procedure for continuity testing the earth bonding of my copper pipework?

just done some plumbing work in the bathroom - i know for a fact that the pipes are cross bonded throughout the house as i've recently fitted a new combi and put in all new central heating, pipes and all, throughout and fitted the clamps myself. the clamps are only at the boiler, however. as all services, dhw, radiator f&r, gas and cold main all meet at the boiler is this the only place to cross bond?

i used an existing earth lead, (6mm earth cable) from the original system that i took out, to take it to earth. how do i test if this is sound and that it does actually go to earth somewhere?

i have a multimeter, just don't know quite how to use it for this particular type of test.
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Postby ericmark » Mon Apr 28, 2008 6:30 pm

You need an "Earth Loop Impedance Tester" and they are not cheap. As with PAT testing machines it uses high current as part of the test so if there is a poor connection it will find it. It also measures in very low ohms scale can't remember off hand but below one ohm. Readings of 0.01 are common and most multi-meters leads are greater than that. This is why they need calibrating so often and why most DIY people can't fill in the required paperwork for the inspection and testing which has to be submitted for Part P. So all you can really do is the inspection part. With all power off you could try to measure but to do so you need to remove each wire which really defeats the object. I have to borrow my sons meter and if he's not available I use the PAT tester as temp test until I can get the correct meter as the PAT tester also using 25 amps to test sorry I can't be more helpful hate telling people what they can't do.
ericmark


Postby chris_on_tour2002 » Mon Apr 28, 2008 11:09 pm

well, you've told me what i need to do and that answers my question. so its either spend a lot of money on equipment that i don't really know how to use or pay somebody a lot of money to do it for me. is it worth it? think i will leave it to trust. the earth bonding cable is there and it disappears and heads off somewhere in the general direction of the consumer unit/earth rod. it was a tidy installation in its day and it appears as though whoever did it was doing a decent job so i shall take a flier on this one! no reason to doubt it i just wanted to prove it to myself that all was well.
chris_on_tour2002
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Joined: Thu Aug 30, 2007 9:14 pm


Postby ericmark » Tue Apr 29, 2008 2:04 am

Sorry to say that's the norm. Only land lords seem to ever get houses inspected and tested. We all though it would go into buyers pack but seems all the real important things have been left out.
On experience if an earth is attached to the house it's normally OK through out the house but you would never believe how many houses have no earths. As water and gas have become plastic and connections to earth rods have eroded away many houses end up with no earth connections.
Also I know were inspectors were due cables have been quickly fitted to gas meters and the like and hidden in the wall. Intention always to return and do it properly but very rarely done.
But as you say normally if it looks good it is good.
ericmark


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