hi lads a little unsure on whether to bond water pipes as the incoming pipe is plastic then goes to copper, i think i have read something like its now considered more dangerious to bond plastic pipes than not any thoughts on this or have i been dreaming

     thanks supra

sure the question is what about the now very common situation where the pipe from the street is blue MPDE but the house piping is copper

now obviously it can't bring in a potential from the ground

but the thing is water pipes are a large network of copper through the house  and could easilly cary a nasty potential round the house

also having the only earth to the pipework system being the  thin earth wires from the cuircuits feeding the bathroom seems wrong to me it goes against the if its earthed it shoudl be earthed well principle

What did I miss lol, I think the simple Answer your looking for is this - bond the copper pipe after any connections, no need to bond plastic.


Why on earth someone couldnt have just told you that god only knows  


Good evening to you!.

Nah it's no problem, I've read them all before Supra, they will go on about this scenario and that, but the end result is the same,  I just summerised what you needed to know to give you an awnser  

The tests that you were talking about there were to really find out how good a conductor water was, and it came back poor, thats not to say water is safe, it's certainly not, it just has a high resistance.

it's more an issue of the copper pipes you have to worry about.

LOL, I thought you was too ashamed to talk about that one  

yep water has a high resistance, hence if you have a bit of moisture around a switch you may get a tingle.

B-A-S is spot on re; introducing an earth potential from outside. But the issue of Main_Eq_Bonding still remains problematic if there's enough volume of copper or interconnected metal to allow it to function as an 'earth'. This is what's meant when people talk of systems being 'earthy' ( I know it's stupid term, but it's what they use) The risk comes from touching the ever mentioned metal which has become live due to fault conditions, while simultaneously touching something else at earth potential. So if there is a large enough volume of copper (dunno how much either) or if it's making a good connection to earth somewhere in the system, then you could have a better path to earth through the victim, so zap. so by bonding anyway if not all copper you avoid this risk, and the faff of working out if it's enough copper in the system to act as an earth.


Gawd I hate plumbing, just had a right pain int the rear of a main bond to oil & water do today. How come they only get the spark in after the kitchen's been done by the bodgers?

No - you've misread what I said.

You: "bond the copper pipe after any connections"

Me: "If the incoming water pipe is plastic then it cannot introduce a potential, and the copper pipes thereafter need bonding just as much as metal curtain tracks do.... "