Alternative to bonding water supply?

[NickD]

The extent of metal pipe in contact with general mass of earth may well be sufficient to make the installation as a whole an ECP. There is no second incomer, yet there is still an extraneous conductive part there, unless of course you are going to treat every pipe which sticks up out of the floor to feed a radiator as a seperate ECP?

Ah, I see what you're trying to say now. At a splitting hairs level yes I do prefer to think of every pipe coming up as an ECP because the idea of the mass of metal being an ECP sticks in my craw, though I accept the guidance is quite happy to look at it that way.

 

[frontier219]

He's not the only one not getting it I think!

How exactly is a pipe going to 'come live' if it is not bonded? the whole point of equipotential bonding is to ensure that that the pipework and other extraneous parts does become 'live' if the supply earth connection becomes live through an external fault.

Re-read what I've written. I'm tired...

 

[TJ Anderson]

In that case, the water pipes would have such a low resistance to the MET they wouldn't require bonding.

However, >23kOhm don't require bonding, but what lower limit would you say the same?

I know it did not require it. It was not extraneous in its own right, and only became same potential as the gas pipe when combi boiler was connected. If the boiler was removed it would go back to non extraneous. I still bonded it though as it was new install and I didn't want another spark in future saying "why did he not bond the water" lol and me not being there to explain it.

 

[Deleted member 26818]

I think some people need to understand the difference between earthing and bonding.
Bonding is intended to equalise differences in potential between extraneous-conductive parts and exposed-conductive parts.
Earthing is intended to provide a return path for current which may become present in exposed-conductive parts under fault conditions.
Neither bonding or earthing are intended to provide a return path for current which may be come present in conductive parts due to poor workmanship.

 

[NickD]

I know it did not require it. It was not extraneous in its own right, and only became same potential as the gas pipe when combi boiler was connected. If the boiler was removed it would go back to non extraneous. I still bonded it though as it was new install and I didn't want another spark in future saying "why did he not bond the water" lol and me not being there to explain it.

I think it's not wise to contemplate too deeply what is truly extraneous or you end up in orange robes with a shaved head sitting on a mountaintop in Tibet going ommmmmmmmmmmmmmmmmmmmm......

 

[Pete999]

That'll be fine as long as you can guarantee the water in that pipe will be 100% pure water and it will never have normal mains water in it or anything like that.

Beat me to it Dave

 

[Engineer54]

There is a very big difference in the rules and the thinking behind those rules, that are applied to ordnance factories and normal buildings, eg domestic houses and flats!!

It doesn't matter if just 100mm of metal gas or water pipe enters a property before being converted to plastic, it will still be bring into that property an extraneous source earth... So officially will need main bonding....

 

[NickD]

There is a very big difference in the rules and the thinking behind those rules, that are applied to ordnance factories and normal buildings, eg domestic houses.

I mentioned the ordnance factory thing purely in reference to reliability of plastic push fit as a connector system, nothing more.

 

[Engineer54]

To be honest, i don't know what you're proposing here?? For electricians to start installing plastic isolation sections to incoming water and gas pipes maybe?? Now that should be interesting!! lol!!

 

[NickD]

To be honest, i don't know what you're proposing here?? For electricians to start installing plastic isolation sections to incoming water and gas pipes maybe?? Now that should be interesting!! lol!!

Mostly it was just like a thought experiment to hear other people's input and take on things, which can be a good way to improve my own understanding/grasp of things. It's been useful.