eathing

[raychem]

Not sure wether this is the right forum but here goes.I have replaced some copper water pipe in my house with plastic pipe,do I have to bridge the section of plastic pipe with earth wire to keep the continuity of the earth or will the fact that the pipes carry water be good enough to preserve the earthing.

 

[ryanj]

Water will NOT be good enough to carry the earthing current.

Where is the pipe and what is it used for?

 

[securespark]

As I understand it from talks with Paul Cook at the IEE, if you have majority plastic piping (rising main and elsewhere), then you do not need to main earth bond (you can't if it is plastic). If, however, you have a length of plastic from the s/cock then it changes to copper, you must bond where it changes.

 

[ban-all-sheds]

will the fact that the pipes carry water be good enough to preserve the earthing.

What "earthing"?

Copper pipes sometimes need to be earthed, but they are never used to carry an earth.

 

[ban-all-sheds]

If, however, you have a length of plastic from the s/cock then it changes to copper, you must bond where it changes.

If a piece of copper pipe is not capable of introducing a potential, generally an earth potential, because it is insulated from the mass of The Earth by a piece of plastic pipe, how does it qualify as an extraneous-conductive-part?

And if it's not an e-c-p, it does not need to be bonded.

 

[raychem]

Ryanj, it is mains cold water pipe between kitchen and bathroom and hot water from boiler to bathroom.

 

[securespark]

My dear Ban,

As I have said before, I am in total agreement with you about earthing - but I simply repeat what Paul Cook has told me as his is a popular opinion of the IEE. It's not just Paul who thinks this way.

Perhaps I should have a sig that says so!!

 

[ban-all-sheds]

And yet when it comes to supplementary bonding he says that it isn't needed if things are supplied by plastic pipes....

 

[securespark]

Yeah, I know...

I've spoken to him countless times over the years, and I still can't work out his reasoning.

 

[Damocles]

The answer seems to be a no, but not for the reason you suggest. Water does not conduct electricity very much and plastic pipe does not conduct it at all. It is not essential generally that there be continuity through the pipework system. On the whole it would be much better if none of the pipes were conductors.

The problem comes if you use metal pipes and plastic fittings. This can give you small plastic sections between conductors. So there is a poor earth, which introduces the possibility of shock without guaranteeing disconnection. This is still not a problem unless it happens in a high risk area, i.e. bathroom.

So if you have plastic fittings on metal pipes in a bathroom, then you may have to bond each section together. I have yet to see a definitive answer on this.

 

[Lectrician]

I've heard whispers that bathroom supp bonding is to be altered again...anyone else heard this??