earthing water pipes

[james king]

hi all! we were at a job to day and the water was not earthed but the home owner said the spark did not have to earth it because it was plastic incomer! but then from the stop tap was copper! is this correct? i was to busy chasing walls to here what my boss said

 

[telectrix]

hope your boss told him he was totally wrong. metallic water pipe needs bonding whether the incomer is plastic, lead or even kryptonite.

 

[Sparky Ninja]

Regulation 544.1.2 buddy.

 

[james king]

no he deff said if it kryptonite its fine haha

 

[Des 56]

hope your boss told him he was totally wrong. Metallic water pipe needs bonding whether the incomer is plastic, lead or even kryptonite.

:d:d:d and





My smilies have started learning the alphabet,where are they gone

 

[SimpleSimon]

My bonding knowledge is alot to be desired.
Do I remember a post last week of someone stating that bonding services with incoming plastic is liable to introduce an earth potential?

 

[malcolmsanford]

Sort of Simon. The actual plastic incomer more than likely will not introduce a potential, so you will not need to bond that. Where is can go wrong is if then the house installation is copper there is a good chance that because we are also bonding the gas pipe which normally is metal, and that and your copper internal water pipe will somewhere in the house meet up normally at a boiler.

So when you bond the internal water installation what your effectively doing is supplementary bonding. To make sure that all the pipework is at the same potential.

 

[SimpleSimon]

Sort of Simon. The actual plastic incomer more than likely will not introduce a potential, so you will not need to bond that. Where is can go wrong is if then the house installation is copper there is a good chance that because we are also bonding the gas pipe which normally is metal, and that and your copper internal water pipe will somewhere in the house meet up normally at a boiler.

So when you bond the internal water installation what your effectively doing is supplementary bonding. To make sure that all the pipework is at the same potential.

Gotcha so if both services were plastic incoming there would be no need to main bond? As you wouldn't need to make the services the same potential. ?

 

[malcolmsanford]

That is right. niether the gas or water installations would be able to introduce a potential to earth if they were both supplied in plastic. It would be equivelent to bonding a metal window or door frame or any other metallic object in the installation that would not have the ability to produce a potential.

 

[SimpleSimon]

Thanks Malcolm.

 

[telectrix]

but, as the water pipes are fixed to walls and pass through walls, can they not introduce earth potential through the fabric of the building?

 

[SimpleSimon]

but, as the water pipes are fixed to walls and pass through walls, can they not introduce earth potential through the fabric of the building?

Suppose it could if it's in close vicinity to any structural steel?

 

[IQ Electrical]

Here's some guidance from the IEE, not updated to 2008 but still has some relevant points and some interesting stuff on the 'water is a good conductor' myth:

 

[malcolmsanford]

Suppose it could if it's in close vicinity to any structural steel?

If you were using the structual steel as an earth electrode as in reg 542.2.1 theorectically you could get a problem. As the reg says you can use either the foundation metalwork or welded ree bar, note welded and not tied, but these systems would not be readily accessible as they would be embeded. So the scenario could be if you drilled into your wall and hit a ree bar screwed a metal pipe clamp to the wall with your metal screw and then fitted your pipe, if there was an earth fault you could make that pipe live, it's possible but un-likely. Besides as your making this system a TT it would be RCD protected.

As for a normal metal frame building as the new factories are, you actually bond the structual steelworks. ie the U and I beams back to your MET. So again if your services for gas and water were plastic but then metal and attched to any of the beams you still would not need to bond those pipes, same way as metal racking in such a building does not need bonding, even if it's bolted to the metal of the building.