Water pipe bonding

[davecooper]

I have recently been carrying out some work which has required me to lift a lot of upstairs floorboards and it has enabled me to see the wiring that feeds into the flat roof space of a single story extension. The extension was built well before we moved in. What I have found is that they have run an earth bonding wire from the pipework close to the stop cock up and through the roof space to emerge beneath my bathroom. However, there is no easy route through to the consumer unit so they have picked up the ring main earth in a junction box beneath the bathroom.

My question is, should this earth cable ideally extend all the way to the earth block at the consumer unit rather than use the ring main earth? The work we are doing in the house has given me a chance to extend the earth cable back to the main earth block. Is it ok to run the current cable to a copper pipe close by and then run the new cable from either the same clamp or a second clamp on the same pipe? Although the original cable appears to be around 6mm, I would use 10mm for the new cable, is this adequate?

 

[Taylortwocities]

If this conductor is for bonding then it does not go to the earth block.
SEB conductors are usually 4mm²
more info in the WIKI
http://www.diynot.com/wiki/Electrics:Supplementary-equipotential-bonding

 

[davecooper]

Apologies, for Bonding read Earthing. At present there is an earth cable between my gas main and the earth block, there is no direct connection between any water pipe and the earth block. My understanding is that there should be.

 

[ban-all-sheds]

they have picked up the ring main earth in a junction box beneath the bathroom.

Or maybe they have bonded the pipe to the protective conductor of a circuit supplying the bathroom...

 

[Taylortwocities]

Apologies, for Bonding read Earthing. At present there is an earth cable between my gas main and the earth block, there is no direct connection between any water pipe and the earth block. My understanding is that there should be.

Is the incoming water main plastic?
If so, "earthing" (actually main bonding) is not required.

 

[davecooper]

Yes, the incoming water main is plastic. I am not really sure why an earth cable was run from close to the water main, up a wall and through the ceiling to pick up the upstairs ring main earth in the main house. I thought I had read that both the gas and water main should be earthed to the main earth terminal, but perhaps this was for a metal water main. With the current state of work in the house, now is an ideal time to find a route through to the CU. If I don't have to then that is probably a days work saved.

 

[davecooper]

Yes, the incoming water main is plastic. I am not really sure why an earth cable was run from close to the water main, up a wall and through the ceiling to pick up the upstairs ring main earth in the main house. I thought I had read that both the gas and water main should be earthed to the main earth terminal, but perhaps this was for a metal water main. With the current state of work in the house, now is an ideal time to find a route through to the CU. If I don't have to then that is probably a days work saved.

 

[davecooper]

Bit of a reword to my previous reply. I do know why this cable was run but not why they took a difficult route into the main house rather than pick up the ring main earth in the kitchen. Still, that is unimportant, just want to know what I should do.

 

[EFLImpudence]

Bit confusing so far.

Apologies, for Bonding read Earthing.

No, bonding is correct.

At present there is an earth cable between my gas main and the earth block,

That is the Main Bonding Conductor.

there is no direct connection between any water pipe and the earth block. My understanding is that there should be.

Not if the supply pipe to the building is plastic.

 

[davecooper]

Ok, thanks very much for that.

 

[PBC_1966]

And if the system is copper pipe throughout the house? Do you really want a fault to that pipework at any point to make the entire system live throughout the house? (Assuming that it isn't earthed anyway via a boiler, immersion heater, etc.).

 

[ban-all-sheds]

And if the system is copper pipe throughout the house?

What if it is?

Will those pipes be extraneous-conductive-parts?

Do you really want a fault to that pipework at any point to make the entire system live throughout the house?

Do you really think that that's what bonding is for?

 

[ban-all-sheds]

I do know why this cable was run but not why they took a difficult route into the main house rather than pick up the ring main earth in the kitchen.

OK - if you know why it was run, tell us why you think it should have been connected to the protective conductor of a circuit in the kitchen.

 

[PBC_1966]

What if it is?

Will those pipes be extraneous-conductive-parts?

A fault which places a potential on, say, a kitchen tap could in turn introduce that potential to the bathroom plumbing.

 

[bernardgreen]

A fault which places a potential on, say, a kitchen tap could in turn introduce that potential to the bathroom plumbing.

With bits of plastic plumbing mixed with copper plumbing that potential could be on the cold tap while the hot tap is being held at ground ( Neutral ) via copper pipe to the hot water cylinder and it's earth immersion heater.