earth to water main

[calvert]

Ive just had a new rising main fitted which is all plastic except for the brass stopcock and about 100mm of copper pipe. If I connect the earth from the CU to the copper bit of pipe is it doing anything? Where should it go to? My house has the old type of electric supply with earth rod (cant remember what its called )

 

[calvert]

just read the similar posts. Its a TT supply that has just had new earth rods (2) fitted so does that mean the earth wire to the mains is redundant?

 

[Taylortwocities]

You must provide the earth bonding to the water installation. It is BONDING the water pipes INSIDE the house to the main electrical earth (your earth rods).
It is not getting an earth from the external water supply pipe.

I guess that after the stop cock the water supply connects to the copper water piping inside the house?

Whereabouts is this located? Is is near the stopcock, or somewhere else?

 

[calvert]

Thanks for your answer. The plastic pipe runs for about 12 metres in all before it joins copper to a combi on the other side of the house. The earth rods are at the front so about 4 metres from the rising main...So what do you think?

 

[GaryMo]

The earthing conductor which connects to your earth rod should terminate into a MET (main earthing terminal). From this terminal you should run a 10mm2 g/y conductor (protective equipotential bonding conductor) and this should terminate via a BS951 earth clamp to copper piping on the consumers side of the main stop tap.

So, plastic piping enters your property, terminates to 100mm piece of copper pipe and a stop tap, back to plastic, rises then back to copper?

All you're doing is ensuring that any metallic parts within the equipotential zone which can introduce a potential from outside are tied together at the same potential as earth.

 

[calvert]

Thanks GaryMo for putting it so clearly

 

[securespark]

It can be 6mm² on TT for PEB's and as low as 2.5mm² for the conductor to the rod, depending upon installation conditions & cable type.

 

[GaryMo]

Yes, but I thought calculating the minimum size of protective conductors (in this case, his earthing conductor) by using the adiabatic equation may be a little OTT for DIY'ers!

 

[calvert]

Yes you are right. The calcs are beyond me. I've actually got 10mm, i realise way over the top but no one can say its too weedy!

 

[GaryMo]

It's belt and braces and what most electricians would install anyway.
I certainly do.