Earthing the neighbours water?

[CRAIGNEWHAM]

Afternoon,

Doing a rewire/CU change at an upstairs flat, (a detached building with an upstairs and downstairs seperate flats) and checking the main bonding. It looks like the water pipe for the downstairs flat go up through the kitchen of the upstairs flat into the attic as the water tank etc is up there. I'm assuming I have to main bond this, but is it ok if its potentially bonded to 2 CU's?
Maybe a daft question?
Any help appreciated
Craig

 

[RWJ]

Is there two separate supply's? (Not just two meters)

 

[CRAIGNEWHAM]

Not sure to be honest?
The meter cupboard for the upstairs flat is on the outside wall. How could I check? should I find the downstairs one and see if it feeds upstairs?

 

[Engineer54]

If the downstairs DNO supply cable is an ''in/out'' of the cut out, or if the tails from the cut out have been henley blocked and one set disappears, then the DNO supply is a ''Single' supply!!!

 

[CRAIGNEWHAM]

Thanks, Ill look.
How does this effect it?
Is bonding it to the upstairs CU safe to do then?

 

[Wiredspark]

Wait a minute this is a daft question. If it's a tank, it's not fresh running water, it's not the water main. The water main needs to be bonded as above with a 10mm2 g/y, but the "hot" water stuff needs only be equipotentially bonded. So as the water main enters the flat upstairs it needs to be bonded within 600mm.

 

[CRAIGNEWHAM]

But if I equipotentially bond it, Im putting a connection between the 2 CU's? is that ok, safe?

 

[Deleted member 9648]

Main bond the water service at the point of entry to each flat if there are two separate DNO supplies ,one for each flat,with the head in the flats.
If there is one DNO supply with check meters serving each flat main bond the water service at the point of entry to the building back to the MET. You will also need to main bond back to the flat CU at the point of entry to each flat as a potential may be intoduced via the other flat,

 

[CRAIGNEWHAM]

So if there is just one supply for the 2 flats, then so long as its bonded downstairs to their CU then thats enough?
There will be pipework in the upstairs flat though that could end up having no bonding it anything happens downstairs and upstairs would never know?