Bonding problem.

[mikparkes]

Ok this might seem daft but it's got me a bit stumped.

A couple of weeks ago I was asked to do an Electrical Inspection report on an upstairs flat. I failed the installation on many things including a damaged Consumer Unit and Main equipotential bonding of the water supply. The problem with the Bonding is that I can't find the incoming water supply to the building to see if there is any.

I have been asked to repair the problems with the electrics which are all easy enough except I still can't find the incoming water supply to the building. I have checked everywhere in the flat and the only water in there appears to be fed from downstairs in 15mm plastic pipes. I know Main Bonding is normally the first thing to check and but it appears the main supply must be in the downstairs flat where I am not even working.

I have looked in the downstairs flat and spoken to the occupant (94 year old lady) and her daughter and apparently they have no idea where the stop tap is after 8 years living there. The only course of action I can see is to rip out the old lady's kitchen and bathroom until i find the supply. This is something I am loathe to do as I know all the pipework feeding the upstairs sinks and shower is plastic.

Please tell me there is a reg i'v missed that will allow me to finish my work and sign the place off.

Thank you

 

[Silly Sausage]

Treat the flat as an installation in its own right, with its own MET.
Test any exposed Cu pipework whether it is Extraneous or not, and if it is, bond it to the MET.
GN8 will have all the information you need.

 

[MarkieSparkie]

If you can confirm that the incoming water supply and its distribution is via plastic pipes there should no need to main bond the water supply, in fact to bond in this situation would arguably be less safe than not bonding. However, if there is any extraneous metal pipework on the consumer side of the stop cock it will need to be main bonded back to the MET.

 

[Sintra]

If the water supply to the flat is in 15mm plastic then why does it need bonding. If it isn't an extraneous conductive part then it shouldn't even be on your report.

 

[mikparkes]

Wasn't sure I could treat the flat as an installation in it's own right with regards to main bonding as i'v never had a problem finding it before.

Thanks for the advice guys.

 

[Engineer54]

Wasn't sure I could treat the flat as an installation in it's own right with regards to main bonding as i'v never had a problem finding it before.

Thanks for the advice guys.

You ''Always'' treat every flat/apartment in a multi dwelling building as a separate installation in it's own right. The main earthing point MET for the building, will be at the main electrical supply intake position, and the only place you are able make a meaningful Ze test. The main earthing points in the flats will be EMT'S, where you test Zdb (Zs). All flat/apartment EMT's should be connected to the MET with appropriately sized earthing conductor.

As far as bonding within a flat, if the supply in, is plastic as is the rest of the plumbing then obviously no need to bond. If the supply in, is plastic, and there is a boiler with metal pipes to bathroom etc, personally i would bond theses as a matter of course as they may still be extraneous via the building structure. Or as the saying goes if in doubt ...bond!! Fine is you can test to check for being extraneous, but more often than not, parallel earths can or will, give you misleading results!!