No bonding to water supply on new build

Wilko · Dec 22, 2016

Hi - long story if you've time, with a question at the end

I was at a new build tonight, a 2br flat, part of a block of 28 done by a big company. I'm there to change 3 light fittings, but couldn't refrain from having a look while I was there. Certs in place, looking reas good in CU which was metal with 2 RCD. TNCS. Nice 16mm going from cutout to CU but only one 10mm coming out. Read cert and it says 'bonding to gas' but no mention of water. Look under sink, there is the brass stop cock with copper pipes to and from but no bonding evident. Looked for the gas bonding conductor but couldn't find it either. So I got Wander out and checked, sure nuff boiler gas inlet pipe was 0.05 ohms to MET, but the water stop cock was floating. So remembering @Pete999 vid I used my insulation tester and got 180K Ohms on the 250V test. So I'm guessing they judged the incoming water supply not an extraneous conductive part, so they hadn't bonded it. Likely all the flats will be the same. To me this is a gutsy call. Is it correct?

telectrix · Dec 22, 2016

probably the water comes in in plastic. 180K tells you it's not extraneous.

Rpa07 · Dec 22, 2016

Good use of an MFT Wilko, and good use of snooping time! Most of us would have looked in the food cupboards but no, there you are proving customer safety! You rock!

sajeel · Dec 22, 2016

The mains water head be plastic and feed into a water manifold then each flat will have its own supply via plastic the only metal will be from stopcock onwards and you can get away without bonding although its good practice to bond and there would be no harm in bonding water where plastic changes to copper, most projects work on budget and deadline so save cost and time.

Wilko · Dec 22, 2016

Rpa07 said:
Good use of an MFT Wilko, and good use of snooping time! Most of us would have looked in the food cupboards but no, there you are proving customer safety! You rock!

No one has moved in yet, so the cupboard was bare

Midwest · Dec 23, 2016

If the pipework within the flat is metal, then reg 528.3.4 must be considered. Presumably it is all plastic within the flat.

davesparks · Dec 23, 2016

Did you test it with the earthing conductor disconnected ?

Wilko · Dec 23, 2016

davesparks said:
Did you test it with the earthing conductor disconnected ?

No. Just one end of wander into MET and go for a walk to the kitchen sink. So testing was between copper water stop cock and MET while it was still connected to DNO supplied TNCS earth.