Unable to verify Water bonding present

Discussion in 'Electricians' Talk' started by kangooman, Jan 4, 2007.

  1. kangooman

    kangooman New Member

    Hello all,

    Went to a job this morning and the guy I was working for checked earthing and bonding to water and oil.

    Great stuff, main earth and oil both ok.

    However, there was no evidence of any water bonding.
    Checking DB, there was a 10mm earth to which we were able to follow in roof space until it went behind a joist and down into the kitchen wall. Although this is about 2m from the water stop cock, we were unable to find the end of this cable and it seems to have siply been left in the wall.

    I find this hard to believe but if you can't find the end what more can you do.

    The guy made the decision that he assumed it is conneceted to the water somewhere and all was well.

    I feel however that because we could not verify both ends we should have installed a new water bond.
    I did not say anything to the guy until we left as it was his job but just gave him my opinion.

    Your views appreciated please.

    Many thanks.
     
  2. sparkybird

    sparkybird New Member

    I think you know the answer!
    You could have tested the continuity to earth from the water pipe. 0.05 ohms or less is deemed to be bonded. Putting this on the cert would have covered you. As it is you (or your boss) is a bit exposed..

    SB
     
  3. kangooman

    kangooman New Member

    Nice one SB,

    Just not come accross this, either there is bonding present or not and certainly no sign of any earth clamp on any of the pipework and thought that one had to be present within something like 600mm of entering property.

    Thanks for your time.
     
  4. Coloumb

    Coloumb Screwfix Select

    Is the water feed now supplied in plastic perhaps?

    You should also note that the bonding point should really be accessible and if you can't see it I doubt that it is.
     
  5. kangooman

    kangooman New Member

    Col,

    Think you have just hit the nail on the head with this one.
    yes, the supply to the stopcock was in blue plastic so if that had been changed at some point from copper then I guess that the bonding is not required.

    Many thanks for that.
     
  6. syholl

    syholl New Member

    Just beacause the supply is plastic, it should still be bonded unless the whole lot is plastic... When taking out kitchens, its quite common to find that somebody has disconnected the earth and then cut the earth wire near to where it comes out of the wall...

    Sounds like you need to put a new one in.
     
  7. Coloumb

    Coloumb Screwfix Select

    Just beacause the supply is plastic, it should still
    be bonded unless the whole lot is plastic
    ... When
    taking out kitchens, its quite common to find that
    somebody has disconnected the earth and then cut the
    earth wire near to where it comes out of the wall...

    Sounds like you need to put a new one in.

    Why? If it's not extraneous then your only gonna make the whole install more dangerous under fault conditions.
     
  8. kangooman

    kangooman New Member

    Many thanks syholl,

    Although we found where the cable went down the wall from the roof space above the kitchen, we were unable to find any evidence of it elswhere and we had units, boards and appliances out.


    Thanks for your time.
     
  9. Coloumb

    Coloumb Screwfix Select

    Col,

    Think you have just hit the nail on the head with
    this one.
    yes, the supply to the stopcock was in blue plastic
    so if that had been changed at some point from copper
    then I guess that the bonding is not required.

    Many thanks for that.

    kangoman, you had better be 110% certain that's the case.
     
  10. kangooman

    kangooman New Member

    Roger that.

    Will take a reading and or contact the water company.

    Just a bit confued why you feel that if it is plastic then bonding is not required but syholl thinks that it should be bonded even if it is plastic.

    Thanks.
     
  11. sparky308

    sparky308 Member

    The point of main equipotential bonding is to ensure that the (presumably copper) pipework in the house is all at the same potential. It doesn't matter if the supply pipe is plastic - the copper internal pipework still needs bonding. If however, the internal pipework is all plastic, then it's not & conductor & can't be bonded.
     
  12. Coloumb

    Coloumb Screwfix Select

    The point of main equipotential bonding is to ensure
    that the (presumably copper) pipework in the house is
    all at the same potential. It doesn't matter if the
    supply pipe is plastic - the copper internal pipework
    still needs bonding
    . If however, the internal
    pipework is all plastic, then it's not &
    conductor & can't be bonded.

    Even if it's not extraneous?

    The point of bonding is to make sure that all the extraneous parts are of an equal potential under fault conditions. Therefore there aint no point doing this unless the parts your bonding are extraneous. If the supply is fed by plastic how can the copper be extraneous?

    Bonding in these conditions just makes the non-extraneous parts live under fault conditions. Madness.
     
  13. 2 wheeled ant

    2 wheeled ant New Member

    The point of main equipotential bonding is to
    ensure
    that the (presumably copper) pipework in the house
    is
    all at the same potential. It doesn't matter if
    the
    supply pipe is plastic - the copper internal
    pipework
    still needs bonding. If however, the internal
    pipework is all plastic, then it's not &
    conductor & can't be bonded.

    Even if it's not extraneous?

    The point of bonding is to make sure that all the
    extraneous parts are of an equal potential under
    fault conditions. Therefore there aint no point doing
    this unless the parts your bonding are extraneous. If
    the supply is fed by plastic how can the copper be
    extraneous?

    Bonding in these conditions just makes the
    non-extraneous parts live under fault conditions.
    Madness.

    I agree with both of you, as both have valid points, however i would bond it as its in the green & brown guidance books
    Ant
     
  14. sparky308

    sparky308 Member

    Even if it's not extraneous?

    The point of bonding is to make sure that all the
    extraneous parts are of an equal potential under
    fault conditions. Therefore there aint no point doing
    this unless the parts your bonding are extraneous. If
    the supply is fed by plastic how can the copper be
    extraneous?

    Bonding in these conditions just makes the
    non-extraneous parts live under fault conditions.
    Madness.

    Agreed. Bonding non-extraneous conductive parts is madness. But I'd argue that copper pipework is usually classified as an extraneous conductive part because it's likely to introduce an earthy potential - for instance via the boiler, which is fed by a copper gas pipe, which is either bonded itself or in contact with the earth.
     
  15. kangooman

    kangooman New Member

    Sparky, col & 2 wheel,

    I aslo agree with you all and have put foward very valid points.

    However, I want to do what is correct and not what you think and I wiss it was a simple case of sparky and col agreeing and that would make life easy.

    So, although I agree with you all, still not 100% sure what is the correct action to take bearing in mind I do aggre with your comments.

    Thanks for your time, again!
     
  16. chill-man

    chill-man New Member

    Had a case on a new build recently where incoming water supply was plastic,then about 3 metres of copper installed,then the rest was all plastic.Rang Napit to ask if this copper needed main equi bonding and they said yes.????
     
  17. kangooman

    kangooman New Member

    chill,

    Think I get the general idea where this is going but at the same time don't want to waste my time or cutomers money.

    Thanks for the comment, great to hear other folks also come up against problems at times.

    Thanks.
     
  18. 2 wheeled ant

    2 wheeled ant New Member

    The on site guide is only a guidance book but supposed to be BS7671 to 2002 with ammendments to 2004
    page 25, para 4.3 says you do bond it.
    Ant
     
  19. Coloumb

    Coloumb Screwfix Select

    Then in the EG to the BR they changed to "do it" to "may need to do it".

    You have to decide for yourself on each cases merits.
     
  20. splater-and-duck

    splater-and-duck New Member

    Drives ya a bit daft dont it. you go to a job. in itself dead simple then no bond. Price pulling half the house apart to get the cables through to bond and befor you know it the jobs gone out the window with time spent going to the job in the first place and doing the quotes.
     

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