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Thread: Earthing problem while doing a COC

  1. #1
    Full Member Tonye's Avatar
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    Earthing problem while doing a COC

    Some advice please.
    I recently completed testing for a COC at a townhouse in a complex of 11 units.
    When doing the Ze earth loop impedance test, I obtained a reading of 5,6 ohms.

    I gained access to the meter kiosk which feeds the whole complex and tested there & obtained the same reading.
    This proved that it was definitely a council problem.
    I notified the inspector with the relevant Annex K form.

    Two weeks later, I was informed that the problem had been resolved.
    I did further tests and obtained the same reading.
    I then arranged to meet the council maintenance guy at the kiosk.
    The wiring arrangement was TNS.

    The 11kv mini sub was about 20 meters away from the kiosk.
    When opening the mini sub we found that almost all the earth cabling from 70mm to 16 mm had been stolen.

    I walked across the road to another kiosk and tested a 1,3 ohm earth loop test.

    I was told that it could take 6 months to repair and that I could not issue the COC.

    My client is obviously not happy as this is holding up the transfer of the property.

    I asked the inspector if we could do a TNC-S connection at the kiosk untill the matter has been resolved.

    This was denied.

    My question is, currently the TNS system has an earth problem and surely it would be better to have a TNC-S
    Earth system.

    Or am I missing something

  2. #2
    Diamond Member AndyD's Avatar
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    The 1.3 ohm at the kiosk over the road isn't very impressive either. Maybe that the council couldn't provide a safe TNCS system because of insufficient points to PME. Whatever their reason for declining it was probably a good reason because if there was a cheap and easy way around the issue I'm sure they would have taken it.

    Did you discuss any other options with the inspector after he declined to TNCS the supply? What's the ground like in that particular area? Maybe you could TT the installation by installing a local earth mat and abandon the earth from the supply authority entirely?
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    Full Member Tonye's Avatar
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    I have drafted another letter to the inspector requesting that I do a TNCS connection until they repair their earth issue.
    If I get a reading of say 1.3 ohms, it is still within spec and can at least issue the COC.
    It is also at least better than the current 5,6 current reading.
    Quite frankly, I have done more than I should have on this problem in an effort to help my client.
    If this is again rejected, then the client will have to wait for the council to do the necessary repairs.
    Thanks for the input Andy.

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    Gold Member Sparks's Avatar
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    It would benefit your business if you did the TNCS and the reading is good enough. You will then be able to certify indicating the supply as such and compliancy.
    The supplier will never know and not care neither. You are obligated to your client not the supplier. Deeds office closes soon. I would do it without even thinking twice.

  5. #5
    Full Member Tonye's Avatar
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    Hi Sparks, after a month, the council have resolved the issue.
    They installed an earth matt at the Mini Sub & connected it to the Earth Busbar.
    The earth loop tested at 0,17ohm.
    Thanks for the advice though.

  6. #6
    Gold Member Sparks's Avatar
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    Glad it is finally sorted. I deal with property transfers every day and know how the clients can sometimes be. Considering that it is their homes and the amounts they have committed to paying for years, one cannot blame them.

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