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main protective equipotential bonding

Giles D

Would anyone be able to advise on non verification of bonding to the incoming water to a residential property and the subsequent reasoning for not issuing an EIC.

When completing the testing for the installation of 6 new circuits and a new consumer unit for these additional circuits, I could not verify the bonding to the oil or the water pipes. I informed the builder who had contracted me, that this would need to be completed before an EIC could be issued, and I also copied the client into the mail,

This is an old cottage in a country location, The water stop cock is in a boxing at the front door and the intake and consumer units are at the rear of the property. I had advised that getting the bonding cable to the water would be difficult and would possibly need to be run around the outside of the property and then in through the wall to the water. The oil would be easier as it was very close to the intake.

I offered to give a cost to complete this work, but the client advised that a colleague, who was an electrician would complete this and they would notify me once it had been completed. 
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They advised it had been done and I returned and tested both the oil and the water. I got a reading on the oil but not the water. I also could not see the connection to the water anywhere. I informed them of this and they said it was in the loft and they would get their electrician to do it again. I informed them it needed to be within 600mm of entering the property and or before the first T. 
They advised again it had been done. I returned and this time I got a reading of 0.37, but again, I could not see the connection. The client says that they are going to be getting a new water supply in phase 2 of the works, in the near future.

Am I correct in advising that I still cannot issue an EIC. As the reading is too high, I cannot see the connection so it is therefore not accessible for maintenance and it is not within the 600mm of entering the property or before the first T.
Or, should I issue the EIC and put a departure from the regs and a note that the client has been informed and takes responsibility. My gut tells me I shouldn’t issue the EIC until I can verify the bonding

any thoughts would be much appreciated 

Regards Giles 

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    K

    Key BS 7671 requirements for main protective bonding of incoming water services:

    Main protective bonding is required where the metallic water service is an extraneous-conductive-part capable of introducing earth potential into the installation. It must be connected to the Main Earthing Terminal (MET). (Regulation 411.3.1.2)

    The bonding conductor should be connected as near as practicable to the point of entry of the water service into the building and generally before any branch pipework. Industry guidance commonly references connection within 600 mm of the point of entry/meter position where practicable.

    The bonding connection should be accessible for inspection, testing and maintenance. If the connection cannot be located and inspected, verification of compliance becomes difficult. This is a fundamental certification issue rather than simply a test-result issue.

    The bonding conductor must be correctly sized in accordance with Regulation 544.1.1. Typical domestic PME (TN-C-S) installations commonly require 10 mm² copper main bonding conductors.

    Verification should include:

    Visual confirmation of the bonding connection.
    Confirmation that the conductor is continuous back to the MET.
    Confirmation that the connection is made to the correct section of incoming metallic pipework.
    Confirmation that any labels, clamps and terminations are suitable and secure.

    Applying that to your scenario:

    The fact that you obtained a continuity reading of 0.37 Ω does not by itself prove compliance. If you cannot physically identify the bonding connection, cannot verify where it is connected, and cannot confirm that it is installed at the incoming water service in accordance with BS 7671, then you cannot fully verify the main protective bonding arrangement.

    Therefore, your concern is justified: the issue is less about the measured resistance value and more about the inability to inspect and verify the bonding installation you're being asked to certify.

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  • 0

    K

    Key BS 7671 requirements for main protective bonding of incoming water services:

    Main protective bonding is required where the metallic water service is an extraneous-conductive-part capable of introducing earth potential into the installation. It must be connected to the Main Earthing Terminal (MET). (Regulation 411.3.1.2)

    The bonding conductor should be connected as near as practicable to the point of entry of the water service into the building and generally before any branch pipework. Industry guidance commonly references connection within 600 mm of the point of entry/meter position where practicable.

    The bonding connection should be accessible for inspection, testing and maintenance. If the connection cannot be located and inspected, verification of compliance becomes difficult. This is a fundamental certification issue rather than simply a test-result issue.

    The bonding conductor must be correctly sized in accordance with Regulation 544.1.1. Typical domestic PME (TN-C-S) installations commonly require 10 mm² copper main bonding conductors.

    Verification should include:

    Visual confirmation of the bonding connection.
    Confirmation that the conductor is continuous back to the MET.
    Confirmation that the connection is made to the correct section of incoming metallic pipework.
    Confirmation that any labels, clamps and terminations are suitable and secure.

    Applying that to your scenario:

    The fact that you obtained a continuity reading of 0.37 Ω does not by itself prove compliance. If you cannot physically identify the bonding connection, cannot verify where it is connected, and cannot confirm that it is installed at the incoming water service in accordance with BS 7671, then you cannot fully verify the main protective bonding arrangement.

    Therefore, your concern is justified: the issue is less about the measured resistance value and more about the inability to inspect and verify the bonding installation you're being asked to certify.

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