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Lightning electrodes

lyledunn

A relatively small parish church has 8 down conductors connected to rod electrodes. Each electrode measured separately ranged from 215 ohms to 12 ohms with the overall value being around 8 ohms. Now I am aware that the overall value should be less than 10 and that each individual electrode should be no more than 8x10. We have one at 215 and one at 135, the others meeting that requirement. It is easy for me to advise that the system does not meet code but I do not have the expertise to assess the implications of the situation. I would appreciate your opinion. 

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    The invitation to tender required the periodic inspection of the fixed wiring and the testing of the lightning earth electrodes. It was not within our remit to deliberate on the effectiveness of the LPS. However, I must say that my interest in the subject was very much kindled and it is that which needs scratched.

    The lids of the inspection pits were extremely difficult to lift. Even the church warden said that he didn’t think they were ever lifted before. I suspect that previous tests were done without removing the test link at each down conductor! 
    As for experts who ply their trade in this field and having glanced through the DEHN technical document on LPS, I have no hesitation in elevating them in regards to esteem.

    However, on another church, the expert company are looking £2500 to reduce the electrode resistance from 10.8 ohms to what they say is an absolute minimum of 10 ohms! 

     

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  • 0

    The invitation to tender required the periodic inspection of the fixed wiring and the testing of the lightning earth electrodes. It was not within our remit to deliberate on the effectiveness of the LPS. However, I must say that my interest in the subject was very much kindled and it is that which needs scratched.

    The lids of the inspection pits were extremely difficult to lift. Even the church warden said that he didn’t think they were ever lifted before. I suspect that previous tests were done without removing the test link at each down conductor! 
    As for experts who ply their trade in this field and having glanced through the DEHN technical document on LPS, I have no hesitation in elevating them in regards to esteem.

    However, on another church, the expert company are looking £2500 to reduce the electrode resistance from 10.8 ohms to what they say is an absolute minimum of 10 ohms! 

     

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