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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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    Are the collection electrodes connected at the top, for example by a ridge wire ? - if so, the effect is nothing like as dramatic - just the current does not divide evenly and the ground bounce is highly asymmetric. There  is greater chance of damage to things like telephones and so on due to induced voltages. The maximum strike that can be tolerated before damage occurs is reduced.

    In practice a side strike to a well connected electrode is likely.

    Mike.

     

     

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  • 0

    Are the collection electrodes connected at the top, for example by a ridge wire ? - if so, the effect is nothing like as dramatic - just the current does not divide evenly and the ground bounce is highly asymmetric. There  is greater chance of damage to things like telephones and so on due to induced voltages. The maximum strike that can be tolerated before damage occurs is reduced.

    In practice a side strike to a well connected electrode is likely.

    Mike.

     

     

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