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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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    For some reason too the lightning in the USA tends to be more violent, probably due to temperature and humidity differences. The voltage required to discharge through a km of the atmosphere is enormous, although the capacitance to a cloud is small. 1 million volts and dryish conditions needs a gap of about 1 metre on a bad day, the grid at 400kV has spaces of about 3 metres worst case, so is resistant but the arc horns will flash over even with a nearby strike. The insulators provide considerably more distance than this although crackle a fair bit when it rains.

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    For some reason too the lightning in the USA tends to be more violent, probably due to temperature and humidity differences. The voltage required to discharge through a km of the atmosphere is enormous, although the capacitance to a cloud is small. 1 million volts and dryish conditions needs a gap of about 1 metre on a bad day, the grid at 400kV has spaces of about 3 metres worst case, so is resistant but the arc horns will flash over even with a nearby strike. The insulators provide considerably more distance than this although crackle a fair bit when it rains.

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