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I have a quick question about lightning ground rods. We had a Kohler generator large enough to power most of the house installed for my 82 year old mother. The installer ran the line connecting it to the breaker box inches away from a grounding rod. My mother’s house had never been struck by lightning in the 40 years before but now it has been struck 4 times in 3 years. The generator was also struck these times. Could the line's proximity to the grounding rod be causing the damage after a strike?

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Since there is electrical proximity to the lightning rod it is not surprising that the generator was also struck.

Because of the high energy and current levels associated with lightning (currents can be in excess of 150,000 amps), and the very rapid rise time of a lightning strike, no protection system can guarantee absolute safety from lightning. Lightning current will divide to follow every conductive path to ground, and even the divided current can cause damage. Secondary "side-flashes" can be enough to ignite a fire, blow apart brick, stone, or concrete, or injure occupants within a structure or building.

You do not give enough details of the generator, is it powered by gas ?

One has to understand how lightning strikes: There are downward leaders and upward streamers,:

When a stepped leader approaches the ground, the presence of opposite charges on the ground enhances the strength of the electric field. The electric field is strongest on grounded objects whose tops are closest to the base of the thundercloud, such as trees and tall buildings. If the electric field is strong enough, a positively charged ionic channel, called a positive or upward streamer, can develop from these points.

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As negatively charged leaders approach, increasing the localized electric field strength, grounded objects already experiencing corona discharge exceed a threshold and form upward streamers.

So the addition of a grounded metallic structure close to the lightning rod, which is designed to throw upward streamers (as the lightning rod is) so the lightning falls on it, will enhance the streamers.

There are articles connecting pollution with lightning.vIt might be that the exhaust of the generatro next to the lightning rod enhances the upward streamers too.

It might be that both these effects are at work, although the statistics is not high enough( yet?) Maybe you should change the location of the generator , or get one of the modern lightning protection.

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