If that was actually the case, I would surmise that the "ground rods" were not connected to a proper rebar cage (i.e., Ufer ground) that would normally be able to able to distribute the lightning current over a sufficiently large surface. Simply putting a couple of ground rods inside a concrete base is folly, but that is not at all the same as having a proper Ufer ground inside the base, nor is it the same thing as running a conductor through the base to a sufficient external ground.
It does not advance the technical competency level of our hobby to make broad generalizations based upon narrow and poorly defined anecdotal instances.
Dave AB7E On 4/25/2018 3:10 PM, Ken G Kopp wrote:
I should have been more specific in suggesting that grounds that might end up carrying a lightening charge not be run through concrete. The following is from personal "real world" experience. I know of two specific cases where tower bases were blown apart by lightning hits to the towers because ... in the interest of "neatness" ... their ground rods were -inside- the concrete bases. These two events took place in the Tampa Bay (St. Petersburg) area of Florida. The Tampa Bay area has the distinction of having the highest number of lightening strikes in the western hemisphere, BTW. I worked aboard a USC&GS (NOAA) ship at the time and we did a lot of lightening-related research. Picture flying a balloon-borne wire to deliberately attract lightening! Concrete is rarely "dry" even after years of "curing". The dampness becomes steam that's instantly created by the current from strike flowing through the ground that's -inside- the concrete. This steam becomes part of the explosion. 73! Ken Kopp - K0PP ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
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