Hi, Gary.
Yes, I agree. I didn't mean to say that concrete cannot explode. It
certainly can, and non-uniform heat accomplishes the task quite well.
I just don't believe that concrete is **more likely** to explode because
it has a good ground wire running through it as some have claimed, and
as you just stated, there doesn't appear to be any verified example
where that has happened. My limited ability to reason through the
process of a lightning strike as I outlined in my previous posting
suggests to me that a properly grounded wire exiting a foundation
should, if anything, reduce the chance for explosive damage. Maybe I'm
wrong ...
As several folks have pointed out, though, lightning is notoriously
capricious and anything can happen. There are hams with tower and
station ground systems that are based upon what might charitably called
superstition who have never had a hit, and we have hams with decently
engineered ground systems who've suffered major damage. Who says mother
nature doesn't have a sense of humor? Maybe she reads these forums and
just likes to mess with us.
Thanks for the reply.
73,
Dave AB7E
Gary Schafer wrote:
> I have seen a few concrete bases cracked from lightning strikes. These were
> all where there was no ground system attached to the tower at all. Just the
> tower attached to the J bolts in the concrete. I can't recall seeing one
> cracked where there was a ground system attached.
>
> A few years ago where I had my boat docked a palm tree was hit by lightning.
> The tree was close to the concrete sea wall and it blew out a chunk of the
> sea wall and concrete shrapnel flew in many directions. I think there was a
> crack in the concrete before the lightning strike so there was probably
> moisture in the crack. So yes concrete can explode.
> The EMP screwed up the compass and a few other things on the boat. The
> compass came back to normal after a few weeks but it had quite an error for
> awhile.
>
> For anyone that disbelieves concrete can explode into shrapnel, if you have
> an acetylene torch (I don't know if a regular propane torch is hot enough)
> just hold the flame an inch or so from your concrete floor in the garage for
> a few seconds and you will get a big bang and a chunk of concrete will
> explode out sending bits everywhere. Wear safety glasses. It doesn't need to
> have a crack in it either.
> I am not saying this will happen in a tower foundation as I have never seen
> it happen there.
>
> 73
> Gary K4FMX
>
>
>
>
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