Hi,
A number of years ago, I attended a lightning demonstration at
the Boston Museum of Science. During this demonstration, the lecturer
was inside a steel cage while lightning bolts were created by a Van de Graf
(sp?) generator. The bolts were very bright, and the noise was so loud
that I wished I had brought earplugs with me. (Only a little louder than
the bolt which was unleashed directly over my house last night and which
woke me out of a dead sleep.)
After the lecture, I had the chance to talk to him personally. I
had recently put up a 100 foot tower which was the tallest object for many
miles. (It was so high in reference to the rest of the local geography
that from its top I could see more than 30 water towers, and also on a clear
day I could see the tops of the power lines going over the Cape Cod canal,
which I presume to be on the order of 15 miles distance from my QTH. I asked
him why I had not received any lightning hits. He said that lightning does
not automatically hit the highest item in the area. When a bolt discharges,
he said it heads toward ground and will only deviate about 20 to 30 feet in
any direction. Thus it would be theoretically possible for a lightning bolt
to directly hit the ground 50 feet from my 100 foot high tower if the land
was cleared all around it.
My tallest tower is now only 85 feet tall, yet I have had towers
above tree level for almost 15 years and have yet to experience a lightning
hit. The towers are grounded, yet I am not sure how good the ground is at
this point in time. To what do I attribute my lightning-free experience?
Only Divine providence. However, the moral of the story is that you should
not expect to be safe from lightning strikes simply because there are taller
objects nearby than your tower.
73, Dave Clemons K1VUT
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