Lightning is certainly one of Old Mother Nature's principal weapons as well
as being extremely unpredictable. My House/Shack is on the side of a hill
with the Antenna Farm on top of the hill about 120 yds away with an
additional 30 ft. of elevation. There is a metal "lightning rod" extending
high enough to provide a "cone of protection" for the house and is grounded
directly. And there are five other metal antennas on that roof, two to a
separate ground and three to still another which is close to the shack
"ground field" which is three additional ground rods. All ground rods I
mention are the standard 8 ft. copper plated steel items. Each of five
antennas in the antenna field also have individual ground rods and I guess
if you follow the cable shields you could say that they are all connected
together. A couple of years ago I counted all ground rods and came up
with 23. Before all of the metal was added and the "lightning rod" was the
only metal extending about 20 ft. above the roof and we had an electrical
storm my wife would complain that she could feel her hair trying to rise in
response to the field coming from the cable which ran across the roof and at
it's closest point was only 6-7 ft. from her head as the crow flies. But
after all the additional metal was added in the form of antennas with
grounds she no longer complained.
I do not claim to understand what goes on around here at an elevation of
about 102 ft. above the valley floor but I believe that we have been
"fortunate" (or lucky if you prefer that word) and we have so much metal in
the air that most "discharges" are not of the type that is accompanied by
thunder! Two years ago we had a tree die that was no more than 30 ft. from
the house. Since I have not always been able to accurately predict where
trees will fall that I cut myself I hired a professional to take it down and
he took one look at it, reached up and stripped off a piece of bark and
commented, "See those lines? This tree was struck by lightning. That's
what killed it!" But no lightning related damage to structure or equipment
here for nearly 15 years!
My only thought on the subject was that only a fool would fail to disconnect
an antenna that rises above the house roof during an electrical storm. I
freely admit that I have several ham radio VHF antennas (and a GPS antenna
supplying the disciplined system for frequency reference) well below roof
peak level (clear view to south for GPS, of course) that I do not
disconnect from inexpensive radios maintained for the purpose.
This is risk I accept. And I certainly have seen paths followed by
lightning that are truly amazing! ....and horrendously damaging. Never
forget that you only live once and you do have a perfect right to enjoy your
hobby without fear.
Regards,
Lee A. Mushel K9WRU
----- Original Message -----
From: "quartz55" <quart...@hughes.net>
To: "Discussion of precise time and frequency measurement"
<time-nuts@febo.com>
Sent: Sunday, September 15, 2013 12:13 PM
Subject: Re: [time-nuts] New NTBW50AA
. I'm not thrilled having it above the beams, it's the highest metal thing
in the area and most likely more prone to lightning than anything else
excpet the trees and it will blow around a bit up there as well as rotating
once in a while. I did have a strike here once, but it was down by the barn
and was looking for the underground telephone cables, it blew apart a post
and knocked off the boards, it was maybe 100 yards from the shack. It
wouldn't be much of a problem to dig a tiny trench to the fence and I may
try that after this precise survey is done, then do another and see if
anything changes. I could hide it i
n a bird box at the fence too. After all at this point I'm just playing.
I'll eventually make up my mind. Also, I don't have an attic, so that's
not an option.
Dave
N3DT
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