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Author Topic: Lightning Protection - Ladder Line Doublet specific  (Read 28740 times)
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WB2CAU
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« Reply #25 on: July 13, 2005, 07:02:31 AM »

Quote from: K1JJ
"This theory contends that the old lightning rod on the barn was
the right thing to do for the wrong reason. "


Yep, agreed!

Here's some actual experience:  

I would say that neighbors should be happy that a ham's tower
is protecting their neighborhood. And it's not by attracting strikes
away from their houses, but instead, bleeding off the charge for
the area. I have read that a tall tower will neutralize an area of
at LEAST 1/2 mile radius.... but have no scientific data to prove
this.

Before I put up towers here, I would get many, many strikes
during summer storms in the immediate area. You could count
the seconds and know they were real close, and even see
damaged trees in the woods. And, I had my share of ruined
computer cards, telephones, etc.

But now, if you were to go to the next set of hills and look at the
site here, you would see a hill top with 190' towers sticking up
high above the hill top tree line- in the clear. Common sense would
say they should be hammered all the time. But guess what? I
can't remember when these towers were hit last! It appears
they bleed the charge off and protect the area. I still hear smaller
trees getting hit within 1/2 mile or so, but not the towers. I find
this interesting.  

They are all well grounded with 15 miles! of 160M ground radial
system tied in underground. All towers are tied together underground.

So, here's an actual experience supporting the idea that a lightning
rod is for bleeding and neutralizing - and if hit, well, it will also form
a Faraday cage around the building as a bonus and pass high current
for an instant.

I look at it like one of those dragging leather straps you see under
cars sometimes. The car is kept at the same potential as the road
and the charge built up from the rubber tires spinning on the road is
bled off.

So, your ho doesn't get belted when she steps out of your ride with
her 9" spike heels.  

73,
T


Tom, I think there's substance to this theory.  I also believe that there might be some statistical evidence to back it up if we had access to it from the insurance companies.

The average home today does not have any metal protrusions as it did in years past. In the 50s, 60s, and 70s, everyone had a TV antenna that should've been properly grounded offering the kind of protection you describe.  Today's average home does not.  Using this logic, and your theory, it would seem to conclude that lightning strikes upon homes would be statistically higher lacking this dissipation path to ground.  Is the data regarding this kind of statistic available on the web? I would believe that a dip in statistics during the "antenna" decades would be overwhelming evidence to add scientific credibility to this.

I had mentioned this in a previous post (a few years ago) and no one responded.

BTW, Tom Vu, another great avatar!

Eric - WB2CAU
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K1JJ
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"Let's go kayaking, Tommy!" - Yaz


« Reply #26 on: July 13, 2005, 11:36:47 AM »

Hi Eric,
Very interesting observation.

Yes, with most TV antennas using an aluminum ground cable
to Earth ground, this statistic would possibly work. Though, the
ground usually consists of only a short steel or copper rod and
may be in the order of 20 ohms+ depending upon ground conductivity.  
But something is better than nothing when it comes to bleeding
off a charge.

That wud be a good question to pose to a actuarial manager at a
large insurance company. I'll bet he wud sit up and think of it as
mind food to ponder.  But becuz lightning strikes on house are so
rare, it probably has not gotten much attention. If they were
real common, you can be sure insurance comapnies wud
have required lightning rods by now, or the rates wud be
adjusted accordingly. Just like when you own a dog with a biting
history or drive like a drunk.

73,
T
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WA1GFZ
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« Reply #27 on: July 13, 2005, 11:38:52 AM »

I wonder if your avatar could produce enough static to do some real world testing if she was up on the peak of the roof.
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