[TowerTalk] spider balls

Wed Jul 28 16:55:56 EDT 2004

This whole thread on bleeding off charges from clouds has been interesting,
educational and entertaining to me.  In my case, I cannot image this bleed
theory has any relevance at all.  But others seem to think it is a way to
avoid damage.  To each their own.

At my QTH in Tomball, Texas (25 miles NW of Houston), there have been five
observed strikes on the single 150 foot tower located near the center of the
property.  The tower went up in 1999.  The property is approximately 16
acres, about 850 feet square, and flat as a pancake.  It is one parcel out
of a 100 acre farm that was active until the farmer passed away about 40
years ago.  Soil is sandy loam down to 3 or 4 feet, then iron ore for many
more feet (have dug to 20 feet so far).  There are about 50 large pine trees
scattered about and another 100 or so live oak trees planted in 1985.  The
tract was purchased in 1977.

Lightning has been a frequent visitor to this site.  Before the tower was
erected ten pines were hit and killed.  Since the tower went up not a single
tree has been hit.  So, apparently the 150 foot tower has protected the
average 80 foot trees quite well - so far.

Storms here with lightning are fast and furious.  Dark clouds can seemingly
appear out of nowhere.  There is likely not a spot for miles around that has
never been struck by a bolt.  In fact, I assume that when the next two
towers go up, it will be an invitation for more strikes.

Up until the last two strikes, I never lost a single piece of equipment.  I
felt smug in the ground system design and implementation.  All ground rods
were connected in a single point.  What changed my luck was when we
remodeled the house two years ago and connected to the shack (separate
building with separate AC power lines) with telephone, TV (satellite) and
computer LAN.  The last two strikes killed all phones, everything on the
LAN, and TV service in the shack.  I thought the first strike was a fluke.
Now I realize that these connections are the problem.  The LAN cable has
been removed and will soon be replaced with wireless router.  The TV and
telephone lines will remain, but will be properly grounded at the entry
panel.

Keith

  _____  

From: Jerry Keller [mailto:k3bz at arrl.net] 
Sent: Wednesday, July 28, 2004 3:04 PM
To: keith at dutson.net; 'TowerTalk'
Subject: Re: [TowerTalk] spider balls

Those are pretty big assumptions. Since there are so many variables, and
they likely vary so widely, I doubt the chances that any particular set of
assumptions can represent a "typical" strike for the purposes of discussion
or analysis. I see what you're getting at, but I doubt that lightning
phenomena can yet be defined in terms that would allow predictive
description. We might get close, but not close enough.

You're also assuming that the static build-up happens in a very short time,
immediately prior to the strike. What if the ground potential sometimes
"bleeds" off more slowly (or in a relatively long time, as it accumulates)
so that the potential doesn't rise to the strike level?

The phenomena over their antenna fields, described by John, W0UN and Don,
VE6JY, as viewed by them from vantage points where they can see the storms
come and go, cannot be dismissed simply because they seem inconsistent with
current theory.

73, Jerry K3BZ

----- Original Message ----- 
From: Keith  <mailto:kjdutson at earthlink.net> Dutson 
To: 'TowerTalk' <mailto:towertalk at contesting.com>  
Sent: Wednesday, July 28, 2004 2:54 PM
Subject: RE: [TowerTalk] spider balls

There is little doubt that porcupines will help bleed off static charges
better than nothing at all.  However, a lightning strike has little to do
with static charge bleed off.  Instead, a strike is the result of the
buildup of a huge potential in rapid succession (a matter of seconds in many
cases).  Assume that a bolt of lightning originates from a height of 1000
feet and is going to ground rather than horizontal within the cloud.  Also
assume the potential must be about 20KV to jump an inch.  The 1000 foot arc
would require a minimum potential of approximately 240 million volts
(1K*12*20K).  Can you imagine what would happen if the little porcupine ball
were to bleed off just 10 percent of this potential to avoid a strike?  Can
you say vaporization? <grin>

Keith

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Chuck Dietz W5PR
Sent: Wednesday, July 28, 2004 12:29 PM
To: 'Towertalk Reflector'
Subject: RE: [TowerTalk] spider balls

If you have ever heard the static buildup on big antennas when a storm is
nearby, it will make you a believer that the porcupines might work.  I have
no empirical evidence, but how can it HURT???

Chuck W5PR

_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.

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_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.

_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk