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From: Ron Youvan[SMTP:ka4inm@gate.net]
Sent: Saturday, August 21, 1999 2:19 AM
To: Tower Talk
Subject: Re: [TowerTalk] Lightning 'porcupines' & rods
Hi:
<< it's a lack of proper grounding which allows excessive static charge
buildup to initiate a skyward moving leader. >>
I was definitely taught: the leader is produced when the charge in the ground
traveling under and with the charged cloud/air mass is conducted (through
(ground based) conductors (with sufficiently low resistance) up to a point
where the potential difference exceeds the breakdown requirement of
the medium (air + rain {if any}) if the conductor can support the current
flow the lightning stroke will result, otherwise the stroke CAN be blown by
air flow (wind) onto other nearby objects, with sufficient potential
difference many non-conductors can be caused to conduct an electron flow.
Good grounding with high current carrying capacity enhances the ability
to cause the needed leader, the mass (current holding ability) of the structure
(inversely) controls how much ground current will occur from each stroke.
If enough electron (or holes) can get into the tower (fast enough) before
the stroke occurs, (the next stroke) the ground current will not rise to
levels that cause damaging differences (between the power ground and
telephone ground, and the tower ground etc.)
I have been told by several tower construction crews and repair persons:
if its over 1,000 feet tall (which infers a 6' face or greater) you will not
have any problems from lightning. This seems to be true. I have watched
lightning strike the tower I work at and all of the towers around hundreds
of times (within 10 or 15 minutes), faster than a machine gun with no damage
resulting. (the guys I work with wouldn't climb a 1,000' tower with a 3' face)
What is wrong with my understandings?
EVERYTHING!!!
73 (= Best Regards) de Ron ka4inm@qsl.net
VISIT my HAM WEB SITE at: http://www.qsl.net/ka4inm
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