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Re: [TenTec] RE: Power Supply & Equip. grounding

To: <tentec@contesting.com>
Subject: Re: [TenTec] RE: Power Supply & Equip. grounding
From: "Stuart Rohre" <rohre@arlut.utexas.edu>
Reply-to: tentec@contesting.com
Date: Thu, 11 Dec 2003 16:45:20 -0600
List-post: <mailto:tentec@contesting.com>
Lightning protection technology has changed over the years.   The heavy duty
woven down leads were used before WW2 in a British colonial school lightning
rod installation I know about. (Where I taught in the mid 60's).

The woven down leads you describe are probably similar and a far more robust
than flat copper braid familiar to most hams.  However, it has been known
for many years in RF Engineering that wide flat solid copper conductors have
the lowest self inductance, and thus the least choking effect on a surge of
lightning current.  Strong magnetic fields accompany the down stroke and can
blow apart lighter gauge strands of wire, in a fusing effect.

What you describe on the FAA facility also acts as a static charge
dissipation array of sharp pointed conductors, and is planned to bleed off
charging that might produce a full stroke, thus the woven conductors may not
ever take a direct hit, if the points continue to function over the years.
It all depends on the maintenance of the earthing electrodes, water table,
soil conductivity etc.  The whole system has to be working to get full
protection.
-Stuart
K5KVH


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