From: WarmSpgs@aol.com
Message-ID: <6c.c6cfce8.2870f2fe@aol.com>
Date: Sun, 1 Jul 2001 17:41:18 EDT
Subject: Re: LF: Lightning
To: rsgb_lf_group@blacksheep.org
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In a message dated 7/1/01 3:22:38 PM Eastern Daylight Time, sm6pxj@swipnet.se 
writes:

<< I have chosen to ground the antenna in a separate ground stake, with no 
connection to the main station gnd. >>

This strikes me (no pun intended) as a very good idea.

In broadcast practice, our masts are normally earthed to as effective a 
ground system as we can possibly achieve.  Even so, however, when lightning 
does strike the tower, the whole earth system rises above local terrestrial 
average potential for a brief moment.  During that interval, current will 
attempt to flow--no, let me amend that--current WILL flow through any 
convenient conductive path away from the immediate vicinity.

When the potential of the station earth is raised this way, the resulting 
current often passes through equipment on its way out to the electric mains 
and their ground system, telephone lines and other cables, etc.  Heavy-duty 
commercial gear is designed to handle a certain amount of this mistreatment 
by Mother Nature, but even so, damage is a common result.

At home, however, I've had personal experience with what happens when the 
local ground gets elevated above the potential of the rest of the world by a 
relatively small nearby strike (about 25kA).  Satellite receivers, computer 
modems, videocassette recorders, etc., are not nearly as sturdy as a 
broadcast transmitter!

Therefore, if your provide a preferred path to earth that is as independent 
of your radio shack's ground system as possible, the chances of protecting 
your ham equipment are significantly improved.

73,
John