To: | wrt@dslextreme.com, <towertalk@contesting.com> |
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Subject: | Re: [TowerTalk] Ground Rods |
From: | Jim Lux <jimlux@earthlink.net> |
Date: | Tue, 04 May 2004 09:49:09 -0700 |
List-post: | <mailto:towertalk@contesting.com> |
At 08:07 AM 5/4/2004 -0700, Bill Turner wrote:
On Mon, 3 May 2004 18:38:26 -0600, Grillo's wrote: The voltage in a lightning stroke is immaterial (mostly because it's spread over many thousands of meters of air), but the current is what does the damage (or, in some cases, the di/dt, which induces a voltage in nearby conductors). The goal is to keep the voltages in your system low enough to be reasonably handled. Figure 25kA for a typical lightning stroke.. 25kA at 5 ohms is 125V.. not enough to flash over in air and well within the transient suppressing ability of many devices. 25kA @ 300ohms is 7500V, more than enough to flashover to adjacent conductors, and well beyond most transient suppression devices. So.. reasonably low impedance is a "good thing", although the practical difference between 5 ohms and 10 ohms isn't all that signficant. Jim, W6RMK _______________________________________________ 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@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk |
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