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Re: [TowerTalk] Porcupines and other wives tales

 To: "'Jim Jarvis'" , Re: [TowerTalk] Porcupines and other wives tales "Keith Dutson" Tue, 4 Jul 2006 15:03:56 -0500
 ```>The measured energy of the strike is not the point here. The point is to try and prevent the charge build up to where the strike occurs. Well, if you are going to prevent a strike, you basically have to bleed off all of the strike energy. I don't think that is possible. A cloud that is charged by the conventional rain drop method does not have the potential to form a strike. This charge has been measured just prior to a strike and found to be far short of the potential required to draw the arc. The latest theory is that random cosmic rays strike the cloud causing a portion to be supercharged. The question is now how fast does this happen? I certainly do not know the answer, but if it is a matter of seconds, there is nothing that can bleed off the charge and stop the strike. 73, Keith NM5G -----Original Message----- From: towertalk-bounces@contesting.com [mailto:towertalk-bounces@contesting.com] On Behalf Of Jim Jarvis Sent: Tuesday, July 04, 2006 1:59 PM To: towertalk@contesting.com Subject: [TowerTalk] Porcupines and other wives tales I had tuned out on the water tower-omni antenna lightning protection, and noticed the "porcupine" post. Things morphed somewhat, I see. To avoid forensic reading and proper attribution, let me say that some folks have said some right things....and a few may underestimate the problem or over-estimate the potential for remediation. consider this exchange: Just look up measured energy > of > a strike and compare it to the ability of the porcupine to dissipate > this The measured energy of the stike is not the point here. The point is to try and prevent the charge build up to where the strike ocurrs. -0- The point (no pun intended) is to bleed off the charge faster than the ground charge builds, whether it be moving into the area, building up, or both. If that charge is building on the object faster than it can be bled off and a feeder is produced that connects then the object will be hit. When that strike ocurrs the current comes from an area considerably larger than the tower and contains far more energy than would have been available from the tower. -0- It's all well and good to try and bleed off charge via lightning rods...even 'fattened' ones like porcupines. But those rods have a fixed ability to handle the discharge of an approaching charged cloud. Lifetime of a porcupine with a direct strike is measured in nS. [snip] _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
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