To: | Jim Brown <jim@audiosystemsgroup.com>,"Tower Talk List" <towertalk@contesting.com> |
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Subject: | Re: [TowerTalk] Conductive Concrete and Grounding |
From: | Randy <randy@verizon.net> |
Date: | Tue, 25 Jan 2005 23:25:16 -0500 |
List-post: | <mailto:towertalk@contesting.com> |
At 09:43 AM 11/19/2004, Jim Brown wrote:
Gentlemen, <snip> Jim Brown K9YC Jim: My personal, layman's point-of-view is that lightning is wicked, wicked stuff, and largely refuses to do what is expected of it. It *will* cause concrete to explode exactly like wood, trees, etc., i.e. the sudden vaporization of the moisture within causing a violent expansion thereof. It likes to jump into and out of conductors, I suppose due to the inductance it "sees" as well as the electrolytic charging of whatever (normally) non-conductors it's trying to drain into, and probably a host of other variables I'm unaware of. I locate underground water leaks for a living, and I can tell you that lightning wreaks havoc on copper systems, "almost" always from a strike to the AC mains, the cold pipe generally being tied to the ground/neutral buss at the breaker panel (sometimes the hot line is also bonded to the cold at the water heater, which is where the connection to the panel is usually made, hereabouts anyway). Personally, I wouldn't want such a system in either a residential setting for safety of persons and equipment, nor would I want it in a tower base for structural considerations. I have no idea whether a potent, direct hit could cause such a failure, but in any event I think you'd want to Cadweld each and every point where the rebars crossed, and I wonder whether the flexing of the bars during the pour might crack the joint. Also, bear in mind that concrete is caustic to such an extent that a copper pipe in direct contact with it will, eventually, most likely leak, so I'd have to question the long-term viability of any copper conductor passing into the concrete; I think you'd have to bring the steel outside of the concrete and bond to it above ground, preferably. I was under the impression that Ufer grounds were only in use as a last resort, i.e. desert conditions, but I could be wrong... 73 de KZ4RV Randy _______________________________________________ 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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