I was the first to use the term "exploding tower base" in this discussion. The term "exploding" was probably not correct. As several others have phrased it, an instant expansion of steam is more correct. Concrete is never totally "dry" in the context of this conversation.
I witnessed lightening blowing apart the two tower bases I spoke of in person, directly, and in real-time. It happened in the mid-sixties at the St. Petersburg, FL Coast Guard base. As someone else has mentioned; the Tampa Bay region has the highest incidence of lightening in the Western Hemisphere. To the one of you who accused my of lying ... I was there ... you weren't. At the time I was an ET aboard the USC&GS (Now NOAA) Oceanographic Survey ship Hydrographer/WTEI and we were in the area deliberately attracting lightening with balloon-hoisted cables. I -do- know something about the infinite uncertainty of lightning. I'm a retired electric power company two-way radio tech and have probably dealt with more types of towers than most of you. Large electric transmission line towers are almost always set on four concrete piers, and are grounded with (usually) copper straps cad-welded to each tower leg and connected to ground rods a bit away from the cement. Each of us can search long enough to find "facts" that support our various positons, especially on today's Internet. Here in the mountains of the West ... as well other regions ... finding and maintaining a "good" ground at a radio site atop a mountain can be a "challenge". It's almost never done with ground rods. My power company employer has several hundred mountain-top microwave and/or radio sites. Been there, done that, as they say. One responder spoke of fitting a copper pipe with a garden hose fitting and "flushing" it into the ground. That works very well, and is how some of my 14 grounds are installed. It helps if the downward end is partly flattened, BTW. A much bigger problem overall than lightening is water collecting in tower legs, especially in climates where it can rust (undetected) from the inside and / or freeze and split one or more legs. There's an accepted way to avoid this. 73! Ken Kopp - K0PP On Apr 18, 2017 at 4:30 PM, <[email protected]> wrote: > some 40 years ago, maybe longer I put up a 50' rohn 25G tower. Dug the > hole and set the tower base in it alone with a 12' 3/4" ground rod and poured the cement, left about 6" of ground rod protruding. I bonded to that rod and grounded the tower. 3 years later I had a huge lightning strike on my tower and yes.. it cracked that base. never again Ronnie W5SUM > ______________________________________________________________ > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
