Hi Kim,
Do you have some literature to support this? Not saying it's incorrect, I'm
honestly just curious to read the material.
Sean WA1TE
On Mon, Jun 26, 2017 at 7:28 PM Kim Elmore <cw_de_n5op@sbcglobal.net> wrote:
> I'm a research meteorologist at the National Severe Storms Lab in Norman,
> OK. I don't do Lightning research but know others that do. Here's what I
> know from them: 1) static porcupines don't work, 2) in order to induce a
> noticeably higher probability of cloud-to-ground lightning strikes, an
> object needs to be at least 200 ft above the average surface (not terrain).
> Tree tops become part of the average surface.
>
> Kim N5OP
>
> "People that make music together cannot be enemies, at least as long as
> the music lasts." -- Paul Hindemith
>
> > On Jun 26, 2017, at 15:50, Bob Shohet, KQ2M <kq2m@kq2m.com> wrote:
> >
> > Over the past 18 years, my tall 130’ tower has been hit by lightning
> (not lightening) at least four times that I know of and the shorter tower,
> 100’ at least three times. Both have rebar in concrete with less then
> desirable grounds due to being on ledge. In fact that 130’ has only 18”
> depth of concrete at the deepest point, although I tried to compensate by
> making the base bigger - much 4’ x 5’. Perhaps I have been fortunate but
> there have been no issues with cracking or damage due to lightning
> strikes. I did use No 2 bare copper for the ground for all three legs with
> three – four horizontal ground rods on each because they are mostly shallow
> with depth of 12’ or less (ledge). I have no idea how effective they
> actually are but no issues with anything explosive as a result of the
> lightning. I also use a pier pin (into the cement) and “floating” base on
> each tower so the lightning has had plenty of opportunities to affect the
> concrete if it was going to do so.
> >
> > 73
> >
> > Bob KQ2M
> >
> >
> > From: Gary Schafer
> > Sent: Monday, June 26, 2017 4:29 PM
> > To: 'Patrick Greenlee' ; towertalk@contesting.com
> > Subject: Re: [TowerTalk] Lightening
> >
> > It can happen. Several years ago I had my boat docked at a friends place
> and
> > a palm tree got hit by lightning. The concrete seawall about 10 feet away
> > had a large chunk blown out of it. This was a salt water canal. There was
> > rebar in the seawall.
> > It didn't do any damage to the boat except for the compass being off by
> > about 90 degrees for about a month and it slowly returned to normal.
> >
> > In another life I used to write subcontracts for two way radio tower
> > installations so I saw quite a few towers mounted on and in concrete. In
> > that time I did see a few foundations that cracked due to lightning
> strikes
> > on the tower. However most if not all of those towers did not have
> auxiliary
> > ground rods at the base of the tower.
> >
> > 73
> > Gary K4FMX
> >
> >> -----Original Message-----
> >> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
> >> Patrick Greenlee
> >> Sent: Monday, June 26, 2017 1:32 PM
> >> To: towertalk@contesting.com
> >> Subject: Re: [TowerTalk] Lightening
> >>
> >> There seems to be an urban myth in popular circulation about foundations
> >> being subject to being blown to bits or at least cracked open
> >> sufficiently for them to fail due to lightning. If this were a real
> >> threat wouldn't it be common experience with Ufer grounds? Can anyone
> >> provide a reference to a properly documented incident where lightning
> >> blew apart a foundation?
> >>
> >> I'd be happy to abandon my current thinking and get on board with the
> >> lightning blows up concrete folks it there were sufficient factual
> >> evidence.
> >>
> >> Patrick NJ5G
> >>
> >>
> >>> On 6/26/17 11:23 AM, Clif Keely via TowerTalk wrote:
> >>> Reading through some of the comments here recently have me trying to
> >> recall some of the comments I have read over the years. I seem to
> >> recall several that spoke to using 2 or 3 ground rods on a tower which
> >> might not be a bad idea. I should think one of the reasons would be to
> >> keep the discharge energy from making steam within the concrete base and
> >> that explosive burst of steam, producing a lot of cracking within the
> >> block and with that reducing it's ability as a solid base. I have no
> >> research to support this but offer it only as a thought. For myself if
> >> I hear thunder I disconnect antenna and power cables. After that I keep
> >> my fingers crossed as I think lightning will do what ever it bloody well
> >> wishes.
> >>> _______________________________________________
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