Well, I plan to build a 40' tower... I don't expect it to get hit with or
without the porcupine due to the three taller towers around it!
Chuck W5PR
:-)
On Mon, Jun 26, 2017 at 7:15 AM, David Robbins <k1ttt@verizon.net> wrote:
> So, just how often does a tower get hit... lets look at some statistics and
> physics. A 40' tower guyed with steel wire may collect lightning strokes
> from a 100' square area, more or less, but probably not much more. This
> accounts for some attraction, the rolling ball, ieee estimates of
> attraction
> of strokes to tall structures, etc. Now, how many strokes would you expect
> in that area per year... from NLDN data there are about 25 lightning
> flashes
> per square mile per year in central florida, the lightning capital of the
> states. Multiply, divide, invert, like 1/(((100*100)/(5280*5280))*25)
> gives
> you something like 1 lightning strike every 100 years in that 100' square,
> some rounding applied. Now most of the rest of the country only has 5 to
> 10
> flashes per square mile per year which makes that more like 1 strike every
> 250 to 500 years. And lets see, most lightning causes little or no visible
> damage if the tower is properly grounded... a small blackened crater may
> show for a fresh one on a steel tower, maybe more obvious if it hits an
> aluminum tower or antenna, but after a while they will look like a rust or
> corrosion pock mark... so if you aren't watching you may not even know your
> tower got hit, so factor in the percentage of time you are actually
> watching
> your tower during thunder storms, and how likely does that make it that you
> would see your tower get hit!
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt@arrl.net
> web: http://wiki.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373
>
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
> Chuck
> Dietz
> Sent: Monday, June 26, 2017 11:48
> To: David Gilbert
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] Fwd: Interesting Site
>
> Oh no, all u guys are wrong! I have had one of those on my 40 foot tower
> and
> have never been struck by lightning...
>
> Chuck W5PR
>
> :-)
>
> On Mon, Jun 26, 2017 at 1:35 AM, David Gilbert <xdavid@cis-broadband.com>
> wrote:
>
> >
> > A good indication of the voodoo "science" involved in that link is the
> > fact that he built it with 500 (!) points. Ask yourself what 500
> > sharp points would do that a few pointed different directions
> > wouldn't. In fact, pack enough points grouped close together and you
> > make the static field effect approximate a smooth sphere.
> >
> > I'm always amazed that a hobby like ours, supposedly based in physics
> > and the real world, perpetuates so much garbage like this ...
> > especially when there are much more rigorous studies readily
> > accessible out there on the internet to debunk it.
> >
> > Dave AB7E
> >
> >
> >
> > On 6/25/2017 2:32 PM, Hans Hammarquist via TowerTalk wrote:
> >
> >> This topic has been discussed too may times and there seems to be
> >> nobody with a definite answer. I have dissipators on my own tower.
> >> They are rather easy to make. I haven't gotten any lightning strikes
> >> in them during the few years the tower been up. That doesn't mean
> >> they are effective. I have notice that I have had no strikes on my
> >> house, something that happened on a relatively regular basis, since
> >> the tower went up. I think the tower itself was the contributing factor
> to that, though.
> >>
> >> I had a 0-0, stranded aluminum cable at hand when I raised the tower
> >> and decided to put three, one on each leg, of them up. You can view
> >> they on my facebook page. Does it work? Honestly, I have no idea. I
> >> do think that you can build these dissipators yourself for a much
> >> lower price than what they are offered at.
> >>
> >> With 73 de,
> >>
> >> Hans - N2JFS/SM6BXX
> >>
> >>
> >> -----Original Message-----
> >> From: Don W7WLL <w7wll@arrl.net>
> >> To: Towertalk <towertalk@contesting.com>
> >> Sent: Sat, Jun 24, 2017 11:25 pm
> >> Subject: [TowerTalk] Interesting Site
> >>
> >>
> >> Ran across this looking for something else and noticed a section on
> >> towers, grounding and other items we are all interested in. Sample
> article.
> >>
> >> http://www.thebdr.net/articles/steel/twrs/TT-dissipators.pdf
> >>
> >> Don W7WLL
> >> _______________________________________________
> >>
> >>
> >>
> >> _______________________________________________
> >> TowerTalk mailing list
> >> TowerTalk@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/towertalk
> >> _______________________________________________
> >>
> >>
> >>
> >> _______________________________________________
> >> TowerTalk mailing list
> >> TowerTalk@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/towertalk
> >>
> >
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|