[TowerTalk] Lightning... and pointed rods!

[Brian Smithson]

I have absolutely no scientific basis for this, but I grew
suspicious of the real effectiveness of those porcupines as
I was coming home from as business trip. We were landing in
low clouds passing near some power lines. Those power towers
are higher than my towers and yet they still seemed pretty
small even at 'final approach' altitude. Sure seems hard to
believe any sort of 'spiny ball' on one of them would have
much affect on cloud/ground charges.

-Brian n8wrl

> -----Original Message-----
> From: owner-towertalk@contesting.com
> [mailto:owner-towertalk@contesting.com]On Behalf Of David Robbins
> Sent: Thursday, October 26, 2000 3:57 PM
> To: Bob Wanderer
> Cc: TOWER REFLECTOR
> Subject: Re: [TowerTalk] Lightning... and pointed rods!
>
>
> its just not possible to neutralize the charge between the ground
> and cloud that
> way.  compare the currents measured on the downlead from one of
> those things to
> the total charge of many coulombs built up between the cloud and
> ground.  also
> the ions produced by the area of corona around those spikes travels
> way too slow
> to ever get near the cloud.  the shielding effect of the cloud of ions would
> also probably cover too small an area to be really useful and would be blown
> away easily in a wind.  there are two reports that i know of that
> have studied
> them in detail, both concluded that they didn't work as advertised.
>  i have also
> read other articles from the international conference on lightning
> protection
> that basically debunked them.
>
> To quote John Anderson (consultant to where i work on lightning protection
> design software) from a recent class we gave on lightning
> protection design for
> transmission lines:
>
> <quote>
> Abdul M. Mousa, "The Applicability of Lightning Elimination Devices to
> Substations and Power Lines," IEEE Transactions on Power Delivery, Vol. 13,
> No. 4, Oct. 1998m pp. 1120-1127.
>
> Paper was peer-reviewed by six reviewers under threat of lawsuits. Paper
> states that these devices do not work as the manufacturers claim.
>
> 1997 Report on Dissipation Arrays, funded by FAA, Naval Research Labs, NASA,
> and USAF
>
> The report, 274 pp., compiled by 17 scientists and engineers from around the
> world, provides no definitive physical or theoretical evidence that
> lightning dissipation arrays prevent lightning. The USAF presented photos
> showing the arrays being hit by lightning.
> <unquote>
>
> unfortunatly these spiney things have become a fad and have gathered many
> supporters who claim they work.  but as stated other places most of the
> improvement is probably due to simultaneous improvement in grounding or just
> plain luck.  we have done other studies that show year to year variations of
> 10:1 or more in the numbers of strokes to the ground over fairly
> large areas.
> so it would not be surprising to have several strokes to a large building or
> airport one year then nothing for the next several years... of course if you
> installed hedgehogs after the first year they are credited with
> protecting you
> the next couple years.
>
> Bob Wanderer wrote:
> >
> > Sorry, Norm, but the spline balls working that way (as they
> > were originally touted) is just not true (please substitute
> > a much stronger but politically incorrect term).  When I was
> > at PolyPhaser, we used to provide a video from two TV
> > stations and the FAA in Tampa proving the incorrectness of
> > these beliefs.  The one from the FAA (just before the camera
> > stopped running) clearly shows one of these "hedgehogs"
> > being hit.  The FAA was interested in them (for obvious
> > reasons) until the truth became obvious.  Then they were
> > touted in another manner.
> >
>
> --
> David Robbins K1TTT
> e-mail: mailto://k1ttt@berkshire.net
> web: http://www.berkshire.net/~robbins/k1ttt.html or http://www.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://k1ttt.net
>
> --
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