The purpose of franklin style lightning rods is to provide a preferred point
for the stroke to attach and then provide an easy path to ground for the
current. There is nothing you can do to 'drain' the charge away since it is
being attracted straight out of the earth by the charge built up at the
bottom of the thundercloud. The best you can do is provide the sharp point
to initiate a streamer to connect to the downward moving leader and then
keep that current out of your building.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Patrick Greenlee
Sent: Saturday, August 08, 2015 16:19
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Static Discharge Porcupines?
My quick literature search showed the US Navy and others tested the ESD
(Electrostatic Dissipation devices AKA porcupines) and found them to not
reduce the frequency or number of lightning strikes on their test
structures.
Seems counter-intuitive to me but I can't argue with their results as I have
no experimental results to the contrary. From what I read the porcupines
can't handle the currents required to prevent the charge building up and
having a strike.
I'm sure folks in the business of selling protective devices put the best
face on their product as possible but...
In my early years I was taught that lightning rods were to prevent a strike
by draining off the charge preventing a build up sufficient to make for a
strike and to be well grounded with low resistance-low inductance paths to
ground in case they took a strike. Oh well, empiricism trumps theory and or
wishful thinking.
Patrick NJ5G
On 8/7/2015 10:12 PM, Jim Lux wrote:
> On 8/7/15 7:39 PM, Tony wrote:
>>
>> All:
>>
>> I came across this video from Nott Ltd that describes how their
>> static discharge arrays or "Porcupines" help disapate static
>> electricity to prevent lightning strikes.
>>
>> https://www.youtube.com/watch?v=JYILAHIx2lk
>>
>> I understand they are used in several industries including
>> communications towers and was wondering if anyone has experience with
>> them. Installation is easy enough, but I wonder how this work work
>> with crank-ups?
>>
>
> Totally ineffective.
>
> You're not going to "dissipate" the charge in a thunderstorm.
>
> http://lists.contesting.com/_towertalk/2004-07/msg00971.html has a
> discussion. Run back and forth in the thread for more discussion.
>
>
>
>
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