[Novalug] outdoor ethernet cable, falacy of lightening arrestors.
James (Jim) Darlack
jmdarlack at yahoo.com
Mon Jul 9 18:45:17 EDT 2012
It doesnt have to carry the lightening, just give it a lower impedance than other paths. Hense, lightening rods.
At.. what is the rule of thumb in atmosphere at sea level.... 1/4"=10,000 Volts?
Soooo. how many quarter inches between earth/ground, and a storm cloud.
And, with that high voltage, and incredible high frequency, since it is a pulse, and mammoth amounts of current? Definately it has a mind of its own.
One of the funniest fads, were lightening rods, with round 1/4" or smaller aluminum wire from the rod to ground, even if it had a loooooong grounding rod, salt liberally sprinkled with lots of water to let it soak. One minor zap, and any round conductor offers such a lower impedence to the pulse? Vaporized. May help channel the lightening. And generally single shot solution
The solution, typically, is a very thin, 2" or wider copper foil from the lightening rod, to the ground rod, with NO kinks. Flat is far lower impedance to lightening/pulses.
And lets not get starte how to EMP proof an encousure! Faraday cage? Been there, did that, RF continues to leak in.
SCIF? Hmm... I hope that it is never tested for EMP... accept in a certification labroatory.
What we do for EMP testing, is a pittance to the real thing, ie, ligthening and air bursts.
And to boot, years ago, there was a presentation that indicated to run wires thru conduit, and that wasnt necessarily EMP proof. At best, it is MASA (mutually assured stone age).
Soooo keep all tube radios, old manual generator, and get lots of excercis, touching your toes. One day it may come in handy to bend over, and kiss the world good bye. At least, you possibly will have an interesting final view.
Totally UN-CLASS, college physics. Who knows what is recomended today.
South West email, we will get letters... Flame on, my friends.
From: Alex Smith (K4RNT) <shadowhunter at gmail.com>
To: James Ewing Cottrell 3rd <JECottrell3 at comcast.net>
Cc: novalug at calypso.tux.org
Sent: Monday, July 9, 2012 4:15 PM
Subject: Re: [Novalug] outdoor ethernet cable
You seriously doubt that it could happen?
While I do wish him well, it's an awfully risky move, and I doubt it complies with building code.
On Mon, Jul 9, 2012 at 6:04 PM, James Ewing Cottrell 3rd <JECottrell3 at comcast.net> wrote:
On 7/9/2012 5:56 PM, Alex Smith (K4RNT) wrote:
>If anyone in the neighborhood gets struck by lightning, both houses will
>>probably go up in flames, since copper does conduct electricity. They
>>should have used fiber.
I forgot to mention...one is a Rabbi...God will protect them :)
>But seriously, if lightning hits the middle of the wire, do you think 8 strands of #22 wire will carry the energy to either house before they melt?
>On Mon, Jul 9, 2012 at 5:36 PM, James Ewing Cottrell 3rd
>><JECottrell3 at comcast.net <mailto:JECottrell3 at comcast.net>> wrote:
>> I knew two guys who stretched an ethernet cable across the street
>> between their houses. It was draped between two trees to cross the road.
>> They were both Orthodox Jews in the Orthodox section of Pikesville, so
>> it's unlikely their neighbors will complain.
" ' With the first link, the chain is forged. The first speech censured, the first thought forbidden, the first freedom denied, chains us all irrevocably.' Those words were uttered by Judge Aaron Satie as wisdom and warning... The first time any man's freedom is trodden on we’re all damaged." - Jean-Luc Picard, quoting Judge Aaron Satie, Star Trek: TNG episode "The Drumhead"
- Alex Smith (K4RNT)
- Dulles Technology Corridor (Chantilly/Ashburn/Dulles), Virginia USA
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