Cone of protection is addressed.
Volume 1 is theory, volume 2 is application.
The military requires 1/0 cable exterior to the building, commercial
practice is #2AWG.
Ground rod spacing is address.
Overall a very good reference based on practical experience and backed
with theory.
73
Glenn
WB4UIV
On 8/6/2016 1:19 AM, Bill Hawkins wrote:
Hi Glenn,
Your advice is excellent.
Seems like every time we have a lightning discussion there is no
distinction between an EMP and a direct hit.
I started work in 1960 at a blasting cap plant in upstate New York. The
powder magazines were protected by tall masts according to the "cone of
protection" theory. The angle of the cone varied between 45 and 60
degrees. The earth ground resistance of the mast was measured by a
hand-cranked device that looked like a megger but read earth resistance
to less than a tenth of an ohm. Had the lightning but never lost a
magazine.
You say MIL-HDBK-419 covers EMP. Does it also cover cone of protection
for direct hits?
I was fascinated by the idea that a simple capacitor discharge into an
inductor could be greatly enhanced by reducing the diameter of the
inductor with a conventional explosive, described in one of Stephen
Coonts' books, if my failing memory recalls correctly. And so I learned
what I could about EMP. Never built anything, just interesting behavior.
Best regards,
Bill Hawkins
-----Original Message-----
From: time-nuts [mailto:[email protected]] On Behalf Of Glenn
Little WB4UIV
Sent: Friday, August 05, 2016 9:47 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts]GPS antenna selection - lightning
A very good reference for EMP protection is MIL-HDBK-419.
This is downloadable for a number of web sources.
It is about 600 pages and is in two volumes.
This discusses a number of different sources of EMP such as nuclear and
lightning.
A lot is for protection of military industrial complexes, but, there is
a lot that pertains to us.
I worked for a military complex that assembled nuclear missiles.
The site was built to this handbook specs.
We had no EMP related damage at the site.
Number one rule, bond all grounds together. If something on your
property takes a hit, you want everything on your property to elevate to
the same level and the same rate.
If you have multiple, non bonded grounds, there is a different reference
for each ground. This is a major source for disaster.
I spent seven years in lightning mitigation. I was told by professionals
that I was wrong. The third time that their tower was struck, destroying
all of the lights and attached equipment, they followed my
recommendations. That was ten years ago. The three hits were within four
months of each other. The site has been free of destructive hits since
then.
73
Glenn
WB4UIV
--
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Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV [email protected] AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
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