In , w_tom wrote:

Cited was an industry professional who demonstrate simple
protection even for amateur radio installations. He discussed
protection without damage for *all* radios, including
repeaters. You think effective earthing requires what
commercial broadcasters install? Yes, some so deny the power
of earthing. Very little protects radios from most direct
lightning strikes. However some will cry that such earthing
cannot protect from the rare 1%. If earthing is only 99%
effective, then no money should be spent - all earthing is
useless? Reality, effective protection from direct lightning
strikes is about simple and inexpensive earthing. Frank
Gilliland has even posted unrealistic and fictional numbers,
and then denies the power of earthing - a concept well proven
in virtually every town throughout the world.


Now you are starting to twist my words. I never said proper grounding was
ineffective. On the contrary, it's absolutely necessary. And while it -may-
protect a radio against damage from most -nearby- strikes that would otherwise
cause damage (probably the source of your 99% figure), grounding alone is -not-
enough to protect against a -direct- strike to your average CB station, which is
what we were talking about. The method I provided is enough to greatly increase
the odds of the equipment surviving a -direct- strike. My information is based
on over 25 years of real-life field experience as a CB operator, a military
radio tech (USMC), a commercial radio tech, and a broadcast engineer. It is also
based on a BS in Electronics Engineering (specialized degree), the basic laws of
physics, detailed observations and common sense. It is -not- based on a few
internet references that can be easily countered with a few other internet
references.


BTW Frank, to correct your post: low *resistance* (not
impedance) ground is fine for AC line protection. A low
*impedance* ground is necessary for lightning protection. One
must know the difference to understand simple earthing
concepts - and why earthing is so effective. How can you be
so critical of earthing and not even know the most basic of
basics - impedance verse resistance?


Maybe you should read my posts again -- I have already addressed the issue of
inductive and capacitive reactances. Or maybe you don't know that impedance
equals resistance plus reactance. The fact is that lightning covers a wide
spectrum of frequencies, so there is no way to 'tune' your ground for lightning,
and therefore no way to establish a low impedance beyond keeping the resistance
as low as possible.


Even basic numbers such as the typical pulse width are silly
speculation. Typical lightning strike is a classic 8/20
usec. That is microseconds - not 0.1 seconds - which is why
lightning does not have the energy content of myth.


Later.....


Furthermore, 1,000,000 volts does not appear at that
lightning strike. In fact a major destructive direct strike
to the building is well defined in research papers - as to not
exceed 6,000 volts.


What research papers? Where can I read them?


One should first learn the science.
Basic electrical circuit theory makes it obvious why the
millions of volts up there don't appear down here. Either
those millions of volts must be up there or down here - cannot
exist in both locations.


Yes it can. First, you need to understand the basic fundamentals -- Ohm's law. A
bolt of lightning will carry X amps along the full length of its path. So if
that path experiences a point of high resistance, the result is high voltage.
The point of high resistance might be an air-gap device or it might be a fused
ground wire, both of which will put hundreds of thousands, or even millions, of
volts on the line. But for the sake of argument, let's assume that the air-gap
is sparking and the wire isn't melting. Ok, did you pay attention to the ground
rod example? Apparently not. Let's try this again:

10,000 amps x 1 ohm = 10,000 volts

Now I'm sure that you are going to whine about 'impedance', but the fact remains
that no matter how much reactance the ground system may add, it still -adds- to
the resistance, which is 1 ohm (for an exceptional ground, I might add). That
means if there is -any- reactance, or a less than exceptional ground, the
voltage will be HIGHER!!! And I suppose I have to show you the equation again
for a -typical- household ground of 50 ohms:

10,000 amps x 50 ohms = 500,000 volts

Now let's plug in your stroke duration numbers from above:

500,000 volts x 10,000 amps = 5,000,000,000 watts
5,000,000,000 watts x .000008 sec = 40,000 joules
40,000 joules x 5 strokes (average per strike) = 200,000 joules

Are you STILL going to say that lightning doesn't pack a whollop? And why are
you totally ignoring the fact that it doesn't matter how much energy lightning
may carry, but how much energy lands in the wrong place, which is the REAL issue
here?


Again, first semester circuit theory
that every graduate of West Point and Annapolis has learned.


So why haven't -you- learned it?


Please first learn that basic circuit theory before disputing
IEEE papers, other well proven research, and NEC requirements.

Correctly noted is that most people don't climb trees to
search for lightning damage to trees. But then researchers
such as Alan Taylor of the US Forestry Service are not just
most people. Lightning has such low energy that most every
tree directly struck has no appreciative damage. Speculate
all you want. He did the work and wrote the paper.


It's not a matter of speculation. High power doesn't necessarily mean
catastrophic damage, especially where nature and the laws of evolution are
concerned. Live wood conducts lightning very well, probably due to the fact that
lightning happens all the time and trees have had jillions of years to adapt. It
has nothing to do with energy, but survival. If every tree was killed by a
direct strike, there wouldn't be very many trees left on this earth.


Using your reasoning for why earth cannot conduct the
electricity even in a badly polluted salt marsh:


Whoa, hold on there! I never said ANYTHING of the sort -- in fact I said quite
the opposite! A 1 ohm ground rod is damn good, if not impossible! Don't you have
ANY practical experience with grounding, either?


then
obviously lightning could never conduct miles across the sky
and obviously lightning does not strike a non conductive
earth. Why does air conduct miles of lightning that only
contains millions of volts? First learn the many stages of
how air and earth become such excellent conductors. Does a
cloud strike 5 miles diagonal to connect cloud to charges on
earth? Of course not. Lightning travels 3 miles straight
down and then 4 miles through earth to complete a circuit.
Lightning takes a more conductive path via air and earth
rather than an electrically longer 5 mile path only through
air. Conductive earth is also why earthing a direct strike
(the single point earth ground) is such effective protection
from a direct strike.


More and more you are demonstrating that you know very little of the subject.
While I may not know exact figures as to lightning voltage, current, stroke
duration, etc, etc, it's because the differences are insignificant. I just did a
little research on my own and found that lightning has anywhere from 1 to 25
strokes per strike, each stroke lasting anywhere from 10 usec to 500 msec, can
carry current from 10 to 500,000 amps, blah, blah, blah. The point is that
lightning is wonderfully erratic, which I already knew. And here's some more
facts: Lightning doesn't always travel straight down (jeez, one would think that
you have never seen a thunderstorm before!). Ask any pilot, commercial or
private, and they will tell you that lightning can travel many, many miles.
There is one case I remember where a stroke came out of the clouds, ran parallel
to the earth, over some hills, and seemingly came out of a clear blue sky 20
miles away to strike some little kid riding a bicycle. That's a fact. Lightning
isn't very predictable, and certainly doesn't behave according to the rules of
the NEC. The sooner you figure that out the better.


Because even simple concepts of impedance verses resistance
are not understood, then even safety grounds (third prong in
wall receptacle) are confused with earth ground. Safety
ground is different from motherboard ground is different from
chassis ground is different from automobile ground is
different from breaker box ground is different from power
plant ground is different from earth ground. Most all are
interconnected, but are still electrically different. Learn
about impedance. No earth ground is found in wall receptacles
because the wire length - and therefore impedance - of that
third prong wire is just too far from earth ground. Again,
one must first understand impedance to appreciate what world
renown experts (some quoted here) have said about earthing.


You obviously have never wired a house, either.


It takes but a few milliamps to kill a human. Does that
prove lightning must be a high energy event - because it too
kills? Learn how easy a human can be killed before posting
such assumptions.


Where did I make such an assumption? I distinctly remember posting the
following:

"The power of a bolt of lightning isn't the big issue here since it doesn't take
much power to cause damage. The issue is how well you are protected from
whatever amount of power that -does- make it to the surface."

So do you have a reading problem (dare I say 'communication deficit')?


Even posted is that a buried coax is protected from
lightning transients. That is ridiculous as even made bluntly
obvious in a Polyphaser application note about damage to an
improperly earthed telephone exchange; transient damage via
buried wires.


You are twisting my words again. I said buried coax provided -better- protection
than most other methods. If you don't believe me, go visit a few radio stations.
And if you want me to comment on your reference, post the link.


Obvious in that long reply - even basic electrical concepts
are not understood. Real world professionals and generations
of scientific experience prove basic earthing is effective
protection. Even the NEC requires OP to earth ground his
antenna also for human safety.


Basic electrical knowledge - impedance verses resistance -
was not even understood and still Frank said everyone is wrong
about earthing.


Really? Where did I say that? Regardless, I said before that if you want to talk
about reactance, we can go there. Do you need me to start?









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