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.

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?

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

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

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.

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.

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.

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.


Frank Gilliland wrote:
CB radio antennas are not commercial station towers. The latter are
verticals that have a direct connection to ground and the ground
radials. Actually, an AM broadcast tower is almost a perfect
lightning rod by design because it not only shunts the lightning
directly to ground, but also distributes the power from the
strike over the whole counterpoise field. So the tower stays at a
relatively low potential even during a direct strike. And what
-does- manage to sneak onto the line has to deal with some rather
expensive protection devices. Antennas mounted seperately on towers
(FM/TV BC, cell, commercial, etc) have the same problems as any
other antenna, but those problems are usually minimized by the use
of coax. More below.

Let's start with his numbers.

Millions of volts? Yes. But same voltage does not appear
everywhere in a circuit - basic circuit theory. Those
millions of voltage are in the sky. Surge protection is about
making those millions of voltage appear elsewhere which is why
industry professionals discuss impedance. A low impedance
connection to earth means no millions of volts.

A low impedance ground is fine for AC line protection, but it
doesn't guarantee lightning protection. We have all heard that
lightning takes the shortest path to ground, but that's not really
true since electricity will take EVERY path to ground available.
Lightning creates it's own conduit from the clouds, but once
it hits a conductor on the ground it behaves just like any other
form of electricity -- almost. The fact is that wire has
resistance, and the resistance of copper increases with
temperature, which is what happens when it passes the current from
a lightning strike. When that happens it will continue it's path
to ground (assuming the wire doesn't fuse), but other paths will
share more of the load. And because there is a resistance, there
will also be a voltage potential across that resistance. If that
voltage potential is high enough it will happily arc over to
another ground path, and frequently does. More below.

Millions of amps? Only in dreams. Most lightning is below
20,000 amps and of such short duration as to not be high
energy. Lightning typically so low energy at the strike
location (not to be confused with what is miles above) that
well over 90% of all trees struck leave no indication of that
strike.

Let's take your figure of 20,000.... no, let's go even lower.
Let's say only 1000 amps @ 1,000,000 volts. And let's say this
is an unusual strike in that it only hits once, not multiple
times like a normal strike. And let's say the duration of the
hit is 1/10 of a second. This will be a pathetic bolt of
lightning to be sure! Ok, so let's do some numbers:

1,000,000 Volts x 1000 Amps = 1,000,000,000 Watts
1,000,000,000 Watts x 0.1 sec = 1,000,000 Watt/sec

One million joules is "low energy"? Get a grip.

Trees struck by lightning usually -do- leave an indication of
being struck, but most people don't climb them to search for the
point of contact, which is typically nothing more than a spot
about one or two cm in diameter that has been charred. And while
the reason trees are able to survive direct lightning strikes
is still the subject of debate, the reason they make good
lightning rods (efficiently conducting the strike to ground)
shouldn't be so suprising when you take a look at a cross-section
of the root structure -- interesting how it resembles an
electrical discharge, isn't it?

Ok, back to your low impedance ground. A ground rod is used to make
an electrical connection to the earth. But the impedance of that
connection can be anywhere from a few ohms to a few hundred ohms,
depending on the type of rod and the conditions of the soil. Let's
just say we have a ground with an unbelievable impedance of 1 ohm
(a solid-silver rod in a heavily mineralized salt-water marsh
that was recently used for dumping copper turnings from a very
poorly run machine shop).....

1000 amps x 1 ohm = 1000 volts

So with an almost impossibly good ground and a puny bolt of
lightning you -still- have 1000 volts at the top of your ground rod.
So a more typical ground impedance of 50 ohms (not coincidence) and
a more typical lightning strike of 10,000 amps will put 500,000
volts on your grounding strap.....YIKES!!!!! This is a fact, and it
certainly doesn't seem to jibe with your statement that the
voltage at the bottom is insignificant!

How big need a wire be to shunt (earth) lightning? Even the
US Army training manual TM5-690 requires 10 AWG wire to
conduct the direct lightning strike without damage.

Ever hear the term "military intelligence"?

Same wire
found in 20 or 30 amp AC electric boxes because lightning is
not the millions of amps so often claimed in urban myths.
Unlike Frank, numbers are provided by multiple, reliable
sources.

The ground wire in house wiring is intended for fault protection,
not lightning strikes. For example, if the hot wire in your
vintage all-metal Craftsman drill suddenly comes loose and shorts
to the case, since the case is grounded it will shunt the majority
of the current to ground through the ground wire, not through
the person using the drill. And if your breakers and wiring are up
to code (neutral grounded at the box), that current lasts only
for a very short time, limiting any damage to the person and the
drill. Therefore, the ground wire in your house doesn't need to be
as thick as the main wires, and it isn't. Next time you visit your
local hardware store, look at the specs on a spool of house wire --
hot and neutral may be #10 while ground will be #12. Another spool
may have a pair of #12 wires and #14 for ground. If this ground
wire was intended for lightning protection, wouldn't it all be the
same size? Fact: the NEC doesn't define ground wire size based on
it's ability (or inability) to protect against lightning.

Another who does this for a living:
From Colin Baliss "Transmission & Distribution Electrical
Engineering":
Although lightning strikes have impressive voltage and current
values (typically hundreds to thousands of kV and 10-100 kA)
the energy content of the discharge is relatively low ...

Relative to what?

or Martin A Uman in All About Lightning
Most of the energy available to the lightning is converted along
the lightning channel to thunder, heat, light, and radio waves,
leaving only a fraction available at the channel base for
immediate use or storage.

Then I guess all the people that have been killed by lightning
didn't die from the power in the lightning, did they? And all
the damage to electrical equipment caused by lightning wasn't
from the lightning at all, was it? And that pro golfer that was
knocked flat on the links by a nearby strike must have been hit
in the head with a ball at the exact same time, huh? No, no and
no.....

....

It's obvious that you have no experience in the real world
with lightning damage. Get some.

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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On Sat, 14 Feb 2004 20:39:45 -0500, w_tom wrote:


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


Frank is 100% correct in what he posted. You have chosen to either
not fully read what he posted, or you are having trouble trying to
comprehend what he wrote. Take some time and read what others, who
have real experience, have written on the subject.

A person who so poorly protected his own home as to suffer
completely unnecessary computer and TV damage will now teach
me? One who even posted the classic urban myth about concrete
damage to prove Ufer grounding does not work? You just
realized something: someone on the other side does have a few
decades of experience and engineering degrees. If you had
one, then the concept of resistance and impedance would have
been correctly posted. However someone even did read 'tower
talk' - and posted citations from 'tower talk' in direct
contradiction to your posted myths. Well at least you are not
posting personal attacks this time. The world can get better.

In the meantime this is a discussion about the OPs antenna
mast; not a forum for personal attacks. The OP must earth
his antenna mast both for lightning protection AND as required
by the National Electrical Code. That answers his question.
Please feel free to address the purpose of this thread - the
Original Poster's original request for information -
Zeeeeeeee3 originally posted:
Planning to install a base antenna as soon as things warm up and
could use some help..........

So far I have an Imax 99 antenna.
I was thinking of attaching it to the garage side of my house
which is about~20 feet high at the peak. I would take a 5'
piece of antenna mast and pound it several feet into the
ground to secure the bottom and then attach 2 more 10' pieces
on top of that. The mast could be secured to the house with
several of those wall mount brackets. How does this sound
so far?

Now I understand that it must be grounded. Would having the
bottom section of mast pounded into the ground as I mentioned
suffice? or will I need to attach it to a seperate 8' ground
rod? If a seperate rod is needed, do I attach the ground
wire to the antenna mounting plate or the mast or either?
Near the top of the mast or near the bottom?

I also have read of the need for a 'static discharge unit' for
my coax. Could anyone recommend one? Google searches are not
helping me out much.

Have some more questions, but this seems enough for now. Any
help would be really appreciated. I've been trying to piece
information together from the web, but still need some more
help.

Lancer wrote:
Frank is 100% correct in what he posted. You have chosen to either
not fully read what he posted, or you are having trouble trying to
comprehend what he wrote. Take some time and read what others, who
have real experience, have written on the subject.

On Sun, 15 Feb 2004 15:58:03 -0500, w_tom wrote:

A person who so poorly protected his own home as to suffer
completely unnecessary computer and TV damage will now teach
me? One who even posted the classic urban myth about concrete
damage to prove Ufer grounding does not work? You just
realized something: someone on the other side does have a few
decades of experience and engineering degrees. If you had
one, then the concept of resistance and impedance would have
been correctly posted. However someone even did read 'tower
talk' - and posted citations from 'tower talk' in direct
contradiction to your posted myths. Well at least you are not
posting personal attacks this time. The world can get better.

In the meantime this is a discussion about the OPs antenna
mast; not a forum for personal attacks. The OP must earth
his antenna mast both for lightning protection AND as required
by the National Electrical Code. That answers his question.
Please feel free to address the purpose of this thread - the
Original Poster's original request for information -
Zeeeeeeee3 originally posted:

It has several times, which you have chosen to ignore. Use proper
grounds and disconnect his equipment from the antenna and mains.
Your answer is use proper grounds, but don't disconnect any equipment.
Now which one makes more sense? Which one would better protect his
equipment? Which one offers more protection?

In , Lancer
wrote:

On Sun, 15 Feb 2004 15:58:03 -0500, w_tom wrote:

A person who so poorly protected his own home as to suffer
completely unnecessary computer and TV damage will now teach
me? One who even posted the classic urban myth about concrete
damage to prove Ufer grounding does not work? You just
realized something: someone on the other side does have a few
decades of experience and engineering degrees. If you had
one, then the concept of resistance and impedance would have
been correctly posted. However someone even did read 'tower
talk' - and posted citations from 'tower talk' in direct
contradiction to your posted myths. Well at least you are not
posting personal attacks this time. The world can get better.

In the meantime this is a discussion about the OPs antenna
mast; not a forum for personal attacks. The OP must earth
his antenna mast both for lightning protection AND as required
by the National Electrical Code. That answers his question.
Please feel free to address the purpose of this thread - the
Original Poster's original request for information -
Zeeeeeeee3 originally posted:

It has several times, which you have chosen to ignore. Use proper
grounds and disconnect his equipment from the antenna and mains.
Your answer is use proper grounds, but don't disconnect any equipment.
Now which one makes more sense? Which one would better protect his
equipment? Which one offers more protection?


Hey Lancer, don't make it too simple. It's all about "impedance", don'cha know?






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On Sun, 15 Feb 2004 15:04:05 -0800, Frank Gilliland
wrote:

In , Lancer
wrote:

On Sun, 15 Feb 2004 15:58:03 -0500, w_tom wrote:

A person who so poorly protected his own home as to suffer
completely unnecessary computer and TV damage will now teach
me? One who even posted the classic urban myth about concrete
damage to prove Ufer grounding does not work? You just
realized something: someone on the other side does have a few
decades of experience and engineering degrees. If you had
one, then the concept of resistance and impedance would have
been correctly posted. However someone even did read 'tower
talk' - and posted citations from 'tower talk' in direct
contradiction to your posted myths. Well at least you are not
posting personal attacks this time. The world can get better.

In the meantime this is a discussion about the OPs antenna
mast; not a forum for personal attacks. The OP must earth
his antenna mast both for lightning protection AND as required
by the National Electrical Code. That answers his question.
Please feel free to address the purpose of this thread - the
Original Poster's original request for information -
Zeeeeeeee3 originally posted:

It has several times, which you have chosen to ignore. Use proper
grounds and disconnect his equipment from the antenna and mains.
Your answer is use proper grounds, but don't disconnect any equipment.
Now which one makes more sense? Which one would better protect his
equipment? Which one offers more protection?


Hey Lancer, don't make it too simple. It's all about "impedance", don'cha know?


Couldn't I get a correct impedance match with a 1/4 wave of bus bar?
Now what did he say the frequency of lightning was?

In , Lancer
wrote:

On Sun, 15 Feb 2004 15:04:05 -0800, Frank Gilliland
wrote:

In , Lancer
wrote:

On Sun, 15 Feb 2004 15:58:03 -0500, w_tom wrote:

A person who so poorly protected his own home as to suffer
completely unnecessary computer and TV damage will now teach
me? One who even posted the classic urban myth about concrete
damage to prove Ufer grounding does not work? You just
realized something: someone on the other side does have a few
decades of experience and engineering degrees. If you had
one, then the concept of resistance and impedance would have
been correctly posted. However someone even did read 'tower
talk' - and posted citations from 'tower talk' in direct
contradiction to your posted myths. Well at least you are not
posting personal attacks this time. The world can get better.

In the meantime this is a discussion about the OPs antenna
mast; not a forum for personal attacks. The OP must earth
his antenna mast both for lightning protection AND as required
by the National Electrical Code. That answers his question.
Please feel free to address the purpose of this thread - the
Original Poster's original request for information -
Zeeeeeeee3 originally posted:

It has several times, which you have chosen to ignore. Use proper
grounds and disconnect his equipment from the antenna and mains.
Your answer is use proper grounds, but don't disconnect any equipment.
Now which one makes more sense? Which one would better protect his
equipment? Which one offers more protection?


Hey Lancer, don't make it too simple. It's all about "impedance", don'cha know?


Couldn't I get a correct impedance match with a 1/4 wave of bus bar?
Now what did he say the frequency of lightning was?


I don't think he did, but if you post an arbitrary value I'm sure he will
provide you with the correct information. I -do- know that lightning is
monitored by listening to the Schumann (sp?) resonance, which is a constantly
changing frequency down around 8 Hz. So let's see, we would need a ground strap
that is resonant over a frequency range of, say, around 1 to 20 Hz..... so how
much money are you willing to spend on this little project? Because the only way
I see of doing this is with a megawatt negative impedance converter!







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"w_tom" wrote in message
...
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.

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?

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

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

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.

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.

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.

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.


Frank Gilliland wrote:
CB radio antennas are not commercial station towers. The latter are
verticals that have a direct connection to ground and the ground
radials. Actually, an AM broadcast tower is almost a perfect
lightning rod by design because it not only shunts the lightning
directly to ground, but also distributes the power from the
strike over the whole counterpoise field. So the tower stays at a
relatively low potential even during a direct strike. And what
-does- manage to sneak onto the line has to deal with some rather
expensive protection devices. Antennas mounted seperately on towers
(FM/TV BC, cell, commercial, etc) have the same problems as any
other antenna, but those problems are usually minimized by the use
of coax. More below.

Let's start with his numbers.

Millions of volts? Yes. But same voltage does not appear
everywhere in a circuit - basic circuit theory. Those
millions of voltage are in the sky. Surge protection is about
making those millions of voltage appear elsewhere which is why
industry professionals discuss impedance. A low impedance
connection to earth means no millions of volts.

A low impedance ground is fine for AC line protection, but it
doesn't guarantee lightning protection. We have all heard that
lightning takes the shortest path to ground, but that's not really
true since electricity will take EVERY path to ground available.
Lightning creates it's own conduit from the clouds, but once
it hits a conductor on the ground it behaves just like any other
form of electricity -- almost. The fact is that wire has
resistance, and the resistance of copper increases with
temperature, which is what happens when it passes the current from
a lightning strike. When that happens it will continue it's path
to ground (assuming the wire doesn't fuse), but other paths will
share more of the load. And because there is a resistance, there
will also be a voltage potential across that resistance. If that
voltage potential is high enough it will happily arc over to
another ground path, and frequently does. More below.

Millions of amps? Only in dreams. Most lightning is below
20,000 amps and of such short duration as to not be high
energy. Lightning typically so low energy at the strike
location (not to be confused with what is miles above) that
well over 90% of all trees struck leave no indication of that
strike.

Let's take your figure of 20,000.... no, let's go even lower.
Let's say only 1000 amps @ 1,000,000 volts. And let's say this
is an unusual strike in that it only hits once, not multiple
times like a normal strike. And let's say the duration of the
hit is 1/10 of a second. This will be a pathetic bolt of
lightning to be sure! Ok, so let's do some numbers:

1,000,000 Volts x 1000 Amps = 1,000,000,000 Watts
1,000,000,000 Watts x 0.1 sec = 1,000,000 Watt/sec

One million joules is "low energy"? Get a grip.

Trees struck by lightning usually -do- leave an indication of
being struck, but most people don't climb them to search for the
point of contact, which is typically nothing more than a spot
about one or two cm in diameter that has been charred. And while
the reason trees are able to survive direct lightning strikes
is still the subject of debate, the reason they make good
lightning rods (efficiently conducting the strike to ground)
shouldn't be so suprising when you take a look at a cross-section
of the root structure -- interesting how it resembles an
electrical discharge, isn't it?

Ok, back to your low impedance ground. A ground rod is used to make
an electrical connection to the earth. But the impedance of that
connection can be anywhere from a few ohms to a few hundred ohms,
depending on the type of rod and the conditions of the soil. Let's
just say we have a ground with an unbelievable impedance of 1 ohm
(a solid-silver rod in a heavily mineralized salt-water marsh
that was recently used for dumping copper turnings from a very
poorly run machine shop).....

1000 amps x 1 ohm = 1000 volts

So with an almost impossibly good ground and a puny bolt of
lightning you -still- have 1000 volts at the top of your ground rod.
So a more typical ground impedance of 50 ohms (not coincidence) and
a more typical lightning strike of 10,000 amps will put 500,000
volts on your grounding strap.....YIKES!!!!! This is a fact, and it
certainly doesn't seem to jibe with your statement that the
voltage at the bottom is insignificant!

How big need a wire be to shunt (earth) lightning? Even the
US Army training manual TM5-690 requires 10 AWG wire to
conduct the direct lightning strike without damage.

Ever hear the term "military intelligence"?

Same wire
found in 20 or 30 amp AC electric boxes because lightning is
not the millions of amps so often claimed in urban myths.
Unlike Frank, numbers are provided by multiple, reliable
sources.

The ground wire in house wiring is intended for fault protection,
not lightning strikes. For example, if the hot wire in your
vintage all-metal Craftsman drill suddenly comes loose and shorts
to the case, since the case is grounded it will shunt the majority
of the current to ground through the ground wire, not through
the person using the drill. And if your breakers and wiring are up
to code (neutral grounded at the box), that current lasts only
for a very short time, limiting any damage to the person and the
drill. Therefore, the ground wire in your house doesn't need to be
as thick as the main wires, and it isn't. Next time you visit your
local hardware store, look at the specs on a spool of house wire --
hot and neutral may be #10 while ground will be #12. Another spool
may have a pair of #12 wires and #14 for ground. If this ground
wire was intended for lightning protection, wouldn't it all be the
same size? Fact: the NEC doesn't define ground wire size based on
it's ability (or inability) to protect against lightning.

Another who does this for a living:
From Colin Baliss "Transmission & Distribution Electrical
Engineering":
Although lightning strikes have impressive voltage and current
values (typically hundreds to thousands of kV and 10-100 kA)
the energy content of the discharge is relatively low ...

Relative to what?

or Martin A Uman in All About Lightning
Most of the energy available to the lightning is converted along
the lightning channel to thunder, heat, light, and radio waves,
leaving only a fraction available at the channel base for
immediate use or storage.

Then I guess all the people that have been killed by lightning
didn't die from the power in the lightning, did they? And all
the damage to electrical equipment caused by lightning wasn't
from the lightning at all, was it? And that pro golfer that was
knocked flat on the links by a nearby strike must have been hit
in the head with a ball at the exact same time, huh? No, no and
no.....

....

It's obvious that you have no experience in the real world
with lightning damage. Get some.

While this pains me, Frank's right. You can go on
with your babble, but there's no reasonably priced grounding
system that will protect you as good as unplugging everything
from the wall and antenna.

Landshark


--
Hard things are put in our way,
not to stop us, but to call out our
courage and strength.