Put it in an empty jim beam bottle


In article , Twistedhed says...

LOL,,only your off-topic sidestep definitions don't apply in this case.
The original poster was referring to a device, as in "gadget", not a
"scheme",such as you presented in your desperate squirm for deflection.
In fact, all had no problem comprehending such, with the sole exception
of your self,,,...tsk tsk.,,and here you go again, the low self-esteem
and self-hatred you are forced to deal with, ****ing you off to no end,
manifesting in misdirected anger from your darkness. Such hostility for
no reason other than your personal problems.....that makes you a
......lid.

On 13 Feb 2004 12:44:50 -0800, Harmony wrote:

Put it in an empty jim beam bottle


LOL, I like that... old wives tale was a mason jar...

In , w_tom wrote:

......Same earthing ground that also connects to AC
electric, telephone, and cable TV wire.....
snip
......... Note an antenna
tower and building each have their own earth ground. Each is
earthed as if it were a separate structure. Every incoming
wire makes a connection to that earth ground. To make the
'system' work better, a ground wire interconnects the antenna
and building earth grounds:


........BAD idea. Tying your ground rods together makes a ground loop, which is
deadly for radio equipment. Use a completely -seperate- ground system for your
radio. Sink a ground rod where the coax enters the shack, tie the coax shield
directly to this rod (don't forget to waterproof the connection), and run your
ground strap and coax as close together as possible. Here's a diagram:

http://www.aimcomm.net/sparky/ground.gif

DON'T rely on your coax shield for a ground strap!!! You can braid a heavy-duty
strap using old power cords and it shouldn't cost you more than a few dollars at
the local thrift shop.

If AC noise becomes a problem, rewire the AC outlets used by the radio so their
ground goes to the new ground rod via the ground strap. Do NOT connect the
neutral (white) wire to this ground!


http://services.erico.com/public/lib...es/tncr002.pdf


Page has moved. Update your link.


Static is irrelevant. A few hundred volts of static will
not damage any properly built radio. You could even static
shock your car radio antenna or a portable radio antenna
without damage. That would be as much as 18,000 volts - and
still no damage.


Many radios aren't built "properly", and most modern radios use JFET or MOSFET
frontends, which are VERY suseptible to damage from static, even from potentials
as low as 50 volts (the breakdown potential of the protection diodes). That's
not the only problem -- static buildup on the antenna causes horrific noise!
Fortunately, the best solution is an easy one: shunt the center conductor of
your coax to ground with an RF choke, something on the order of 1 milliHenry or
larger (even an audio or power supply choke will work). Locate the choke at the
grounding block (see diagram) as any lightning strike will travel through that
choke and you don't want it inside the shack when that happens. On the upside,
it makes a beautiful blob of copper and iron that you could probably sell on
ebay for a decent price (after the smell goes away, of course).


The earthing is required by NEC for human safety AND also
provides transistor safety. If lightning is provided a path
to earth ground via that exterior rod, then it too will not
seek earth ground, destructively, via your radio. Direct
strike lightning damage is that easily avoided.


Wrong. If the coax is plugged into the radio when lightning hits the antenna,
it's safe to assume that your radio will fry. Period. Doesn't matter how much
protection you have. Why? Because lightning packs a few million volts (not an
exaggeration) and will jump just about any gap to ground. But gaps are also
resistors, and since lighting also carries a few million amps (again, not an
exaggeration), you are going to have a SIGNIFICANT voltage potential on your
coax. In fact, the potential and current are so high that the core insulation
breaks down for the full length of the coax and it is literally cooked from end
to end. I've seen it more than once. And that's WITH proper grounding!

Unplug the coax from the radio when not in use. If you want to use a "device",
get one of those big blade switches so there is a big gap, and wire it so the
antenna is shorted to ground when not connected to the radio.


Unfortunately, too many don't have necessary earthing, suffer
damage, and then declare nothing could have helped.
Generations of technical history say otherwise. Its all about
earthing - as even required by code.


Get some field experience. THEN come here and talk about lightning protection.








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http://www.astrosurf.com/lombry/qsl-...protection.htm

This site has some good info.

Manufacturer changed URL for that Technical Note again:
TN CR 002 The Need for Coordinated Protection

http://www.erico.com/public/library/...es/tncr002.pdf
This figure demonstrates how a radio can be protected even
from lightning strikes.

Static is irrelevant to radios because, as was posted
Every electronics manufacturer ... takes great lengths to
control static.
If static on an antenna was destructive to a radio, then every
time a human static discharges to that radio (many times
higher voltage), then the radio is damaged. But human static
discharge does not damage those JFETs. Internal protection
easily installed because static has such low current AND short
duration. Radio design assumes an antenna has been properly
earthed as even required by the NEC which therefore makes
internal protection effective.

Cell phone towers, 911 dispatcher radios, telephone
switching computers connected to overhead wires everywhere in
town. All must suffer direct strikes and not be damaged - as
was standard even before WWII. Why? Earthing, as described
in the below text, and demonstrated in that manufacturer's
figure makes protection even inside the radio effective.

If such earthing was not effective, then 911 emergency
dispatch and telephone operators would have to remove headsets
(stopped working) during every thunderstorm. They don't stop
working, do they. Protection so routine that it even makes
static electric discharge problems irrelevant and trivial by
comparison.

OPs antenna and antenna lead must connect as demonstrated by
that industry professional's technical note. For that matter,
visit this and many other 'real world' manufacturers whose
products are also effective because they discuss the most
critical component - earthing.


Lancer wrote:
On Fri, 13 Feb 2004 14:41:50 -0500, w_tom wrote:
The antenna requires an earth ground, first, as required by
National Electrical Code. That mounting rod should be
connected to an eight+ foot earth ground rod (available even
in Home Depot and Lowes). This required by NEC for human
safety, but also to protect transistors.

Incoming wire should enter building at the service entrance
so that a ground block (maybe $1 at Radio Shack or Home Depot)
connects 'less than 10 feet' to the building's single point
earth ground. Same earthing ground that also connects to AC
electric, telephone, and cable TV wire. Do not even think an
AC receptacle or water faucet will provide that necessary
earthing.

NEC requirements have changed since 1990 to require a
service entrance ground rod. You may need to install this
earth ground rod at the service entrance. Many homes don't
even have that much which is another reason why some homes
suffer household electronics damage.

Principles are demonstrated in this figure. Note an antenna
tower and building each have their own earth ground. Each is
earthed as if it were a separate structure. Every incoming
wire makes a connection to that earth ground. To make the
'system' work better, a ground wire interconnects the antenna
and building earth grounds:

Static is irrelevant. A few hundred volts of static will
not damage any properly built radio. You could even static
shock your car radio antenna or a portable radio antenna
without damage. That would be as much as 18,000 volts - and
still no damage.

The earthing is required by NEC for human safety AND also
provides transistor safety. If lightning is provided a path
to earth ground via that exterior rod, then it too will not
seek earth ground, destructively, via your radio. Direct
strike lightning damage is that easily avoided.
Unfortunately, too many don't have necessary earthing, suffer
damage, and then declare nothing could have helped.
Generations of technical history say otherwise. Its all about
earthing - as even required by code.

Unfortunately Frank Gilliland has exaggerated his numbers
due to insufficient experience and too much time listening to
myths. His numbers will be exposed as fiction.

Field experience says repeatedly that antenna and radio can
suffer direct strikes without damage. That is proven about 25
times every year atop Empire State Building since the 1930s.
According to Frank, they must suffer damage 25 times per
year. 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.

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.

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. 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.

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 ...

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.

In short, Frank Gilliland's numbers are classic myths.


Pre WWII ham radio operators demonstrated what was required
for protection. First they would disconnect antenna and still
suffer damage. Then placed antenna lead in a mason jar, and
still suffered damage. But when antenna was connected to
earth ground, then no damage. Neither a mason jar nor "one
of those big blade switches" sufficiently blocks destructive
transients. Of course not. Lightning was not blocked by
miles of air. Is a mason jar or knife switch to do what miles
of air could not? Of course not. For no damage, provide the
destructive transient what it wants - earth ground.

zeeeeeeee's antenna installation is demonstrated by a
figure in TN CR 002 The Need for Coordinated Protection
(corrected URL)

http://www.erico.com/public/library/...es/tncr002.pdf

Need anyone suffer damage from direct lightning? Of course
not. Such damage is considered a human failure because proper
earthing is so effective and so inexpensive. Another
professional who makes that point in direct contradiction to
posted myths:
http://www.harvardrepeater.org/news/lightning.html
Well I assert, from personal and broadcast experience spanning
30 years, that you can design a system that will handle *direct
lightning strikes* on a routine basis. It takes some planning
and careful layout, but it's not hard, nor is it overly
expensive. At WXIA-TV, my other job, we take direct lightning
strikes nearly every time there's a thunderstorm. Our downtime
from such strikes is almost non-existant. The last time we went
down from a strike, it was due to a strike on the power company's
lines knocking *them* out, ...
Since my disasterous strike, I've been campaigning vigorously to
educate amateurs that you *can* avoid damage from direct strikes.
The belief that there's no protection from direct strike damage
is *myth*. ...
The keys to effective lightning protection are surprisingly
simple, and surprisingly less than obvious. Of course you *must*
have a single point ground system that eliminates all ground
loops. And you must present a low *impedance* path for the
energy to go. That's most generally a low *inductance* path
rather than just a low ohm DC path.

Important point. This professional did not say
'resistance'. He said 'impedance' which is why wire length is
so critical. 'Impedance' is why an incoming wire (antenna,
CATV, telephone) must first drop down to make a short
connection to earth before rising up to enter a building.
Just one of the "careful layout" techniques learned from
underlying theory tempered by decades of experience.

zeeeeeeee's tower requires earthing to meet human safety
requirements of National Electrical Code AND to provide
transistor safety. Earthing required twice over. Once
properly earthed, then even unplugging for protection would be
unnecessary - as has been demonstrated too many times at too
many locations since before WWII.


Frank Gilliland wrote:
In , w_tom wrote:
The earthing is required by NEC for human safety AND also
provides transistor safety. If lightning is provided a path
to earth ground via that exterior rod, then it too will not
seek earth ground, destructively, via your radio. Direct
strike lightning damage is that easily avoided.

Wrong. If the coax is plugged into the radio when lightning hits
the antenna, it's safe to assume that your radio will fry. Period.
Doesn't matter how much protection you have. Why? Because lightning
packs a few million volts (not an exaggeration) and will jump just
about any gap to ground. But gaps are also resistors, and since
lighting also carries a few million amps (again, not an
exaggeration), you are going to have a SIGNIFICANT voltage
potential on your coax. In fact, the potential and current are so
high that the core insulation breaks down for the full length of
the coax and it is literally cooked from end to end. I've seen it
more than once. And that's WITH proper grounding!

Unplug the coax from the radio when not in use. If you want to use
a "device", get one of those big blade switches so there is a big
gap, and wire it so the antenna is shorted to ground when not
connected to the radio.

Actually that astrosurf.com author misses the point. He
cites a benchmark in surge protection, then assumes the surge
protector (or more of them) provides protection. Even
Polyphaser does not make that claim. Far better information
are the legendary application notes from Polyphaser. Do they
discuss their products? Of course not. Polyphaser discusses
THE protection - earthing.

Making a short connection to earth is so critical that
Polyphaser even makes protectors with NO connection. Instead
the protector mounts directly ON earth ground. Polyphaser
application notes are at:
http://www.polyphaser.com/ppc_pen_home.asp

Why did the author suffer damage? Every damaged item was
part of a circuit from cloud to earth. Only damaged were
items that completed a path to earth.

BTW, those manufacturers who discuss earthing make serious
protectors. Visit their product line appreciate what serious
protector products are.

Randy wrote:
http://www.astrosurf.com/lombry/qsl-...protection.htm

This site has some good info.

"w_tom" wrote in message
...
Unfortunately Frank Gilliland has exaggerated his numbers
due to insufficient experience and too much time listening to
myths. His numbers will be exposed as fiction.

Field experience says repeatedly that antenna and radio can
suffer direct strikes without damage. That is proven about 25
times every year atop Empire State Building since the 1930s.
According to Frank, they must suffer damage 25 times per
year. 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.

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.

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. 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.

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 ...

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.

In short, Frank Gilliland's numbers are classic myths.


Pre WWII ham radio operators demonstrated what was required
for protection. First they would disconnect antenna and still
suffer damage. Then placed antenna lead in a mason jar, and
still suffered damage. But when antenna was connected to
earth ground, then no damage. Neither a mason jar nor "one
of those big blade switches" sufficiently blocks destructive
transients. Of course not. Lightning was not blocked by
miles of air. Is a mason jar or knife switch to do what miles
of air could not? Of course not. For no damage, provide the
destructive transient what it wants - earth ground.

zeeeeeeee's antenna installation is demonstrated by a
figure in TN CR 002 The Need for Coordinated Protection
(corrected URL)

http://www.erico.com/public/library/...es/tncr002.pdf

Need anyone suffer damage from direct lightning? Of course
not. Such damage is considered a human failure because proper
earthing is so effective and so inexpensive.

So, you claim that ALL lightning strikes can be safely shunted to Earth,
with no damage along the path? Well, I don't have 30 years experience in the
electrical transmission and distribution industry, but I do have 25 years.
And I have seen properly earth grounded transmission and distribution poles
where the awg #6-#4 CU wires were mostly vaporized. Sure, there were bits
and short pieces left, but for the most part, the wire was gone. I confer
with you most of what you say, but you would be not completely honest to say
that all lightning strikes can be earthed with no damage. Possible? Maybe.
Practical? Nope.There will be strikes of magnitude where practical
techniques fail.

In , w_tom wrote:

Unfortunately Frank Gilliland has exaggerated his numbers
due to insufficient experience and too much time listening to
myths. His numbers will be exposed as fiction.

Field experience says repeatedly that antenna and radio can
suffer direct strikes without damage. That is proven about 25
times every year atop Empire State Building since the 1930s.
According to Frank, they must suffer damage 25 times per
year.


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.....

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.


In short, Frank Gilliland's numbers are classic myths.


Pre WWII ham radio operators demonstrated what was required
for protection. First they would disconnect antenna and still
suffer damage. Then placed antenna lead in a mason jar, and
still suffered damage. But when antenna was connected to
earth ground, then no damage. Neither a mason jar nor "one
of those big blade switches" sufficiently blocks destructive
transients. Of course not. Lightning was not blocked by
miles of air. Is a mason jar or knife switch to do what miles
of air could not?


You bet it will!

Suppose you use one of those basic air-gap devices. Ok, you have 10,000 amps
passing through a gap that now consists of plasma. But even plasma has
resistance and will develop a considerable voltage across it. Plus, there is the
brief voltage potential that exists across the gap immediately before the plasma
is ignited, as well as after it is extinguished. These are the voltages that
will be developed across the conductors of the transmission line going into the
shack. How high is that voltage? It can peak at several thousand volts, and the
arc itself can develop several hundred volts across the points. That's enough to
fry a radio. Even if the impedance is high coming into the shack, it will still
destroy any overload protection in the radio, making it vulnerable to more
serious damage from nothing more than a surge or static discharge.

The coax doesn't offer much protection by itself, but it can limit the maximum
voltage entering the shack (or coming down the tower from the antenna). Every
type of coax has a core insulation that is rated for a certain breakdown, or
'pucture' voltage. RG-58 is rated for 1900 volts RMS, or roughly 2800 volts
peak. That means the coax is going to permit 2800 volts into the shack before it
fails and starts arcing internally. That's still enough to fry a radio. And
that's assuming the lightning hits the antenna and not the coax. If it hits the
coax, that's a different game altogether.

There are other factors that can put large voltages on the coax, since inductive
and capacitive reactances of a ground system, while small, can become very
significant when the current is on the order of 10,000 amps. We can take that
route too if you want.

The fact is that simply sinking a ground rod is NOT ENOUGH. A large blade switch
will easily block any voltage that can make it through the coax. Additionally,
it will also protect the coax by shorting it, thereby preventing a voltage high
enough to cause the insulation to fail. This is a method that has been proven
time and time again since the beginning of radio.


Of course not. For no damage, provide the
destructive transient what it wants - earth ground.

zeeeeeeee's antenna installation is demonstrated by a
figure in TN CR 002 The Need for Coordinated Protection
(corrected URL)

http://www.erico.com/public/library/...es/tncr002.pdf


"Equipotential Earth Bonding" = ground loop = bad news when using unbalanced
transmission line (coax). Whoever made that design has no experience with radio
communication systems, which is especially evident because most commercial
stations bury their coax, affording a level of protection far superior to the
design in your reference (....gawd I hate pdf's!).


Need anyone suffer damage from direct lightning? Of course
not. Such damage is considered a human failure because proper
earthing is so effective and so inexpensive. Another
professional who makes that point in direct contradiction to
posted myths:
http://www.harvardrepeater.org/news/lightning.html
Well I assert, from personal and broadcast experience spanning
30 years, that you can design a system that will handle *direct
lightning strikes* on a routine basis. It takes some planning
and careful layout, but it's not hard, nor is it overly
expensive. At WXIA-TV, my other job, we take direct lightning
strikes nearly every time there's a thunderstorm. Our downtime
from such strikes is almost non-existant. The last time we went
down from a strike, it was due to a strike on the power company's
lines knocking *them* out, ...
Since my disasterous strike, I've been campaigning vigorously to
educate amateurs that you *can* avoid damage from direct strikes.
The belief that there's no protection from direct strike damage
is *myth*. ...
The keys to effective lightning protection are surprisingly
simple, and surprisingly less than obvious. Of course you *must*
have a single point ground system that eliminates all ground
loops. And you must present a low *impedance* path for the
energy to go. That's most generally a low *inductance* path
rather than just a low ohm DC path.

Important point. This professional did not say
'resistance'. He said 'impedance' which is why wire length is
so critical. 'Impedance' is why an incoming wire (antenna,
CATV, telephone) must first drop down to make a short
connection to earth before rising up to enter a building.
Just one of the "careful layout" techniques learned from
underlying theory tempered by decades of experience.


Although your statement is inconsistent with your pdf reference, the reason coax
is sometimes physically located at ground level at the entrance to the shack is
because of the differences between RF ground and DC ground, -not- because of the
effect of inductive and/or capacitive reactance in a lightning strike. If that
were the case then the antenna system would need to be 'tuned' for lightning,
which is nearly impossible since lightning has no fixed frequency.


zeeeeeeee's tower requires earthing to meet human safety
requirements of National Electrical Code AND to provide
transistor safety. Earthing required twice over. Once
properly earthed, then even unplugging for protection would be
unnecessary - as has been demonstrated too many times at too
many locations since before WWII.


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







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Lightning builds plasma wires that can short high energy,
utility power through other copper wires. Lightning simply
creates the short circuit. Then a higher source of energy -
AC electric utility - follows to vaporize those copper wires.
That point was described by Colin Baliss:
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 and most
of the damage to power plant is caused by 'power follow-through
current'. The lightning simply provides a suitable ionized
discharge path.

Yes direct strikes have caused damage. This was a problem
in the early days of ESS-1 - the first electronic switching
computers for telephone systems. And so engineers then
reevaluated the earthing system in those few 'problem' Central
Office buildings to correct the reason for electronic damage -
human failure.

Described above is not a best solution. But then a best
solution is typically not required. Above described system
will not avoid damage from every possible direct strike. But
then many of these 'rare' direct strikes have never been
experienced by many - maybe most - people. For example,
something called hot lightning may discharge the entire cloud
in one single strike. It has been observed - just like
tornados have been observed (most people also will never
witness a tornado in their lifetime).

Defined here is effective protection for most direct
lightning strikes. It costs so little. To enhance same for
the other maybe 1%, serious facilities such as 911 systems,
cell phone towers, telephone switch stations, and nuclear
hardened maritime facilities spend far more than a few $10.
They spend $thousands more on earthing alone just to also
protect from the last 1% of worst case lightning strikes.

I cite nuclear hardened facility especially since a 1998
IEEE paper described a Norwegian maritime station damaged by a
lightning strike. They discovered major installation faults
in the earthing system for what was suppose to be a nuclear
EMP protected station. Faults that even permitted lightning
to cause damage. Again, failure directly traceable to a
human. Major construction required to repair a simple
earthing flaw.

Homes contain superior earthing systems that we still don't
use today. Ufer grounds could have been installed using
existing structure - if planned for when footing were poured.
But we still don't install superior earthing systems in new
homes 30 years after the transistor existed. Costs to use that
Ufer ground on existing homes are now extreme because Ufer
grounding was not enabled when house construction started. OP
must make do with simple earth ground rods. Properly
installed, the Original Poster is quite unlikely to suffer any
damage from direct lightning strikes. For but a few $10, he
gets a massive increase in direct lightning strike
protection. Not perfect. Just a massive improvement.

Randy wrote:
So, you claim that ALL lightning strikes can be safely shunted to
Earth, with no damage along the path? Well, I don't have 30
years experience in the electrical transmission and distribution
industry, but I do have 25 years. And I have seen properly earth
grounded transmission and distribution poles where the awg #6-#4
CU wires were mostly vaporized. Sure, there were bits and short
pieces left, but for the most part, the wire was gone. I confer
with you most of what you say, but you would be not completely
honest to say that all lightning strikes can be earthed with no
damage. Possible? Maybe. Practical? Nope.There will be strikes
of magnitude where practical techniques fail.