You have the frequency spectrum chart for lightning. Each
frequency is AC current. Each frequency contains some of the
energy from CG lightning.

How were radio transmitters created only from DC batteries?
A spark gap created AC from DC. Not very efficient. But like
lightning, the discharge through a non-linear medium (the
spark gap) puts energy into the AC regions - as demonstrated
by that frequency spectrum chart.

If lightning were only DC, then capacitors (ie. open
switches rated to exceed the breakdown voltage) would be
sufficient to block lightning. Lightning cannot be stopped.
Even if the breakdown voltage is not exceeded, still some
current passes through the switch due to AC components of that
lightning strike. If lightning were only DC, then long wires
to earth would easily ground lightning. Again, it is the AC
components of lightning that causes telcos to put their
switching computers up to 50 meters after the surge protector
AND put their surge protector right on earth ground. Wire
impedance of lightning puts significant energy in AC
components - as demonstrated by that frequency spectrum chart.

Either energy can be transferred by DC, or energy can be
transferred by AC. Clearly much of the energy from lightning
is found in AC (radio frequencies).

Wire has impedance. A sharp bend is the equivalent of
increasing that inductance (and therefore impedance) by
factors such as 6 times - a ballpark number. To 60 hz
electricity, this impedance is trivial and irrelevant. But
lightning is different electricity. We are talking about
10,000 amps with a rising edge of 8 microseconds. Anything
that increases wire inductance (such as splices, sharp bends,
routing through metallic conduit, etc) means a lightning
transient will seek alternative paths inside the building.

One trick in commercial radio stations to make lightning
seek earth ground is to feed the antenna through a coiled wire
or ferrite bead. That ferrite bead may be trivial to a radio
transmitter. But to lightning, that ferrite bead encourages
lightning to take earth ground at the antenna base rather than
find earth through the adjacent transmitter shed. Again, it
is the sharp rise time of that pulse combined with the massive
(and short) currents that make low impedance ground wire so
important to lightning protection. Generally increasing the
wire gauge provides little benefit. Decreasing wire length
(and therefore wire inductance) provides a much better
improvement.

To provide numbers as example: the 50 feet of 20 amp
electric wire may be less than 0.2 ohms resistance. That same
wire could be 120 ohms impedance to lightning. Voltage
difference be between a wall receptacle and earthed breaker
box if a plug-in protector were earthing a tiny 100 amp
surge? Less than 12,000 volts. That 0.2 ohms resistance is
not the problem. That 120 ohms impedance is just another
reasons why plug-in protectors are not properly earthed at
wall receptacles.

To reduce wire impedance, some installations use flat ribbon
wire instead of solid copper. However other problems such as
weather and corrosion must also be considered which is why
solid wire is often used for earthing. Military facilities
are suppose to inspect this earthing system every 5 years or
less. How often does the home owner do his inspection? Many
home owners don't even know an earth ground exists or is
necessary. Just another reason why we make compromises
between lower impedance wire and corrosion resistant
solutions.

Many reasons for keeping a lightning rod earth ground wire
outside the building involves factors beyond the scope of this
discussion. But one reason why: once inside the building,
then a destructive transient has a building is chock full of
conductors. The building concrete. The heating system.
Linoleum tile. Etc. The point is once lightning is inside
the building, then the building has too many conductive paths
to create destructive and induced transients. This is but
another reason why we earth transients before transients enter
the building.

Analysis and elimination of those so many conductive paths
inside a building is just too expensive and complicated.
Earth lightning outside the building and a majority of
destructive transients are eliminated. Keep lightning outside
the building so that protective circuits inside appliances are
not overwhelmed. Earth a transient through an adjacent plug-in
protector - even a trivial 100 amp transient and the protector
is something less than 12,000 volts relative to ground -
ineffective protection.

BTW, we earth to accomplish two goals. First we conduct
lightning to earth by the most conductive path possible. But
realities say we cannot do that well enough. So we attempt to
make earth beneath the building equipotential using concepts
such as single point ground, Ufer or halo grounds, etc.
However we can never make earth equipotential enough. So we
make the earthing connection more conductive.

Effective protection costs so little and is so much more
effective when the system is planned for and installed as
footing are poured. Add on solutions, as is standard in most
construction today, tends to be either more expensive or less
effective. One man's experience:
http://scott-inc.com/html/ufer.htm

Choreboy wrote:
Isn't the definition of AC electricity whose current changes direction?
Are you saying all lightning strikes change direction?

Ground wires from any surge protector must avoid sharp
bends. As I have so often done, a published source:
US Army Training Manual 5-690
3.4 Lightning protection subsystem (p 46) ...

I wonder why they specify insulated wire. Uninsulated wire is easier to
inspect and easier to identify as a ground. Stranded wire has less
inductance than solid, but what about flat braid? I think it's
specified for commercial transmission towers because it has less
inductance than stranded wire.

If an Army technician had thirty feet of ground wire to connect
terminals ten feet apart, he might leave the extra twenty feet
taped in a coil halfway between. I agree that a loop like that
would be bad. By comparison, how bad would it be to have a sharp
bend around a wooden corner?
...

An external ground wire would be easy to inspect and less likely to be
damaged by humans. Are there more technical reasons?

The telegraph operator was not transmitting DC. Equation
for AC power transmitted by the telegrapher is demonstrated in
a famous equation (as taught in electromagnetic wave theory):
Telegrapher's Equation. For example voltage is defined by two
natural exponentials to the power of a positive and negative
imaginary number (for length of the wire) times Gamma (a
function of wire resistance, inductance, leakage resistance
and capacitance). You need not learn this equation. Even
telegraphers, using a battery and a code key, were not
transmitted DC electricity. They were transmitting AC
electricity that made learning the Telegrapher's equation
necessary.

Your example assumes some erroneous parameters. Length of
that pulse alone is not significant. A sharper rise time
means more energy ends up in higher frequencies. Start with
the rise and fall times of that pulse. For lightning, this is
modeled at 8/20 microseconds - not a 0.001 second pulse.
Furthermore the pulse is driven by a current source - not by a
voltage source. Voltage will increase as necessary so that a
given current will flow. Give lightning a low impedance path
to earth and the millions of volts in lightning appears
elsewhere - not inside the structure. CG Lightning is defined
in terms of current because CG lightning is driven by a
current source; not a voltage source.

Furthermore, a 20 ohm earth ground assumes electricity at 60
hz 120 volts is same as electricity that even creates plasma.
Resistance is not constant for electricity at all ranges.
Does earthing resistance remains at 20 ohms, or does
resistance drop due to higher frequency and current
parameters? Just another parameter that makes lightning
protection interesting.

Choreboy wrote:
w_tom wrote:
The term DC pulses is an oxymoron.

Isn't DC electrical current that flows in only one direction?
In 1883, when a telegraph operator hooked up a battery and
started pressing his key, wasn't he generating DC pulses?
(There may have been a little AC activity each time the key
broke contact.)
...

I don't know if they were familiar with AC when they defined the Henry.
Across one Henry of inductance, it takes one Volt to increase the
electrical flow by one Ampere per second.

Suppose a grounded terminal gets hit by a 1000-Volt pulse lasting .001
second. Suppose the grounding rod has 20 ohms to ground, and there's a
1 Henry choke between the terminal and the rod.

The thousand Volts will increase the current through the inductor at
1000 Amperes per second. At the end of 1 millisecond, current will have
increased to one Amp. In view of the resistance at the ground rod,
voltage will have increased to 20 Volts.

Things will be entirely different on the hot side of the choke. What
appears to be a short for unvarying DC will appear to be an open for a
quick, low-impedance pulse. Who needs AC theory for that?

Once again, you miss the point in favor of arguing and trying to prove that
your perspective is superior. Your use of the terminology "made of sine
waves" was incorrect, he called you on the matter and you continued to
maintain that postition and argue the point. My point was not to argue that
a wavelet analysis was better, only that sine waves are only on choice for
decomposing a signal. Once again, you are the one that looks like a yo yo.

Leonard

"w_tom" wrote in message
...
I appreciate what CJT is saying which is why I included the
concept of boundary conditions. However to be more
technically correct, then most readers would not understand
the concepts. Yes, sine waves go forever in time. The 'sine
waves' that combine to construct a pulse have boundary
conditions; exist only during the period of that pulse.

Wavelet as a better description would be nice. But I
believe most don't even know what a wavelet is. I would not
even know how to begin to describe a lightning pulse in terms
of wavelets. Where would we even start? Define a pulse in
terms of a Daubechie, Mexican Hat, or Morlet wavelet? I
think not.

Furthermore, I was not sure of CJT's math background. For
example, what is a true impulse? Literally every frequency in
that spectrum. But did CJT understand that basic math
concept? I thought not after a few posts suggested I had
better keep it simpler: describe a pulse in terms that all may
understand - sine waves. Then made the concept a little more
complicated - added boundary conditions.

Wavelets - way too complex. To comprehend the destructive
(almost capricious) nature of lightning, it is simply better
to limit a lightning pulse description to a wide spectrum of
frequencies (numerous sine waves of different frequencies that
are summed together).

Leonard Caillouet wrote:
w_tom,

While you are correct in many ways, CJT is also correct in
pointing out that your suggestion that lightning is made of
sine waves is faulty application of Fourier. You could just as easily
say that lightning is made of wavelets
(and more correctly, actually) or many other functions. These are all
just
mathematical constructs to describe a complex phenomenon as components
that
can be manipulated for analysis. The point that lightning is a pulse and
can be analyzed by its component frequencies should be clear. That it is
"made of sine waves" is an equally clearly faulty application of the
concept. If you would learn to be a bit more humble in accepting
criticism
of your language, useage, and out of context application of concepts, the
correct basis of your arguments might be more often appreciated. Mostly,
you end up looking like an idiot.

Leonard

If Leonard Caillouet had a better way to answer the
question, then he would have posted it. However everytime a
reply from Leonard Caillouet arrives, it is routinely another
'attack the messenger' post rather than an answer to a
technical question. Leonard remains consistent. Post personal
attacks rather than attack the question with facts. Where did
he even once try to answer the posters question? That would
be a pleasant and unnatural surprise.

Leonard often demonstrates only enough technical knowledge
to lob hand grenades. Keep your head down. Leonard is back.

Leonard Caillouet wrote:
Once again, you miss the point in favor of arguing and trying to
prove that your perspective is superior. Your use of the
terminology "made of sine waves" was incorrect, he called you on
the matter and you continued to maintain that postition and argue
the point. My point was not to argue that a wavelet analysis was
better, only that sine waves are only on choice for decomposing a
signal. Once again, you are the one that looks like a yo yo.

w_tom wrote:
snip
Many reasons for keeping a lightning rod earth ground wire
outside the building involves factors beyond the scope of this
discussion. But one reason why: once inside the building,
then a destructive transient has a building is chock full of
conductors. The building concrete. The heating system.
Linoleum tile. Etc. The point is once lightning is inside
the building, then the building has too many conductive paths
to create destructive and induced transients. This is but
another reason why we earth transients before transients enter
the building.

There you go again. Linoleum and concrete aren't very good
conductors.

snip
http://scott-inc.com/html/ufer.htm

snip

See that rebar protruding beneath the pad?

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w_tom wrote:
Pulses are sums of numerous frequencies - numerous sine
waves. A pulse is not just a pulse. Like all waveforms, the
pulse is also a sum of various sine waves (of different
frequency, amplitude, and phase). IOW a pulse is not just a
pulse. A pulse is what happens when numerous sine waves (with
boundary conditions) are summed together.

You continue to confuse mathematical analysis with physical reality.


That is also true of lightning. Lightning is not some DC
pulse.

Define DC. Has there ever in the history of mankind been anything
that qualifies under your definition? Could there be? Would the
current flowing in a flashlight that's turned on, then off, be "DC?"

How do you account for the discussion at the Web page you cited earlier
of positive and negative lightning?

Lightning is AC electricity - at numerous radio
frequencies.

I was trying to be clear. Lighting is electricity. But the
electricity called lightning does create electromagnetic waves
that will be of same frequency.

Ground wires from any surge protector must avoid sharp
bends. As I have so often done, a published source:
US Army Training Manual 5-690
3.4 Lightning protection subsystem (p 46)
d.1(i) Installation of surge arresters is shown for
grounded and ungrounded service ... In order to prevent
introducing excessive inductance and resistance in the
transient path to the surge arrester, No. 4 AWG (minimum)
insulated stranded copper wire of the minimum feasible
length must be used to make the interconnection(s) unless
otherwise recommended and guaranteed by the manufacturer.
Also, the interconnecting wiring must not contain loops
or sharp bends. Otherwise, the response time of the surge
arrester will be delayed and a higher clamp voltage than
that of the surge arrester will be impressed across the
protected equipment, thus increasing the possibility of
damage. In the event a very fast transient should occur,
it is quite likely that the surge arrester would never
turn on, and all of the transient energy would be
dissipated by supposedly protected equipment.

Interesting. Since you didn't provide a Web cite for context, I had
to look for one. The closest I could find was this, at pages 77-80 +/-:

http://ccb.org/docs/DMMHNAV/419A2.pdf

It's clear why they say to avoid loops, since inductance in
the path could lead to the result they describe -- sharp bends less
so. Query how sharp a bend you can put in #2 (or even #4) wire, anyway.

It's also interesting (to me) that they separately fuse the surge
protectors. It seems to me a fuse could present more of a discontinuity
than a sharp bend, and could also contribute some potentially
significant resistance (relative to copper wire).

I never said the earthing wire for a lightning rod must not
be surrounded by a building's girders.

As I recall you did say it shouldn't have a coil around it. Girders
could comprise a series of shorted one turn coils.

I only said the
preferred method of routing that earthing wire is to keep it
outside the building. This for reasons beyond the scope of
this discussion which is impedance, the purpose of earthing,
and characteristics of a lightning pulse that makes it so
challenging.

snip

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The current discussion was whether your statement that lightning is made of
sine waves was correct. I charitably pointed out that the basis for may of
your posts is correct but your application of ideas often takes tangents and
you refuse to accept that there is anything out of context in what you say.
I do not claim to have superior knowledge to anyone on the matter and do not
feel compelled to attempt to demonstrate how much I know. You consistently
demonstrate a great deal of knowledge, but applying it in a manner that is
at best condescending and pedantic and at worst contextually inappropriate
and misleading. Your obvious preference for verbosity and debate make your
posts less useful than they would be if you were trying to be helpful.

It is a shame that your ego gets in the way of your ability to provide
useful information.

Leonard

"w_tom" wrote in message
...
If Leonard Caillouet had a better way to answer the
question, then he would have posted it. However everytime a
reply from Leonard Caillouet arrives, it is routinely another
'attack the messenger' post rather than an answer to a
technical question. Leonard remains consistent. Post personal
attacks rather than attack the question with facts. Where did
he even once try to answer the posters question? That would
be a pleasant and unnatural surprise.

Leonard often demonstrates only enough technical knowledge
to lob hand grenades. Keep your head down. Leonard is back.

Leonard Caillouet wrote:
Once again, you miss the point in favor of arguing and trying to
prove that your perspective is superior. Your use of the
terminology "made of sine waves" was incorrect, he called you on
the matter and you continued to maintain that postition and argue
the point. My point was not to argue that a wavelet analysis was
better, only that sine waves are only on choice for decomposing a
signal. Once again, you are the one that looks like a yo yo.

It helps to have EE knowledge and a few decades of
experience before making blanket statements (without any
supporting facts or numbers) about concrete conductivity. CJT
did not even understand the basic math and AC nature within
impulses (a spectrum of sine waves during the impulse). Now
he just knows concrete is not conductive? And we should agree
because CJT posts no supporting facts, numbers, or citations?

An Ufer ground is described in:
http://dayton.akorn.net/pipermail/to...er/026083.html
[TowerTalk] UFER Ground???
An Ufer ground ... this may be the ENTIRE ground system. Since
the concrete is conductive and there is lots of concrete area
in contact with the soil, it does a pretty reasonable job.

For some reason, CJT has decided that concrete is not a good
conductor of lightning only because it is not as good a
conductor to car batteries and 60 Hz utility electricity. He
uses classic junk science reasoning to support his feelings.
He provides not one supporting fact for his speculations. He
just knows and therefore we should know he is correct.

Lurkers who would learn and prosper from long proven
technical knowledge have numbers for concrete conductivity,
and a description of why concrete is so effective:
http://www.psihq.com/iread/ufergrnd.htm

Which do we believe? A blanket statement made without
supporting facts to promote speculations and rumors. Or the
science that says concrete is a good conductor as demonstrated
in virtually every town, cited even in the National Electrical
Code (NEC), and is demonstrated by numbers. I guess CJT will
next be writing a letter demanding the NEC correct their
standards. CJT denies concrete is conductive because somehow
he just knows. His personal knowledge is sufficient. Next he
will accuse ME of being patronizing?

Demonstrated was CG lightning's AC nature that demands
effective protection systems have short (ie. less than 10
feet) connections to earthing. Just another reason why
plug-in protectors with long connections (if any) to earth
ground provide ineffective protection. The AC nature of
lightning says an effective protector must be connected short
to earth ground. The AC nature of lightning is why properly
earthed 'whole house' protectors are so effective (as well as
a less expensive solution).

CJT wrote:
There you go again. Linoleum and concrete aren't very good
conductors.

snip
http://scott-inc.com/html/ufer.htm

w_tom wrote:
It helps to have EE knowledge and a few decades of
experience before making blanket statements (without any
supporting facts or numbers) about concrete conductivity. CJT
did not even understand the basic math and AC nature within
impulses (a spectrum of sine waves during the impulse).

I'll let the visitors to this forum judge for themselves which
of us has the better understanding of what a Fourier analysis
really means.

That, after all, was what brought me to this thread -- your
apparent misunderstanding of the difference between an analysis
technique and reality.

Now
he just knows concrete is not conductive?

I didn't say it wasn't conductive. I said it wasn't a _good_
conductor -- like copper, steel (e.g. rebar), etc. It's apparently
a better conductor than dirt, which earns it a place in this discussion.

You don't want to address my points, so you attempt to redirect the
discussion on these tangents.

And we should agree
because CJT posts no supporting facts, numbers, or citations?

An Ufer ground is described in:
http://dayton.akorn.net/pipermail/to...er/026083.html
[TowerTalk] UFER Ground???
An Ufer ground ... this may be the ENTIRE ground system. Since
the concrete is conductive and there is lots of concrete area
in contact with the soil, it does a pretty reasonable job.

Better than dirt, anyway (probably mostly because it retains water
better) ...


For some reason, CJT has decided that concrete is not a good
conductor of lightning only because it is not as good a
conductor to car batteries and 60 Hz utility electricity.

For some reason, w_tom seems to think concrete is a better conductor
of lightning than it is of other electricity. He gets excited about
small increases in impedance caused by bends in copper wire, but then
apparently thinks concrete is a great conductor in comparison.

He
uses classic junk science reasoning to support his feelings.
He provides not one supporting fact for his speculations. He
just knows and therefore we should know he is correct.

Lurkers who would learn and prosper from long proven
technical knowledge have numbers for concrete conductivity,
and a description of why concrete is so effective:
http://www.psihq.com/iread/ufergrnd.htm

Odd, isn't it, how much of that article's focus is on the rebar
in the concrete?

Which do we believe? A blanket statement made without
supporting facts to promote speculations and rumors. Or the
science that says concrete is a good conductor as demonstrated
in virtually every town, cited even in the National Electrical
Code (NEC), and is demonstrated by numbers. I guess CJT will
next be writing a letter demanding the NEC correct their
standards. CJT denies concrete is conductive because somehow
he just knows. His personal knowledge is sufficient. Next he
will accuse ME of being patronizing?


I'll let the visitors to this forum decide whether you have a
patronizing attitude.

Demonstrated was CG lightning's AC nature that demands
effective protection systems have short (ie. less than 10
feet) connections to earthing. Just another reason why
plug-in protectors with long connections (if any) to earth
ground provide ineffective protection. The AC nature of
lightning says an effective protector must be connected short
to earth ground. The AC nature of lightning is why properly
earthed 'whole house' protectors are so effective (as well as
a less expensive solution).

Apparently you advocate throwing away all plug-in surge protectors,
which, after all, rely on Romex grounds that might have sharp bends and
might exceed 10 feet, and prefer instead the purity of concrete
grounding pads for all.


CJT wrote:
There you go again. Linoleum and concrete aren't very good
conductors.

snip
http://scott-inc.com/html/ufer.htm


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CJT knows things despite no supporting facts, numbers, nor
industry citations. Provided were supporting numbers and
sources that CJT doesn't even challenge. He just ignores what
industry professional have long been saying.

Pulses are chock full of frequencies. Described in simple
terms to be easily understood by those without sufficient
math: pulse is sine waves with boundary conditions. CJT's
replies are decrees without any supporting facts or numbers.
He arbitrarily declares in one and two sentence replies that
all those industry professionals, well proven experience, and
scientific concepts must be wrong. No reason why. He just
decrees. He even denies that concrete is a good conductive
material. Somehow he just knows so much better than Ufer and
other professionals who recommend this good conductor
solution. Somehow he even ignored the numbers so that he can
say concrete is not a good conductor.

CJT knows better than science. Nothing more can be said if
one arbitrarily knows better than the professionals and
generations of experience. We are done. CJT just knows
better.

Meanwhile, those who want effective protection start by
installing, inspecting, or upgrading that protection: the
single point earth ground. Then connecting each incoming
utility wire to that earth ground either using a hardwire
connection or via a 'whole house' protector. A protector is
only as effective as its earth ground.

CJT wrote:
I'll let the visitors to this forum judge for themselves which
of us has the better understanding of what a Fourier analysis
really means.

That, after all, was what brought me to this thread -- your
apparent misunderstanding of the difference between an analysis
technique and reality.
...

I didn't say it wasn't conductive. I said it wasn't a _good_
conductor -- like copper, steel (e.g. rebar), etc. It's apparently
a better conductor than dirt, which earns it a place in this discussion.

You don't want to address my points, so you attempt to redirect the
discussion on these tangents.
...

w_tom wrote:
CJT knows things despite no supporting facts, numbers, nor
industry citations. Provided were supporting numbers and
sources that CJT doesn't even challenge. He just ignores what
industry professional have long been saying.

Pulses are chock full of frequencies. Described in simple
terms to be easily understood by those without sufficient
math: pulse is sine waves with boundary conditions. CJT's
replies are decrees without any supporting facts or numbers.
He arbitrarily declares in one and two sentence replies that
all those industry professionals, well proven experience, and
scientific concepts must be wrong. No reason why. He just
decrees. He even denies that concrete is a good conductive
material. Somehow he just knows so much better than Ufer and
other professionals who recommend this good conductor
solution. Somehow he even ignored the numbers so that he can
say concrete is not a good conductor.

CJT knows better than science. Nothing more can be said if
one arbitrarily knows better than the professionals and
generations of experience. We are done. CJT just knows
better.

Meanwhile, those who want effective protection start by
installing, inspecting, or upgrading that protection: the
single point earth ground. Then connecting each incoming
utility wire to that earth ground either using a hardwire
connection or via a 'whole house' protector. A protector is
only as effective as its earth ground.

Sputter away, small man.


CJT wrote:
I'll let the visitors to this forum judge for themselves which
of us has the better understanding of what a Fourier analysis
really means.

That, after all, was what brought me to this thread -- your
apparent misunderstanding of the difference between an analysis
technique and reality.
...

I didn't say it wasn't conductive. I said it wasn't a _good_
conductor -- like copper, steel (e.g. rebar), etc. It's apparently
a better conductor than dirt, which earns it a place in this discussion.

You don't want to address my points, so you attempt to redirect the
discussion on these tangents.
...


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