"Anne Lurie" wrote in message
.com...

Well, I happened to have the paperwork from one of our APC UPS units right
here, and it says (in part): "Power line transients that APC products
have
been designed to protect against, as recognized by industry standards,
include spikes and surges on AC power lines."
This reply is not targeted at the last poster, but at what seems to be a
general bit of confusion in the group.

There are spikes and surges on power lines as a result of everyday
industrial usage in the general area. Surge suppressors work well for
these. Most commercial surge suppressors these days use a 3 prong plug
which should provide an adequate ground for this purpose. A lightning
strike miles away may also lead to a spike which is amenable to
a surge suppressor. But, a direct lightning strike in the close
neighborhood
can generate lots of power, and no surge suppressor will protect from that
(lightning, in fact, acts so bizzarrely that I doubt anything (including
lightning rods)will provide 100% protection.) I agree that a surge
suppressor without a ground is next to useless, but most have such a ground
these days.

By the way, lightning rods are not supposed to "draw the lightning" away
from the protected structure. Any wire you might use would be far too flimsy
to carry such a load. What a lightning rod does is to slowly discharge the
atmosphere surrounding it (that is why it should have a sharp point) and to
lessen the probability of a strike in the area (look in any physics book).

An earlier poster mentioned a ground fault interrputer circuit (GFI). This
is intended to save your life from electrocution if you should happen to
touch a live power line while your feet (or other part) is grounded. The
GFI
senses that there is current going from hot directly to ground (through
you)
without going back through the GFI and the unit shuts off the juice before
any damage can be done. All bathroom and outdoor sockets should be
equipped with GFIs for safety. However, a GFI does nothing to protect
equipment
from surges, spikes, or lightning.

I have several friends whe have had their surge suppressor "blow up" (it
was doing its job) in response to a massive line surge, and the attached
equipment was not damaged. Other equipment in the house did not fare so
well. This is by no means "proof" of effectiveness, but I do not believe a
good surge suppressor is as useless as one correspondent seems to believe.

bern muller

Bern et al,

Lightning is a definitely a phenomenon. I had a friend with a computer with
two surge protectors, and a voltage regulator on his computer system and
when his home got zapped the electrical discharge traveled through the two
surge protectors destroying them, and then, evidently followed on the
outside of his voltage regulator and when it got to the end of the line
where his computer was it melted the case on his monitor and fried the
inside of the CPU case and blew up his printer.

I had an electrical surge take out one of the telephone jacks and kill my
modem. Now-a-days, if it is raining, and certainly if there is thunder, the
computer does not get turned on and if heard while being used, it is
immediately shut off. I also the unplug the main plug from the wall socket.
I have a surge protector and a UPS, put I certainly don't take chances with
lightning. In addition, when I got a new phone jack I setup the line to my
computer where when I am finished with using my computer I disconnected the
telephone line to isolate the computer from telephone line.

Tom L.L.
===============================
"bmuller" wrote in message
s.com...

"Anne Lurie" wrote in message
.com...

Well, I happened to have the paperwork from one of our APC UPS units
right
here, and it says (in part): "Power line transients that APC products
have
been designed to protect against, as recognized by industry standards,
include spikes and surges on AC power lines."
This reply is not targeted at the last poster, but at what seems to be a
general bit of confusion in the group.

There are spikes and surges on power lines as a result of everyday
industrial usage in the general area. Surge suppressors work well for
these. Most commercial surge suppressors these days use a 3 prong plug
which should provide an adequate ground for this purpose. A lightning
strike miles away may also lead to a spike which is amenable to
a surge suppressor. But, a direct lightning strike in the close
neighborhood
can generate lots of power, and no surge suppressor will protect from
that
(lightning, in fact, acts so bizzarrely that I doubt anything (including
lightning rods)will provide 100% protection.) I agree that a surge
suppressor without a ground is next to useless, but most have such a
ground
these days.

By the way, lightning rods are not supposed to "draw the lightning" away
from the protected structure. Any wire you might use would be far too
flimsy
to carry such a load. What a lightning rod does is to slowly discharge the
atmosphere surrounding it (that is why it should have a sharp point) and
to
lessen the probability of a strike in the area (look in any physics book).

An earlier poster mentioned a ground fault interrputer circuit (GFI).
This
is intended to save your life from electrocution if you should happen to
touch a live power line while your feet (or other part) is grounded. The
GFI
senses that there is current going from hot directly to ground (through
you)
without going back through the GFI and the unit shuts off the juice
before
any damage can be done. All bathroom and outdoor sockets should be
equipped with GFIs for safety. However, a GFI does nothing to protect
equipment
from surges, spikes, or lightning.

I have several friends whe have had their surge suppressor "blow up" (it
was doing its job) in response to a massive line surge, and the attached
equipment was not damaged. Other equipment in the house did not fare so
well. This is by no means "proof" of effectiveness, but I do not believe a
good surge suppressor is as useless as one correspondent seems to believe.

bern muller

Any spike and surge on power lines that occur from everyday
industrial usage would then destroy dimmer switches daily.
Such spikes are typically so small as to be called noise. So
small that even dimmer switches, electronic timer switches,
and GFCI outlets are not damaged by such trivial events. This
noise is too small to even cause plug-in protectors to react -
to even meet let-through voltage.

All electronics and even pumps have internal protection
sufficient to withstand such trivial noise transients. It is
routine to have a direct strike without damage. The well
proven method is 'whole house' type protection connected to
earth ground. If nothing can stop damage from a direct
strike, then clearly the telco replaces their $multi-million
switching computer annually. Clearly there are a few days
every year when local phone service is down. If not
interrupted annually, then damage from direct lightning
strikes is easily avoided.


By the way, lightning rods are not supposed to "draw the lightning"
away from the protected structure. Any wire you might use would be
far too flimsy to carry such a load. What a lightning rod does is
to slowly discharge the atmosphere surrounding it

This is the scam promoted by the Early Streamer Emission
industry. Since the National Fire Protection Association
rejected their claims, one ESE retailer (Hearly Bros) sued the
non-profit NFPA to bankrupt this public interest
organization. ESE manufacturers claim that lightning rods
bleed charge from the atmosphere - in direct contradiction to
professional papers and to NFPA requirements. Dr Abdul Mousa
is especially critical of that ESE scam - that lightning rods
slowly discharge the air.


The US Army defines in TM5-690 a wire size sufficient to
discharge lightning without damage. 10 AWG. This makes
complete sense once one learns a direct lightning strike has
so little energy. Unfortunately too many will make wild
claims without first learning those numbers. Its called junk
science reasoning. Please note how often posts state facts
with numbers, cite industry professionals and application
notes, and are based upon decades of experience. If lightning
vaporizes wires, then Ben Franklin did not exist to sign the
Declaration of Independence.


A lightning rod above the pond and properly earthed by 10
AWG or heavier wire is more than sufficient to intercept and
divert lightning to earth without pond damage. If not, then
Disney World guests would be often struck by lightning.
Notice those lightning rods everywhere in Disney World?
Protection from direct lightning strikes is easily
implemented, does not vaporize wire if properly installed, and
will only be as effective as its earth ground.


Any surge protector that blows up as a result of a surge did
not do its job AND was grossly undersized. Surge protector,
properly sized, routinely earth surges without damage or human
knowledge. But plug-in protectors don't even claim such
protection. So they are undersized. It causes the naive to
'feel' that it sacrificed itself to protection the adjacent
appliance.

The surge protector was so grossly undersized that a surge
too small to overwhelm existing protection in an appliance,
instead, damages the undersized surge protector. A marketing
ploy. The naive will then make wild assumptions, claim the
surge protector sacrificed itself, and recommend more grossly
undersized protectors that cost more than the effective 'whole
house' protector. Adjacent appliance was not damaged because
the surge was too small to overwhelm internal appliance
protection - but destroyed the grossly undersized surge
protector.


GFCI on pond electrical power is essential to human safety.
But what protects that GFCI? 'Whole house' surge protector or
lightning rod - both connected to the most critical system
component - earth ground. These are facts well proven since
the 1930s. And yet still some will use junk science
reasonings about industrial spikes and surges, confuse power
verses energy in lightning, misrepresent what lightning rods
do (promote the ESE scam), promote a grossly undersized surge
protector marketing ploy, and even claim that effective
protection is not possible.

Damage from lightning is so well proven, so inexpensive, and
so reliable that the damage is considered a human failure.
Those who say otherwise will have to explain why township
telephone service is not interrupted for a few days every year
by lightning. Damage from direct strikes is routinely avoided
even when a computer is connected to overhead wires everywhere
in town.

If lightning struck that pond, then that pond may connect to
geology that lightning seeks. Best to install a lightning
rod, properly earthed, to provide lightning with a
non-destructive path. Plug-in protector (power strip and UPS)
don't even claim to provide effective surge protection.

bmuller wrote:
There are spikes and surges on power lines as a result of everyday
industrial usage in the general area. Surge suppressors work well for
these. Most commercial surge suppressors these days use a 3 prong plug
which should provide an adequate ground for this purpose. A lightning
strike miles away may also lead to a spike which is amenable to
a surge suppressor. But, a direct lightning strike in the close
neighborhood
can generate lots of power, and no surge suppressor will protect from that
(lightning, in fact, acts so bizzarrely that I doubt anything (including
lightning rods)will provide 100% protection.) I agree that a surge
suppressor without a ground is next to useless, but most have such a ground
these days.

By the way, lightning rods are not supposed to "draw the lightning" away
from the protected structure. Any wire you might use would be far too flimsy
to carry such a load. What a lightning rod does is to slowly discharge the
atmosphere surrounding it (that is why it should have a sharp point) and to
lessen the probability of a strike in the area (look in any physics book).

An earlier poster mentioned a ground fault interrputer circuit (GFI). This
is intended to save your life from electrocution if you should happen to
touch a live power line while your feet (or other part) is grounded. The
GFI
senses that there is current going from hot directly to ground (through
you)
without going back through the GFI and the unit shuts off the juice before
any damage can be done. All bathroom and outdoor sockets should be
equipped with GFIs for safety. However, a GFI does nothing to protect
equipment
from surges, spikes, or lightning.

I have several friends whe have had their surge suppressor "blow up" (it
was doing its job) in response to a massive line surge, and the attached
equipment was not damaged. Other equipment in the house did not fare so
well. This is by no means "proof" of effectiveness, but I do not believe a
good surge suppressor is as useless as one correspondent seems to believe.

bern muller

I wrote:

By the way, lightning rods are not supposed to "draw the lightning"
\ away from the protected structure. Any wire you might use would be
far too flimsy to carry such a load. What a lightning rod does is
to slowly discharge the atmosphere surrounding it


"w_tom" wrote in message

This is the scam promoted by the Early Streamer Emission
industry.

Actually, this is the scam first promoted by Benjamin Franklin. Turns out he
was wrong. So was I in my previous posting, so I may well be the first
newsgroup poster in history to admit to error. Being somewhat elderly, I
tried to recall what we learned about lightning in physics class, and got it
mixed in with what we learned about Franklin in history class. It seems even
Ben realized later in his life that lightning rods do not discharge clouds,
but merely provide a safe path to ground for the lightning.

The US Army defines in TM5-690 a wire size sufficient to
discharge lightning without damage. 10 AWG. This makes
complete sense once one learns a direct lightning strike has
so little energy.

Hmmmm. It seems to me knocking bricks off of buildings, or splitting trees,
or making very loud noises and bright lights suggests more than "so little
energy". Various non commercial websites suggest that a typical lightning
strike releases 250 KWH of energy. A big one may release 10 times that much.
That is a lot of energy. Admittedly, most of that is dissipated in the air
above where it strikes, but I think it is disingenuous to characterize it as
"little". It is not a lot, for example, compared to what it takes to light
New York city. On the other hand, that amount of energy is concentrated in
less than a millisecond, so it is very intense.

notes, and are based upon decades of experience. If lightning
vaporizes wires, then Ben Franklin did not exist to sign the
Declaration of Independence.

Ben's kite did not actually get struck by lightning, but just picked up the
cloud charge. His kite string was not a copper conductor and did not conduct
a large current.

A lightning rod above the pond and properly earthed by 10
AWG or heavier wire is more than sufficient to intercept and
divert lightning to earth without pond damage.

Most lightning rod manufacturers use 2 or 0 gauge wire as the down wire. 10
gauge seems to me a little flimsy. Given that a 10 gauge copper wire has a
resistance of about 1 ohm per 1000 feet, and given a total length of wire
of about 50 feet, we are dealing with 0.05 ohms of resistance. Given also
that an average lightning strike can have a current of 10,000 amps (NASA has
measured at least one strike of 100,000 amps)(and that the conductor takes
the entire current) we are dealing with a dissipated power of 10000^2*.05
or 5 million watts. Or 100,000 watts per foot of wire. Admittedly this is
for a very short time. But I submit that 100000 watts applied to a foot of
this wire over a millisecond will melt or otherwise seriously damage that
wire.

Ben,

There is a lot of power in lightning. I was told that the measurement of a
10 mile long streak of lightning would power a city of 5,000 people for a
year. Be that as it may, I read about a guy that observed "ball lightning"
(I know it is not normal lightning) hit a concrete gate piling with a chain
on it that had links about 6 inches long and 4 inches wide, and was very
heavy, and it explode the piling into dust and welded all the links of chain
into a solid length of metal. He wasn't very old when this happened but the
older people said it was a good thing that he was not close because the
energy dissipated was a lot. Pictures of the chain and the pilings were in
my Weekly reader when I was in the fourth grade.

Mother Nature has a tendency to pack a punch.

Tom L.L.
---------------------------------------------
"bmuller" wrote in message
s.com...
I wrote:

By the way, lightning rods are not supposed to "draw the lightning"
\ away from the protected structure. Any wire you might use would be
far too flimsy to carry such a load. What a lightning rod does is
to slowly discharge the atmosphere surrounding it


"w_tom" wrote in message

This is the scam promoted by the Early Streamer Emission
industry.

Actually, this is the scam first promoted by Benjamin Franklin. Turns out
he
was wrong. So was I in my previous posting, so I may well be the first
newsgroup poster in history to admit to error. Being somewhat elderly, I
tried to recall what we learned about lightning in physics class, and got
it
mixed in with what we learned about Franklin in history class. It seems
even
Ben realized later in his life that lightning rods do not discharge
clouds,
but merely provide a safe path to ground for the lightning.

The US Army defines in TM5-690 a wire size sufficient to
discharge lightning without damage. 10 AWG. This makes
complete sense once one learns a direct lightning strike has
so little energy.

Hmmmm. It seems to me knocking bricks off of buildings, or splitting
trees,
or making very loud noises and bright lights suggests more than "so little
energy". Various non commercial websites suggest that a typical lightning
strike releases 250 KWH of energy. A big one may release 10 times that
much.
That is a lot of energy. Admittedly, most of that is dissipated in the air
above where it strikes, but I think it is disingenuous to characterize it
as
"little". It is not a lot, for example, compared to what it takes to light
New York city. On the other hand, that amount of energy is concentrated in
less than a millisecond, so it is very intense.

notes, and are based upon decades of experience. If lightning
vaporizes wires, then Ben Franklin did not exist to sign the
Declaration of Independence.

Ben's kite did not actually get struck by lightning, but just picked up
the
cloud charge. His kite string was not a copper conductor and did not
conduct
a large current.

A lightning rod above the pond and properly earthed by 10
AWG or heavier wire is more than sufficient to intercept and
divert lightning to earth without pond damage.

Most lightning rod manufacturers use 2 or 0 gauge wire as the down wire.
10
gauge seems to me a little flimsy. Given that a 10 gauge copper wire has a
resistance of about 1 ohm per 1000 feet, and given a total length of wire
of about 50 feet, we are dealing with 0.05 ohms of resistance. Given also
that an average lightning strike can have a current of 10,000 amps (NASA
has
measured at least one strike of 100,000 amps)(and that the conductor takes
the entire current) we are dealing with a dissipated power of 10000^2*.05
or 5 million watts. Or 100,000 watts per foot of wire. Admittedly this is
for a very short time. But I submit that 100000 watts applied to a foot of
this wire over a millisecond will melt or otherwise seriously damage that
wire.

Let's review where all that energy was applied and how much
- with numbers so that we don't do what junk scientists must
do.

Don Kelly in Newsgroup sci.physics.electromag on 4 Nov 2000
entitled "Oddball question":
In a large storm, there is an appreciable amount of energy but
most of this is dissipated as heat and light in multiple strokes
over the duration of the storm (and a wide area) ... A typical
stroke will reach its peak in about 1-2 microseconds and die to
about half peak in 50-100 microseconds. Millionths of seconds,
not seconds! There may be several strokes in the same path but
even 3-5 strokes will take less than 1/1000 second. The strokes
just appear to last seconds.
Yes there is a high peak power in a stroke but this does not
translate into appreciable energy (about 55 KWH (200MJ)for an
average stroke). Energy is what we need, not high peak power.
Allowing an extremely (ridiculously so) optimistic 50% energy
recovery and noting that a high isokeraunic level may be 8-10
strokes/square Km /year- this translates to about 220-275 KWH/
sq Km/year.
A 25 watt bulb running for the full year will require
220KWH/year so a storm could supply one 25 watt bulb /sq Km/year.
How much time and effort should be spent on this miniscule
return?
Yes, a stroke can cause a lot of destruction- that is because
the energy is dissipated in a small area in an extremely short
period of time- say 40,000A for 100microseconds, into 20 ohms
resistance- 32,000,000KW but less than 1 KWH. Lots of power
but little energy.


Tom La Bron wrote:
Ben,
There is a lot of power in lightning. I was told that the measurement of a
10 mile long streak of lightning would power a city of 5,000 people for a
year. Be that as it may, I read about a guy that observed "ball lightning"
(I know it is not normal lightning) hit a concrete gate piling with a chain
on it that had links about 6 inches long and 4 inches wide, and was very
heavy, and it explode the piling into dust and welded all the links of chain
into a solid length of metal. He wasn't very old when this happened but the
older people said it was a good thing that he was not close because the
energy dissipated was a lot. Pictures of the chain and the pilings were in
my Weekly reader when I was in the fourth grade.

Mother Nature has a tendency to pack a punch.

Tom L.L.
---------------------------------------------
"bmuller" wrote in message
s.com...
I wrote:

By the way, lightning rods are not supposed to "draw the lightning"
\ away from the protected structure. Any wire you might use would be
far too flimsy to carry such a load. What a lightning rod does is
to slowly discharge the atmosphere surrounding it


"w_tom" wrote in message

This is the scam promoted by the Early Streamer Emission
industry.

Actually, this is the scam first promoted by Benjamin Franklin. Turns out
he
was wrong. So was I in my previous posting, so I may well be the first
newsgroup poster in history to admit to error. Being somewhat elderly, I
tried to recall what we learned about lightning in physics class, and got
it
mixed in with what we learned about Franklin in history class. It seems
even
Ben realized later in his life that lightning rods do not discharge
clouds,
but merely provide a safe path to ground for the lightning.

The US Army defines in TM5-690 a wire size sufficient to
discharge lightning without damage. 10 AWG. This makes
complete sense once one learns a direct lightning strike has
so little energy.

Hmmmm. It seems to me knocking bricks off of buildings, or splitting
trees,
or making very loud noises and bright lights suggests more than "so little
energy". Various non commercial websites suggest that a typical lightning
strike releases 250 KWH of energy. A big one may release 10 times that
much.
That is a lot of energy. Admittedly, most of that is dissipated in the air
above where it strikes, but I think it is disingenuous to characterize it
as
"little". It is not a lot, for example, compared to what it takes to light
New York city. On the other hand, that amount of energy is concentrated in
less than a millisecond, so it is very intense.

notes, and are based upon decades of experience. If lightning
vaporizes wires, then Ben Franklin did not exist to sign the
Declaration of Independence.

Ben's kite did not actually get struck by lightning, but just picked up
the
cloud charge. His kite string was not a copper conductor and did not
conduct
a large current.

A lightning rod above the pond and properly earthed by 10
AWG or heavier wire is more than sufficient to intercept and
divert lightning to earth without pond damage.

Most lightning rod manufacturers use 2 or 0 gauge wire as the down wire.
10
gauge seems to me a little flimsy. Given that a 10 gauge copper wire has a
resistance of about 1 ohm per 1000 feet, and given a total length of wire
of about 50 feet, we are dealing with 0.05 ohms of resistance. Given also
that an average lightning strike can have a current of 10,000 amps (NASA
has
measured at least one strike of 100,000 amps)(and that the conductor takes
the entire current) we are dealing with a dissipated power of 10000^2*.05
or 5 million watts. Or 100,000 watts per foot of wire. Admittedly this is
for a very short time. But I submit that 100000 watts applied to a foot of
this wire over a millisecond will melt or otherwise seriously damage that
wire.

What is high energy? It takes a backhoe pushing down to
embed a nail into construction lumber. High energy. But it
takes a simple arm attached to a 20 oz hammer to drive that
same 10 penny nail into wood with one hit. Low energy - high
power.

A study by Alan Taylor of the US Forestry Service discovered
most all trees struck by lightning don't even suffer
noticeable damage. It is a rare strike that has sufficient
energy to ignite sugars in the wood and cause severe damage.
But many only see the exception (after the fact) and assume
lightning is this monstrous force.

How energy is applied and how it enables other higher energy
sources makes lightning appear to be this monstrous force.
Lightning really does something equivalent to a spark plug in
a car. Not much energy. But when properly applies, it moves
things.

This comment from a famous industry professional:
Martin A Uman All About Lightning p146
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."

Most energy in lightning is found elsewhere and not at the
strike location. However lightning is a current source. It's
voltage at the strike location will increase, as necessary, to
overwhelm the blocking device AND therefore increase energy
dissipated in that blocking device. Just another reason why
surge protectors cannot stop, block, or absorb a lightning
surge. The best protector is low impedance (not resistance)
meaning that most of the energy dissipates elsewhere such as
in the sky or in the ground.

This need for a low impedance connection to earth is also why
a surge protector must make a 'less than 10 foot' connection
to earth ground - which plug-in protection devices do not
accomplish.

Let's look at another device designed just for shunting
lightning surges to earth - the Metal Oxide Varistor or MOV:
http://www.nteinc.com/Web_pgs/MOV.html
2V150 will shunt up to 4500 amp surge current putting the
device at up to 410 volts. That's 1.845 megawatts - the power
of a small electric power plant! However surges are also
typically 8/20 microsecond events (not milliseconds) meaning
that energy of that shunted surge is about 26 joules. High
power but little energy.

Dimension for leads on a device designed to shunt 4500 amps
are about .03 inches diameter or about 18 or 20 AWG wire. Up
to 1.85 million watts but carried without damage on a 0.8
millimeter thick wire.

10 AWG wire is more than sufficient to shunt a 10,000 amp or
20,000 amp surge. However a rare lightning strike where the
entire cloud is discharged in only one strike. Therefore some
locations will install 4 or 0 AWG wire so that even this rare
200,000 amp lightning strike causes no damage even to the
wire.

Just because a brick is dislodged or a transformer explodes
does not mean lightning has high energy. My arm, a low energy
device, connected to a hammer can dislodge a brick. The
energy required to explode that transformer is provided by the
utility - not by lightning. Without understanding the theory
and numbers, too many falsely assume that lightning is some
monstrous force. It cannot be stopped, blocked, or absorbed
as plug-in surge protectors (and UPSes) claim. But damage is
easily diverted by earthing the surge.

bmuller wrote:
...
Hmmmm. It seems to me knocking bricks off of buildings, or splitting trees,
or making very loud noises and bright lights suggests more than "so little
energy". Various non commercial websites suggest that a typical lightning
strike releases 250 KWH of energy. A big one may release 10 times that much.
That is a lot of energy. Admittedly, most of that is dissipated in the air
above where it strikes, but I think it is disingenuous to characterize it as
"little". It is not a lot, for example, compared to what it takes to light
New York city. On the other hand, that amount of energy is concentrated in
less than a millisecond, so it is very intense.

notes, and are based upon decades of experience. If lightning
vaporizes wires, then Ben Franklin did not exist to sign the
Declaration of Independence.

Ben's kite did not actually get struck by lightning, but just picked up the
cloud charge. His kite string was not a copper conductor and did not conduct
a large current.

A lightning rod above the pond and properly earthed by 10
AWG or heavier wire is more than sufficient to intercept and
divert lightning to earth without pond damage.

Most lightning rod manufacturers use 2 or 0 gauge wire as the down wire. 10
gauge seems to me a little flimsy. Given that a 10 gauge copper wire has a
resistance of about 1 ohm per 1000 feet, and given a total length of wire
of about 50 feet, we are dealing with 0.05 ohms of resistance. Given also
that an average lightning strike can have a current of 10,000 amps (NASA has
measured at least one strike of 100,000 amps)(and that the conductor takes
the entire current) we are dealing with a dissipated power of 10000^2*.05
or 5 million watts. Or 100,000 watts per foot of wire. Admittedly this is
for a very short time. But I submit that 100000 watts applied to a foot of
this wire over a millisecond will melt or otherwise seriously damage that
wire.

On Sun, 27 Jul 2003, w_tom wrote:

Let's review where all that energy was applied and how much
- with numbers so that we don't do what junk scientists must
do.

Don Kelly in Newsgroup sci.physics.electromag on 4 Nov 2000
entitled "Oddball question":
over the duration of the storm (and a wide area) ... A typical
stroke will reach its peak in about 1-2 microseconds and die to
about half peak in 50-100 microseconds. Millionths of seconds,
not seconds! There may be several strokes in the same path but
even 3-5 strokes will take less than 1/1000 second. The strokes
just appear to last seconds.
Yes there is a high peak power in a stroke but this does not
translate into appreciable energy (about 55 KWH (200MJ)for an
average stroke). Energy is what we need, not high peak power.

Which, for "Gee Whiz!" value, works out to on the order of 2x10^12 Watts
over 100 uS...

The US Army defines in TM5-690 a wire size sufficient to
discharge lightning without damage. 10 AWG. This makes
complete sense once one learns a direct lightning strike has
so little energy.

Various non commercial websites suggest that a typical lightning
strike releases 250 KWH of energy. A big one may release 10 times that
much. That is a lot of energy. Admittedly, most of that is dissipated in the air
above where it strikes, but I think it is disingenuous to characterize it
as "little".

A lightning rod above the pond and properly earthed by 10
AWG or heavier wire is more than sufficient to intercept and
divert lightning to earth without pond damage.

Most lightning rod manufacturers use 2 or 0 gauge wire as the down wire.
10 gauge seems to me a little flimsy. Given that a 10 gauge copper wire has a
resistance of about 1 ohm per 1000 feet, and given a total length of wire
of about 50 feet, we are dealing with 0.05 ohms of resistance. Given also
that an average lightning strike can have a current of 10,000 amps (NASA
has measured at least one strike of 100,000 amps)(and that the conductor takes
the entire current) we are dealing with a dissipated power of 10000^2*.05
or 5 million watts. Or 100,000 watts per foot of wire. Admittedly this is
for a very short time. But I submit that 100000 watts applied to a foot of
this wire over a millisecond will melt or otherwise seriously damage that
wire.

In addition to the DC resistance, you need to take into account the
inductance of the grounding wire. In the far more limited world of
industrial high energy discharges, an associate observed multiple
instances where a large laser flashlamp power supply was dumped to the
solid copper lab grounding grid. The cable from the crowbar switch to the
grid was about 4 feet long, running perhaps 30 degrees off the vertical.
They would see sparks "shortcut" from 18 inches or more up the cable, to
the floor, rather than continue down the direct path. What's the dry air
breakdown voltage for 18 inches? These *potentials*, with significant
energy behind them, do occur, even with properly grounded equipment!

Dave

I would question Alan Taylor's credentials if he thinks lightning damage is caused by
igniting sugars. Most of the damage is due to water heating from liquid to vapor and
the expansion explodes tissues.
http://www.tulsamastergardeners.org/...lightning.html


w_tom wrote:
A study by Alan Taylor of the US Forestry Service discovered
most all trees struck by lightning don't even suffer
noticeable damage. It is a rare strike that has sufficient
energy to ignite sugars in the wood and cause severe damage.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
List Manager: Puregold Goldfish List
http://puregold.aquaria.net/
www.drsolo.com
Solve the problem, dont waste energy finding who's to blame
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Unfortunately, I receive no money, gifts, discounts or other
compensation for all the damn work I do, nor for any of the
endorsements or recommendations I make.

What burns to heat a liquid; to create explosive steam?
Alan Taylor's research showed how few trees are actually
damaged because lightning often does not contain sufficient
energy. The energy to make that explosive steam must also be
provided by other sources that can create heat quickly. If
not burning sugars, then what?

wrote:
I would question Alan Taylor's credentials if he thinks lightning
damage is caused by igniting sugars. Most of the damage is due to
water heating from liquid to vapor and the expansion explodes tissues.
http://www.tulsamastergardeners.org/...lightning.html

.... think the electrical coil on a stove. electricity runs thru it and the
resistance of the metal results in it heating. if the heat is high enough, it can
even begin to vaporize the metal. Ingrid

w_tom wrote:

What burns to heat a liquid; to create explosive steam?
The energy to make that explosive steam must also be
provided by other sources that can create heat quickly. If
not burning sugars, then what?


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
List Manager: Puregold Goldfish List
http://puregold.aquaria.net/
www.drsolo.com
Solve the problem, dont waste energy finding who's to blame
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Unfortunately, I receive no money, gifts, discounts or other
compensation for all the damn work I do, nor for any of the
endorsements or recommendations I make.

What burns to heat a liquid; to create explosive steam?
Alan Taylor's research showed how few trees are actually
damaged because lightning often does not contain sufficient
energy. The energy to make that explosive steam must also be
provided by other sources that can create heat quickly. If
not burning sugars, then what?

wrote:
I would question Alan Taylor's credentials if he thinks lightning
damage is caused by igniting sugars. Most of the damage is due to
water heating from liquid to vapor and the expansion explodes tissues.
http://www.tulsamastergardeners.org/...lightning.html