lightning rod question

[Rich Grise]

On Sat, 23 Oct 2004 00:27:53 +0000, Bob Myers wrote:

"Roger Johansson" <no-email@home.se> wrote in message
news:Xns958BEE4F8CDE86336@130.133.1.4...
Rich Grise <rich@example.net> wrote:

I would like some explanation of ball lighting. I have known of a
ball ( corona ) in the cockpit of a sail boat.

Would that be St. Elmo's Fire?

St. Elmo's Fire is some kind of algea which glow in the dark, with the
same chemical processes as in fireflies. AFAIK

No, I'm afraid you're confusing your phenomena. St. Elmo's is definitely
the visible result of an electrical discharge; see

http://www.fact-index.com/s/st/st__elmo_s_fire.html

"Um, general? I think you've got your phenomena scrambled."

Ba-dump-bump!
Tsssssh!
Rich

 

[Roger Johansson]

Rich Grise <rich@example.net> wrote:

http://www.fact-index.com/s/st/st__elmo_s_fire.html

"Um, general? I think you've got your phenomena scrambled."

I found a nice old picture of st. elmo's fire on a ship:

http://www.wordiq.com/definition/St._Elmo's_Fire

The picture makes it very clear that it is a massive discharge from
extended parts of an object, like the mast tops of a sailing ship.



--
Roger J.

 

[Bob Myers]

"Rich Grise" <rich@example.net> wrote in message
newsan.2004.10.23.04.17.58.853140@example.net...

"Um, general? I think you've got your phenomena scrambled."

OK, Rich, that at least SOUNDS like a quote I should
recognize - is it, and if so, from where?

Bob M.

 

[Tom Biasi]

"Bob Myers" <nospamplease@address.invalid> wrote in message
news:8Csed.1473$P32.172@news.cpqcorp.net...

"Rich Grise" <rich@example.net> wrote in message
newsan.2004.10.23.04.17.58.853140@example.net...
"Um, general? I think you've got your phenomena scrambled."

OK, Rich, that at least SOUNDS like a quote I should
recognize - is it, and if so, from where?

Bob M.

I think maybe the actual quote was:
"Well, if I may respectfully submit, sir, I think you've got your phenomena
scrambled, General."

 

[Rich Grise]

On Sat, 23 Oct 2004 13:00:52 +0000, Bob Myers wrote:

"Rich Grise" <rich@example.net> wrote in message
newsan.2004.10.23.04.17.58.853140@example.net...
"Um, general? I think you've got your phenomena scrambled."

OK, Rich, that at least SOUNDS like a quote I should recognize - is it,
and if so, from where?

Firesign Theater, "Everything You Know is Wrong".

Cheers!
Rich

 

[John Popelish]

Myxococcus xanthus wrote:

That's focusing on the cloud-discharging capabilities of -one- rod,
obviously miniscule.

Would be the -combined- effect of (1) thousands of lightning rods in a
moderate-sized community, plus (2) hundreds of miles of transmission
line, telephone line, supporting cable, etc. suspended between
hundreds of tall poles and tall towers, plus (3) tall lamp posts, tall
antennas, etc. have a significant cloud discharging effect?

Order-of-magnitude estimate on this? I'm wondering, since I've seen
several ground/tree strikes while out in rural areas, but only one
direct strike to a tree in the city, and I'm an urban dweller.

Myxococcus xanthus

What about the sharp points on the edges of millions of tree leaves?
At the magnitude of currents involved in corona discharge (not
strikes) the resistance of copper and trees is insignificantly
different.
--
John Popelish

 

[Don Kelly]

"Myxococcus xanthus" <mold-guardian@comcast.net> wrote in message
news:ce5e7813.0410230428.2e265365@posting.google.com...

billb@eskimo.com (William J. Beaty) wrote in message
news:<2251b4e6.0410220942.32c3f461@posting.google.com>...

Why can't a lightning rod discharge the storm? The scale is wrong.
While a needle can discharge an electrostatic generator via ion-leakage
across a large gap, a lightning rod is not like a needle. A lightning
rod is tiny: like one fiber in a piece of felt if we obey the scaling.
If one fiber is slightly taller than the others, well, the high voltage
electrode doesn't care. If you erect a lightning rod, the storm
won't even notice.

Also, the scale is wrong for "charged wind" to transport any charge
upwards. If you hold a needle near a high voltage terminal, the
needle "emits" charged wind which travels at many cm per second,
and there is a significant electric current in the air; on the order
of microamps or tens of microamps. This easily shorts out an
electrostatic generator.

But if we scale things up and use a lightning rod and thunderstorm,
the "charged wind" coming from the tip of the rod STILL TRAVELS AT
CM/SEC SPEEDS AND THE CURRENT IS STILL MICROAMPS. To have a significant
effect on the charged storm cloud, this velocity would have to scale up
too. The lightning rod would have to "emit" an electric wind that
traveled at tens or hundreds of KM per hour, and the electric current
would have to be thousands of times higher than 10uA.

That's focusing on the cloud-discharging capabilities of -one- rod,
obviously miniscule.

Would be the -combined- effect of (1) thousands of lightning rods in a
moderate-sized community, plus (2) hundreds of miles of transmission
line, telephone line, supporting cable, etc. suspended between
hundreds of tall poles and tall towers, plus (3) tall lamp posts, tall
antennas, etc. have a significant cloud discharging effect?

Order-of-magnitude estimate on this? I'm wondering, since I've seen
several ground/tree strikes while out in rural areas, but only one
direct strike to a tree in the city, and I'm an urban dweller.

Myxococcus xanthus
---------

Unlikely- A large conifer forest has thousands of tips each of which is
grounded( poorly but this isn't of imprtance until there is a strike) and
there are records of thousands of strokes in such a forest in one storm.
As for the towers, transmission lines, etc- these are targets. Tall
buildings will produce their own "lightning shadows" or protected
areas(which is what a lightning rod does). The effect of a strike will
depend on their grounding systems. Ever had a transformer fail during a
lightning storm in your urban area? Ever had the lights go out or flicker?

--
Don Kelly
dhky@peeshaw.ca
remove the urine to answer

 

[Rich Grise]

On Sun, 24 Oct 2004 03:56:15 -0700, TimR wrote:
....

Something he never mentioned, but I have run into since, is Ufer
grounding. It certainly gives low ohmic measurements. Do we know how
well it works in real life, i.e. actual lightning strikes?

What is "Ufer grounding"?

Thanks,
Rich

 

[Roger Johansson]

Rich Grise <rich@example.net> wrote:

What is "Ufer grounding"?

http://www.psihq.com/iread/ufergrnd.htm

The "Ufer" Ground

"The term "Ufer" grounding is named after a consultant working for the US
Army during World War II. The technique Mr. Ufer came up with was
necessary because the site needing grounding had no underground water
table and little rainfall. The desert site was a series of bomb storage
vaults in the area of Flagstaff, Arizona.

The principle of the Ufer ground is simple, it is very effective and
inexpensive to install during new construction. The Ufer ground takes
advantage of concrete’s properties to good advantage. Concrete absorbs
moisture quickly and looses moisture very slowly. The mineral properties
of concrete (lime and others) and their inherent pH means concrete has a
supply of ions to conduct current. The soil around concrete becomes
"doped" by the concrete, as a result, the pH of the soil rises and
reduces what would normally be 1000 ohm meter soil conditions (hard to
get a good ground). The moisture present, (concrete gives up moisture
very slowly), in combination with the "doped" soil, make a good conductor
for electrical energy or lightning currents.

Ufer techniques are used in building footers, concrete floors, radio and
television towers, tower guy wire anchors, light poles, etc. Copper wire
does not function well as a "Ufer" ground due to the pH factor of
concrete (+7pH is common). The use of steel reinforcement as a "Ufer"
ground works well and concrete does not chip or flake as has been found
with copper. The use of copper wire tied to the reinforcement rods
outside the concrete shows none of these problems. "


--
Roger J.

 

[Bert Hickman]

izzi4 wrote:

Hello, I was wondering why there is a ball on lighting rods? example
http://www.period1.com/lightni.jpg I was just wondering what the purpose of
the ball is, I know that the point creates a concentrated electric field at
the tip but i can't imagine the balls purpose. Thanks in advance


Decoration. Most of these balls are colored glass.

-- Bert --
---------------------------------------------------------------------
We specialize in UNIQUE items! Coins shrunk by huge magnetic fields,
Lichtenberg Figures ("Captured Lightning" in acrylic), & Out-of-Print
technical Books. Stoneridge Engineering - http://www.teslamania.com
---------------------------------------------------------------------

 

[izzi4]

It seems there is a metal one in this picture which has some arcing under
it, Its hard to believe they serve no purpose.
http://www.francetechnologie.com/cie-pouyet/images/img11.jpg


"Uncle Al" <UncleAl0@hate.spam.net> wrote in message
news:417528CB.8A3E02DA@hate.spam.net...

izzi4 wrote:

Hello, I was wondering why there is a ball on lighting rods? example
http://www.period1.com/lightni.jpg I was just wondering what the purpose
of
the ball is, I know that the point creates a concentrated electric field
at
the tip but i can't imagine the balls purpose. Thanks in advance

A metal rod sticking up into the air is both a silly thing and nearly
indestructible. By adding apical decoration it is transformed into an
asethetic statement, the price goes up, and there is something to be
damaged and repaired/replaced.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf

 

[Jamie]

Rebarb wire in concrete or a simple incased steel rods
in a welded square patern..
if memory serve i think it was Mr Ufer in from WARII hence
the name Ufer ground.
but simply a steel cage connection system in cased in the
concrete.



Rich Grise wrote:

On Sun, 24 Oct 2004 03:56:15 -0700, TimR wrote:
...

Something he never mentioned, but I have run into since, is Ufer
grounding. It certainly gives low ohmic measurements. Do we know how
well it works in real life, i.e. actual lightning strikes?


What is "Ufer grounding"?

Thanks,
Rich

 

[Don Kelly]

"TimR" <timothy42b@aol.com> wrote in message
news:87af0be7.0410250307.232dac1b@posting.google.com...

Roger Johansson <no-email@home.se> wrote in message
news:<Xns958D13BBA247886336@130.133.1.4>...
Rich Grise <rich@example.net> wrote:

What is "Ufer grounding"?


http://www.psihq.com/iread/ufergrnd.htm

The "Ufer" Ground

"The term "Ufer" grounding is named after a consultant working for the
US
Army during World War II. The technique Mr. Ufer came up with was
necessary because the site needing grounding had no underground water
table and little rainfall. The desert site was a series of bomb storage
vaults in the area of Flagstaff, Arizona.

The principle of the Ufer ground is simple, it is very effective and
inexpensive to install during new construction. The Ufer ground takes
advantage of concrete?s properties to good advantage. Concrete absorbs
moisture quickly and looses moisture very slowly. The mineral properties
of concrete (lime and others) and their inherent pH means concrete has a
supply of ions to conduct current. The soil around concrete becomes
"doped" by the concrete, as a result, the pH of the soil rises and
reduces what would normally be 1000 ohm meter soil conditions (hard to
get a good ground). The moisture present, (concrete gives up moisture
very slowly), in combination with the "doped" soil, make a good
conductor
for electrical energy or lightning currents.

Ufer techniques are used in building footers, concrete floors, radio and
television towers, tower guy wire anchors, light poles, etc. Copper wire
does not function well as a "Ufer" ground due to the pH factor of
concrete (+7pH is common). The use of steel reinforcement as a "Ufer"
ground works well and concrete does not chip or flake as has been found
with copper. The use of copper wire tied to the reinforcement rods
outside the concrete shows none of these problems. "

My question really has to do with whether the "good ground" is real or
not under high current conditions. Clearly you can get an extremely
low resistance measurement and pass your safety requirements. It
seems likely this ground would be fine for reducing static charge
effects and for electronic equipment grounding. I asked because I
wondered how well a Ufer ground can actually dissipate the current in
a lightning strike. If the soil outside the foundation continues to
be high resistance soil, it would seem the dissipation must occur
within the rebar.

I know I'm not being consistent claiming #10 wire is enough, then
wondering if a rebar array is enough. <grin> But is there any data?
Actual lightning hitting a Ufer grounded structure? It sounds like a
ground plane not a true ground, but I'm not an electrical engineer and
may not understand the difference.

Often all you need is a ground plane.

--
Don Kelly
dhky@peeshaw.ca
remove the urine to answer

 

[rayjking]

I agree with the #8 wire not seeming to be adequate. The coast guard /
power squadron use the #8 wire and 60 degree protection cone as there rules
but for my sail boat I use a welding cable size ? connected from the
aluminum mast directly( no curves ) to the lead keel. I have observed a boat
being directly hit by lighting about 100 feet away from me. The vhf antenna
made a baby carriage size puff of orange smoke. No one was injured but the
electronics were fried.
I would like some explanation of ball lighting. I have known of a ball (
corona ) in the cockpit of a sail boat.

Ray







"Bob Masta" <NoSpam@daqarta.com> wrote in message
news:4177a8df.925016@news.itd.umich.edu...

On Thu, 21 Oct 2004 04:19:05 GMT, "Don Kelly" <dhky@peeshaw.ca> wrote:

Actually this is extremely questionable. Design that I know of is based
on
the probability of the stroke striking the rod rather than the protected
area. Granted, in some situations, particularly with tall structures,
such
draining does occur (possibly increasing the chance of side
flashes-another
problem) but this is a bonus, not the basis for design.

I'm no expert on this, but I do recall my undergrad Electromagnetic
Fields instructor coming down on the draining side of this issue.
His examples were opposite to yours: He pointed out that the
size of the ground wires on the typical barn or home lightning rod
was far too small to withstand a direct hit. He noted that tall
buildings, which do sustain repeated hits, have massive ground
conductors to handle the current.

That was probably the only meaningful thing I recalled from that
class. All the rest was curls, dels, and other funny symbols.
(That was over 35 years ago. A lot of synapses could have
drained to ground since then!)


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

[Rich Grise]

On Thu, 21 Oct 2004 18:50:22 -0400, rayjking wrote:

I agree with the #8 wire not seeming to be adequate. The coast guard /
power squadron use the #8 wire and 60 degree protection cone as there rules
but for my sail boat I use a welding cable size ? connected from the
aluminum mast directly( no curves ) to the lead keel. I have observed a boat
being directly hit by lighting about 100 feet away from me. The vhf antenna
made a baby carriage size puff of orange smoke. No one was injured but the
electronics were fried.
I would like some explanation of ball lighting. I have known of a ball (
corona ) in the cockpit of a sail boat.

Would that be St. Elmo's Fire?

Ball lighning, like flying saucers, is/are willess spirits trying to
manifest without body, which doesn't work, much to their chagrin. ;-)

It would be kind of interesting to see if it's possible to come up
with something that could catch a ball lightning ball, so we could
study it.

Cheers!
Rich

 

[Clarence]

"TimR" <timothy42b@aol.com> wrote in message
news:87af0be7.0410250307.232dac1b@posting.google.com...

Roger Johansson <no-email@home.se> wrote in message
news:<Xns958D13BBA247886336@130.133.1.4>...
Rich Grise <rich@example.net> wrote:

What is "Ufer grounding"?


http://www.psihq.com/iread/ufergrnd.htm

The "Ufer" Ground

"The term "Ufer" grounding is named after a consultant working for the US
Army during World War II. The technique Mr. Ufer came up with was
necessary because the site needing grounding had no underground water
table and little rainfall. The desert site was a series of bomb storage
vaults in the area of Flagstaff, Arizona.

Don't look now. But Flagstaff is not in a Desert, it is on the slopes of a
volcano!

This is the system used in Feed Mills.

The principle of the Ufer ground is simple, it is very effective and
inexpensive to install during new construction. The Ufer ground takes
advantage of concrete?s properties to good advantage. Concrete absorbs
moisture quickly and looses moisture very slowly. The mineral properties
of concrete (lime and others) and their inherent pH means concrete has a
supply of ions to conduct current. The soil around concrete becomes
"doped" by the concrete, as a result, the pH of the soil rises and
reduces what would normally be 1000 ohm meter soil conditions (hard to
get a good ground). The moisture present, (concrete gives up moisture
very slowly), in combination with the "doped" soil, make a good conductor
for electrical energy or lightning currents.

Ufer techniques are used in building footers, concrete floors, radio and
television towers, tower guy wire anchors, light poles, etc. Copper wire
does not function well as a "Ufer" ground due to the pH factor of
concrete (+7pH is common). The use of steel reinforcement as a "Ufer"
ground works well and concrete does not chip or flake as has been found
with copper. The use of copper wire tied to the reinforcement rods
outside the concrete shows none of these problems. "

My question really has to do with whether the "good ground" is real or
not under high current conditions. Clearly you can get an extremely
low resistance measurement and pass your safety requirements. It
seems likely this ground would be fine for reducing static charge
effects and for electronic equipment grounding. I asked because I
wondered how well a Ufer ground can actually dissipate the current in
a lightning strike. If the soil outside the foundation continues to
be high resistance soil, it would seem the dissipation must occur
within the rebar.

I know I'm not being consistent claiming #10 wire is enough, then
wondering if a rebar array is enough. <grin> But is there any data?
Actual lightning hitting a Ufer grounded structure? It sounds like a
ground plane not a true ground, but I'm not an electrical engineer and
may not understand the difference.

 

[AC]

The purpose of the ball is to stop the windvane falling down. It serves no
electrical function.


"izzi4" <news@rkremser.endjunk.com> wrote in message
news:1098195113.Rs00pYGtkn46fZuq2JsaDA@teranews...

Hello, I was wondering why there is a ball on lighting rods? example
http://www.period1.com/lightni.jpg I was just wondering what the purpose
of
the ball is, I know that the point creates a concentrated electric field
at
the tip but i can't imagine the balls purpose. Thanks in advance

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.795 / Virus Database: 539 - Release Date: 11/12/2004

 

[Don Kelly]

"izzi4" <news@rkremser.endjunk.com> wrote in message
news:1098197415.3Vw79JgN/X5o2dtXc0M+SA@teranews...

It seems there is a metal one in this picture which has some arcing under
it, Its hard to believe they serve no purpose.
http://www.francetechnologie.com/cie-pouyet/images/img11.jpg


"Uncle Al" <UncleAl0@hate.spam.net> wrote in message
news:417528CB.8A3E02DA@hate.spam.net...
izzi4 wrote:

Hello, I was wondering why there is a ball on lighting rods? example
http://www.period1.com/lightni.jpg I was just wondering what the
purpose
of
the ball is, I know that the point creates a concentrated electric
field
at
the tip but i can't imagine the balls purpose. Thanks in advance

A metal rod sticking up into the air is both a silly thing and nearly
indestructible. By adding apical decoration it is transformed into an
asethetic statement, the price goes up, and there is something to be
damaged and repaired/replaced.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf

Still decoration. At one time (early 30's or late 20's ) there were rods
made with a ball at the top based on some half baked idea that came into
vogue (to raise the price, probably) that it would provide better shielding.
To sum up- it didn't work. There have been, are, and will be a variety of
devices made and sold to provide lightning shielding. Typically they don't
do as well as simply sticking a bunch of old bedspring on the roof and
grounding them well - but they are shinier and more expensive.
--
Don Kelly
dhky@peeshaw.ca
remove the urine to answer

 

[izzi4]

wouldn't the head produced be caused by the current through the wire, or is
there another method of heating in lightning strikes i'm not aware of?
Wouldn't this spread the heat through the region of the ball but not farther
along the path of the wire? I hadn't considered the heat involved before,
intresting.


"rayjking" <rayjking@bellsouth.net> wrote in message
news:57vdd.185347$as2.86216@bignews3.bellsouth.net...

Hi,

The ball is usefull in spreading heat from a direct strike. A #8 wire can
carry any known strike but it will bern at the point of the strike without
more thermal mass.

Ray




"izzi4" <news@rkremser.endjunk.com> wrote in message
news:1098195113.Rs00pYGtkn46fZuq2JsaDA@teranews...
Hello, I was wondering why there is a ball on lighting rods? example
http://www.period1.com/lightni.jpg I was just wondering what the purpose
of
the ball is, I know that the point creates a concentrated electric field
at
the tip but i can't imagine the balls purpose. Thanks in advance

 

[rayjking]

The heat generated is much more in the air above the wire. The power
generated causes the vapor in the air to turn to steam
and the rapid expansion of the steam creates the thunder.

Ray






"izzi4" <news@rkremser.endjunk.com> wrote in message
news:1098304865.P9Vr5QmkrFMYnFmF/F0mIg@teranews...

wouldn't the head produced be caused by the current through the wire, or
is
there another method of heating in lightning strikes i'm not aware of?
Wouldn't this spread the heat through the region of the ball but not
farther
along the path of the wire? I hadn't considered the heat involved before,
intresting.


"rayjking" <rayjking@bellsouth.net> wrote in message
news:57vdd.185347$as2.86216@bignews3.bellsouth.net...
Hi,

The ball is usefull in spreading heat from a direct strike. A #8 wire
can
carry any known strike but it will bern at the point of the strike
without
more thermal mass.

Ray




"izzi4" <news@rkremser.endjunk.com> wrote in message
news:1098195113.Rs00pYGtkn46fZuq2JsaDA@teranews...
Hello, I was wondering why there is a ball on lighting rods? example
http://www.period1.com/lightni.jpg I was just wondering what the
purpose
of
the ball is, I know that the point creates a concentrated electric
field
at
the tip but i can't imagine the balls purpose. Thanks in advance