lightning rod question

[izzi4]

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

 

[Uncle Al]

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

 

[Sam Wormley]

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

Oh the irony--you're standing in the front yard when the lightning strikes
the lightning rod... potentially saving your life. The thermal shock
of the strike fractures the glass ball, half hurled striking your head
killing you! Oh the irony.

 

[Vermin]

On Tue, 19 Oct 2004 10:50:24 -0400, "izzi4"
<news@rkremser.endjunk.com> wrote:

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

That would appear to be an "early streamer" type lightning rod. i.e.
it is supposed to attract lightning better than a Franklin rod, by
some means of ionizing the air around it.

There is a lot of debate as to the effectiveness of these devices, in
my opinion they are no better than snake oil and the Australian
standard at least is unsupportive of them (despite appreciable
pressure from manufacturers of these devices).

V.

 

[Doug]

Sam Wormley wrote:

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



Oh the irony--you're standing in the front yard when the lightning
strikes the lightning rod... potentially saving your life. The thermal
shock of the strike fractures the glass ball, half hurled striking your
head killing you! Oh the irony.

If you get killed by this sequence than it was definitely your time to go!

 

[rayjking]

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

 

[Gordon Youd]

What's lightning, life just gets darker with age.

----------------------------------------------------------
"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

 

[Bert Hickman]

rayjking wrote:

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

Not exactly... thunder does not require the presence of water in any
form. Like all sparks, the rapid expansion of the spark channel
creates a shock wave that ultimately creates thunder. For lightning,
the exact mechanisms are subject to some debate, but thunder simply
does not require the presence of water in either vapor or liquid form.

-- 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
---------------------------------------------------------------------

 

[Tom Biasi]

"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
I didn't catch the original post but I thought that this may be a good time

to mention that lightning rods are/were not designed for direct hits. The
purpose is to keep the accumulated charge below a safe level.
Tom

 

[Don Kelly]

"Tom Biasi" <tombiasi@REMOVETHISoptonline.net> wrote in message
news:bNDdd.33560$YM4.10151285@news4.srv.hcvlny.cv.net...

"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
I didn't catch the original post but I thought that this may be a good
time
to mention that lightning rods are/were not designed for direct hits. The
purpose is to keep the accumulated charge below a safe level.
Tom

---------------

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 am aware of a purveyor of lightning protection that claimed that his
protection works on the basis of charge dissipation. I have seen no evidence
that it does. I have no idea if he is still is in business.

Generally the source of the charge is several miles overhead -the rod
doesn't get seen by it. When a leader gets near a rod then it may be a
preferred target for the next step and if it is, then the main stroke will
be to the rod-if not something else gets hit. Design is based on it being
such a target for higher current strokes (but not necessarily lower current
strokes). This is true for protective systems for transmission lines as
well as structures. Catch the damaging strokes know that some of the little
ones will get by.

References:
Moussa & Shrinivasta, "Shielding of Tall Structures Against Direct Lightning
Strokes" Canadian Conference on Electrical and Computer Engineering,
Vancouver, BC, 1988
Energy Systems Journal, Vol. 11, N0.1 1991
EPRI Transmission Reference Book, 345KV and Above.
I believe that IEEE changed its standards to reflect the concepts involved
in these references.
Sorry that I do not have more recent references but I have been retired for
some time.

I agree with Vermin on the lack of usefulness of the ball. There appears to
be no rational basis for its use. Note that its thermal mass is generally
pretty small and by the time it starts to dissipate heat, any damage is
done.

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

 

[w_tom]

A best source of information in this discussion are both
posts from Don Kelly. Especially where he defines what makes
a lightning rod effective: earth ground. We tend to
rationalize only upon what we see. We see the lightning rod
and assume IT is the protection. We then get all hyped over
blunt rods verses pointed rods verses one with a ball. All
irrelevant once the facts are considered. Since we don't see
earth ground, then we tend to forget the most important
component of a lightning protection system.

Don also cites another well regarded expert on the subject -
Dr Abdul Mousa. Dr Mousa's IEEE reviewed papers contain good,
scientific language. But to summarize into laymen's terms -
Early Streamer Emission (ESE) protectors that are suppose to
discharge the air are scams. Air terminals provide the best
or more conductive path from cloud to earth. Which again
demonstrates what makes lightning rods effective - quality of
that earth ground system.

Don't worry about the ball on the end of a lightning rod.
Worry about what makes that lightning rod effective - earth
ground. Lightning seeks earth ground. Either it obtains
earth ground via the building or it obtains earth ground via
the lightning rod. Which is the better conductor - a then
damaged building or a blemished lightning rod? Lightning
protection is about the electrical connection from cloud to
earth which is why protection is only as effective as the
earth ground system and connection to that earthing system.
The most important component is the one we forget about
because we do not see it - earth ground.

Tom Biasi wrote:

Thanks for the info, I'll see what else I can find. Probably the
foremost expert on lightning in this group is Mark Kinsler. I
believe he did his doctorate on the subject. I have not seen
posts from him in a long while.
Tom

 

[Bob Masta]

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 07:33:00 -0400, w_tom wrote:

Don't worry about the ball on the end of a lightning rod.

Hm. And here, I thought it was for catching ball lightning.

;-)
Rich

 

[Rich Grise]

On Wed, 20 Oct 2004 17:56:46 -0400, rayjking wrote:

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.

The water vapor in the air is already steam. That's what steam
is, is water vapor.

The thunder is the sonic boom from the explosive expansion from the
ionization.

Y'know, in a dry climate, how you can shuffle across the carpet and
draw a spark? Snap! Well, thunder is that Snap!, but from a spark
three miles long!

God shuffles across the carpet in Heaven, see, and ....

Cheers!
Rich

 

[Rich Grise]

On Tue, 19 Oct 2004 18:03:22 +0000, Don Kelly wrote:

Still decoration.

That's what I was going to say!

Actually, I was going to guess, "It's a world globe - note the wind
vane"

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.

Cheers!
Rich

 

[Tom Biasi]

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

"Tom Biasi" <tombiasi@REMOVETHISoptonline.net> wrote in message
news:<bNDdd.33560$YM4.10151285@news4.srv.hcvlny.cv.net>...



Still reading?

Well then it's your own fault.

I will always read what you have to say William.

I kind of thought that what I said may cause a "storm".
I recall having correspondence with Mark Kinsler when he began his research
in 1996 or so.
He often said then and it still seems true now that there is no clear
answer.
There are still things much greater than ourselves to discuss however.
Best Regards,
Tom

 

[Roger Johansson]

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

I have heard that ball lightning consists of superheated air, ionized or
plasma or something like that. The lightning has superheated the air and
some charge can maybe linger in the ball lightning. It is like water
droplets on a hot plate. They are isolated towards the hot plate by a
layer of steam. That is why the water droplets can survive so long.

In a dry climate the superheated air, or plasma, can stay together
because the air works as an isolator, somehow.



--
Roger J.

 

[Bob Myers]

"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


Bob M.

 

[Roger Johansson]

"Bob Myers" <nospamplease@address.invalid> wrote:

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

Okay, I must have confused it with another phenomenon. I thought about
something glowing in the water, on the water surface, seen especially when
waves break or the water flows around the bow of a boat, which is
explained as some kind of light emitting algea in tropical waters.

St. Elmo's Fire is obviously, from the examples in that link, an
atmospheric phenomena, similar to ball lightning.

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

The ball lightning explanation, in the link from the above url, is very
similar to my explanation though.

Not a good and complete explanation, but that is approximately what we
know today.



--
Roger J.

 

[Rich Grise]

On Fri, 22 Oct 2004 20:13:39 +0000, Tom Biasi wrote:

"William J. Beaty" <billb@eskimo.com> wrote in message
news:2251b4e6.0410220942.32c3f461@posting.google.com...
"Tom Biasi" <tombiasi@REMOVETHISoptonline.net> wrote in message
news:<bNDdd.33560$YM4.10151285@news4.srv.hcvlny.cv.net>...



Still reading?

Well then it's your own fault.

I will always read what you have to say William. I kind of thought that
what I said may cause a "storm". I recall having correspondence with Mark
Kinsler when he began his research in 1996 or so.
He often said then and it still seems true now that there is no clear
answer.
There are still things much greater than ourselves to discuss however.

Naturally, I'll pounce on this one.

But, let's cut to the quick. People have been "discussing" this sort of
thing since people have been discussing.

There's a new question, howsomever.

And that question is:

What does it _feel_ like to live in the physical plane?

Thanks,
Rich