On Oct 16, 12:13*pm, Jim Lux wrote:
Dave wrote:
A well grounded mast DOES NOT attract lightning any
better than a non grounded mast at the same location.

actually it does. *both the ieee and cigre have been using lightning
statistics data collected mostly from tall masts for many years.
There are well known formulas used to calculate the number of strokes
to a pole or power line, both include the height, and as height
increases so does the number of strokes to the object. *The height
also skews the current distribution with higher structures more likely
to get more high current strokes.

But, is there a difference in strike rate between grounded and
ungrounded towers of the same height. *I would think that the difference
would be very small, and smaller as the height gets bigger.

That's what I'm thinking. I know my well grounded mast is not a
lightning magnet. Some years I get no strikes to it. In fact, I think
it's been a few since the last one. Well, unless it was hit when I
was not at home.
I'm still of the opinion that the ability of an object to stream means
more than if it's grounded or not.
Airplanes are not grounded, and they get popped all the time.
Trees are poorly grounded, and they get popped all the time.
I've known quite a few people over the years that stuck a vertical
on their roof and didn't ground it, and they got popped. Blew
the ungrounded antenna to smithereens too..
Many golfers get popped on the golf course and they are not
really grounded too well unless they are wearing spikes on their
shoes. :/
I think the height of the object relative to it's surroundings, and
it's ability to stream mean more than anything.
Trees are a target lightning pick probably as much as anything,
and most are fairly poorly grounded due to being wood with some
moisture to helps things a bit. I think the trees ability to stream
well is why they get picked on so often. The pointy ends of a
leaf stream well, much like the pointy hairs on the head of a
golfer. And when you have hundreds of leaves on a tree...

But lets say a grounded mast does get struck slightly more than
an ungrounded mast. That would not a logical reason to avoid
grounding it, when the act of grounding the mast pretty much
negates the likelihood of a strike doing much damage to the mast
or the building next to, or under it.
A wooden mast would act much the same as a tree if it did not
have any kind of ground wire running along it's length.
That's why I never use wood masts here.
I'd rather have a grounded mast struck every 5 years with no damage,
vs an ungrounded mast struck every 10 years that led to heavy
damage or even burned the house down.
So worrying about that is kind of silly I think, when you know
an ungrounded mast is big trouble if it ever does get hit.

wrote:
I know my well grounded mast is not a lightning magnet.

At my last QTH, lightning passed up my 40' grounded
tower, my 40' vertical antenna, and all the surrounding
power poles. It instead struck a nearby 6' tall live oak
tree that, on a sunny day, was in the shadow of the tower,
antenna, and power poles. Half of the tree died but the
other half survives.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

On Fri, 16 Oct 2009 12:27:02 -0700 (PDT), wrote:

I think the height of the object relative to it's surroundings, and
it's ability to stream mean more than anything.

Hi Mark,

There's another angle to be observed here. Globally, there is a
potential difference between earth and sky that runs to several
hundred volts per meter, with a current flow on the order of
femtoAmperes per square cM. Not much locally, but for the full
surface area of earth it is the electron conveyor belt charging the
clouds through dust migration.

At this potential and current, absolutely everything is a short
circuit that penetrates the voltage isoclines raising earth towards
the clouds.

73's
Richard Clark, KB7QHC

"Richard Clark" wrote
...
On Fri, 16 Oct 2009 12:27:02 -0700 (PDT), wrote:

I think the height of the object relative to it's surroundings, and
it's ability to stream mean more than anything.

Hi Mark,

There's another angle to be observed here. Globally, there is a
potential difference between earth and sky that runs to several
hundred volts per meter,

The Earth has the excess of electrons. The Earth produce the electric field
about one hundred volts per meter. In a suuny day the electrons migrate up
with the heavy ions (aggregates of H2O molecukes).

with a current flow on the order of
femtoAmperes per square cM. Not much locally, but for the full
surface area of earth it is the electron conveyor belt charging the
clouds through dust migration.

This "electron conveyor belt" charge the air. Next the air becomes cooler
and the condensation take place. Clouds appear. The condensation cause the
voltage rise. All types of sparks jump.
Under clouds the electric field has the opposite direction and thousands
volts per meter.


At this potential and current, absolutely everything is a short
circuit that penetrates the voltage isoclines raising earth towards
the clouds.

The high voltagi in the clouds is lowered by the "electron conveyor belt"
and the lightning.

The "electron conveyor belt" is more effective if the Earth have many sharp
needle.
So there are the two possibilities:

1. If "The intention is to PREVENT a direct lightning strike," - many sharp
needle is used,

2. If the intention is to CATCH a direct lightning strike and conduct a
strike to ground - a polished big ball is used.
S*

In message , Szczepan Bialek
writes

"Richard Clark" wrote
.. .
On Fri, 16 Oct 2009 12:27:02 -0700 (PDT), wrote:

I think the height of the object relative to it's surroundings, and
it's ability to stream mean more than anything.

Hi Mark,

There's another angle to be observed here. Globally, there is a
potential difference between earth and sky that runs to several
hundred volts per meter,

The Earth has the excess of electrons. The Earth produce the electric field
about one hundred volts per meter. In a suuny day the electrons migrate up
with the heavy ions (aggregates of H2O molecukes).

with a current flow on the order of
femtoAmperes per square cM. Not much locally, but for the full
surface area of earth it is the electron conveyor belt charging the
clouds through dust migration.

This "electron conveyor belt" charge the air. Next the air becomes cooler
and the condensation take place. Clouds appear. The condensation cause the
voltage rise. All types of sparks jump.
Under clouds the electric field has the opposite direction and thousands
volts per meter.


At this potential and current, absolutely everything is a short
circuit that penetrates the voltage isoclines raising earth towards
the clouds.

The high voltagi in the clouds is lowered by the "electron conveyor belt"
and the lightning.

The "electron conveyor belt" is more effective if the Earth have many sharp
needle.
So there are the two possibilities:

1. If "The intention is to PREVENT a direct lightning strike," - many sharp
needle is used,

2. If the intention is to CATCH a direct lightning strike and conduct a
strike to ground - a polished big ball is used.
S*

In the early days of lightning conductors, I believe that the French
didn't like the nasty pointy things which the British had installed.
Instead, they decorated theirs with fancy balls at the top - with
sometimes disastrous results.
--
Ian

"Ian Jackson" wrote
...
In message , Szczepan Bialek
writes

"Richard Clark" wrote
. ..
On Fri, 16 Oct 2009 12:27:02 -0700 (PDT), wrote:

I think the height of the object relative to it's surroundings, and
it's ability to stream mean more than anything.

Hi Mark,

There's another angle to be observed here. Globally, there is a
potential difference between earth and sky that runs to several
hundred volts per meter,

The Earth has the excess of electrons. The Earth produce the electric
field
about one hundred volts per meter. In a suuny day the electrons migrate up
with the heavy ions (aggregates of H2O molecukes).

with a current flow on the order of
femtoAmperes per square cM. Not much locally, but for the full
surface area of earth it is the electron conveyor belt charging the
clouds through dust migration.

This "electron conveyor belt" charge the air. Next the air becomes cooler
and the condensation take place. Clouds appear. The condensation cause the
voltage rise. All types of sparks jump.
Under clouds the electric field has the opposite direction and thousands
volts per meter.


At this potential and current, absolutely everything is a short
circuit that penetrates the voltage isoclines raising earth towards
the clouds.

The high voltagi in the clouds is lowered by the "electron conveyor belt"
and the lightning.

The "electron conveyor belt" is more effective if the Earth have many
sharp
needle.
So there are the two possibilities:

1. If "The intention is to PREVENT a direct lightning strike," - many
sharp
needle is used,

2. If the intention is to CATCH a direct lightning strike and conduct a
strike to ground - a polished big ball is used.
S*

In the early days of lightning conductors, I believe that the French
didn't like the nasty pointy things which the British had installed.
Instead, they decorated theirs with fancy balls at the top - with
sometimes disastrous results.

Now everywhere are "the nasty pointy things" but most people do not know why
and if they PREVENT or CATCH.
S*

On Oct 21, 2:49*am, "Szczepan Bialek" wrote:


1. If *"The intention is to PREVENT a direct lightning strike," - many sharp
needle is used,

Good luck.

2. If the intention is to CATCH a direct lightning strike and *conduct a
strike to ground - a polished big ball is used.
S*

Good luck.

wrote
...
On Oct 21, 2:49 am, "Szczepan Bialek" wrote:


1. If "The intention is to PREVENT a direct lightning strike," - many
sharp
needle is used,

Good luck.

2. If the intention is to CATCH a direct lightning strike and conduct a
strike to ground - a polished big ball is used.
S*

Good luck.

The above apply to grounded tower.

For:
" But, is there a difference in strike rate between grounded and
ungrounded towers of the same height. I would think that the difference
would be very small, and smaller as the height gets bigger."

You wrote: "I'd rather have a grounded mast struck every 5 years with no
damage,
vs an ungrounded mast struck every 10 years that led to heavy
damage or even burned the house down.
So worrying about that is kind of silly I think, when you know
an ungrounded mast is big trouble if it ever does get hit."

The grounded tower catch the electrons in form of "electron conveyer belt"
and lightning. If the "belt" is efective enough no lightnings. All local
exces of electrons from the cloud flow without lightning. If no the
lightning appears but it is weak (the sum of electrons is the same).

The strike in the ungrouded tower is always strong.
So You are right.
S*

On Oct 22, 8:40*am, "Szczepan Bialek" wrote:
...
On Oct 21, 2:49 am, "Szczepan Bialek" wrote:



1. If "The intention is to PREVENT a direct lightning strike," - many
sharp
needle is used,
Good luck.

2. If the intention is to CATCH a direct lightning strike and conduct a
strike to ground - a polished big ball is used.
S*
Good luck.

The above apply to grounded tower.

For:
" But, is there a difference in strike rate between grounded and

ungrounded towers of the same height. I would think that the difference
would be very small, and smaller as the height gets bigger."
You wrote: "I'd rather have a grounded mast struck every 5 years with no

damage,
vs an ungrounded mast struck every 10 years that led to heavy
damage or even burned the house down.
So worrying about that is kind of silly I think, when you know
an ungrounded mast is big trouble if it ever does get hit."

The grounded tower catch the electrons in form of "electron conveyer belt"
and lightning. If the "belt" is efective enough no lightnings. All local
exces of electrons from the cloud flow without lightning. If no the
lightning appears but it is weak (the sum of electrons is the same).

The strike in the ungrouded tower is always strong.
So You are right.
S*

no, that is not right. a grounded tower can not dissipate enough
charge to reduce the stroke intensity. towers actually attract MORE
high current strokes than the surrounding ground.

Dave wrote:
On Oct 22, 8:40 am, "Szczepan Bialek" wrote:
You wrote: "I'd rather have a grounded mast struck every 5 years with no

damage,
vs an ungrounded mast struck every 10 years that led to heavy
damage or even burned the house down.
So worrying about that is kind of silly I think, when you know
an ungrounded mast is big trouble if it ever does get hit."

The grounded tower catch the electrons in form of "electron conveyer belt"
and lightning. If the "belt" is efective enough no lightnings. All local
exces of electrons from the cloud flow without lightning. If no the
lightning appears but it is weak (the sum of electrons is the same).

The strike in the ungrouded tower is always strong.
So You are right.
S*

no, that is not right. a grounded tower can not dissipate enough
charge to reduce the stroke intensity. towers actually attract MORE
high current strokes than the surrounding ground.

Well, Szechuan obviously hasn't figured out which way the belt is
pumping electrons, so it's not surprising he's wrong. He also doesn't
understand anything of the physics involved, either, so none of his
nonsensical answers should be a surprise.

tom
K0TAR*