"Gary V. Deutschmann, Sr." wrote

Where lightning will hit, if it hits, can almost be calculated with a
fair degree of accuracy.

Gary, there is no nice way to say this, but I mean no disrespect to your
experience. Unfortunately, what you wrote is absolutely incorrect, and flies
in the face of thousands of lightning experts all over the world, who agree
only that a 300' sphere rolled over a surface will indicate (by touching)
the most likely points of attachment. This means that no taller object
escapes the likelihood of being a point of attachment, period. It doesn't
mean anything below it is free from side attachments and flashovers.
Everything else you followed with was erroneous, based on misconceptions or
complete falsehoods. Places you think lightning "struck", were more likely
the opposite, the point(s) where it *left* a structure.

Every once and awhile a new theory arrives claiming to predict or prevent
lightning, and these have all been discredited, especially the CTS (Charge
Transfer System) of lightning dissipators. There have been and there is no
evidence whatsover that a point of attachment can be either predicted or
prevented. This is even when the best lightning air terminal is in place at
the highest point on a structure. Take your old notes and paper the bird
cage, they offer only false predictions that cannot be replicated or
withstand the studies that have tried this a hundred similar ways.

You have left at your disposal, the ability to make it as easy as possible
for a lightning attachment or near field effect from same, to be absorbed
and routed via capable grounding and surge protection systems. There is
nothing else newsworthy about it.

We did a small project in a college class and made a scale model of a
small city. We knew from past history some of the structures that
were hit and where. From this knowledge we made balls of certain
sizes so they would touch if sitting on the ground the place that was
actually hit. We ended up with only 4 such balls, each a similar size
factor to the others.

On our scale model town we outlined in red lines the most likely
places lightning would hit if it did hit in that area.

Every strike since that time, up until the project was abandoned, has
hit somewhere on the red lines we have drawn.
One such line was on a small single story U-Stor-It building between
two very tall radio station towers, that was assumed to be lightning
proof due to it's location. It was hit and hit hard when neither
tower was hit. We also indicated that if those towers were ever hit,
the location on those towers where the lightning would hit them.
Neither location was near the top either. Two small strikes to one of
the towers were both within 1 foot of where our red line was indicated
on the scale model.

We were so successful in our project we thought for sure some agency
would pick it up and make use of it. But long after I was at school
there, the project was abandoned with something like a record of 94%
accuracy on pinpointing areas where lightning can hit.

TTUL
Gary


Jack Painter
Virginia Beach VA
http://members.cox.net/pc-usa/grounding.htm

"CIL" wrote in message
...
but their tower lighting chokes kept
lightning off the a-c power source.

((( What do you call these chokes, I know I have read about, but at
the moment I am blank.)))


Perhaps you are thinking of an Austin Ring transformer to couple the
power to the beacon lights...........

CIL wrote:
"What do you call these chokes?"

Tower lighting chokes. Every a-c power wire on most AM broadcast towers
is fed through through a high-current r-f choke, beacon, side lights,
and neutral. It avoids shorting out the tower at its base for the r-f
signal.

Another device is used at some stations for the same purpose. It is
called an Austin transformer and consists linked loops to transfer a-c
power while providing little r-f coupling.

Tower lighting chokes must provide better performance for the price
because they seem more prevalent. Tower lighting chokes may all be
wraped around one form or on separate forms. They not only provide good
r-f isolation, but they provide almost complete lightning isolation.
They really keep lightning out of the a-c power circuits on the ground
when used with appropriate bypass capacitors and arresters.

Best regards, Richard Harrison, KB5WZI

Grounding a tower does not help prevent it from getting hit by
lightning. It does however help route the charge safely to ground when
hit. A tower may actually be a little less likely to be hit if not
grounded but that is not a good thing to do.

Placing ground rods out in a radius like the spokes of a wheel around
a tower is a good thing. Placing a connecting wire between rods on the
circle is a waste of wire. It would be better to use that additional
wire for additional radials. The current will travel out away from the
tower. Each ground lead going away from the tower will share the
current. There is no significant current difference between the ground
rods so the ring connection does no good.

First a few ground rods should be placed as close to the tower as
possible to have the shortest lead length from the tower. Additional
ground rods placed on the "spokes" going out away from the tower at
distances twice the rod lengths along each spoke.

Having the connecting wires buried going to the other ground rods will
increase the ground system effectiveness also.

Not being struck because you have a good ground system is not proof
that the ground system prevented it.

73
Gary K4FMX


On Tue, 19 Oct 2004 16:15:04 -0400, "leaf"
wrote:

Sorry for the spelling error crystalls should be crystals. When lightning
hits the Earth, the heat it generates is enough to make glass which is an
insulator. The ground rod becomes isolated from the Earth. If you spread
out the contact area with the Earth as with the fence around the perimeter
of the property, then the energy is not concentrated to one spot. The over
all impedance is also much lower. I would install a ring grounding system
around the tower. A 32ft. diameter ring would do nicely in a clay/rocky
soil. Place 8ft. ground rods in the ground every 16 ft along the 32 ft.
diameter circle (approx. 6 rods). Each rod is then connected to the tower
base with a multistrand 00 copper wire and a ring of 00 copper to connect
each rod together. The connections should be cad welded or at least treated
with a deoxit coating to prevent corrosion. I have had excellent luck with
this approach, no lightning hits and my tower sits up at 870ft. ASL or 650
ft. above average terrain. Note: the tower has a strike counter hooked up
to it so I know no hits have happened. Go to this link to read more
http://www.polyphaser.com/ppc_pen_home.asp .

Frank N1SIF

"CIL" wrote in message
.. .

I would suspect a poor grounding system on the tower. If the ground is a
rod driven into the Earth, then the impedance needs to be as low as
possible. Once the ground system takes a surge, glass
(( (crystalls?)))
will formin the dirt on and around the rod. The impedance then climbs
and the numberof strikes to the tower increase. The amount of
impedance in your groundnetwork determines the amount of static charge
that can build on the towerand how fast the charge can bleed.

(((The tower sites are only about 100 feet apart, ground substance is
the same, clay/rocks, 1st foot then clay.. The first tower ground, is
a 4 ft hole, with ¾" rebar then driven deeper,1.5ft, w/ horz bars 1ft
on center from bottom of hole to top, where a ¾ steel plate was welded
to vertical bars, and to the plate, strong hinge plate connected to 25
rohn tower. The 'other site', is two 4" pipe, 5ft, in the ground, and
welded to fence. Fence is 2"2/8 upset tubing that goes around
property/everything welded. ((fence is 5 foot tall) and as stated part
of the 'gournding system',,,? The first 'site' was not connected to
the primenter fence,,problem???)) If you are familur with the ''bird
tilting over and drinking from the cup", you can picture in your minds
eye, my 'tilting tower'. It is about 75ft tall, with a uhf/vhf duel
band at top of mast, four ft. below that is a two meter horz omni
ground plane.)))

Can you describe how each tower was configured at the top and how it
was grounded? What is important to know if the top ended up with sharp
point (mast, VHF vertical antenna, etc.) or Yagi type antenna, like
tribander etc. without anything pointy protruding above.
Yuri, K3BU

((( Both towers carried almost the same 'items', vhf/uhf , and 4 ft
below that, clover leaf horz ground plane.)))


but their tower lighting chokes kept
lightning off the a-c power source.

((( What do you call these chokes, I know I have read about, but at
the moment I am blank.)))


The broadcaster starts his lightning protection at the tower top with
a small lightning rod extending above and beyond the beacon to take
the hit and avoid expensive repairs at the tower top.


((( Is this something like the antennas I have seen that have a
'center core' copper rod???)))

Tower guy insulators are doubled and tripled where they connect to the
tower so that static breakdown occurs to the earth instead of at the
tower.


((( Where do I 'see/read' about this??)))


One such line was on a small single story U-Stor-It building between
two very tall radio station towers, that was assumed to be lightning
proof due to it's location. It was hit and hit hard when neither
tower was hit

.."How did your team "know" what was struck?

""".my question was and is,,,, why?




(((((((((((((((((((This statement is the one that makes the
most sense to me)))))))))))))))

Lightning is Female. 20 million volts & 100 thousand Amps will do as
it damm
well pleases!

((((Last, but not least,,,,,,, thank you, WILL implement input,
cl&73))))

Hi Jack

That is probably true and the reason the project was abandoned!

Step Leaders can form and reach up from almost any grounded source,
but more often than not, the eventual discharge causes no appreciable
harm.

The small study I helped with was some 25 or 30 years ago and I really
don't remember too much of the details about it, other than apparent
physical damage was almost always within our red zones.

I don't think the spheres we were using were anywhere near 300 feet in
diameter, if I recall they were like 36 feet, 72 feet and 108 feet.
Regardless of the size of the ball, on most structures the red zone
was in the same place. Only on very tall structures would the red
zones be more than one zone at varying heights along the structure.

I do remember our accuracy for the town we modeled was very high over
90%, but then too, we had a LOT of red zones as well since we were
using like 5 different sizes of balls to mark these zones.

You also have to remember, back when I was in Skewl, the correct
answer to a question was considered WRONG. And the wrong answer
correct. EG: Number of Elements, the WRONG answer the skewl demanded
as correct was 45 Elements NO MORE NO LESS, and you had better not
forget the NO MORE NO LESS phrase!
There are 92 Natural Elements and about 114 Elements Maybe More.
But if you put that on your exam, you were graded as the answer being
WRONG.

MOST of the stuff I learned in skewl was Erroneous in Real Life, I
don't doubt that our lightning experiments were also!

TTUL
Gary

Hi Richard

If you recall, I lost a tower to a lightning strike.
Took us forever to figure out why it came down, but we finally did.
Water built up in the leg of the tower, the lighting turned the water
to steam causing the leg to explode.

In some minor cases we found the places where lightning struck through
burn and/or pit marks combined with visual observations of bystanders!
Other times, the foot long melted out section of guttering was a dead
giveaway along with the distortion of the rest of the guttering to
ground.

TTUL
Gary

"Gary V. Deutschmann, Sr." wrote
Hi Jack

That is probably true and the reason the project was abandoned!

Step Leaders can form and reach up from almost any grounded source,
but more often than not, the eventual discharge causes no appreciable
harm.
TTUL
Gary

Hi Gary, I understand completely. Lightning attaching to an object is not
where the damage comes from, it's the way the damn stuff *leaves* that
causes the problems! ;-)

Notwithstanding your hopefully unique experience where water in a tower leg
was superheated. Some private company specifications call for an air
terminal and grounding electrode conductors on all their towers, including
at each fixture (antenna) attachment point.. Even most tower manufacturers
call this unnecessary, recommending bonding of air terminals (if used) to
the tower legs only. But I suppose that a grounding electrode conductor from
tower-top to ground *could* have prevented your loss, by reducing some of
the current in the tower legs in favor of the heavy GEC coming down
alongside them.

Best regards,

Jack

These guys http://www.harger.com/ are the big boys in the lightning
protection business... Get this http://www.harger.com/equipcat.htm it will
answer alot of questions.
Also, see www.polyphaser.com
I have towers at work that the tower crews say the air terminal is kept
shiny from so many hits.


N2QEW

Gary Deutschmann wrote:
"If you recall, I lost a tower to a lightning strike."

Yes. I was saddened by Gary`s misfortune.. My recollection of the event
is that the tower was aluminum. It seems there may have been a poor
electrical connection between tower sections which generated first great
heat. There was a lightning induced failure of one of the tower legs, if
I remember.

The commercial towers erected by one of the companies I worked for, all
had a copper cable about like a welding or jumper cable riunning the
length of the tower, connecting the top plate to the ground system for
the tower. Deep ground rods were connected to each tower leg.

I encountered these towers upon joining the company. I would not have so
specified those tower-length cables in those big steel towers, but it
must have worked as we never had any lightning damage to the towers. In
Gary`s case, such a cable might have prevented a melt-down.

Best regards, Richard Harrison, KB5WZI

On 20 Oct 2004 12:21:27 EDT, am (Gary V.
Deutschmann, Sr.) wrote:
In some minor cases we found the places where lightning struck through
burn and/or pit marks combined with visual observations of bystanders!
Other times, the foot long melted out section of guttering was a dead
giveaway along with the distortion of the rest of the guttering to
ground.

Hi Gary,

By this, I suppose you to mean that any report of strikes to a tower
were those chance occurrences of being seen as a direct hit, and no
one regularly inspected all metal structures for evidence after a
storm to verify unobserved strikes.

73's
Richard Clark, KB7QHC