On Jul 13, 10:52*am, John Ferrell wrote:
I don't remember the sources but I have concluded that the Grounding
wire should be no smaller than #6.

*More than 8 feet of ground rod is of little consequence.

All ground rods should be tied together. Don't put your house between
two electrodes!

The ground rods are better directly under the structure that they are
protecting.

The system does not absorb massive high energy strikes. It starts
bleeding off the energy before the strike builds and thus minmiizes
the effect.

Home improvement stores sell #6 wire, ground rods and connectors.

On Mon, 12 Jul 2010 21:21:24 -0700 (PDT), Tom Horne



wrote:
Can anyone make a recommendation, based on actual training and
experience, as to what width and thickness of copper strap would be
needed as the down conductor from the antenna mounts at the peak of my
house roof, some twenty five feet above local terrain. *I have a a
mount for an antenna at one gable end and a mount for a weather
station sensor array at the other. *What thickness and width should I
use in the earth between the two Grounding Electrode Systems. *I will
drive five eighths inch copper rods, each eight feet long as far out
from the foundation as I can get them or eight feet were possible. *On
one end that will be only six feet due to the proximity of the
property line. *At all of the other rod locations I will be able to
keep them at least eight feet from any underground obstructions. *To
compensate for the proximity *to the foundation wall to the first rod
I will use rod couplers and drive it to hard rock or sixteen feet
whichever comes first. *I'm guessing that in keeping the remaining
rods at least eight feet out from the foundation and sixteen feet
apart that I will only have four rods total in a ring around the back
side of the house. *What is the best way to attach the copper strap to
the support masts and eve brackets themselves? *Do you know of
anything that will make a good connection to the one inch galvanized
iron pipes that I'm using for support masts?

Can you recommend a technique for bonding the interior grounding buss
at the operating position to the exterior vertical copper strap. *I
have no idea how that is usually done.

John Ferrell W8CCW

John
Would you mind sharing what you base that advise on? Much of it
appears contrary to NIST guidance on protective grounding and current
industry practice.
--
Tom Horne, W3TDH

On Jul 13, 1:52*pm, Owen Duffy wrote:
Owen Duffy wrote :

...

But, firstly, you should determine if there are regulatory
requirements, such as NEC etc.

Is "NFPA 780: Standard for the Installation of Lightning Protection
Systems" a relevant standard in your jurisdiction?

Owen

Owen
It is relevant as a consensus standard but it is not adopted as local
or State law. Do you have a link to a copy that can be read online?
--
Tom Horne, W3TDH

On Jul 13, 2:29*pm, Bruce in alaska wrote:
In article
,
*Tom Horne wrote:



Can anyone make a recommendation, based on actual training and
experience, as to what width and thickness of copper strap would be
needed as the down conductor from the antenna mounts at the peak of my
house roof, some twenty five feet above local terrain. *I have a a
mount for an antenna at one gable end and a mount for a weather
station sensor array at the other. *What thickness and width should I
use in the earth between the two Grounding Electrode Systems. *I will
drive five eighths inch copper rods, each eight feet long as far out
from the foundation as I can get them or eight feet were possible. *On
one end that will be only six feet due to the proximity of the
property line. *At all of the other rod locations I will be able to
keep them at least eight feet from any underground obstructions. *To
compensate for the proximity *to the foundation wall to the first rod
I will use rod couplers and drive it to hard rock or sixteen feet
whichever comes first. *I'm guessing that in keeping the remaining
rods at least eight feet out from the foundation and sixteen feet
apart that I will only have four rods total in a ring around the back
side of the house. *What is the best way to attach the copper strap to
the support masts and eve brackets themselves? *Do you know of
anything that will make a good connection to the one inch galvanized
iron pipes that I'm using for support masts?

Can you recommend a technique for bonding the interior grounding buss
at the operating position to the exterior vertical copper strap. *I
have no idea how that is usually done.
--
Tom Horne, W3TDH

You seem to be confusing Lightning Ground, Electrical Ground, and RF
Ground, here, and they are basically three different things. If you
build a Lightning Ground, it may, or may not, be an effective Electrical
Ground. Neither of these will be of any use as an RF Ground, unless you
happen to live in a Salt Marsh. You see Copper Strap Grounds, mostly on
Wood, or Plastic Boats, (ships) used to extend the RF Ground, from the
SeaWater, to the Radio, or Antenna Tuner. Here the Strap becomes part of
the Antenna System, and they need to be engineered, so as to provide as
low of impedance connection, between the two as possible, over the
widest Frequency Range. Some work better than others. Some don't work at
all, and the only way the radio functions at all, is because of Good
Band Conditions.

--
Bruce in alaska
add path after fast to reply

Bruce
I don't know were your getting the idea that I'm confusing the purpose
of the grounding when I specifically asked about lightning protective
down conductors. The other places that I have seen copper strap
grounds is on the Polyphaser web site. Polyphaser is one of the most
respected names in lightning protection for radio installations in the
United States. Let me be clear that since I'm using balanced antennas
I have no pressing need for an RF ground. Lightning grounding is what
I'm interested in and I'm looking for someone with actual field
experience of best practice.
--
Tom Horne, W3TDH

On Jul 13, 2:18*am, Owen Duffy wrote:
Tom Horne wrote in news:e802f6fa-b0e1-471b-bf31-
:

Can anyone make a recommendation, based on actual training and
experience, as to what width and thickness of copper strap would be ...

In this part of the world, we have an Australian / New Zealand Standard
(our version if you like of ANSI, BS etc) which explains the rationale
behind lightning protection, a method of estimating the downcurrent for
protection design purposes and a process for designing down conductors.

Broadly, the scheme is that downconductors are designed to withstand a
few donwstrokes in quick succession without melting the down conductor.
If you work from a peak current of 20kA, it would lead to a down
conductor in copper of at least 25mm^2 which is about #2 to you folk.

I regularly see hams recommend much thinner down conductors, and can only
assume that there is not regulatory guidance or requirement, and I wonder
at the effectiveness of using #6 as often recommended, especially
aluminium as is often the case. Note that reducing conductor size is a
double whammy, you increase the resistance (so the power), and decrease
the mass that has to be heated to melting point, and so the energy
required.

But, firstly, you should determine if there are regulatory requirements,
such as NEC etc.

The question of equipotential bonding conductors ought be dealt with in
the same way, though that is not to imply that they will be the same
size.

Owen

Owen
The NEC only requires 5.261 (mm)2 for the protective down conductor
and 13.30 (mm)2 for the bonding conductor between electrodes. Since
those sizes are at best a bad joke I was hoping to elicit best
practice advise on what size the conductors should actually be as well
as advise on how to accomplish the bonding of the interior single
point grounding buss bar to the exterior grounding conductors and
Grounding Electrode System.
--
Tom Horne, W3TDH

Tom Horne wrote in
:

....
Is "NFPA 780: Standard for the Installation of Lightning Protection
Systems" a relevant standard in your jurisdiction?

Owen

Owen
It is relevant as a consensus standard but it is not adopted as local
or State law. Do you have a link to a copy that can be read online?

Ok, well the question is whether you give it importance, or stay with NEC.
I think it turns out that you have a copy, read it and make you own mind
up.

If it was me, I wouldn't waste the money on an inadequate protection
scheme.

Owen

On Thu, 15 Jul 2010 18:32:02 -0700 (PDT), Tom Horne
wrote:

Richard
I will certainly make the installation code compliant. What I was
looking for help on was how to make it effective in avoiding damage
from lightning.

Hi Tom,

Then that is the end of it. ...but I see more writing below....

I have read all of the applicable material from the
Polyphaser, NIST, and several other sites but what I was hoping to
elicit was specific guidance on what size strap to use for the down
conductors and what size to use for the ground ring so that they might
actually work rather than just comply with the code.

This borders on regret - for what, I haven't a clue.

I can certainly
add any regular wire conductor that would keep the electrical
inspectors happy since I already have 2/0 bare copper for the ground
ring; were only #2 is required and, the ridiculously undersized,
number ten that the code requires for down conductors in hand.

This is not a beauty contest for the diversion of inspectors.

Forgive my not continuing to quote you further as I see that it
NOWHERE employs strap in its description of conductors.

Here is a clue. Call up your insurance agent that provides coverage
for your house against lightning strike. Ask him if your policy would
be honored if your home did not conform to code. Ask him how many
claims had been made for lightning damage to homes that did conform to
code.

73's
Richard Clark, KB7QHC

On Tue, 13 Jul 2010 10:52:14 -0400, John Ferrell
wrote:

I don't remember the sources but I have concluded that the Grounding
wire should be no smaller than #6.

#6 is a minimum required by code here in the Midland MI area. As it's
a minimum, I would not use anything less than #2 Copper.

More than 8 feet of ground rod is of little consequence.

That depends on your soil conditions. Here I'd probably agree as the
soil is usually quite moist and just a couple feet down is just plain
wet.

However a string of ground rods tied together can be quite effective.

All ground rods should be tied together. Don't put your house between
two electrodes!

I'd put a circle of them around the house, all tied together every
16', but due to the garage and driveway, that is not possible.

The ground rods are better directly under the structure that they are
protecting.

I have a 100' 45G 10' from the NW corner of the garage. Tied into it
is a grounding system consisting of 32 or 33 8' ground rods connected
together with over 600 feet of bare #2.

This system consists of a ground rod about a foot outside the concrete
bare in like with each tower leg. The cable is clamped to each tower
leg and comes off in a curve to the ground rod and is extended out in
a straight line at least 80' with additional ground rods every 16'
(give or take a tad) This system also ties into the house electrical
ground. There is an additional run that goes directly from the ground
rod at the base of the 45G to the 25G on the West end of the shop.
From there it goes on around the shop to the mast holding the 144/440
vertical and around the south side to enter the shop to provide
grounding for the station and computers. This also ties the shop
ground (which is on a different electrical feed) to the house ground.


The system does not absorb massive high energy strikes. It starts
bleeding off the energy before the strike builds and thus minmiizes
the effect.

Mine has taken at least 17 direct hits that have been visually
verified. All that energy had to go some where.

The bleeding off theory has been pretty well discussed and discarded
on the tower talk reflector. Read up on the Polyphaser site. They have
some good information. Those lightning balls or porcupines have
proven ineffective. The major work for lightning rods and ground
systems is to divert the lightning away from the interior of buildings
and process control systems in Industry.


Home improvement stores sell #6 wire, ground rods and connectors.

Read the new NEC code for tower and antenna grounding. There is a
reason I went with #2.


On Mon, 12 Jul 2010 21:21:24 -0700 (PDT), Tom Horne
wrote:

Can anyone make a recommendation, based on actual training and
experience, as to what width and thickness of copper strap would be
needed as the down conductor from the antenna mounts at the peak of my
house roof, some twenty five feet above local terrain.

I agree with the #2 recommendation. OTOH there is nothing that will
protect an installation from the big atypical Positive lightning, or
super strikes. That's the stuff that blows holes in airplanes.

I have a a
mount for an antenna at one gable end and a mount for a weather
station sensor array at the other. What thickness and width should I
use in the earth between the two Grounding Electrode Systems. I will
drive five eighths inch copper rods, each eight feet long as far out
from the foundation as I can get them or eight feet were possible. On
one end that will be only six feet due to the proximity of the
property line. At all of the other rod locations I will be able to
keep them at least eight feet from any underground obstructions. To
compensate for the proximity to the foundation wall to the first rod
I will use rod couplers and drive it to hard rock or sixteen feet
whichever comes first. I'm guessing that in keeping the remaining
rods at least eight feet out from the foundation and sixteen feet
apart that I will only have four rods total in a ring around the back
side of the house. What is the best way to attach the copper strap to
the support masts and eve brackets themselves? Do you know of
anything that will make a good connection to the one inch galvanized
iron pipes that I'm using for support masts?

Can you recommend a technique for bonding the interior grounding buss
at the operating position to the exterior vertical copper strap. I
have no idea how that is usually done.

The Polyphaser site has a tutorial on grounding tower legs and coax
shields. this would be applicable to connecting to the 1" pipe.
Use lots on NoAlox between the strap and pipe.

73

Roger (K8RI)

John Ferrell W8CCW

On Thu, 15 Jul 2010 18:54:08 -0700 (PDT), Tom Horne
wrote:

On Jul 13, 10:52*am, John Ferrell wrote:
I don't remember the sources but I have concluded that the Grounding
wire should be no smaller than #6.

*More than 8 feet of ground rod is of little consequence.

All ground rods should be tied together. Don't put your house between
two electrodes!

The ground rods are better directly under the structure that they are
protecting.

The system does not absorb massive high energy strikes. It starts
bleeding off the energy before the strike builds and thus minmiizes
the effect.

Home improvement stores sell #6 wire, ground rods and connectors.


John Ferrell W8CCW

John
Would you mind sharing what you base that advise on? Much of it
appears contrary to NIST guidance on protective grounding and current
industry practice.

Parts come from the code books,
some from experience and
some from observation.

The #6 wire is out of the code book. Reason and observation leads to
the conclusion that whatever you use there is the possibility of a
lightning strike that can vaporize it. That also supports the notion
that the charge must be bled off over time (seconds?) rather than
shunted to ground instantaneously. In a moment of lapsed judgment I
installed a ground rod for an invisible dog fence on the opposite side
of the house from the electric service ground. I also allowed the
TV-Internet cable ground a few feet away. Lightning strikes carbonize
cable coax connectors. Dog fence controller factory repair is $40 per
event. After much consideration I ran a #6 wire between the power
service ground and the rods for the dog fence and cable ground rods.
Much thought was given to this because that route involved putting a
conductive path along the floor joists just beneath my bed! I
considered the fact that copper plumbing is routinely routed without
concern wherever it is needed. No more service calls to the cable
company, no more repairs needed for the dog fence controller!

I have concluded that if more than 8 foot ground rods were required
for effect or code, the supply houses would be selling them. I cannot
argue with redundancy though. THERE IS A POTENTIAL PROBLEM WITH GROUND
RODS THAT ARE NOT BONDED WITH AT LEAST #6 WIRE! Common sense dictates
that protective system be continuously bled to a common level rather
than allowed to build up a differential charge.

My observations have led me to the notion that the frail little #6
wire does not provide the path for a direct strike. It only suggest a
route for the strike. A straight direct route is more likely to be
followed to ground than a longer twisted route. Lightning is a "boss
force". It can and will ionize its own path in a seemingly whimsical
manner. A spin-off cable loop has been popular for antenna entry
points for many years. This is one of those considerations that may
not do anything but it cannot hurt either!

Whatever you do it must:
Meet code, follow the law
Satisfy the Insurance company, don't give them room to wiggle out of a
claim!
Enhance safety
Protect your property.

In spite of all the precautions and preparations that you take you can
only reduce your exposure to the natural forces in life! My dog Shadow
(a black Labrador Retriever) endorses this by retreating to the Master
Bathroom during storm conditions. Midnight, (Shadows Cat) concurs by
hiding in the basement workshop under those same conditions. I
disconnect all ham radio antennas.

At this time I seem to have my problems at bay... but I also have
professionally installed lightning rods on the house.

John Ferrell W8CCW

On Fri, 16 Jul 2010 02:37:18 -0400, Roger
wrote:

On Tue, 13 Jul 2010 10:52:14 -0400, John Ferrell
wrote:

I don't remember the sources but I have concluded that the Grounding
wire should be no smaller than #6.

#6 is a minimum required by code here in the Midland MI area. As it's
a minimum, I would not use anything less than #2 Copper.

More than 8 feet of ground rod is of little consequence.

That depends on your soil conditions. Here I'd probably agree as the
soil is usually quite moist and just a couple feet down is just plain
wet.

However a string of ground rods tied together can be quite effective.

All ground rods should be tied together. Don't put your house between
two electrodes!

I'd put a circle of them around the house, all tied together every
16', but due to the garage and driveway, that is not possible.

The ground rods are better directly under the structure that they are
protecting.

I have a 100' 45G 10' from the NW corner of the garage. Tied into it
is a grounding system consisting of 32 or 33 8' ground rods connected
together with over 600 feet of bare #2.

This system consists of a ground rod about a foot outside the concrete
bare in like with each tower leg. The cable is clamped to each tower
leg and comes off in a curve to the ground rod and is extended out in
a straight line at least 80' with additional ground rods every 16'
(give or take a tad) This system also ties into the house electrical
ground. There is an additional run that goes directly from the ground
rod at the base of the 45G to the 25G on the West end of the shop.
From there it goes on around the shop to the mast holding the 144/440
vertical and around the south side to enter the shop to provide
grounding for the station and computers. This also ties the shop
ground (which is on a different electrical feed) to the house ground.


The system does not absorb massive high energy strikes. It starts
bleeding off the energy before the strike builds and thus minmiizes
the effect.

Mine has taken at least 17 direct hits that have been visually
verified. All that energy had to go some where.

The bleeding off theory has been pretty well discussed and discarded
on the tower talk reflector. Read up on the Polyphaser site. They have
some good information. Those lightning balls or porcupines have
proven ineffective. The major work for lightning rods and ground
systems is to divert the lightning away from the interior of buildings
and process control systems in Industry.


Home improvement stores sell #6 wire, ground rods and connectors.

Read the new NEC code for tower and antenna grounding. There is a
reason I went with #2.


On Mon, 12 Jul 2010 21:21:24 -0700 (PDT), Tom Horne
wrote:

Can anyone make a recommendation, based on actual training and
experience, as to what width and thickness of copper strap would be
needed as the down conductor from the antenna mounts at the peak of my
house roof, some twenty five feet above local terrain.

I agree with the #2 recommendation. OTOH there is nothing that will
protect an installation from the big atypical Positive lightning, or
super strikes. That's the stuff that blows holes in airplanes.

I have a a
mount for an antenna at one gable end and a mount for a weather
station sensor array at the other. What thickness and width should I
use in the earth between the two Grounding Electrode Systems. I will
drive five eighths inch copper rods, each eight feet long as far out
from the foundation as I can get them or eight feet were possible. On
one end that will be only six feet due to the proximity of the
property line. At all of the other rod locations I will be able to
keep them at least eight feet from any underground obstructions. To
compensate for the proximity to the foundation wall to the first rod
I will use rod couplers and drive it to hard rock or sixteen feet
whichever comes first. I'm guessing that in keeping the remaining
rods at least eight feet out from the foundation and sixteen feet
apart that I will only have four rods total in a ring around the back
side of the house. What is the best way to attach the copper strap to
the support masts and eve brackets themselves? Do you know of
anything that will make a good connection to the one inch galvanized
iron pipes that I'm using for support masts?

Can you recommend a technique for bonding the interior grounding buss
at the operating position to the exterior vertical copper strap. I
have no idea how that is usually done.

The Polyphaser site has a tutorial on grounding tower legs and coax
shields. this would be applicable to connecting to the 1" pipe.
Use lots on NoAlox between the strap and pipe.

73

Roger (K8RI)

John Ferrell W8CCW

Roger, I like your response better than mine.

It sounds to me like you have the ultimate solution. I arrived at my
operating point one step at a time and I quit working on the problem
when I quit having problems!

I have a non-Ham friend that lives a couple of miles down the ridge
from me that continues to have lightning related problems that may
benefit from your advice. I will pass along the Wisdom.

Thank you!
John Ferrell W8CCW

On Jul 15, 9:18*pm, Tom Horne wrote:


Owen
The NEC only requires 5.261 (mm)2 for the protective down conductor
and 13.30 (mm)2 for the bonding conductor between electrodes. *Since
those sizes are at best a bad joke I was hoping to elicit best
practice advise on what size the conductors should actually be as well
as advise on how to accomplish the bonding of the interior single
point grounding buss bar to the exterior grounding conductors and
Grounding Electrode System.
--
Tom Horne, W3TDH

It's not that bad a joke.. If the ground connection is good, #10
is plenty thick enough. In fact, it would barely get warm if it
took a strike. Of course, if the connection to ground is bad,
it will be toast. But so would a lot of heavier gauges also..
The connection to ground is the critical factor in such a case.
But I would still follow what the local code says.
The main reason I'm making this post is only to clarify that
under proper conditions, #10 is plenty thick enough to safely
route the strike to ground with no damage to the wire.