Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
Lightning protection




 
The AM Forum
August 11, 2022, 05:13:41 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Lightning protection  (Read 2239 times)
0 Members and 1 Guest are viewing this topic.
WB3JOK
Member

Offline Offline

Posts: 624



« on: April 12, 2022, 11:18:52 AM »

I am putting up a utility pole in my back yard. There are numerous trees taller than the pole nearby, so it won't always be a target for lightning.
Looking for advice on appropriate protection.

Coax feedlines will be buried, then up the wall of the house to the 2nd story shack. A gas discharge tube or spark gap at the bottom of the wall (with a ground rod) sounds like a good place to start.

I assume a straight, heavy conductor should run from the top of the pole to a ground rod at the base. Is any particular gauge best?
Thanks for any tips.
-Charles
Logged
K9MB
Member

Offline Offline

Posts: 181


« Reply #1 on: April 12, 2022, 11:54:54 AM »

I am no expert on this subject, but the ARRl publishes a book on grounding and bonding that may prove useful.

The thing that must be understood, I think, is that there is no such thing as “Ground” in the sense we want it to exist.

Most power surges come in on the lines, not as a result of a direct hit.
When those surges occur, the important thing is to bond the power ground to your own ground system at the point where power enters your shack or house. The “ground” is actually a thing that will rise with the power surge and the difference between the ground and the AC power voltage within that transient is the dangerous thing for your equipment. Bonding all antenna grounds at shack entry to the power will provide the best chance of protection, I understand.

Grounding away from power entry just forms loops that can carry large spikes to destroy your equipment.

I recommend the ARRL book and google it and other better informed Amateurs will have articles published on the subject.

By the way- if your pole gets a real direct lightning hit, nothing can
 save you from damage.
I have a nephew who lived on a hill and a large bolt hit his roof and instantaneously set fire to his attic and burned his house down. That seldom occurs, thankfully…

This subject is far more complex than I ever imagined before I began to research it.

One thing to consider is putting large knofe switches at antenna entry points and shunting antennas directly to ground at the common ground-bonded node. This will provide protection from spikes coming in on feedlines at least…
Logged
WB3JOK
Member

Offline Offline

Posts: 624



« Reply #2 on: April 12, 2022, 12:41:18 PM »

Thanks for the reminder about bonding the feedline entrance to the service entrance. Smiley I'll be reading some more, naturally, but always interested in real-world experience from other hams.

I realize that a direct hit on the pole will probably vaporize any antenna and some of the pole itself  Shocked Fortunately the house is much less likely to be struck (and my insurance is paid up). Mostly I am interested in protecting my equipment. Wire antennas and coax are easy to replace.
Logged
K9MB
Member

Offline Offline

Posts: 181


« Reply #3 on: April 12, 2022, 12:52:19 PM »

My Brother is an electrical contractor who does a lot of fiber and networking as well as AC industrial and Commercial plus residential.
He recommended a whole house solution that mounts at the service entrance that is supposed to protect against transients.
Worth the $300-$500 if it keeps equipment protected but should be a part of a larger solution along with the other things I mentioned.
Once we understand that any wire has inductance, it will become apparent that a very strong, high rise time transient can occur right on a “ground” wire and those spikes are not kind to computers snd modern radios. 😉
Logged
WB3JOK
Member

Offline Offline

Posts: 624



« Reply #4 on: April 12, 2022, 01:41:22 PM »

My service entrance is a bit unusual... from the power pole with meter and utility-provided 200 amp breaker/disconnect about 75 ft away, it is buried and emerges at the wall where the breaker panel is. Typical so far. But many years ago that was the outside wall of the house - then a previous owner built a 1.5 car garage attached to that wall. So now the cable pops up inside the structure!

I already have one of those whole-house transient suppressors (basically a big box full of varistors). It was a flea-market cheap find - for three phase, and one of the phases had been blown but the other two were intact. So I tied them to the hot lines on my 120/240 entrance  Cool
Logged
K9MB
Member

Offline Offline

Posts: 181


« Reply #5 on: April 12, 2022, 03:09:05 PM »

Well the all house devices are what you say snd are probably about as effective as a COVID mask. Some better than others and limited in their effectiveness. 😉

I also have my shop service 75 feet from my main power service entry point on
My house,
The important thing is to make all your station grounds at the common mode where the power enters the shop- station.
The spikes will cause not only the legs to rise, but the common (ground), so if it all goes up together, the potential difference across your equipment will be minimized.

Our service is a 240vac center tapped secondary on the pole pig or equivalent.
The common is grounded at the pole, but transients will cause it to rise very high for very short transients.
The difference for those short periods cause the damage. This points out how failure to bond and ground can make matters much worse- not better if we merely run a “ground” wire to a tod in the earth and do not bond to the common of the service.
Logged
W7TFO
WTF-OVER in 7 land Dennis
Contributing
Member
*
Offline Offline

Posts: 2423


IN A TRIODE NO ONE CAN HEAR YOUR SCREEN


WWW
« Reply #6 on: April 12, 2022, 03:11:56 PM »

If you're going to do it, do it right:

http://www.nottltd.com/

I've protected many towers and buildings with their products in my broadcast career, nary a failure.

73DG
Logged

Just pacing the Farady cage...
WB3JOK
Member

Offline Offline

Posts: 624



« Reply #7 on: April 12, 2022, 03:24:30 PM »

Well the all house devices are what you say snd are probably about as effective as a COVID mask. Some better than others and limited in their effectiveness. 😉
This isn't one of the little baseball-sized ones for home use. It's a potted 8x5x4" brick. I think it'll help.

Quote
The important thing is to make all your station grounds at the common mode where the power enters the shop- station.
Which would be the ground bus in the breaker panel.

Quote
Our service is a 240vac center tapped secondary on the pole pig or equivalent.
Which is exactly the same as what I described as 120/240 with two hot lines  Grin

I just ran a dedicated 240 volt line to the shack for amplifier and large power supply uses. Since it's 99% in an accessible open space above the garage, it will be easy to use the same route to add a 6-gauge (or heavier?) station ground wire back to the service entrance. Has to be better than the #12 in the Romex!
Logged
WB3JOK
Member

Offline Offline

Posts: 624



« Reply #8 on: April 12, 2022, 03:29:28 PM »

If you're going to do it, do it right:

http://www.nottltd.com/

I've protected many towers and buildings with their products in my broadcast career, nary a failure.

73DG

Thanks for the link! I have already been considering a discharge point at the top for "charge dissipation". That's why lightning rods on barns and other buildings are there  Wink
Logged
W7TFO
WTF-OVER in 7 land Dennis
Contributing
Member
*
Offline Offline

Posts: 2423


IN A TRIODE NO ONE CAN HEAR YOUR SCREEN


WWW
« Reply #9 on: April 12, 2022, 04:09:33 PM »

The idea with suppression is to not get hit at all, rather than "armoring up" to withstand a hit.

73DG
Logged

Just pacing the Farady cage...
WB3JOK
Member

Offline Offline

Posts: 624



« Reply #10 on: April 12, 2022, 08:54:35 PM »

In the rural areas that I have lived in, the barns always had multiple pointy objects on the roofs, which are well-connected to earth. They provide a gradual discharge rather than allowing it to build up until lightning strikes. Which is the prevention you mentioned. Not a place to encourage the bolt to hit safely, as the uninitiated may think Grin

However, "armoring-up" is wise, up to a point. A direct hit is going to melt & burn a lot of stuff, but that doesn't mean it is futile to protect against a nearby one...

So, back to my original question. Would solid #6 be OK for the pole to earth? How about from the equipment in the second-floor shack back to the grounded busbar in the breaker panel?
Logged
W7TFO
WTF-OVER in 7 land Dennis
Contributing
Member
*
Offline Offline

Posts: 2423


IN A TRIODE NO ONE CAN HEAR YOUR SCREEN


WWW
« Reply #11 on: April 12, 2022, 09:01:41 PM »

Let me put this another way:

There is a giant bully in the neighborhood.

He is coming for you.  Your choices are to put on something that might lessen the blows, or to simply direct him somewhere else.

This is how suppression works, lightning rods and heavy grounds are not necessary with this technology.

Please go back and read the data, watch the videos.

73DG
Logged

Just pacing the Farady cage...
W3SLK
Member

Offline Offline

Posts: 2490

Just another member member.


« Reply #12 on: April 12, 2022, 10:03:25 PM »

When I was part of the Lynchburg Amateur Radio Club,(LARC), we had a member who started out as an engineer at GE/Ericsson. He originally was interested in lightning as a hobby. Later he became a leading expert at GE that he wound up teaching a course about it at Mary Washington College. He was the one that recommended tying knots in the power cord, (which worked by the way!) and such. He gave us the 'Readers Digest Condensed Version' of his class at a meeting one night. What he explained is there is a stepped leader that first reaches out from a ground object to one coming from a cloud. In some photos you can see these as very dull red. It is when this connects with the leader coming down that you get your bright discharge and the lightning and thunder that we are all accustomed to seeing. His premise is to discharge any electric charge build-up and prevent the connection. However, he did point out one caveat: No matter how much preparation you do, there is always a 'granddaddy' out there that won't give a hoot about your prevention methods and wipe you clean out. I had that happen at my house. Fortunately for me my radios were not connected at the time. I wish I could remember his name because I like to source my references. Unfortunately it was over 30 years ago. 
Logged

Mike(y)/W3SLK
Invisible airwaves crackle with life, bright antenna bristle with the energy. Emotional feedback, on timeless wavelength, bearing a gift beyond lights, almost free.... Spirit of Radio/Rush
K9MB
Member

Offline Offline

Posts: 181


« Reply #13 on: April 13, 2022, 10:23:18 AM »

Everyone seems to agree that the only surefire solution is to wrap your radios in foil, place them in sealed steel containers and place them in a bank vault, or sell out and hide in your basement on a rubber pad😉😂

Suppression and bonding and grounding plus disconnecting antennas and equipment when not in use and not operating during weather likely to produce lightning might be a middle ground.
That is still some risk, however. I was standing in a yard on a calm day that was hazy and a cable tv coax about 30 feet above me vaporized and I could only hear my ears ring for about 45 minutes. Was like someone shooting a high powered rifle with the barrel a foot from my ear. It was not even a real strike and likely came from miles away. The “Bolt out of the blue” is a real thing…😬😉

 By the way, I ran a #4 “ground wire” to my bench. Like Dennis says, it might be useless, but then I still knock on wood when I catch myself saying something arrogant ( keep a plank in my pocket all the time…😉)
Logged
W7TFO
WTF-OVER in 7 land Dennis
Contributing
Member
*
Offline Offline

Posts: 2423


IN A TRIODE NO ONE CAN HEAR YOUR SCREEN


WWW
« Reply #14 on: April 13, 2022, 11:09:27 AM »

Some of you are conflating the issue.

A good grounding system in your shack is necessary for line-borne surges, many of which are from upstream electrical problems.  Proper surge protectors should be across the line in every facility connected to the grid.

My advice was to prevent a direct lightning strike, as the suppression technology is a vast improvement over conventional lightning rods.  In fact, research has shown a rod will lessen the effectiveness of suppression equipment.

73DG
Logged

Just pacing the Farady cage...
W2JBL
Member

Offline Offline

Posts: 663


« Reply #15 on: April 14, 2022, 08:30:39 PM »

   Motorola R-56 standards for grounding would suggest you run #2 starnded down the pole to ground with a ring of buried ground rods around the base of the pole all bonded together. Form there the grounded pole should be connected to the grounds for the power to the house, ham shack and shop. The idea is to get everything at the same potential.

    Whether you agree or disagree with Motorola R-56, the document (about 800 pages of it) is a treasure trove of information on lightening protection and site development. I had about 100 hours of training on it when I worked for Motorola and at times it was both bizzare and over the top. They were really anal about grounding. That said it does work. several times I was at a site when the tower was hit I and was never injured or lost gear at an R-56 compliant site.

    And Mike SLK: I trained at GE Mobile Communications in Lynchburg VA in the late 80's when I went to work for them. Mel Anderson was our instructor and I remember asking him why the TV, VCR, and slide projector in the classroom had knots in their power cords. Mel said the knots were inductance to aid in lightening protection. Small world!   
Logged
W3SLK
Member

Offline Offline

Posts: 2490

Just another member member.


« Reply #16 on: April 14, 2022, 09:09:30 PM »

W2JBL said:
Quote
And Mike SLK: I trained at GE Mobile Communications in Lynchburg VA in the late 80's when I went to work for them. Mel Anderson was our instructor and I remember asking him why the TV, VCR, and slide projector in the classroom had knots in their power cords. Mel said the knots were inductance to aid in lightening protection. Small world!
I was there then also (1988~1992), however I worked as a service engineer for a company called American Hofmann with Duane, KK4AM, (sans KN0R), and Hal DeVust, KA4YNO. A very talented and diverse group of people in the club. I want to say it was Mel, but it has been over 30 years so I can't say for sure. He was very passionate about it and like you said everything was supposed to be at the same potential. The stuff I had knots in the power lines mostly were blasted at the first knot. I only had to get new power cords. The TV we got from my ex's mother and I didn't put them in there at the time. It met its demise with the lightning as well. 
Logged

Mike(y)/W3SLK
Invisible airwaves crackle with life, bright antenna bristle with the energy. Emotional feedback, on timeless wavelength, bearing a gift beyond lights, almost free.... Spirit of Radio/Rush
WB3JOK
Member

Offline Offline

Posts: 624



« Reply #17 on: April 14, 2022, 11:12:27 PM »

  Motorola R-56 standards for grounding would suggest you run #2 starnded down the pole to ground with a ring of buried ground rods around the base of the pole all bonded together. Form there the grounded pole should be connected to the grounds for the power to the house, ham shack and shop. The idea is to get everything at the same potential.

That sounds great. Is that #2 Al or Cu?
I was going to use #6 solid bare copper (which I have plenty of) and one rod, so that is certainly a lower-resistance ground system.

My problem is that the pole is going to be set about 100 ft north of the house. The utility's pole with the transformer and meter is about 75 feet east of the attached garage, and the service is buried and runs under the garage, coming up at the breaker panel.  Ham shack is on the second floor, about 25 ft (and one story) from the breaker panel. How should I bond all those so that they have small voltage differences during a 10 ns, 10,000 amp pulse? Huh
Logged
W7TFO
WTF-OVER in 7 land Dennis
Contributing
Member
*
Offline Offline

Posts: 2423


IN A TRIODE NO ONE CAN HEAR YOUR SCREEN


WWW
« Reply #18 on: April 14, 2022, 11:48:30 PM »

Lightning protection has made great leaps technology-wise.

The standards and methods have changed for towers, where the investment in broadcast/communications can easily top millions in a single facility.

What was the best even 10 or 15 years ago can't compete with today's findings.

Power line surge protection has changed as well, but I am not advising in that area.

73DG
Logged

Just pacing the Farady cage...
DMOD
AC0OB - A Place where Thermionic Emitters Rule!
Contributing
Member
*
Offline Offline

Posts: 1662


« Reply #19 on: April 15, 2022, 10:40:29 AM »

  Motorola R-56 standards for grounding would suggest you run #2 starnded down the pole to ground with a ring of buried ground rods around the base of the pole all bonded together. Form there the grounded pole should be connected to the grounds for the power to the house, ham shack and shop. The idea is to get everything at the same potential.

That sounds great. Is that #2 Al or Cu?
I was going to use #6 solid bare copper (which I have plenty of) and one rod, so that is certainly a lower-resistance ground system.

My problem is that the pole is going to be set about 100 ft north of the house. The utility's pole with the transformer and meter is about 75 feet east of the attached garage, and the service is buried and runs under the garage, coming up at the breaker panel.  Ham shack is on the second floor, about 25 ft (and one story) from the breaker panel. How should I bond all those so that they have small voltage differences during a 10 ns, 10,000 amp pulse? Huh

In terms of lightning physics, it is best to statically dissipate the accumulated charges to ground before they build up and form a step leader, as charges tend to build up and form a step leader from ground to cloud.

In broadcast engineering, static dissipaters are used at the tops of towers to reduce the chance of charge buildup. See picture attached.

For a home system, we have used two of these at the top of poles and towers and brazed to #6 stranded copper wire.  

https://www.northlineexpress.com/7-x-11-light-duty-wire-wire-chimney-brush-1-4-npt.html?utm_source=googleshopping&utm_medium=cse

Phil - AC0OB


* New AM Tower Installation with Static Arrester at Top.JPG (77.01 KB, 916x613 - viewed 84 times.)
Logged

Charlie Eppes: Dad would be so happy if we married a doctor.
Don Eppes: Yeah, well, Dad would be happy if I married someone with a pulse.NUMB3RS   Smiley
WB3JOK
Member

Offline Offline

Posts: 624



« Reply #20 on: April 15, 2022, 11:05:37 AM »

In terms of lightning physics, it is best to statically dissipate the accumulated charges to ground before they build up and form a step leader, as charges tend to build up and form a step leader from ground to cloud.

As I mentioned previously  Grin Although a little Googling shows, somewhat surprisingly to me, that the dissipation theory is still being debated since Benjamin Franklin... for example, https://lightningmaster.com/lightning-protection-theory-more-fuel-for-the-debate/
That chimney brush you recommended looks like a good and inexpensive candidate... if it actually works!

BTW in the most common type of discharge, the leader steps from the cloud to the ground, then the main return stroke traveled from ground back up to the cloud... although the direction really doesn't matter to my antenna or wiring  Wink
Here is more about lightning than you probably want to know: http://www.lightning.ece.ufl.edu/PDF/Published%20Journals/2014/Dwyer%20&%20Uman%20(2014)a.pdf
Logged
DMOD
AC0OB - A Place where Thermionic Emitters Rule!
Contributing
Member
*
Offline Offline

Posts: 1662


« Reply #21 on: April 15, 2022, 12:44:43 PM »

In terms of lightning physics, it is best to statically dissipate the accumulated charges to ground before they build up and form a step leader, as charges tend to build up and form a step leader from ground to cloud.

As I mentioned previously  Grin Although a little Googling shows, somewhat surprisingly to me, that the dissipation theory is still being debated since Benjamin Franklin... for example, https://lightningmaster.com/lightning-protection-theory-more-fuel-for-the-debate/
That chimney brush you recommended looks like a good and inexpensive candidate... if it actually works!

BTW in the most common type of discharge, the leader steps from the cloud to the ground, then the main return stroke traveled from ground back up to the cloud... although the direction really doesn't matter to my antenna or wiring  Wink
Here is more about lightning than you probably want to know: http://www.lightning.ece.ufl.edu/PDF/Published%20Journals/2014/Dwyer%20&%20Uman%20(2014)a.pdf


Thanks, I've had that paper since it was originally published and after the publishing, high speed photography seems to dispute some of the findings.

Here are links to the LBA group's dissipater systems:

https://www.lbagroup.com/blog/how-to-select-lightning-dissipation-systems-for-towers-and-antennas/

https://www.lbagroup.com/products/lightning-protection-dissipaters-portable-masts-rods

some commercial companies call them "spurs"

https://eriinc.com/product/lightning-dissipation-spurs/

https://lightningmaster.com/static-dissipation-arrays/

And here is another practicing BE who has some experience:

https://www.thebdr.net/static-dissipators-black-magic-or-real-protection/

So you have been given a number of suggestions so yuse takes your chances.  Smiley

Phil - AC0OB
Logged

Charlie Eppes: Dad would be so happy if we married a doctor.
Don Eppes: Yeah, well, Dad would be happy if I married someone with a pulse.NUMB3RS   Smiley
WB3JOK
Member

Offline Offline

Posts: 624



« Reply #22 on: April 15, 2022, 01:42:50 PM »

Thanks. That last link is from a broadcast engineer who actually does not seem to have a vested interest in selling static dissipators, and his advice is certainly reasonable on the other common protection methods (some of which I have already implemented).

I wonder if the tall trees all around here are acting as dissipators? My 40x30 steel building in the open has never been hit, and in 20+ years living here I think there was only one lightning strike near the incoming overhead 7200 volt line (I wasn't home, but found a tree that looked like it'd been hit).

I assume that a wooden utility pole should be treated similarly to a tower (except without grounding it to the tower every ten feet, of course)?

Anyhow I'm thinking of putting another 8-10' of steel pipe mast atop the pole, so it'd be easy to put a dissipator brush on it.
Logged
WBear2GCR
Member

Offline Offline

Posts: 4107


Brrrr- it's cold in the shack! Fire up the BIG RIG


WWW
« Reply #23 on: April 16, 2022, 01:40:35 PM »



While I have not actually used it (standard disclaimer language) I vote for the stainless steel chimney brush
method at the top... bleed charge, not discharge charge?

What W2JBL said is about what I have read, you want everything to rise and lower WRT ground, together.
A lot of damage happens when two or more lines end up at different potentials. Like a phone line and an AC line? Etc.

I have reservations about it, when things are a LONG distance away, the self inductance of the line, and the
propagation time seem like they will cause a differential potential between each end?? Not to mention the cost of
very long runs of thick wire, copper or not?

One possible solution may be (and there is a proper name for this...) placing a big iso transformer out at the
remote (shack) end of the AC feed, and creating a local ground system, NOT connected to the house system.
Obviously there is a limitation WRT the breakdown of the iso iron, but it also has significant inductatance...

The run to the tower still needs to be tied to the shack ground...

The ideal situation would appear to be a ring around the QTH, bonded to the service ground, with ground rods spaced
around the ring, AND radials, plus a run to the tower, which has its own smaller ring, and multiple ground rods and radials!
Yeah... ca-ching $$$!!

I dunno...

                    _-_-bear

             
Logged

_-_- bear WB2GCR                   http://www.bearlabs.com
W1ITT
Member

Offline Offline

Posts: 513


« Reply #24 on: April 16, 2022, 05:36:39 PM »

I have been at many of our Uncle's HF Global (military) sites, domestically and worldwide working on GBSLP, the "grounding bonding shielding and lightning protection" program.  We begin with multiple ground rods, ring connected around the antenna towers, with runs to all the guy anchors and their ground rods.  Back to the station we run grounds along the coax trenches, redundant to the coax outer conductors, back to a perimeter ring around the building, with all connections cadwelded (which is great fun in itself). 
I have a similar setup at home, but with thinner wires.  Uncle uses wire as thick as your finger, supplied by the gracious taxpayers.  Uncle doesn't do it, but I have the stainless steel chimney brush dissipator at my own QTH to bleed things off before the charge builds to high levels.  So far, so good.  Also, walk along your road and make certain that the druggies haven't cut the copper ground wires off the neighborhood power poles.  They are part of the dissipation array.
Everything gets grounded.  I've heard anecdotal stories where people say that some things shouldn't be connected to ground, but I believe this is fallacy.  Lightning is fickle and will do as it pleases, but the best we can do is to keep our entire system as close to unipotential ground as possible.  If you are in a location where lightning is common, it doesn't pay to scrimp and that four foot RadioShack ground rod isn't going to be the solution.
73 de Norm W1ITT
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.117 seconds with 18 queries.