Lightning Arrestor?

[Lauri-CoyoteFrostbite]

I like this photo -



I spent a hairy evening in this hut (its actually a cabin perched near the summit of a 13,000+ foot mountain) during what could only be called something out of Modest Mussorgsky's ** "Night on Bald Mountain."

We mostly perched on stools, the legs of which were mounted on large glass telephone-pole insulators; we perched in the centre of the main room away from the windows as lightning flashed all about the mountain .

One hit after another struck that mast, all evening long. With each strike it rang out like a bell, while St. Elmo's Fire crackled and danced along the edges of the window sills.

Even after the storm passed, no one could relax.... and sleep that night was fit-ful at best.


Lauri

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**

 

[MUTNAV]

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".........any thoughts on coiling the coax?............ "

There may be science behind coiling a length of the antenna feed. The theory is the coil forms an inductive loop, in effect becoming an RF choke--of sorts. Since lightning is a high frequency pulse, this coiling of coax supposedly will block a low energy strike that was not sufficient to vapourize the whole she-bang.
Some of our guys swore by doing this-- and I don't disparage the practice. I have seen the results of what direct hits can do, especially to feedlines.

A memorable example was, at first, quite a mystery....... An electrical storm, a site goes off the air-- and when our guys arrived, I got this call ---

"Lauri, you got to see this ......!"
(I always loved calls that started like that)

"Did someone steal the antenna feedline ?"

Approximately 40 feet of large diameter Heliax was simply gone, -as was the vertical antenna it had been attached to. The equipment in a hut was untouched, though all the circuit breakers had been tripped. The first thought was that someone had stolen the line- maybe taken by aluminium/copper scrap collectors. But looking closely where the line had (formerly) lay there was a trail of gray dust leading from the tower to the hut.
Inside the hut the Heliax passed through a thick piece of copper plate/common ground-- then to a coax barrel/surge protector adapter -- and then to a coil of coax. The static (lightning "arrestor") gizmo was fused to this plate, but the coiled coax was untouched.
In a brief flash the Heliax was simply 'gone." But did the coil of coax arrest the further surge ?

Ever after I have always added a few loops to any coax lines as it enters a building.

Call it Black Magic--- but hey, what can it hurt ?


Lauri

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(irregardless, my personal radios I disconnect, when possible, any antennas and power supplies when not in use)

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Now your just being provocative... The image of the person climbing the tower should be wearing proper climbing gear, AND there is no such word as "irregardless")

So are we missing something in the technical literature about coiled wires being useful for intercepting energy, could it be applicable to EMP ?

I know scientist type people like to have everything proven and published, and this idea generally isn't.

Sounds like a good project for a thesis or something.



Thanks
Joel

 

[Lauri-CoyoteFrostbite]

Ah, but Joel, you missed the most important part of that story.....
The part were its all called "Black Magic !

......................... they don't call me a Sorceress for nothing !!

Smiles







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[Brales60]

Ah, but Joel, you missed the most important part of that story.....
The part were its all called "Black Magic !

......................... and they don't call me a Sorceress for nothing !!

Smiles




View attachment 126791


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You're really a tower climber? God bless you. I hate the 3rd step on a 6' ladder.

 

[MUTNAV]

Ah, but Joel, you missed the most important part of that story.....
The part were its all called "Black Magic !

......................... they don't call me a Sorceress for nothing !!

Smiles




View attachment 126791


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BUT, is this something that needs to be studied and quantified a little?

I had thought about ideas like this, in the form of forcing a delay in a high voltage transient, by using a coil of wire, with a voltage sensor at the input of the coil, and a crowbar circuit on the other end of the coil.

With a direct connection between the sensor and the crowbar, the crowbar would trigger before the transient got to it, theoretically protecting a device.

But It would would be great to see someone actually do something (from a high school science project to someone looking for thesis project), study this. Until then, none of the official guidance we use and reference will show anything with using coils or knots for protection.

I've even found a site that combines a lot of EMP information in one location, but haven't seen anything yet on using coils or knots.

EMP Reports - EMP Library for Protection & Education

Our EMP Shield Library has been created to assist the Department of Homeland Security (DHS) in its #1 Strategic EMP Goal referenced in their OCT 2018 publication which can be found in our EMP library of references.

www.empshield.com

Thanks
Joel

 

[mmckenna]

I hate the 3rd step on a 6' ladder.

Truth is, once you get up above about 20 feet, the ending is the same. Just more time to contemplate your choice of career on the way down.
Or "More time between Whoops! and Splat!"
On a more serious note, when properly trained and using the right safety equipment, you learn to trust your equipment and training. It's not as bad as people think. The regulations on tower climbing are are pretty strict, and if followed, it's pretty safe. Where people get into trouble is when they start ignoring the rules.

I think there's some great advice above. For a hobby installation, you could certainly incorporate all these ideas.
At minimum, you should do what the National Electric Code says. That will keep you on the right side of the homeowners insurance and just about anything else. Adding more protection than required, if done correctly, will improve the level of protection.

 

[Brales60]

Truth is, once you get up above about 20 feet, the ending is the same. Just more time to contemplate your choice of career on the way down.
Or "More time between Whoops! and Splat!"
On a more serious note, when properly trained and using the right safety equipment, you learn to trust your equipment and training. It's not as bad as people think. The regulations on tower climbing are are pretty strict, and if followed, it's pretty safe. Where people get into trouble is when they start ignoring the rules.

I think there's some great advice above. For a hobby installation, you could certainly incorporate all these ideas.
At minimum, you should do what the National Electric Code says. That will keep you on the right side of the homeowners insurance and just about anything else. Adding more protection than required, if done correctly, will improve the level of protection.

Gives me ton to think about. That said, I play by the rules whenever I can. I'm not 100% done on my set up, but I already have major grounds and big wire connecting stuff. You probably can't see the ground wires, but they're there.

 

[MUTNAV]

Truth is, once you get up above about 20 feet, the ending is the same. Just more time to contemplate your choice of career on the way down.
Or "More time between Whoops! and Splat!"
On a more serious note, when properly trained and using the right safety equipment, you learn to trust your equipment and training. It's not as bad as people think. The regulations on tower climbing are are pretty strict, and if followed, it's pretty safe. Where people get into trouble is when they start ignoring the rules.

I think there's some great advice above. For a hobby installation, you could certainly incorporate all these ideas.
At minimum, you should do what the National Electric Code says. That will keep you on the right side of the homeowners insurance and just about anything else. Adding more protection than required, if done correctly, will improve the level of protection.

I'm not too confident about incorporating a lot of the ideas.... the possible problem is incorporating ideas "correctly", one idea that I had was to put power leads in a "wave-guide beyond cutoff", as it turns out I think it's against the N.E.C. to do that.

Thanks
Joel

 

[W8HDU]

..... one idea that I had was to put power leads in a "wave-guide beyond cutoff", as it turns out I think it's against the N.E.C. to do that.

You could put power in watertight conduit which is approved under NEC, but the downside is you add a lot of vertical weight and windload.

Lightning mitigation is always give and take. The effort is basically insurance against something bad happening.

Ironically, this morning we're having a good storm here in Lima, OH. Phase 1 of our three phase power is out, and we're on generator. Scanner is active with calls related to the storm.

 

[MUTNAV]

You could put power in watertight conduit which is approved under NEC, but the downside is you add a lot of vertical weight and windload.

Lightning mitigation is always give and take. The effort is basically insurance against something bad happening.

Ironically, this morning we're having a good storm here in Lima, OH. Phase 1 of our three phase power is out, and we're on generator. Scanner is active with calls related to the storm.

OOps your right,,, sorry... I was thinking of when we were trying to isolate a RG-58 cable and its signals, from a set of 5000 volt and 10,000 volt underground power lines (which the people installing it literally laid on top of the RG-58), I suggested maybe put the power lines in iron pipe to shield them, and the engineers said the pipe would probably melt, and to never do that. As it turns out "metalic conduit" is required in a lot of circumstances and it CAN be used in power entry for a wave-guide beyond cutoff arrangement.

I do stand by the idea of not implementing ALL ideas for protection without considering interactions.

Thanks
Joel

 

[W8HDU]

If you take just one suggestion it should be a method in which to steer lightning away from your house and rigs, and let it go into the ground away from things. You can't eliminate it, or prevent it, but what you can do is get it away from the house and rigs.

 

[Ronnierozier2]

Curious, why not outside? My grounds are all outside on my pole. No ground wire on the poly phaser that I can see. Besides the pole, I have a 8' rod running into the ground that everything is tied into.

check out the documentation or the instruction documentation for a polyphaser. The engerneers that designed the 100+ microwave sites we have all over the state of Ms put them right inside the building where the coax enters. I think thats code also. From there they are tied to a grounding halo that extends outside to an underground ground grid at the electrical substation.

 

[Ronnierozier2]

You can place them outside if you weather seal everything really well.
Preferred location is indoors where they are protected from the environment. Also, in a commercial application, it's common to transition from the larger coax coming down the tower to a small coax to connect to the equipment. Better to have that inside than an additional connection just inside.

Thats how our 100+ microwave huts are designed. the polyphaser connects to the larger coax coming down the tower (inside the bldg) and the a smaller 7/8" jumper runs to the final termination point. Microwave networks MX series equipment.

 

[TXFitz]

For those of you who are utilizing a loop of coax (6 turns), is this loop before or after the lightning arrestor? I assume after if the theory is the looping creates higher inductance in the case of a lightning strike.

 

[W8HDU]

Loop should be at the lowest point, on the outside of the shack/house, and if you're using an "arrestor", put it before the loop, and make sure it's WELL grounded. I would suggest copper strap, or woven braid from it to a "deep" ground rod. The theory is the loop will act as resistance to the strike, therefore seeking the best path to ground which would be the arrestor and the ground rod. You can't eliminate lightning, but you can coax it to take another path which won't be into your shack/home. Make sure the ground rod is DEEP, and that you're nowhere near gas lines or water lines.

 

[MUTNAV]

Loop should be at the lowest point, on the outside of the shack/house, and if you're using an "arrestor", put it before the loop, and make sure it's WELL grounded. I would suggest copper strap, or woven braid from it to a "deep" ground rod. The theory is the loop will act as resistance to the strike, therefore seeking the best path to ground which would be the arrestor and the ground rod. You can't eliminate lightning, but you can coax it to take another path which won't be into your shack/home. Make sure the ground rod is DEEP, and that you're nowhere near gas lines or water lines.

Coax the lightning, no pun intended I assume.

 

[W8HDU]

Coax the lightning, no pun intended I assume.

Coax, the verb, as in "to manipulate to a desired end by adroit handling or persistent effort". Let lightning strike. Just somewhere where it does no damage to your shack, house, or equipment.

 

[MUTNAV]

Yes, a coax loop that as a system helps coax the lightning to take a differrent path..

Like it would be easier to lead some people if they got the lead out.



Thanks
Joel