Lightning prevention system.

[mark_morwood]

Originally Posted by tkeithlu

It's the reason that advice on self protection has you crouch with a rounded back rather than simply sitting on the ground or lying flat.

I may be wrong, but I think the reason for crouching rather than sitting or lying on the ground is that you don't want to become an alternative path for the voltage dissipating outwards through the ground from a strike near you. There will be quite a voltage gradient across the ground surface radiating outwards from a strike.

[garyfdl]

Originally Posted by mark_morwood

I may be wrong, but I think the reason for crouching rather than sitting or lying on the ground is that you don't want to become an alternative path for the voltage dissipating outwards through the ground from a strike near you. There will be quite a voltage gradient across the ground surface radiating outwards from a strike.

I think you're right. By crouching, you reduce your height, and the only your feet are in contact with the ground. You make yourself as small a target as possible, and minimize any potential area of contact.

[s/v Jedi]

Take the coax connector out of your VHF radio, then slowly move the center pin of the cable connector towards the threaded outer (chassis) part of the radio connector. See the spark? Now you have created a lightning rod.

You can see the spark when the atmosphere is charged even when there isn’t any lightning (yet).

The theory behind the (bottle) brush dissipators is that they do exactly like the coax experiment but with hundreds of much sharper points, keeping the electric field muted enough for higher charged items around you to attract the strike. I always use the word “camouflage “ when trying to explain this: when you wear camouflage someone may still see you, but the guy jumping up and down in signal orange and yellow clothing sure is easier to find

[sparau]

Originally Posted by tkeithlu

QUOTE:"Timber mast and dyneema?"

Sparau, that's the conduction error. Before striking, lightning is a static electric charge, such as your shuffling leather shoes over a wool carpet. The fact of striking a particular point is independent of any conductive qualities. Once it starts discharging, however, it will take the easiest and often multiple routes from ground to cloud, so the damp salty dyneema and mast may become routes, with the superheating of any water in the route producing explosive steam.

Isn't that self contradictory?
You are saying that it will take the easiest path, i.e. the most conductive. Or in the shoes example my finger zapping someone rather than arcing 2 meters to the ground.
So the timber mast isn't like a tree, it's dry and a good insulator so shouldn't get used as a path over the air. Good point about the dyneema being wet though.

[mark_morwood]

Originally Posted by sparau

So the timber mast isn't like a tree, it's dry and a good insulator so shouldn't get used as a path over the air. Good point about the dyneema being wet though.

I suspect even dry wood, let alone a wooden mast wet from rain, is a better conductor than air.

But in any case, you probably want a decent conductor and lightning rod on a wooden mast just in case you do get hit, as because of residual moisture wood has a tendency to explode/split if asked to carry a large current.

[Frankly]

Being a conductor or non conductor has negligible effect on the original lightning strike attachment (almost totally dependent on relative altitude to surrounding objects). The results after the current starts to flow is almost totally dependent on the electrical conductivity of the path.

A sharp point dissipating a static charge works almost 100% in a laboratory setting (I have seen it demonstrated dozens of times). Most agree that in a real world situation, kind of like peeing in the ocean and expecting the water level to rise.


Frankly

[GordMay]

Originally Posted by Frankly

... A sharp point dissipating a static charge works almost 100% ...

Actually, a BLUNT tip (±1/2" dia round) probably makes a better Lightning Rod (Air Terminal) than a sharp tip.

The results of this study suggest that moderately blunt metal rods (with tip height-to-tip radius of curvature ratios of about 680:1) are better lightning strike receptors than are sharper rods or very blunt ones.
➥ https://www.jstor.org/stable/26185821

[valhalla360]

Originally Posted by sparau

Timber mast and dyneema?

Salt crusted with a bit of rain water to create an electrolyte makes for nice conductors.

[valhalla360]

Originally Posted by tkeithlu

....

This device may supply a tiny amount of protection by being rounded. It can be marketed, and the company make big bucks, because there is no way to disprove it's efficiency. Very few boats are hit by lightning, so it worked, and if a boat so equipped is struck, then that was a special case that not even this very effective device could block.

More like no one bothers to challenge them in the court system. As they are making the claim, they have a burden to prove it. I do agree proving it one way or the other is near impossible and their first response is likely to be you are in the 1%.

[valhalla360]

Originally Posted by garyfdl

I'd say you're right. The interesting thing (to me) is that well heads stick up inches above the ground, and get hit, when trees, poles, buildings, etc mere feet away are often untouched.

Generally it will take the path of least resistance but with lightning, that may be across multiple paths and items may still be damaged even if they don't take a direct strike. It's often hard to say exactly what happened.

Are these direct strikes or is it coming in via the powerlines feeding the well pump. Clearly from the description of the coax cable the building was impacted. Likewise trees may have been impacted. The charge that could blow out the electric motor on the pump may be far less than what it takes to blow up a tree trunk.

[valhalla360]

Originally Posted by tkeithlu

It's the reason that advice on self protection has you crouch with a rounded back rather than simply sitting on the ground or lying flat.

I suspect it's more closely related to telling kids to get under their desks in the event of a nuclear attack. Makes them feel like they are doing something.

[garyfdl]

Originally Posted by valhalla360

Generally it will take the path of least resistance but with lightning, that may be across multiple paths and items may still be damaged even if they don't take a direct strike. It's often hard to say exactly what happened.

Are these direct strikes or is it coming in via the powerlines feeding the well pump. Clearly from the description of the coax cable the building was impacted. Likewise trees may have been impacted. The charge that could blow out the electric motor on the pump may be far less than what it takes to blow up a tree trunk.

I will say these were direct strikes as there was no interruption of power or (apparent) damage to electrical components in either case.

The arcing of the coax was occurring before the strike. After the strike, it stopped. I attributed the arc to an induced current due to the build up of static charge in the air.

There was no apparent damage to the trees (burns, blown off leaves, branches, etc) or to anything else in the vicinity of the well heads.

As to multiple paths, you are correct; I have first hand experience with that as well.

Kitty-corner from us is a Catholic church. The steeple is 150-200' high; everyone calls it the 'neighborhood lightning rod'. I will speculate it gets hit once a year (at least). During storms with a lot of lightning, I would go out on the side porch and watch the steeple, to see if it got hit.

About 25 years ago, we had such a storm. There was a strike, not to the steeple, but to the back chimney of our house. Didn't blow it apart, but blew brick and mortar all over the back yard. A leader also came down between the houses near the porch where I was standing - scared the crap out of me. A surge came in on our phone line - wrecked 3 phones and 2 computers (this was back when it was dial-up internet). - Not done yet. - The house next to ours, where the leader came down and scared me? He had his refrigerator and TV blown out. The house behind us had their satellite dish and box fried. Friend across the street lost his phones and computer (he fed off a completely different pole). Amazingly, there were no fires in any of the cases. But the point being, this was not 'one' bolt of lightning, there were many individual leads striking all over the place.

Oh, and one more thing... I don't go out on the porch anymore to see of the steeple gets hit

[valhalla360]

Originally Posted by garyfdl

I will say these were direct strikes as there was no interruption of power or (apparent) damage to electrical components in either case.

The arcing of the coax was occurring before the strike. After the strike, it stopped. I attributed the arc to an induced current due to the build up of static charge in the air.

There was no apparent damage to the trees (burns, blown off leaves, branches, etc) or to anything else in the vicinity of the well heads.

The strike could have been hundreds of yards away and the well casing acting an uber ground rod could have taken a large amount of current that would have gone into the building via the wiring. It may have been acting to unintentionally protect the electronics in the building.

It might have hit a tree a few hundred yards away but close enough to the electrical lines that you got a spike that took out the pump motor but not the electric supply.

Lots of weird things can happen with lightning. So I would call speculation, unless you literally saw the lightning strike the well head while not hitting the adjacent building and trees.

[Frankly]

Gord the argument of sharp vs round point has being going on for years. Some of the lightning equipment companies provide pointed, some round, and some both.

I used to specify the standard Faraday Cage (sharp point) set up on the high rise and Condo buildings that I designed. One one beach condo the Electrical Contractor submitted one of these flying saucer on a single mast in the middle of the roof. There are a bunch of high rise condos on the beach with such systems. It came with a 10 million $ insurance policy against damage so I allowed it. Those high rise condos out on the beach get struck quite regularly. Never heard of any complaints from either type.

The main thing is to provide high (relative to the surrounding area) well grounded conductor(s) down to Mother Earth/ Mother Ocean. Use the remainder of your good luck to by a lottery ticket.

The IEEE did an extensive study years back. They admitted the entire business was based on a bunch of "rules of thumb" and guess work that usually works. Nothing as straight foreword as the laws governing gravity to rely on.


Frankly

[garyfdl]

Originally Posted by valhalla360

The strike could have been hundreds of yards away and the well casing acting an uber ground rod could have taken a large amount of current that would have gone into the building via the wiring. It may have been acting to unintentionally protect the electronics in the building.

It might have hit a tree a few hundred yards away but close enough to the electrical lines that you got a spike that took out the pump motor but not the electric supply.

Lots of weird things can happen with lightning. So I would call speculation, unless you literally saw the lightning strike the well head while not hitting the adjacent building and trees.

It is speculation/anecdotal, but speculation based on observation and evaluation, and anecdotal in that many, many well repairmen have told the me the same 'story'. i.e. wells getting hit with no other apparent damage to any other nearby objects or people.

And I do know evidence can be hard to find. On a separate occasion, the b-i-l's pole barn (actually a 30 x 36 'garage') was hit, with no significant' damage. Reason we know? His b-i-l was inside when it happened. Said a fireball shot across the floor. He was unhurt but shaken (actually crapped his pants). When we checked th place for damage, the only thing we found was a pencil eraser sized burn on the side of the 'barn' where a metal fence post was leaning, Actually tack-welded the post to the siding.

And you are absolutely right. "Lots of weird things can happen with lightning."