Lightning Protection vs. Lightning Elimination 6

[Loopee]

I'm currently doing a study of existing lightning protection at a chemical plant. I will be making recommendations to the client about maintaining his current NFPA 780 style protection with air terminals, conductors and ground rods.

I have also been reading much about the Dissipation Array Systems promoted by companies that claim to eliminate lightning in the area protected. I've also read many critiques, some in this forum, of these systems that call the techniques non-scientific, snake oil, etc. In fact there seems to be a real war going on over whether this works or not. After all I've read, I have to admit to being a skeptic also.

My question is this: Is there anyone who HAS tried these techniques and believes that there is some merit to them?

 

[VEBill]

You may have already stumbled across my opinion on this topic already:

It borders on being trivial to conduct a rigorous scientific experiment to prove that these so-called Lightning Prevention systems work. Once this has been done, documented, peer reviewed, published, duplicated, etc., - then there wouldn't be any argument. Until then, file under snake oil.

 

[ZapSib]

nothing is lost nor created, only modified.
then i do not belive it is possible not to eliminate the lighing but I may belive it is possible not to eliminate the consequence of lighing but to catch the consequence ( overvoltage, heating) to avoid any trouble on the plant.

Whatever, I did not get involved in such stuff yet.

 

[BobbyNewmark]

Suppose the system does suppress spontaneous lightning. It always works, flawlessly, under all weather conditions. So you remove all conventional overvoltage protection equipment from the plant.

Now any disgruntled employee can fry the plant by drawing down a bolt of artificial lightning, using a spool of fine wire and a model rocket. Now any ecoterrorist can fry the plant by discharging a big capacitor into your power feed.

P.S. If you find yourself needing more paranoia, try working for a defense contractor for a few years.

 

[Loopee]

I will never recommend to the client that he replace the conventional methods, I'm just wondering whether or not to add any of these "elimination" techniques.

I will be trying to contact some of the references given but this forum seems to work so well I thought I'd try here also.

Also-In the promotional material I've read I have not read anything about factoring in wind strength and direction. They may create ions but ions are still molecules and can still be dissipated by wind. In other words, even if it did work as claimed it seems that it would only work on very still air.

 

[bogeyman]

I worked for an explosives manufacturer on a large mile square site, the site had a single grided mat underground at 12 foot pitch and all the buildings had overkill lightning conductor instalations. In 16 years I only new of one strike and this was to a 150 foot poplar tree.
I was informed by the safety folks that this low strike rate is to be expected when a large area is held at equal potential by the grounding mats, maybe this is what they call lightning elimination scheme.

 

[Higgler]

Interesting bogeyman,
I'd expect laying all that wire wasn't done on a whim and sounds reasonable based on that history.
It might be worth researching other explosive sites to see if they have similar, or different lightning strike solutions.
Possibly the edge of the metal grid at the explosives site has some elevated lightning rods on it to help keep strikes off the center area. Was this site in a valley or slight depression too?

kch

 

[Compositepro]

A ground mat/grid would be effective in mitigating the destructive effects of a lightning strike but would not have any effect on the likelihood of a lightning strike. That is controlled by the atmospheric conditions that generate static electricity.

 

[VEBill]

If Lightning Prevention schemes actually work, then why couldn't they be wired to ground using 22-ga wire?

 

[FiltrationEngineer]

I worked at a 40 acre plant in Florida. They had this lightning system that had lots of things that looked like wire brushes sticking into the air and grounded. They were placed about every 25 feet along the highest parts of every structure.

During the summer when we get lots of lightning storms, you could see the effect. The lighnting gets "pushed" off of the plant and strikes all around the perimeter in the trees. To my knowledge, they never had a strike at the plant. I don't understand the theory behind it, but it definently worked.

 

[Loopee]

Thank you Filtration Engineer. That is exactly an example that helps. I've recently heard of other examples as well. I'm just having trouble believing the reasoning given. For example the ionizing current for each of the dissipation array elements is given as being in the order of milliamps. This ionization current is supposed to neutralize the potential difference between cloud and ground to diminish the chance of a lightning strike. I can imagine that except for the magnitudes involved.
The lightning strike itself is going to have thousands of amps-nature's way of neutralizing the potential difference- and how could milliamps ever be enough? Then there is the wind question I had earlier. It's all very puzzling but I've pretty much decided to concentrate on empirical evidence. If I can find a compelling number of people who have witnessed the benefits, I'll relay that to the client.
Could you share with me the name of the company you mentioned.

 

[VEBill]

"...concentrate on empirical evidence..."

That's called anecdotal evidence.

http://en.wikipedia.org/wiki/Lightning_rod#Lightning_prevention

Review some of the citations linked from Wiki. Dig further through the links. There's a fairly clear consensus, at least from those applying rigorous scientific thinking.

 

[VEBill]

This one is actually quite amusing:

http://www.lightningsafety.com/nlsi_lhm/ESE_court_case.pdf

 

[Loopee]

Thanks to VE1BLL for the references and I'll certainly check them out.
In the meantime though, I still have an open question about actual results. If anyone else has experience or observation (good or bad results) of ESE or dissipation array lightning "preventors" use, please let me know.
The first ESE company I've contacted seem to be reluctant to give me an up-to-date customer reference list. Hmmmm.

 

[BJC]

Loopee
I have been on a cooling tower when a very dark and low cloud rolled over the tower. The tower was a mechanical draft tower with 10 cells and was about 35' or 40' high.
There were 5 points on each cell. All of the points started arcing into the air. The arcs were very visable against the dark cloud. It looked like a Frankenstein movie or something. I was with the superintendant of the subcontractor that built the tower.
when the sparks started he said "Lets get the H_ _ _ out of here and took off running. I followed.
There is no doubt the system was disapating charge, the question was how much and if that was sufficient to prevent a strike. The same superintendant has just finished another job rebuilding a duplicate tower ( complete with the same lightning protection system) that had been struck by lightning and burned down.
This was one of the last wooden tower built in the US. There was enough redwood in them for hundreds of picnic tables.

 

[Loopee]

BJC
Thanks for that anecdote. I think I would have been moving along pretty fast also if I'd seen that.
By "points" did you mean the standard air terminals? I wonder what kind of lightning protection, if any, the wooden tower had?

 

[BJC]

Standard points, right out of the Thompson catalog. They were 18" or 2' long copper with plated points. Five on each cell, with 10 cells per tower. There were two towers about 4o yards apart. The protection system was pretty standard designed by Thompson.
As I though I wrote in another post here ( it either got deleted or I screwed up poosting it) the system was a requirement of Factory Mutual. Other systems may work just as well or better but if the insurance companies doesn't accept them they wont's cover the structure. Acceptance by them usually requires a UL masters license.

If your ever through the Denver Airport and have time walk around on the upper elevations and look out on the roof(S). If your stuck in a lightning storm I am sure you can see blue sparks going into the air.

 

[bogeyman]

A little bit more anecdotal information,
I was under the impression that the electrical charge was dissipated due to the presence of the large number of finials atop all the buildings on the explosives site, geographicaly the site was (it is alas now closed) situated on the lancashire plain south of preston at about 200' above sea level some 5 miles away from the rising penine hills. The last vestiges are still visible on google maps.
In our instrument workshop (bang in the middle of the site) we had a pole mounted VHF whip antenna on the roof (about 30' up with 28" of whip) when the thunder storm risk was high the N type connector in the radio test area used to arc over at a rate seemingly proportional to the severity of risk... tick.. tick.. tick.. etc.
even when this occurred there were no on site strikes but often several around the perimiter.
The arc legnth would have been about 2.5mm, shorting the cable may have been sensible.

 

[BJC]

More lightning war stories.
I had a crew of surveyors sitting in a truck waiting for a little dark cloud to blow over. It was only raining a little so I had the window down with my arm resting on the bottom of it. I noticed that every hair on my arm was sticking straight out. Not just mussed up a little but STRAIGHT out! I pulled in my arm and rolled up the window. About 30 seconds later lightning struck a tree about 30 yards away. It was like a 105 going off beside your ear. I though we were going to have to go back to camp and change underwear.

 

[VEBill]

There was an excellent science show (maybe Nova?) on TV a few years ago. They seemed to have all the latest footage and up-to-date theories.

One thing I clearly remember was the upward streamers trying to make contact with the interconnected 'puddles' of charge on the way down. The first streamer that happens to make contact gets the full blast, and then all the other 'puddles' of charge along the way are subsequently discharge down the same path. This is why you often see pulsating strokes.

But even the unconnected streamer (a 100-foot long 'spark') is a serious event and will certainly take out your home theatre system.

There was a nice picture of a streamer from a house and a streamer from a tree. The tree happened to make first contact with the charge 'puddle' and it took the hit. The house was lucky.

The whole explanation provided by the show all made perfect sense and also fits smoothly into my overall understanding of physics.

But 'Lightning Prevention' doesn't fit and doesn't make sense. You would have to ignore several 'order-of-magnitude issues' for it to even begin to make sense.


Also, in the court case previously linked, they weren't even claiming Lightning Prevention. They were only claiming a slightly larger protection zone. Even that modest claim was found to be unsubstantiated.