Our lightning suppression standard was a Corporate std. and certainly not NEC. Plant was right on the coast at a mean elevation of ~18'. Highest point on the plant was the "Still House" where we had 27 fractional distillation columns both inside the ~100' tall building and outside of it for the tallest columns. Each one containing gaseous terpene oils vapor. Not something you wanted a strike on. Never had one due to the individual columns' lightning suppression systems. In the plant yard were massive 60-80' tall piles of Southern Yellow Pine Fat Lighterd stumps awaiting processing. Acres and acres of stump piles. Not as tall as the columns but regular recipients of strikes before an aerial grounding suppression was installed. One strike, which ignited the stumps, caused such a massive fire that the combined fire fighting forces of several counties were unable to extinguish it. Stump piles had to be dismantled and moved to contain it and let it burn out over several weeks' span after isolating it. That was when the grounding aerials were strung on massive wooden poles above the piles and no further incidents occurred. Here in the summer months afternoon thunderstorms for a few hours are the norm for many months so we get a lot of lightning and resultant fires.

 

Lightning is unpredictable so I usually tried to stay inside and away from lightning prone structures during a storm. At a typical receiver station in something like mangrove swampy ground you can see structure streamers during near strikes.
https://www.google.com/maps/place/2...249aafb3c3!7e2!8m2!3d24.5664082!4d-81.6725001
Closed.

 

Lightning is unpredictable? I think I can qualifiably say two predictable things about lightning:

1) It takes the path of least resistance. Not necessarily the shortest distance, as there are documented cases of lightning striking well away from the storm. A bicyclist was struck while riding on a sunny day. A nearby storm about six miles away was brewing. Lightning would seemingly logically take the shortest path to ground. But in this particular case it found the bicyclist.

2) It can be predictably unpredictable in that you never know where or when it will strike. OK, silliness aside, you still know when you should run for cover, so it's not predictable but you can predict when conditions are likely dangerous and take cover.

You ask if copper pipe is sufficient for grounding. We have assumed one of two things. Or maybe two things as well. First is that you want to use a copper pipe as a copper grounding rod. A pipe that is NOT a part of your water system. Second is that you want to add grounding to your already structural plumbing of copper pipe and use that as a ground source. Here's what I see wrong with both applications: First, driving a copper pipe into the ground into soil that is easily driven into - the copper pipe is not going to stand up to the pounding you're going to give it. Even if you crimp the end of it, the force of driving it into the ground can bend and kink the pipe, which weakens its structure. You may never succeed in getting it into the ground far enough. However, you mentioned the idea of using water to hydraulically drill the pipe into the ground. Back when I was a boy I drilled into the ground (clay and sand) (Los Angeles area) using a hydraulic method. Really upset my dad too. I never knew why. That might work, but here's where the second point I believe it won't be sufficient; that's because the copper wall is not thick enough to handle the kind of current the strike is going to deliver. You MIGHT contain the strike once, but a second strike will absolutely show the weakness of using copper piping.

Others have suggested using a copper plated steel rod. I've used such. You can pound them into MANY soil types successfully - AND they can handle the current delivered by the strike. My advice (probably all others as well) is to use a properly designed and purposed grounding rod for the task. Wanting to take a shortcut is a good way to give yourself a false sense of security. However, in all my many decades of life I've never had a house hit by lightning. I even had a couple CB antenna's posted as sentries in the sky and they have never been struck. You're more likely to suffer flood damage than lightning damage.

However, lightning on a power line has a chance of transmitting into your home in the way of a voltage spike. Line suppressors are pretty good at arresting such spikes. But I've never lost any electronics because of a strike on power lines. And there have been a few close strikes in my neighborhood. And yes, there have been house fires started by lightning. But I think you're more likely to experience flood damage than damage from lightning as I said in the previous paragraph. You can still pursue your goal. However, we've given you what we believe to be the best advice on the subject. But advice is only as good as the person who takes it - provided it was good advice to start with.

Lightning? Ground rod.
Copper pipe? Not a good idea.

Bottom line you have. Sojourn on you must, young Padawan.

 

Do not forget, your panel ground is not there for lightning protection and has its own job to do. If you wish to install lightning protection install its own dedicated grounds, NOT your panel ground.

 

Lightning is unpredictable? I think I can qualifiably say two predictable things about lightning:

1) It takes the path of least resistance. Not necessarily the shortest distance, as there are documented cases of lightning striking well away from the storm. A bicyclist was struck while riding on a sunny day. A nearby storm about six miles away was brewing. Lightning would seemingly logically take the shortest path to ground. But in this particular case it found the bicyclist.

#1 seems correct at first glance but lightning does not take the path of least resistance because there is no initial path of least resistance. Lightning makes is own path that's chaotic (with a bias from the electric field) due to the thermal ionization of a current path in atmosphere. The path of least resistance would be a straight line. You seldom see that with a lightning strike. During the strike discharge (AC) it follows the path of least impedance (no sharp bends in grounding conductors) not resistance.

 

Dear all,
Thank you very much for your laborious answers.
First of all I have to tell you that I`m writing from Romania - sorry for my English grammar mistakes.
This is a lightning system design for a new house.
I understand that you do NOT recommend using a copper pipe as an earth-termination system (rod) [I was thinking to have 3 electrolytic electrodes using 10ft 1" copper pipes with 2 caps each (1 small hole in each) filled with ordinary table salt, dipped in a large earth hole (made with a 1" sharp iron pipe, then with a 1 1/2" sharp iron pipe, drilled with a rotary hammer - extracted with a jack) filled with bentonite clay like here: http://www.esgroundingsolutions.com/different-types-of-grounding-electrodes/ - the last type].
What about using a 1/3" /0.04 thick copper pipe as down-conductor system and a 0.7" copper pipe for the air-termination system? Is this going to explode on the first lightning strike?
Many thanks!

 

@Nick_28 Couldn't tell you if it would explode. But a pipe with caps on both ends can constitute a pipe BOMB. Salt LOVES moisture and will absorb moisture from all around. Moisture turns into steam energy when super heated. During a lightning strike I would have to guess that a salt filled pipe bomb would probably explode. In fact I'm rather confident it would.

@nsaspook By "Path of least resistance" I meant by the path created by the plasma generated by the spires of energy reaching up toward each other. Like you said, once they connect they create a path that is seldom straight. The shortest distance between two points. But that doesn't always mean the path of least resistance. Going home one evening there was a wreck on the freeway that shut down 99.8% of all north bound traffic. It would have taken several hours to get home that route. Another path that was 166% longer was to go around a mountain, but without the resistance, and I got home in less than two hours. And the path around the mountain was not a straight line.

Anyway, I may have failed to fully convey my meaning when I said that lightning takes the path of least resistance. It still does because "Air" is an insulator. Lightning has to punch through that insulation, and doing so it generates a plasma. Yes, spook, you're right. There are TONS of factors that redirect electro-magnetic energy. Other electro-magnetic emissions such as radio towers, factories, power plants and a whole host of other naturally occurring factors such as earths own magnetic field all conspire to trick lightning into following an irregular path. However, I still stand behind my statement that it follows the path of least resistance.

Imagine two heads of broccoli, one hanging upside down, the other standing straight. Move them closer together and once the two touch THAT becomes the path for lightning. And no, I'm not saying broccoli has anything to do with lightning (but it might) I'm just using it to illustrate how lightning eventually propagates between sky and earth.

 

@Nick_28 Couldn't tell you if it would explode. But a pipe with caps on both ends can constitute a pipe BOMB. Salt LOVES moisture and will absorb moisture from all around. Moisture turns into steam energy when super heated. During a lightning strike I would have to guess that a salt filled pipe bomb would probably explode. In fact I'm rather confident it would.

@nsaspook By "Path of least resistance" I meant by the path created by the plasma generated by the spires of energy reaching up toward each other. Like you said, once they connect they create a path that is seldom straight. The shortest distance between two points. But that doesn't always mean the path of least resistance. Going home one evening there was a wreck on the freeway that shut down 99.8% of all north bound traffic. It would have taken several hours to get home that route. Another path that was 166% longer was to go around a mountain, but without the resistance, and I got home in less than two hours. And the path around the mountain was not a straight line.

Anyway, I may have failed to fully convey my meaning when I said that lightning takes the path of least resistance. It still does because "Air" is an insulator. Lightning has to punch through that insulation, and doing so it generates a plasma. Yes, spook, you're right. There are TONS of factors that redirect electro-magnetic energy. Other electro-magnetic emissions such as radio towers, factories, power plants and a whole host of other naturally occurring factors such as earths own magnetic field all conspire to trick lightning into following an irregular path. However, I still stand behind my statement that it follows the path of least resistance.

Imagine two heads of broccoli, one hanging upside down, the other standing straight. Move them closer together and once the two touch THAT becomes the path for lightning. And no, I'm not saying broccoli has anything to do with lightning (but it might) I'm just using it to illustrate how lightning eventually propagates between sky and earth.

IMO a better statement would be that the lightning bolt generally follows the path of least energy expenditure during its travel in the atmospheric insulator in a Non-Ohmic ionized gas conductor. The reason I don't like path of least resistance here is that it's not a all or nothing proposition with circuits or lighting with many paths for current in a conductor. The current in any one defined path of the resistive surface is proportional to the resistance of the entire surface.

https://www.ecmweb.com/content/path-least-resistance

 

A lightning bolt doesn't really follow the "path of least resistance", but instead follows Ohm's law. As with strikes with multiple "arms", the most of the current will follow the lowest resistance path, with less current following the next lowest resistance path, etc., until the total energy to be dissipated is depleted. Just because one "arm" has the lowest resistance doesn't mean that it gets all the current. Like a current shunt, most current goes thru the shunt, but current also goes thru the measurement path of the shunt - in true Ohm's law fashion (with a little plasma physics thrown in to really mess things up).

 

Do any of you guys actually have a lightning rod system ? I do. My barn is from the early 1900's, it's ~40 feet long with 3 lightning rods spaced evenly across the roof(4 spaces). It's rods are made from what today would be similar to 1/2" copper pipe with a pointed tip. They are then held by a 3 legged iron fixture, screwed to the roof. The rods are all inter connected with what looks like solder wick, a braided copper strap, that is ~3/4" across. The braid is then clamped to an iron ground rod driven into the ground, know idea how deep. It is original to the barn. and from the looks of it it's never been hit.

 

The purpose of a lightning conductor is to provide a lower resistance path to ground than the path via the building, so that the conductor takes the brunt of the discharge current. I don't think it makes much difference how that lower resistance path is achieved, and whatever it consists of is likely to be vapourised by a direct lightning strike.

 

The purpose of a lightning rod is NOT to provide a path for a lightning bolt, but is instead meant to dissipate the STREAMERS before they get a chance to connect to others.

 

from the looks of it it's never been hit.

Then it is doing its job very well!

 

Then it is doing its job very well!

Yeah, but they didn't do much for an apple and a cherry tree a few hundred feet from the barn. They got hit and split one at a time in the 30 years I've lived here.

 

The so-called "cone of protection" has pretty steeply sloped side angles. When it comes to lightning there are no real hard and fast rules. You are merely playing the odds and can lose all bets.

 

The so-called "cone of protection" has pretty steeply sloped side angles. When it comes to lightning there are no real hard and fast rules. You are merely playing the odds and can lose all bets.

True that, lightning and explosives don't mix.
http://thevane.gawker.com/july-10-1926-the-day-nature-blew-up-a-town-in-new-jer-1602586498

 

The so-called "cone of protection" has pretty steeply sloped side angles. When it comes to lightning there are no real hard and fast rules. You are merely playing the odds and can lose all bets.

I wasn't trying to imply that the rods on the barn should have protected the trees. Just meant that lightning does strike near my house.

The "cone of protection" is why there are 3 rods and 4 spaces in the system on the barn.

 

The purpose of a lightning rod is NOT to provide a path for a lightning bolt, but is instead meant to dissipate the STREAMERS before they get a chance to connect to others.

Hadn't thought of it that way before. But as I contemplate this statement I have to wonder. From some of the video's I've seen, these streamers reach upwards FROM the ground. So it may be possible that elevating the level of the ground artificially via a lighting rod system, could it be possible you might attract More lightning?

@shortbus says his system has never been hit that he knows of. In the number of houses I've lived in, rented or owned, I've never experienced a lightning strike. And I've personally been VERY close to lightning. Back in 1976 I was working at a church camp in Big Bear California. Summer afternoons were often punctuated with thunder storms. As we had been digging a trench for water, sewage and power, the trench was about 3 or 4 feet deep. We had the CB radio on so we could communicate between the lodge and the worksite. Every afternoon we could hear the static generated by the lightning. This one afternoon for no particular reason Joey says "If your hair stands on end you're about to be hit by lightning." True or not - I don't know. Nevertheless, what must have been maybe 5 minutes after that statement we all began to have that tingly fuzzy feeling. Everybody was jumping into the trench. As I went down into the pit "I CAN SWEAR" I saw a bolt of lightning pass from one side of the trench to the other side just about arms length in front of my face. I don't recall any heat experiences so I'm probably reacting to something I saw out of the corner of my eye and as I reacted to look in that direction I THOUGHT lightning had passed within inches of my face. Lightning had actually struck a Jeffery Pine approximately 30 feet away from where I was at the time. So even if I wasn't inches away from lightning I was at least 30 feet away.

Back on topic: IMO copper plumbing - I'm thinking of the type that you solder - probably wouldn't be strong enough to withstand a direct hit. Streamers? Probably. But a full on hit, I'm dubious on that one.

Well, that's my opinion and I'm sticking to it. Until someone gives me a new opinion. ")

 

Not much can stand up to a direct hit. It even melts sand into glass. Lightning does not entirely strike from the sky as the ground potential will rise to meet it. There are slo-mo films showing this. The "Theory" is that the Pointy Thing aimed at the sky drains the charge to ground before it becomes a full-fledged destructive stroke of lightning. There was lots of discussion about the ariel being pointed that I do not remember the details of. There was something also about a spherical shape below the point. Been too long to remember the details and it was from a book in our engineering library at work specifically on lightning phenomena and suppression thereof. Not a sales brochure on lightning rods written by marketing. A good and interesting read.

 

For grounding my ham tadio antenna tower, my tower ground connections are 8foot sections of 5/8 inch copper tubing that I used to run pieces of size 3/0 copper cable into the ground. The tube is crimped around the wire for about 2 inches at the top., and each section of the wire is clamped to aone of the three tower legs. Because the tube is not nearly stiff enough to ground, I first made the holes for it by driving sections of 1/2 inch steel water pipe in to make the holes, after which I could pull the pipe put and slide the tubing in. That worked quite well. I did need to twist the pipe in the ground to keep it from getting stuck ad I was driving it in, In my area the ground contains a lot of clay, and so the holes did not immediately collapse when I pulled the pipe out and pushed the tube in.
This ground was to direct a lightning strike energy, it is not presented as the required electrical utility entrance safety ground, and so it does not fall into any of that discussion. The good news is that the copper does not rust away and cease to serve after a few years. It has survived two direct hits, which evaporated the vertical antennas on top of the tower. So copper pipe used for grounding does work for that purpose. It may not meet all of the code requirements but it does function quite well.