Lightning safety

[mudpuppy000]

So with all the lightning last year I'm wondering if we should ground all of our EMT structures. We usually just secure them with ratchet straps so there's not much of a good electrical contact other than the tubes resting on the playa surface. We also have a few carports but those seem like they'd be a little better, with lag screws into the playa through the carport feet.

[Popeye]

In short NO.
Very simply, lightening is attracted to ground. When a lightening rod is installed it is isolated from the building and the rod is grounded (earthed is probably a better term here) separately from the building. A lightening rod protects a building by attracting lightening to itself and through the rod to the earth, bypassing the building.

[ygmir]

well, except that if a metal structure is energized, and not grounded, or grounded well, said charge will seek ground, and that can be a person who is grounded, touching, or standing nearby, if they are a better ground that other options.
I'd ground, for that reason. you can install a lightening rod, and isolate, as well, but make it higher that the structure.
And yes, lightening goes to ground (technically, the electrons are flowing from earth to the cloud, picking the path of least resistance, and the charge/bolt flows the other direction, IIRC).
so, by grounding you do make a path, but, take the chance if it gets energized, that the current will find it's own path to ground, perhaps via a person or equipment.

tough call, really.

[Ratty]

Mudpuppy and I live in California. We don't see many lightening rods. All of our homes are grounded in the sense that someone drove a 6 foot stake into the ground and ran a wire to our plumbing. I never would even have thought of a lightning rod. We don't see those things that hang off of the bottoms of cars either. Do people still have those or have they disappeared like canvas water bags on the grill? Please tell me what those were for. Out there it would be an effort to attract the 'hit'. (If you wanted to get hit.) Too much tall competition.

[FIGJAM]

The canvas water bags were an old style canteen and the old cars would overheat, so the water was handy for the radiator.

The water actually was cooler cause the bag acted like a evap cooler.

[Ratty]

Thanks Figgy, I remember it well on our 57 Ford stationwagon but my Dad never gave us a drink out of it. I think it had a picture of an indian in a headdress. It's 350 miles from LA to Bishop. But it takes 2 days even in a new car. After all, it was a Ford.

[mudpuppy000]

I was off playa last year but remember reading that BMIR got hit with lightning during one of the storms. They were thankful that they had grounded their antenna and were back on the air/internet shortly afterwards. Seems like that is a situation where it worked well.

[The Rod]

A couple weeks ago, lightning hit a 100 foot tall pine tree at a buddies place. The top half of the tree exploded, the bolt spiraled down the trunk where it blasted a 6 inch deep trench in the soil to an extension extension cord lying on the ground about 20 feet away, melted the rubber and traveled 100 feet down the cord to the outlet in his shop, blew up the breaker box and found ground in the grounding rod my friend installed a week before the storm.

And I think about the storm last year, and then I think about the multitude of tall metal structures out there, festooned with all manner of lights and gadgets tied into extensive power grids made up of generators, battery banks and extension cords...

I heard about a few folks getting struck last year, no deaths though.


In conclusion, as someone who likes to build big things out of metal, I would be really interested to hear what some folks with some expertise would have to say about lightning precautions we could take on the playa..

[some seeing eye]

Look around you, are you or your structure the tallest thing? Worry about that. If you have some sort of tower, especially with pointy elements up high, you might think about grounding. You don't want to be walking around on the open playa, you don't want to have the point of a metal shaft umbrella pointing up and you don't want to be standing next to a structure that might conduct lightning to earth in an electrical storm.

[Popeye]

well, except that if a metal structure is energized, and not grounded, or grounded well, said charge will seek ground, and that can be a person who is grounded, touching, or standing nearby, if they are a better ground that other options.
I'd ground, for that reason. you can install a lightening rod, and isolate, as well, but make it higher that the structure.
And yes, lightening goes to ground (technically, the electrons are flowing from earth to the cloud, picking the path of least resistance, and the charge/bolt flows the other direction, IIRC).
so, by grounding you do make a path, but, take the chance if it gets energized, that the current will find it's own path to ground, perhaps via a person or equipment.

tough call, really.

I don't disagree with what you said but I think it is safer not to ground. I am not an expert here but:
Clouds build up a potential voltage until this potential is high enough to overcome the resistance between it and another cloud, the earth, an art car or a building. Then it will arc, choosing any or all of these depending on air resistance and the difference in potential between them. The lightening bolt will stop when the potential is decreased to the point where the difference in potential cannot overcome the resistance. A dome skeleton will "fill up" faster than the earth and current flow to the ungrounded dome will be shorter in duration than current flow to the earth or a grounded dome. The charge on an ungrounded dome will dissipate relatively slowly to the earth. While the bottom of the dome is on playa dust I would not expect (never been measured as far as I know) there to be a good electrical connection to earth here. I think this connection would be more capacitive than resistive, slowing current flow. Think how the condenser in your old auto ignition system would bleed off. If it was grounded Current flow would last longer and because of resistance in the wire, dome, etc. would create heat, ionize the metal frame, and generally do a lot of damage. Not to say that lightening attracted to an ungrounded dome would not cause damage but I think it would be less and lightening would be more likely to be attracted to the earth.

[Popeye]

I was off playa last year but remember reading that BMIR got hit with lightning during one of the storms. They were thankful that they had grounded their antenna and were back on the air/internet shortly afterwards. Seems like that is a situation where it worked well.

The antenna got hit and acted as a lightening rod. Lightening traveled down the antenna to ground, not going through the equipment.

[GreyCoyote]

In short NO.
Very simply, lightening is attracted to ground. When a lightening rod is installed it is isolated from the building and the rod is grounded (earthed is probably a better term here) separately from the building. A lightening rod protects a building by attracting lightening to itself and through the rod to the earth, bypassing the building.

NO NO NO and NO.

The physics of lightning are well established and are a matter of Code.

Ground a metallic structure. Always.

Grounding does NOT make the structure more "attractive" to lightning. It simply controls the strike currents when it does get hit. Control is everything. You want to divert the strike currents into a harmless current sink, ie, the ground. Ask any telecom engineer why he grounds the fuzzy flock out of his towers. This is why.

Fwiw, the grounding system in a metal frame building ties DIRECTLY into the structure itself.

I will seem I can find the lightning tutorial I used to use when Inget home tonight. Its an eye-opener and puts the physics back into a very misunderstood subject.

Ground it. Always. Or die.

[Mojojita]

During our storm on Monday last year, I remember telling the kids on a big metal scaffold next to our camp to get the hell off of it until the storm passed.

One of our Greeters got tingled pretty hard because he was standing next one of the greeter bells when lightning struck. Was fine but a little too close for comfort.

[mudpuppy000]

Ok, so that's kind of what I thought. Any recommendations on how to effectively ground something on the playa? I'm imagining running a cable to some sort of earth penetrator.

[mooserider]

As short and straight a wire as possible. You don't want curves or bends in the wire to cause inductance to resist the lightning discharge. And heavy (6 gauge is as small as you should really consider, heavier is preferred). No soldering, because the heat will melt it; use only mechanical connections to connect the wire to the structure and the ground rods (ground clamps, etc.).

[GreyCoyote]

We use a 18 inch length of dead-laid welding cable (1/0, mostly because I had it and the connectors to go with it). We take two copper ground rods about 30 inches long and pound them flush with the ground on opposite corners of the dome frame.

Note that this is far too short of a ground rod for normal use, but it is all we can reasonably do on the playa. Ideally those rods should be 8 feet long, but that just isnt going to happen on the playa without some hydraulics! A gallon or two of water dumped over the rod makes for a very solid ground (the chlorides in the soil are wonderfully conductive!)

I use a crimped and soldered lug on each end of the cable. The crimp assures a good mechanical connection and the solder makes for a low resistance joint. (The advice about not using soldered connections is good if that is your only means of holding the joint together. In this case, the solder is just icing on the cake. No worries about it melting, as its backed-up by the crimp). A short length of shrink tube over the barrel of the fitting makes a playa-proof connection.

Likely overkill, but I was damn Skippy happy I had this system working for me when that bolt went directly overhead and hit an art car a short distance away. That event made a believer out of me!

[Popeye]

In short NO.
Very simply, lightening is attracted to ground. When a lightening rod is installed it is isolated from the building and the rod is grounded (earthed is probably a better term here) separately from the building. A lightening rod protects a building by attracting lightening to itself and through the rod to the earth, bypassing the building.

Grey: I almost did not answer this because I do not want start a fight. You are a knowledgeable and well respected Eplayan, giving good, honest imformation. In this instance you are mistaken. More damage will be done to a grounded metal structure than to an ungrounded one. When you ground a metal structure you are constructing a lightning rod no matter if it looks like one or not. Lightning is more likely to strike a grounded metal structure than an ungrounded one. The examples given in this thread of the pine tree and the antenna are both of grounded structures. I don't know why the art car was hit but wonder if the lightning bolt hit next to the car and the car was in the strike zone.
Sometimes it is useful to look at extremes. As yourself which is more likely to be hit by lightning. a chunk of steel floating 200 feet above the playa completely isolated from ground (I don't know how it got there) or a 100 foot grounded lightning rod? The chunk of steel has no path for current to flow.

A copy of NFPA 780 is here http://www.uscg.mil/petaluma/TPF/ET_SMS ... PA_780.pdf

UL requirements for an approved installation of a lightning system are here http://www.ul.com/global/documents/offe ... ion_AG.pdf check out 4.12 to 4.13

NO NO NO and NO.

The physics of lightning are well established and are a matter of Code. True, Installation of Lightening Protective Systems NFPA 780 is the main document controlling design and installation of lightening rods. The National Electric Code controls the installation and design of Premises wiring systems- the wire in your house or office. Both documents state that lightening protection and premises shall have separate ground systems that are bonded together. The NEC states that grounding is required to enable circuit breakers to trip (I'm paraphrasing) and to mitigate the effects of a lightening strike. This mitigation occurs when lightning hits a pole next door or down the street and the current travels along the power line to your house. It will go to the house ground rod before it gets into your wiring system and your ground rod will reduce damage to your house. NFPA 780 and the NEC both require sepatate grounds for lightning rods and premises wiring. They are required to be bonded together. Illustrations I have seen show the lightning rod to have the lower impedance to ground.

Ground a metallic structure. Always If it has a wiring system or if it is a lightning rod.

Grounding does NOT make the structure more "attractive" to lightning. It simply controls the strike currents when it does get hit. Control is everything. You want to divert the strike currents into a harmless current sink, ie, the ground. True, but you don't divert current by running it through the building, except in the impossible instance of a zero resistance frame and a zero resistance ground. IRL the building frame and the ground have resistance. Work is done when the resistance is overcome and heat is generated. Ask any telecom engineer why he grounds the fuzzy flock out of his towers. This is why. Telecom ground rings are installed to reduce ground loops and thus noise, improve shielding. Lightning strikes are mitigated as discussed above. See https://en.wikipedia.org/wiki/Ring_ground

Fwiw, the grounding system in a metal frame building ties DIRECTLY into the structure itself. Building steel is bonded to the ground system. If a hot wire happens to touch building steel then the breaker will trip and the building will not become energized. Nothing to do with lightning.

I will seem I can find the lightning tutorial I used to use when Inget home tonight. Its an eye-opener and puts the physics back into a very misunderstood subject.

Ground it. Always. Or die.

[Roundabout]

Ok. For the first time, this year, the Playa Choir will have a 44' diameter performance dome at 6:00 and K. It will by far be the tallest thing in the neighborhood. Ulisse and GC, can you guys come to some sort of agreement? Should our dome be grounded or not? It's important! The lightening last year scared the bejesus out of us.

[ygmir]

Ok. For the first time, this year, the Playa Choir will have a 44' diameter performance dome at 6:00 and K. It will by far be the tallest thing in the neighborhood. Ulisse and GC, can you guys come to some sort of agreement? Should our dome be grounded or not? It's important! The lightening last year scared the bejesus out of us.

I feel the think Ulisse is not considering, is if the metal structure does become "energized", with no ground, it will seek a path. And if you are standing barefoot, and touching or even nearby, it may well choose you as least resistance.....even if only partially.

[Popeye]

Ok. For the first time, this year, the Playa Choir will have a 44' diameter performance dome at 6:00 and K. It will by far be the tallest thing in the neighborhood. Ulisse and GC, can you guys come to some sort of agreement? Should our dome be grounded or not? It's important! The lightening last year scared the bejesus out of us.

I feel the think Ulisse is not considering, is if the metal structure does become "energized", with no ground, it will seek a path. And if you are standing barefoot, and touching or even nearby, it may well choose you as least resistance.....even if only partially.

You're right I was thinking about the dome not someone walking nearby. Can't say what will happen to this guy, but the dome is in contact with the playa and once the cloud-dome-air resistance thing is equalized the "charge" on the dome will bleed into the playa. Probably be ??less than a second.

What we need to do is build the Playa Choir Dome and experiment! Seehow much damage is done with it grounded, then rebuild it and try it ungrounded. If we can't get any volunteers to camp inside maybe a few propane tanks...

[Captain Goddammit]

Set it up next to Dr. Megavolt.

[Token]

Always ground! You can't go wrong by grounding a dome.

Let me do this again but more better loud.

ALWAYS FUCKING GROUND A GOD DAMN DOME!!!

OK, now that this is out of the way, the peanut gallery can toss authoritative sounding things all day and all night.

All the ideas and opinions being tossed go out the window because no one knows how much energy will be released by a lightning strike, how conductive the Playa is in that area at that point in time, extent of ionization in the air near the strike ... Ya la la la loo.

Ground it! 3' OK, so a few. 4' better. Always crimp/clamp and use thickest cable you can find.

Done. Settled science.

[digital]

The best place to be if a lightning storm comes - your vehicle (and away from tall metal structures).

The storm last year was intense and I remember the strikes well. Thank goodness BMIR grounded well and no one was hurt. It was pretty obvious when the strikes were coming so best thing to do is have a plan and seek vehicular structure as soon as possible. If away from your vehicle, get low to the ground away from tall metal objects. Basic stuff I'm sure we all know. Lightning is not difficult to predict. Consider one of these for added protection: http://amzn.com/B00EO1H3X8

[Molotov]

Indoors is a relative term on the playa.... best bet is a vehicle with a metal top or maybe a metal playa storage or housing unit.

As a lightning strike survivor when I was in the Army in Georgia, I respect Nature's power. In 1973, my unit was waiting out a summer t-storm by standing in the bleachers under a metal carport type roof, adjacent to a light pole with security light, which was struck first. The strike came off the pole and passed through the metal bleacher framework-and some troops were standing on metal bolts and not the wooden planks. 18 of them went down like they were tasered and were later taken to the hospital. Two soldiers found out that the outline of their GI dog tags was scorched into their white T-shirts-but they didn't feel a thing. It was a superbolt-after passing through the bleachers, the lightning entered a parking barrier made of steel cable and 4x4 posts. It splintered 15 posts, then hit a jeep, blowing out two tires. Needless to say, all military discipline broke down and we panicked and ran for the barracks a quarter mile away in the rain-dragging the wounded with us. It's a wonder nobody died.

[Token]

Nothing like a good personal story.

Many decades ago when I was a wee lad in my teens, in Europe, mountains in the Dinaric range ...

Summer storm rolled in while I was hiking. I was in some rolling hill meadows so I went tucked down in a low area between some hills where a seasonal creek had caved a bit of a gulch.

I took a knee to get low to the ground.

Lightning struck a tree on top of the hill. Split down the middle and pulverized the top half. I was ~ 100 yards away, half that distance down in elevation.

The distance between my left foot and my right knee was in the 1 to 2 ft range, and I also had my left hand touching the ground ~ another foot toward the lightning strike.

Threw me back straight on my ass.

The few feet between my left hand and right knee touching the ground at about 100 yards from the strike gave me a big-ass jolt, sucked the air out of my lungs and left me dazed.

Now I had respect for Lightning going in to this adventure, but let me tell you, coming out gave me a whole new perspective on how serious this can get.

Since that time, new rules:

Squat down like ya gonna take a crap. Might happen so be prepared.
Keep feet together and hope you got some rubber to the ground.
Hug them knees tight and do not touch the ground with your hands.