Texas Lightning

[SarahCaravel]

Ok this has probably been covered somewhere, and I REALLY wish this awesome app had a search tool so I could avoid redundancy, but I'm new to this forum, new to Airstreaming (bought my baby ('69 Caravel) last June, came from Cali and have been living in Texas and fulltiming it in my sister's driveway since October. (It counts!)
But here's the deal: a friend of mine recently questioned whether I was properly grounded, as we have a BIG storm coming tomorrow, and he values my aliveness. It was something I never questioned because of my tires, but HE says my Airstream is in danger of a lightning strike because I've got her hitch propped on wooden blocks up front. He says I need something made of thick rubber between my hitch and the ground. Frankly, until yesterday, I was more concerned about being carried off to Oz by a tornado or having one of the limbs from the beautiful oak I'm parked beneath come crashing down on me or having crazy Texas hail leave softball size dents in my aluminum happy place. Texas is a little nuts like that. But do I have to worry about being struck by lightening on top of everything else? If so, the solution is what?
My Airstream is my everything. And I'm the queen of naive.

Afterfact: I found a lightening discussion(& that handy search feature) but my question is still unanswered and I can't seem to delete this post or move it to its proper place.
Bear with me.

[markdoane]

I would go inside your sisters house first.

Then I would probably make sure the trailer is well grounded, rather than trying to insulate it from the ground. You want the lightning to roll off the outside to ground, rather than trying to find ground through you, your plumbing, or your power cord.
Just my opinion. Your results may vary.

[masseyfarm]

Welcome to the Air Forums. This forum is Electric!

Dave

[DKB_SATX]

I thought you wanted to reduce the weight of your trailer until I started reading...

IMHO you're much more at risk from wind (linear or rotating) and hail (just as you thought before) than you are from lightning in a normal residential neighborhood, because the Airstream isn't particularly tall or spikey. Things like trees, utility poles and antennas are more likely to take a direct strike.

As long as the trailer is plugged in, there's a path to ground through your wiring, so somehow insulating the jack foot with rubber isn't going to make a huge difference unless you unplug. If you're still concerned, you could drive a rod into the ground and hook up with a fairly heavy-gauge wire to the A-frame (where the safety chains attach, e.g.) but I think markdoane has it exactly right. Sleep in the house that's somewhat more attached to the ground tonight for your personal safety.

When was the last time that oak tree was trimmed properly? I have a tree service come every couple of years to trim/maintain the trees that overhang my roof a bit... I like the shade (the trees are south and southwest of my house, respectively... makes a big difference in a Texas summer!) but don't want to repair the roof from having a big limb come crashing down. It's a bit late for the tree service today, but if the tree is well-maintained you've done what you can short of finding covered parking in the next few hours.

[DKB_SATX]

Oh, and welcome to Texas. If you're uptight about what's predicted for tonight, you may need xanax in May.

I grew up in north TX and when I moved down to central and south texas for 15 years or so, I kinda missed "real" thunderstorms. I met my partner down there, and we eventually moved to Fort Worth. He grew up in Del Rio, and was ready to leave the Metroplex the first time the sky turned green. 5+ years later I don't think he's really used to it yet, but he doesn't panic anymore.

[Protagonist]

Originally Posted by SarahCaravel

But here's the deal: a friend of mine recently questioned whether I was properly grounded, as we have a BIG storm coming tomorrow, and he values my aliveness.

We all value your aliveness. The only people who should value your deadness are probate attorneys.

If you're on shore power, you're already grounded, by virtue of the ground conductor in the shore power cable. Such a small wire may not be up to the task of conducting a lightning strike away from your trailer, but it is better than nothing.

If you're worried, you can take your trailer safety chains, which are connected to the frame by bolts at one end, and connect them to a copper ground rod driven into the soil next to the driveway. This will provide a direct path to earth that doesn't go through the shore power cable. But in the event of a lightning strike, you might find all of the chain links welded together by the heat of the strike.

If the safety chains aren't long enough, you can take a regular automotive jumper cable and do the same thing. That might actually be a better option, in fact.

Also, there's something called the 45° rule: Find the highest fixed point around, whether it's a tree, house, telephone pole, light pole, whatever. This tall structure provides protection in a 45° cone under it, and if your trailer fits entirely within the cone, you're protected. Lightning strikes will hit it before they can hit your trailer.

On telephone poles, you probably have seen that the top wire, at the very top of the pole, is a bare wire. That wire doesn't carry any power, and it's not put there just as a bird perch; it's a ground wire, to protect all of the wires under it, since all of the other wires are within a 45° angle below it. Somewhere along the route of the wires, there's a down-conductor leading from that top wire to ground. So, if there's telephone poles nearby with a bare wire on top, that's your most likely protection, by the 45° rule.

[utee94]

The potential difference from cloud to ground is so very, very large, that a little bit of insulation isn't going to make any difference in the case of a lightning strike.

Think about it-- wood isn't a particularly good conductor. In fact it's quite bad at conducting electricity. And yet trees still take lightning strikes regularly, and provide an adequate path to ground for that electricity. To the massive voltage potential accumulated in the clouds, that tree looks like nothing more than a tiny little resistor, which is easily overcome. Any small amount of insulation you place between your trailer and the ground, will most likely provide even less resistance than a tree.

You can ground your trailer if you like, to attempt to provide a better path for a potential lightning strike rather than through your shore power cable, but the truth is that the lightning might or might not follow such a path, because the difference in resistance of your grounding cable, or the axle and tires, or just jumping through the air, is tiny compared to the large voltage potential stored in the clouds.

All a long way of saying, go in the house during the storm. And probably, unplug your shore power cable, so you don't get a surge coming the OTHER direction, into your trailer from the power grid itself.

[SSquared]

You don't need to do anything extra for lightening safety. An enclosed metal vehicle is a safe place to be. That is because lightening (and any electric charge) will automatically travel across the outer surface. As for grounding, think of it this way: The lightening has to leap thousands or tens of thousands of feet to reach your trailer. It's not going to care about how good the path is, for the final six inches of its route to ground. It will find a way.

I once attended an electricity demonstration at a science museum. The demo was in a large auditorium with equipment that could generate 20-million-volt sparks (smaller than outdoor lightening, but still impressive). The demonstration took place inside of a space that was enclosed in wire screening. Inside the demonstration area, the operator was enclosed in a cage, like a bird cage. The operator cranked the equipment up to full power, and had it blast his cage. He took his hands and placed them flat on the inside surface of his cage, right where the bolts were hitting. He was not harmed.

You can read up on lightening at the National Oceanic & Atmospheric Agency's website, at NWS Lightning Safety Overview.

Here's a couple of key quotes:

A safe shelter from lightning is either a substantial building or a enclosed metal vehicle.

A safe vehicle is any fully enclosed metal-topped vehicle such as a hard-topped car, minivan, bus, truck, etc. While inside a safe vehicle, do not use electronic devices such as radio communications during a thunderstorm.

In spite of these quotes, I do suggest going into the house when a storm comes. That's because of the danger from wind gusts and tornadoes (and because it's more fun to watch a storm with good company).

One of my favorite camping memories is a spring storm in Rocky Mt. Nat. Park: Lightening blasting away on Deer Mountain outside the front window of our trailer, and blasting away on McGregor Mountain outside the rear window. It was a great show.

[slowmover]

When Texas decides to have some weather it doesn't fool around.

A MIDLAND or other weather radio is a requirement. Hook it up to 12V and keep it within arms reach of the bed when in the TT. Set the warning to your county and the ones directly surrounding it.

You may be awakened several times in a night, but that just means it's time to consider options. About the time I hook up the truck to the TT is when it starts to pour, but it makes me feel better that both are connected to each other.

"Green sky" is no joke . . one can expect both hail and tornadic winds at that point.

After 50-years in Dallas I learned that the 45-degree rule was in effect as to Ft. Worth's proximity to Dallas . . by the time a tornado has it's way heading eastbound through Cowtown we in Dallas were going to get wet . . and that's about all.

Cowtown, for those who are about to die, we salute thee!!

And when an F5 finally does hit the plaited womb (Metroplex) expect that it will have no precedent short of the Lisbon earthquake.

.

[CanoeStream]

Hi SarahCaravel. Welcome to the forums!

Go to the search tool on the overhead taskbar. Enter one word: Faraday .. Our search tool works best if you keep it simple and just enter one word. And then read away. There are quite in-depth discussions saying that risks in an Airstream are quite similar to those inside a car -- ie, very low. The body of an Airstream sitting on tires provides a so-called Faraday cage of protection around the interior contents.

When caught outside in the open, seek low ground and get as low as you can. I remember a soccer game with our daughter where the young women standing or running had hair sticking straight away from their heads. Now that was dangerous!

Wind can be a more significant hazard. Understand where solid structures or potential shelters are when you set up in a campground.

[SuperTrouper]

Originally Posted by SSquared

I once attended an electricity demonstration at a science museum. The demo was in a large auditorium with equipment that could generate 20-million-volt sparks (smaller than outdoor lightening, but still impressive). The demonstration took place inside of a space that was enclosed in wire screening. Inside the demonstration area, the operator was enclosed in a cage, like a bird cage. The operator cranked the equipment up to full power, and had it blast his cage. He took his hands and placed them flat on the inside surface of his cage, right where the bolts were hitting. He was not harmed.

To prove the point, I was at this demonstration of modulated lightning at Maker Faire a few years ago. The guy in the middle is wearing chainmail. I always loved teslacoils and the smell of Ozone!

http://m.youtube.com/#/watch?v=Pdrqd...%3DPdrqdW4Miao

RE: Green and purple skies, dumpling shaped white clouds first and then black tiger tails. Perfect silence on the ground (no animals, no wind) as the sky boils and blackens then, just a puff of a cool breeze, a rustle of a tree or the corn in the fields and then all hell breaks loose. Head for the basement! I remember southern Minnesota in the summers well. It was never the lightning that scared me it was the howling of the wind. I was lucky to never hear the "Freight Train" or have the house pulled off of us.

[SuperTrouper]

http://www.youtube.com/watch?v=PdrqdW4Miao&sns=em

Try this link for the Lightning Guy

[Pileus]

Here are the guidelines I follow when camping the mountains of West Texas:

1. You do not want to be plugged in during an electrical storm. If lightning strikes your trailer, it will fry your electrical circuits as the bolt of lightning grounds through your umbilical cord.

2. The earth you are parked on and the clouds overhead have opposite charges. If you ground your trailer to the earth, it will pick up the same charge as the earth: i.e. it becomes a target for a strike. Disconnecting the water, sewer, electrical lines and insulating the jack stand and stabilizers from the ground will keep your trailer from picking up the ground charge--making it less of a target. NO the rubber tires and wooden blocks do not insulate you from a strike. A bolt of lighting will go a hundred miles across the sky and wont be intimidated a6 inch jump from rim to ground. But, insulating the trailer from the ground keeps it from picking up the ground charge and being a target in the first place.

Faraday cage of the aluminum will protect you inside...except for the noise.

For hail, get it under a cover.

[Lily&Me]

Yikes, Sarah!! Have your questions been answered?

What a wealth of intellect here. I am always astounded.

Welcome to the Forums. We are in high-wind country, too, something we respect and live with all year round these days,


Maggie

[utee94]

So how'd it go?

We got some rain down here in Austin this morning, and about a 25-degree temperature drop. Hope all went well for you.

-Marcus

[dlb435]

Yes, you're safe in the trailer.
Yes, it's a good idea to disconnect the power cord.
Yes, lower the antenna. (no need to tempt the gods of lightning)
No, you don't need a grounding rod. You are more likely to either be injured or damage the trailer if you install a ground rod because this will channel all of the power through the ground point.
The only danger it to be stepping out of the trailer at the exact moment a lighting blot strikes. At that fraction of a second, you become the path to ground.
So, if you're in a lighting storm, either stay out of the trailer or stay in. Going in and out is a bad idea.
You are at far more risk when towing the trailer.
Deaths from lightning in the US per year: about 50
Deaths on the highway in the US per year: about 34,000

[Pileus]

More information can be found at the National Lightning Safety Institute. This link explains the cone-of-protection myth:

Cone of Protection Myth - National Lightning Safety Institute

SOME GENERAL RECOMMENDATIONS FOR RV USERS INCLUDE:

If you are in a severe storm the best protection is to lift your jacks and unplug. You may run some risk of personal injury as you are exposed while you are unplugging. Do not store your power cable under your RV. Retract and store all deployed antenna. Disconnect external TV/Satellite antenna wiring. Are the RV jacks deployed directly on the ground? Is your generator on? Both of these situations increase your chance to attract lightning.
On a 30 or 50-amp shore power cord, the connector connects the RV frame ground to the shore power earth ground. This path is designed to prevent an electrical shock from touching an electrical enclosure. The power cable will not provide a sufficient conductor to ground in the event of a lightning strike to the RV frame.
Reported incidents and related injuries make it clear that a person inside a fully enclosed metal vehicle must not be touching metallic objects connected to the outside of the vehicle. Door and window handles, radio dials, CB microphones, gearshifts, steering wheels and other inside-to-outside metal objects should be left alone during close-in lightning events. Do not wash hands or take a shower during a storm. Do not get close to electrical appliances such as the TV or plug in laptop PCs. In no circumstances, during close-in lightning, should the passengers attempt to step off the RV to the ground in an attempt to find another shelter. Very dangerous Step Voltage and Touch Voltage situations are created when a "dual pathway to ground" is created. Lightning voltages will attempt to equalize and they may go through a person in order to do so. Do not get on the roof of your RV when a storm is nearby! Don't be an isolated tall object, and don't be connected to anything that may be an isolated tall object.
To further lower your odds, don't park your RV near the tallest trees or utility poles. Rubber tires provide zero safety from lightning. After all, lightning has traveled for miles through the sky: four or five inches of rubber are no insulation whatsoever. Avoid higher elevations, wide-open areas, tall isolated objects, and water-related activities. Avoid unprotected open structures like picnic pavilions, and rain shelters.
Lightning has been known to strike more than 10 miles from a storm in an area of clear sky. There is no defense for lightning's bolt-out-of-the-blue occasional strike. But for the most part, lightning safety is a risk management procedure. Early recognition of the lightning hazard, with an awareness of defensive options, will provide high levels of safety.
Essentially, the most dangerous times occur from a weak storm without too many flashes, at the edge of a larger storm, or early or late in the life of a storm. Much of a storm's lightning remains within the clouds, leaping from the negatively charged bottom of the clouds to the positively charged top. When an object on the ground, such as a tree, building or an RV, becomes positively charged, the lightning sparks to the ground. A bolt of lightning can be as great as 15 million volts.
Lightning leaders from thunderclouds proceed in steps of tens of meters, electrifying ground-based objects as they approach the earth. Ground-based objects may launch lightning streamers to meet these leaders. Streamers may be heard (some say they sound like bacon frying) and seen (we may notice our hair standing on end). A connecting leader-streamer results in a closed circuit cloud-to-ground lightning flash. Thunder is the acoustic shock wave from the electrical discharge. Thus, thunder and lightning are associated with one another.
Recreation Vehicles and Lightning What happens when lightning strikes a recreation vehicle? I have determined that few, if any, RVs get struck while mobile. They are mostly vulnerable when connected to shore power and/or when they have their jacks deployed without at least five inches of wood or some other insulator between the jacks and ground. I have noted that RVs are more susceptible to damage from induced lightning surges when connected to shore power and lightning hits nearby transformers
Electrically speaking, at lightning's higher frequencies, currents are carried mostly on the outside of conducting objects. A thick copper wire or a hollow-wall metal pipe will carry most of the lightning on outer surfaces. This phenomenon is called Skin Effect. The same holds true for lightning striking a metal vehicle: the outer surface carries most of the electricity. The persons inside this steel box are partially protected by a partial Faraday Cage.
If an RV is manufactured of fiberglass, a direct lightning strike will likely go right through the vehicle, even if the vehicle body does not conduct electricity. Wet surfaces alter the current path. One of the most dangerous places is just outside of a vehicle, because electric current travels around the outside of vehicles.

[SarahCaravel]

Hey guys. Thanks for the number of awesome responses and sorry for the slow reply. I feel better, feel like my worries were properly placed in the first place (wind, hail carry a greater risk than chance of lighting). I'm just outside of Fort Worth- for now. And though I'm still not sure of the BEST course to take for lighting-strike preparedness, I can see that my buddy was a bit short-sighted in harping about my hitch being propped on rubber when I'm plugged into the house. But the worry he caused was a good thing because I learned a TON. Thanks again for all the info. You'll be hearing more from me (after I use the search feature and do a fair amount of research on my Airstream obsession topic of the moment, of course.) Be well, everybody! And like my friend's gynecologist used to always tell her, if you can't be good, be careful! (She didn't listen and has three kids and no Airstream.)
:-)
Sarah

[slowmover]

I have determined that few, if any, RVs get struck while mobile. They are mostly vulnerable when connected to shore power and/or when they have their jacks deployed without at least five inches of wood or some other insulator between the jacks and ground.

Yes, this thread is a keeper.

E-Z enough for me to further cut down some pressure-treat I bought last year for some other uses. I've decided I really don't like plastic jack/tire pads (such as LYNX LEVEL), so I'll make the wood into dedicated pieces for the stabilizing jacks.

And, SarahCaravel, that was quite funny about the friend.

.

[DaveFL]

Danger from lightning by being in your AS, most of the planes in the sky would be falling out of the sky, very similar construction, much better than my fiberglass MH. Lightning has a general rule Faraday proved it, but always exceptions to any rule. My advice don't touch metal while in the middle of a storm, my son in law would say don't be on the phone or in the shower.