SAFETY : >>>>Lightning Strikes<<<<

[hex]

Holy Mackeral Saphire! What's the story on being inside your Airstream in an electrical storm?

Lightning! I mean.

Has anyone any scary stories?

I mean if I was curled up against the outside wall in one of those minature twin beds in a rear bath model, or just happened to be turning off the kitchen faucet...yall get my drift. How safe are we?

[53flyingcloud]

Hex,
Maybe that's the answer to why my A/S has a grounding post mounted on the rear bumper ???
It originally came from Texas....
actually, if you have a isolation transformer feed for your shore power, you should be just fine...

[smily]

I am an industrial electrician and I have implemented many types of lightning protection.

Do not fall into a sense of security by the old myth "The tires will insulate you from ground"

This is complete bunk!

Lightning is many thousands of volts that can travel many miles with absolutely no conductor other than air and or rain.

an 10 inch rubber tire will provide little or no insulation between 250,000 volts and ground.

A ground wire will provide some benefit but remember we are talking about a current that well exceeds a typical ground conductor of #6 AWG.

Many precautions can be taken but the truth is that lightning is a devastating beast and when the big man wants to hit you with lightning it will happen.

There are many stories and lore of the effects of lightning, from lightning melting brass beds to traveling along the ground from the shoreline of a body of water.

I have literally seen a Suburban truck pulling a aluminum pontoon boat down the highway and get struck by lightning. The result was burn marks on the roof of the vehicle and complete destruction of the wiring harnesses in the tow vehicle and the light harness to the Pontoon boat.

Moral of the story is: Pray to God you never have to deal with the possible effects of lightning.

Safety measure would be vacate metallic structures and find lowest location that you can.

Smily

[hex]

Smily wrote;

Safety measure would be vacate metallic structures and find lowest location that you can.

OK so where do you go to? Your truck? I doubt that many Wallyites ever get out of a warm bed and go spread out in a "dry" creekbed in a downpour.

Actually I bet most of yall just hunker down and stay inside the trailer.

How unsafe is ~~that~~??

This question deserves ~~More~~ discussion, I think!

Also what is an ~~isolation transformer feed~~?

Are any aware of injuries or death to Airstream users due to lightning striking the trailer?

[uwe]

I heard that a safe place to be is inside a vehicle, because of the galvanic cage effect. I have no clue what this really means. Anyone heard of this? I'll do a search.

[smily]

I will humor you and point out that the recommendation was simply a safety measure should one not feel safe in his or her ALUMINUM, CONDUCTIVE Airstream.

The odds are in your favor as far being struck by lightning but if you must have the scientific theory behind it here it is in laymens terms.

The AS is made of Aluminum, a very good conductor, a much better conductor than the human body. There for should one be within his or her AS and the AS is struck by lightning, the elctrical current will seek the shortest and and best condutive path to ground and or ground to positive.

(Technical side note, Lightning is the neutralization of two opposite charges, Ionized particles neutralizing)


The lightning will more than likely travel down the outer shell of the AS and continue to ground via the jack post or levelers if they should be in contact with the ground. It may even jump the small distance from the wheel, (metal rim), to ground. See above.

There may be collateral damge to other parts of the AS and even surrounding areas,(the human body possibly),

I too would opt for staying within my trusty AS and hope that it is indeed a better conductor than myself and most importantly get on the hot-line with the big man and put in a few important words before the line is cut.

Smily

[uwe]

http://www.lightningsafety.com/nlsi_...ngeffects.html

There are actually a bunch of sites that deal with lightning safety. I just put in lightning and safety in a search engine.
The text confirms what Smily wrote. Providing the least possible resistance for the currrent is the general idea, I guess.

But, it's like Smily says, if the big man has plans for you, then none of it matters.

[hex]

As one who enjoys a little humor, I must say I find very little in this subject.


from 5.1.1 of Uwe's above link;

"A risk management approach to lightning safety must assume the AFS* will be struck by lightning. Now what? By adopting a judicious combination of lightning protection subsystems, we can attempt to mitigate lightning’s consequences. Since each AFS is unique, as is each lightning flash, the lightning safety engineer must apply site-specific designs. Application of subsystem approaches for air terminals, conductors, bonding and shielding, earth electrodes, surge protection devices/transient limiters, etc. will depend on geographic location and risk to the AFS. Good guidance is found in reputable codes and standards such as IEEE 142, and 1100, Air Force 32-1064, NASA E-0012E, FAA 019c, Army 385-64, Navy OP5, German DIN 57185, South African SABS 03-1985, UK MOD ESTC No. 7, and the IEC 61024 venue."

(emphasis added by Hex)

* Let us assume the AFS is our Airstream Trailer.


Since the inner and outer skin are both fastened to the same ribbing, I presume that the whole "cage" + total skin (out & inside), if struck will conduct the charge. I also assume that it is very easy in some models, to be in contact with the inside skin while sleeping in the bunk or side full bed,as well as in other situations of habitating the trailer.

Even if the tounge jack or the stabilizing outriggers (or even if we drove a copper bar into the ground and connected to trailer each nite) carried the charge away and into the ground. What would happen to the poor schmuck (probably me ) that was sleeping against the vinyl covered aluminum inner wall?

Now Smily are you in or out? Your 1st post says you'd vacate trailer , your 2nd says you'd stay and pray. which one is the joke?

Also why do I suspect Wally was too busy planning his next trek thru the Sudan to bother hiring a lightning safety engineer? However he did come from the aircraft industry. I know that lightning hits aircraft, which after all are not grounded, and the crew and passengers seem to survive. Perhaps it is the gavanic cage thing, surely in military planes I have been on, the floor is metal and connected directly to the outer skin of the fuselage. So I still don't get it! Are we safe or not?

[davidz71]

A good friend of mine was awakened early in the morning to a thunderous crash and shaking of his house. He looked out the window and saw the gutter outside his second floor bedroom window hanging down. He looked in dismay at his fullsize Chevy Blazer which had its windshield busted out. Further investigation showed a burning hole through the carpet of the vehicle and a hole through the floorboard of the vehicle so that you could see the ground below. I still do not see how this could have happened but strange things happen with weather.

[thenewkid64]

I may be wrong, but my understanding of lightning is that it will take the easiest path to ground.

If you have your tailer "grounded" with the tounge jack and levelers as well as grounded through the connection to shore power and your TV antenna is up does the tv antenna act like the old fashioned, mis-named lightning rods?

My understanding is that the lighting rods do not attract the lightning but actually help to repel it because they are discharging positive ions in the form of static electricity that is present on the ground. This is a very small amount of output, but it can be enough to cause lightning to look elsewhere to go to ground.

That being said, if you take a direct hit on the trailer I would be worried more about the alumimum being set on fire than the electricity issue. Burning Alumimum is VERY difficult to put out! I think I would rather go quick than roast. What a morbid though, yuck.

Persuasions, more science, corrections??

[uwe]

Hex,
I understand your fear and concern, and you're right - not much humor in it.
If you use the link and read on, then it will say that the current from lightning will look for the easiest way to earth/ground, and will find it and go through it regardless of the resistance of the connection. It is a very mightyly powerful electrical discharge reaching in excess of 1 Million volts and 50kA.
So, if you have the jacks down, the tongue is grounded, and you have an additional well earthed ground spike, then chances are that the damage will be minimal, and you won't get hurt. Extreme currents will flow, and probably things will get ugly somewhere under the trailer.
If the lightning bolt has to travel through moist air to get to earth/ground, then that's a resistance that's probably megaohms, which means the lightning bolt will cause heat and destruction if it has to pass through it once your trailer gets hit.
This might have been the case with Davidz's friend's truck.
So the best you can do, if you're worried that lightning will strike, is earth your trailer very well, and sleep tight. Everything else is out of your control. I am not sure if there is a definite answer whether or not you're safer inside or outside, because there are so many important factors that would change the outcome.

[smily]

As I said before,

Quote:
"Safety measure would be vacate metallic structures and find lowest location that you can".

In my first post, I did not say what I would do. I merely pointed out that this was a safety measure.

My decision would be based upon my surroundings.
I have literally boated to the shore during an electrical storm due to the fact that there were no trees around me and I certainly was the highest, eleveted, conductive, element, in my surroundings. I opted for locating my self nearer but not next to some trees on the bank. The idea was to try to find a conductive path that was better than my body.

It is a physical fact that one is safer in a low elevation than being in an elevated enviroment during an electrical storm.

The point here is that the current WILL find the path of least resistance.

I merely stated that I know that the Aluminum trailer is a good conductor especially when grounded. A much better conductor than myself. Therefore the AS is the least resistive path. If I were concerned for my safety, the minimal that I would do is NOT TOUCH THE SKIN OF THE TRAILER. The floor is made of wood so I would stay in the middle of the floor and pray to god!


Very Respectfully,
Smily

[canny_banjo_man]

Hi Smily....
...Nothin 2do with being in an A/S...but a few years ago, the good Lord must have been upset with me, 'cos he sent a !!ZZZ!!...a big one, it melted my CB antena from 21 feet to quarter of an ounce, the scaffold pole was almost buckled in half, and pulled off it's mounting, no sign of the coax at all...only a charred connector hanging from the interior wall...
Now I don't know much about ELECTRIC, you see, Gas I can hear & smell...WATER I can hear & see...but 'ole Man Electric...well You can't see it, you can't always hear it...but upon my word, you sure CAN feel it...lmao...
All have a good day now...Chris.....

[hex]

Uwe in an above post you mention a "galvanic cage".
I think what you were thinking about is a "Faraday Cage". Faraday was the guy who invented something electrical and important, maybe the joy buzzer Actually I think it was the generator.


One definition of Faraday Cage is at http://scienceworld.wolfram.com/phys...radayCage.html

Note: Faraday is often spelled Farraday.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


The following is something I came across in my research.

Unlucky Strike

Experts have always said an automobile is one of the safest places to be during an electrical storm, but when lightning struck a parked car at the Black Coaches Association Bowl in Blacksburg, Va., on Aug. 27, the vehicle exploded. What happened?
“Nothing is perfectly safe,” says Jim St. John, a research scientist with Georgia Tech’s School of Earth and Atmospheric Sciences, but being in a car during an electrical storm is still one of the safest places to be.
Because a car is made of metal, it can attract lightning — and a secondary charge could ignite fuel fumes in a nearly empty fuel tank. That is possibly what happened at the BCA Bowl, St. John says. But the shell of the car still serves as protection for its occupants.
“The metal body of the car works like a Farraday cage,” St. John explains, referring to Michael Farraday, the 19th-century experimental scientist who invented the generator.
Farraday created a metal cage that he would stand in to prove that an electrical charge running through the cage would not harm him. “The current runs around the body of the car and the tires afford some protection as well. What you don’t want to be is something that is going to be part of the current path.”
Or drive around in an electrical storm with a nearly empty fuel tank.
In this case, officials decided to call off the preseason game that pitted Georgia Tech against Virginia Tech.

©2000 Georgia Tech Alumni Association

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This brings up a couple more concerns;

The gas tanks on the aluminum skinned Motorhomes.
The propane tanks on all our RVs.

There's just never enough to think about is there???

[hex]

This thread never was answered convincingly for me, so I wrote to the National Lightning Safety Institute and finally recieved the following reply. I included a pretty good description of Airstream design. Although I would have preferred more depth, I think the answer is well worth noting.
(BTW KenSmiley's 2nd.answer above was very much similar.)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~

From: "NLSI - Richard Kithil" <rkithil@lightningsafety.com> |
Regarding: Airstreams and Lightning
Sat, 7 Dec 2002

Thin-skinned objects such as Airstreams are
NOT safe from lightning. Indirect (nearby)
strikes may couple/attach to conductors
on the ground into the trailer. Direct strikes
will be dangerous to people touching any
conductors inside or outside the Airstream.

Having said the above, the Airstream interior
likely will be safer than being outside on the
ground. Inside, at least, there is some Faraday-
like shielding available. While inside them
during close-in lightning, avoid touching any
conductors such metal and electrical objects.


National Lightning Safety Institute (NLSI)
Richard Kithil Jr., Founder & CEO
891 Hoover Ave., Louisville CO 80027

Email: rkithil@lightningsafety.com
Web: www.lightningsafety.com
---------------------------------------------------------
A non-profit, non-product organization
providing objective information about
Mitigation of the Lightning Hazard.

‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘

[Pahaska]

It's all relative. Experimental data is usually the best approach when the sample is large and the variables are many. Here we have a very large sample ... thousands of Airstreams, dozens of years, thousands of storms, thousands of locations ..

Now, how many Airstreams can you count that have been destroyed or even damaged by lightning? How many persons can you count that were killed or injured in lightning storms while in Airstreams?

Not many and probably not any. Than would indicate an almost vanishingly small risk. Not zero, by any means, but less than, say comeone crossing the centerline and running into you (I have personally observed that numerous times).

Conclusion, I'll stay in the A/S and not worry about it. In the scale of life's risks, this is a very small one.

Are we safe in our home? Not totally. As a boy, we had a big blue ball of plasma float around our living room for seconds and our telephone literally explode in front of us.

[Pahaska]

A much larger risk is being in a sailboat with a 25' aluminum mast overhead. Most boats, as they are delivered, have no lightning grounding. I grounded my mast to two copper plates by the keel and had no problems.

Some years ago, I had just came in second in a sailboat race. There was a storm nearby, but not overhead. I was standing on the dock congratulating the winner when I put my hand on the boom of his boat to steady myself against the heaving dock. Lightning picked that moment to strike a boat moored several hundred feet out into the water.

I happened to be looking down at the moment and saw a fat blue spark from my ankle to a cleat on the dock. It seemed like I watched that spark for a long time, but it was probably just a fraction of a second before I was thrown violently about 10 feet down the dock. It was probably the muscle in my leg contracting that threw me.

I was lucky and had no injuries other than a leg that stayed sore for months.

[smily]

Pahaska,

Did you make the call?

You know the one I am talking about................

Smily

[Pahaska]

I'm pretty much an atheist I see the world as a set of probabilities. I just was fortunate that time.

[Gordon Watt]

Lightning

I was merrily flying along in a Cessna Citation Jet at 30 something thousand feet and a bit too close to a thunder storm.

Lightning struck the radome on the nose and exitted near the tail.
During it's travel through the plane, it fried the auto-pilot.

For the Ham Radio guys:
The Winnipeg Amateur Radio Club had a presentation from a professional, on the subject of lighting.

For radio towers, you have to have nine ground rods for each leg of the tower to properly dispel the electrical charge.

Your surge protectors are of no use if lightning charge comes down the line. All electronic stuff should be un-plugged and disconnected from cable etc. as it COULD be destroyed.

Lightning demands respect.