Reply
 
Thread Tools Search this Thread Display Modes
 
Old 06-13-2007, 10:56 PM   #1
3 Rivet Member
 
1963 26' Overlander
Cleveland , Georgia
Join Date: Apr 2007
Posts: 123
Lightning storm question

As much as I have read the forums I have not yet seen this discussed, so I am hoping it is not a concern.
My wife and I were standing on our porch as a thunder storm with lots of lightning approached. She said " I guess the camper would not be a safe place during a lightning storm."
That prompted me to think about the aluminum construction and its vulnerability (for lack of a better word) to a lightning strike. I have learned in many classes in my job that inside your car is a very safe place to be because the car would ground a lightning strike. (The same would apply to a loose powerline. Stay in the car!) But would it apply to the airstream?
Does anyone have any advise on this topic? Or, even better, an actual experiance with this type of event.

Trying to keep this from being me...

Thanks ahead...
__________________

__________________
Rusty

Some days you're the windshield,
Some days you're the bug!

"Life's a garden, dig it" Joe Dirt
bigeasy63 is offline   Reply With Quote
Old 06-13-2007, 11:35 PM   #2
Rivet Master
 
Janets Husband's Avatar
 
1977 Argosy Minuet 6.0 Metre
1964 26' Overlander
1977 25' Tradewind
Eastern , Washington
Join Date: Jan 2004
Posts: 865
Images: 6
Good Question

I have never heard of anyone being hurt due to a lightning strike in a trailer.
Lightning has the attribute of traveling the path of least resistance, which means it would travel over the skin then jump to ground at the point of least resistance (It would be like being in a Faraday Cage). If you were not connected to shore power it should jump to ground probably at the banana wraps. If you were connected to shore power it would probably go through the safety ground of the plug and blow out some of the electrical systems in the trailer and power pedestal. In any situation with lighting activity it is best to refrain from operating electrical devices, and stay put. I will consult my lightning protection materials and follow up later with any other information.
__________________

__________________
Peace
Gary
Janets Husband is offline   Reply With Quote
Old 06-13-2007, 11:55 PM   #3
Rivet Master
 
Fyrzowt's Avatar
 
2000 25' Safari
West of Fort Worth , Texas
Join Date: Aug 2006
Posts: 6,697
Images: 8
While aluminum conducts better than steel, both are conductive metals, on wheels. Not much difference IMO. On the other hand, there is no "Phd" behind my name. That truly makes it just my opinion doesn't it...
Dave
__________________
Fyrzowt is offline   Reply With Quote
Old 06-13-2007, 11:56 PM   #4
4 Rivet Member
 
wanderer1's Avatar
 
1986 Argosy
ocala , Florida
Join Date: Apr 2007
Posts: 271
Images: 24
Hello rusty,I've heard something 'bout rubber tires keeping you safe in a car,I guess it would if be safe when towing or unhooked to power/water.Gary may be right on when plugged in.I do know semi's pulling tankers w/gas/oil have ground straps that drag the ground as they travel.Not 100% sure,but think this is done in case of a lightning stike.May be for static elec. when hooked to fuel pumps.....Brian
__________________
wanderer1 is offline   Reply With Quote
Old 06-14-2007, 12:32 AM   #5
Rivet Master
 
dscluchfc's Avatar
 
1984 31' Excella
Abernathy , Texas
Join Date: Jun 2002
Posts: 849
what about those stabilizer footpads on the ground??????
__________________
David
TAC # TX-18

AIR # 410
http://www.flickr.com/photos/dsphotoscapes
dscluchfc is offline   Reply With Quote
Old 06-14-2007, 01:49 AM   #6
VAC President
 
Buttercup's Avatar
 
1977 27' Overlander
1954 25' Cruiser
1990 34.5' Airstream 345
VC Highlands , Nevada
Join Date: Mar 2005
Posts: 2,149
Send a message via Skype™ to Buttercup
Well I can speak with some authority on this topic.

We use professional (and very expensive) lightning monitoring equipment where I work to monitor where lightning is striking near our high voltage transmission lines. A lightning strike is measured by a couple variables; Type(cloud to ground, ground to cloud and cloud to cloud), current flow in thousands of amps and multiplicity (how many times the strike... ahhh, struck). The potential of a lightning strike is in the multiple megavolt range. But as with any flow of electricity, it is not the voltage that does the damage, it is the current flow. The potential difference between the cloud and ground (or between any 2 points for that matter) is what makes the current flow.

The tires of a vehicle do nothing to insulate you from a strike. Here is some pictures of a dump truck that got into a 25,000 volt line for a half of a second. All but 2 of the tires were intact. The rest were either blown or bulging and almost blown. The dust, grease and dirt on tires help conduct the electricity.

When you are in a car you are not protected by the tires but rather by the fact that you are surrounded by metal. The metal distributes the potential all around you evenly (an equipotential zone) and therefore, if there is no potential difference, you will not get shocked. this fact is so well known in my industry that we design substations with this fact in mind. It is also this fact that allows lineman to fly to and land on an energized transmission line and perform work without the helicopter or lineman getting blown to smithereens.

So for the airstream the same is true, you have a metal shell that will dissipate the strike over the entire body of the trailer leaving the occupants inside relatively unharmed. But the real danger may be from the sound and from any fire danger. I bet that a hole the size of a quarter would be cleanly blown from a normal strike. having the stabilizer pads down will only help conduct the current to ground, but that may save your tires so that could be a good thing.

If the trailer is plugged in than this would certainly pose some concerns because the potential from the shell is going to try to get out through whatever means necessary and that could mean some high voltages get imposed onto electronic equipment while they are plugged in. This includes battery chargers, etc. But this would be because the electricity if finding a nice path to ground through the power cord.

As a side note, in all the years I have been monitoring lightning strikes on a high voltage transmission grid I have not seem lightning be attracted to a power line more than anything else. I have not done research on this but I can say that lightning seems to hit the ground near lines as it does the lines themselves. I mention this because the lightning seems to have the same probability of striking a metal trailer as it would any other part of the ground or trees or whatever.
__________________
Buttercup's Web Site. WBCCI #17330, 11281 & 7830. VAC Past President, TAC NV-2 & NV-3
Buttercup is offline   Reply With Quote
Old 06-14-2007, 03:36 AM   #7
3 Rivet Member
 
volvophile's Avatar
 
Vintage Kin Owner
colorado springs , Colorado
Join Date: Nov 2005
Posts: 149
Images: 14
Heres the theory Ive always gone by since a 9th grade physics class:
Electrical current has what is called a "skinning Effect". Where the current tends to move on the outside of the conductor. (or the actuall electrons that are moving) Substations will use large diameter pipe for high current transmission, both for cooling, and also because current wouldnt be moving through the middle of the pipe if it where solid.

Airstreams, metal cages, and cars for that matter, act like the same pipe. The current moves on the outer skin of the metal to ground and not through the inner surface.
There are some rather spectacular exibits where people are hanging out in a suspended metal cage that is being struck by bolts of lightning from a Tesla coil.
I think The heat and general violence of a lightning strike may tear up the aluminum skin, pop a few rivets and blister the zolatone, but the ocupants should be safe for the first strike.

I generally let my safety chains lay on the ground to provide a path for lightning in hopes that it would spare my $60 power cord.
__________________
Champagne wishes and Caviar dreams!
Budwieser budget.
volvophile is offline   Reply With Quote
Old 06-14-2007, 04:50 AM   #8
VAC President
 
Buttercup's Avatar
 
1977 27' Overlander
1954 25' Cruiser
1990 34.5' Airstream 345
VC Highlands , Nevada
Join Date: Mar 2005
Posts: 2,149
Send a message via Skype™ to Buttercup
Not skin effect

Quote:
Heres the theory Ive always gone by since a 9th grade physics class:
Electrical current has what is called a "skinning Effect". Where the current tends to move on the outside of the conductor. (or the actuall electrons that are moving) Substations will use large diameter pipe for high current transmission, both for cooling, and also because current wouldnt be moving through the middle of the pipe if it where solid.
In the case of a lightning strike the skin effect would be negligible and perhaps non existent. Skin effect is a frequency dependent effect, the higher the frequency, the greater the skin effect. So that is not the factor in the case of a lightning strike hitting a trailer. While the arc does radiate in an very wide spectrum, each frequency only has a small portion of overall energy. The main amount of energy is in the near DC release of discharge.

Substations use aluminum pipe not because of skin effect OR cooling but rather because it is lightweight and an excellent conductor. The hollow shape of the buss works is for strength and for having a lightweight way to conduct the current. A lightweight buss is easier to support with insulators and less prone to breaking under strain. Besides, aluminum is cheap and easy to work with. But substations are not constructed that way due to skin effect or for cooling.
CLICK HERE for more info on Skin Effect.

Quote:
Airstreams, metal cages, and cars for that matter, act like the same pipe. The current moves on the outer skin of the metal to ground and not through the inner surface.
Actually, at the frequency of lightning and even a tesla coil the current will easily penetrate the entire thickness of the metal. At 60 hertz the skin effect is REALLY big! See this chart for more info. I believe that the chart shown in wikipedia may be mislabeled as skin depth when it perhaps should be magnetic permeability. But anyway...

Quote:
There are some rather spectacular exibits where people are hanging out in a suspended metal cage that is being struck by bolts of lightning from a Tesla coil.
This is what is called a faraday shield, and the purpose is not a skin effect but again an equipotential zone around the person in the cage. They are being energized at the potential of the tesla coil, but because they have the same potential all around them they do not get shocked. (yes, tesla coils operate at higher frequencies,in the megahertz range, and skin effect would be more of a concern) - but still in that case but we really are talking about 2 things here. And anyway, you need really higher frequencies to get into the range of skin effect you are thinking about here. See this article for more information.

That helicopter video I linked to in the earlier post shows faradays principal. The guy in the helicopter doesn't get electrocuted because he is at the same potential as the line, 500,000 volts. There is no potential difference between him and the energized line he is crawling on. It is the same reason birds can sit on a 25,000 line and not get electrocuted because they are also at the same potential as the line. They clearly are not protected by skin effect because they are standing on the skin and they are clearly not insulated from the line.

Quote:
I generally let my safety chains lay on the ground to provide a path for lightning in hopes that it would spare my $60 power cord.
Well that may help but I am fairly sure that the bonding of the cord neutral and ground connection will look like a lower impedance than a piece of chain laying on the ground. Besides, the trailer is connected to the ground connection of the power cord. I am betting that the cord will take a hell of a hit if it gets struck no matter what.
__________________
Buttercup's Web Site. WBCCI #17330, 11281 & 7830. VAC Past President, TAC NV-2 & NV-3
Buttercup is offline   Reply With Quote
Old 06-14-2007, 06:14 AM   #9
3 Rivet Member
 
Roadschooler's Avatar
 
2000 34' Limited
Brevard , North Carolina
Join Date: Apr 2007
Posts: 100
Send a message via Yahoo to Roadschooler
Wow

Cool thread! Thanks for the info all, I feel most informed
__________________
Roadschooler is offline   Reply With Quote
Old 06-14-2007, 06:51 AM   #10
Site Team
 
, Minnesota
Join Date: Aug 2003
Posts: 6,940
Images: 59
Here is a previous discussion of lightning. And another one. And a third one.
__________________
markdoane is offline   Reply With Quote
Old 06-14-2007, 07:33 AM   #11
Aluminut
 
Silvertwinkie's Avatar
 
2004 25' Safari
. , Illinois
Join Date: Feb 2003
Posts: 10,334
I'd have to agree, I believe you'd be fine, unless you had a CCD and just happened to be touching the metal inside.
__________________
Computers manufactured by companies such as IBM, Compaq and millions of others are by far the most popular with about 70 million machines in use worldwide. Macintosh fans note that cockroaches are far more numerous than humans and that numbers alone do not denote a higher life form. -NY Times 11/91
Silvertwinkie is offline   Reply With Quote
Old 06-14-2007, 08:01 AM   #12
VAC President
 
Buttercup's Avatar
 
1977 27' Overlander
1954 25' Cruiser
1990 34.5' Airstream 345
VC Highlands , Nevada
Join Date: Mar 2005
Posts: 2,149
Send a message via Skype™ to Buttercup
Quote:
Originally Posted by Silvertwinkie
I'd have to agree, I believe you'd be fine, unless you had a CCD and just happened to be touching the metal inside.
Well even then you would be O.K. Just like the guy in the cage with the tesla coil zapping all around you.
__________________
Buttercup's Web Site. WBCCI #17330, 11281 & 7830. VAC Past President, TAC NV-2 & NV-3
Buttercup is offline   Reply With Quote
Old 06-14-2007, 08:24 AM   #13
Aluminut
 
Silvertwinkie's Avatar
 
2004 25' Safari
. , Illinois
Join Date: Feb 2003
Posts: 10,334
Yea, I know, I was just taking a cheap CCD shot to play around with the rookies, it's why I put a after it.
__________________
Computers manufactured by companies such as IBM, Compaq and millions of others are by far the most popular with about 70 million machines in use worldwide. Macintosh fans note that cockroaches are far more numerous than humans and that numbers alone do not denote a higher life form. -NY Times 11/91
Silvertwinkie is offline   Reply With Quote
Old 06-14-2007, 08:51 AM   #14
3 Rivet Member
 
1963 26' Overlander
Cleveland , Georgia
Join Date: Apr 2007
Posts: 123
Quote:
Originally Posted by markdoane
Here is a previous discussion of lightning. And another one. And a third one.
Thanks md, I thought this would be a common topic, I've just never seen it. Plus, me and search don't jeeha.

Wow, thanks everyone. Ask for an inch...get a mile on the forums. I just wanted to make sure I wasn't camping in a 26 foot lightning rod.
Thanks bc for the in depth explanation.
__________________

__________________
Rusty

Some days you're the windshield,
Some days you're the bug!

"Life's a garden, dig it" Joe Dirt
bigeasy63 is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Storm Door smily Doors & Locks 9 11-25-2009 05:16 AM
Skylight part question ColtSAA45 Roof Vents, Skylights & Fans 3 04-22-2004 09:05 PM
Number Decals Question wagsrp Airstream Motorhome Forums 7 10-11-2002 09:18 AM
Battery Dead/Power jack question jcanavera Jacks, Stabilizers, Lifting and Leveling 34 08-16-2002 02:51 PM
Tire sizing question casarodante Tires 5 07-02-2002 11:19 PM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 04:15 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.