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Curious Question... Lightning


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#1 DeWat

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Posted 20 April 2012 - 06:05 PM

Since we are expecting storms this weekend, it made me think about the coach as a new owner. I am one who has always heard, and believed that cars are gounded due to their rubber tires. Well, when my Hurricane is on its levelers on my home pad, three of the four wheels (I'm counting the dualies as one) are off the ground, and the fourth is not exactly on the ground either. Well, due to this, I am reasonably assured that the tires are not grounding the MH. With that said, if I am on the levelers boondocking and not connected to shore power, what happens if a lightning storm approaches? Again, this is a curiousity question.
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#2 TombstoneJim

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Posted 20 April 2012 - 06:27 PM

"what happens if a lightning storm approaches? "

There will be thunder , lightning, probably rain and maybe hail.
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#3 DeWat

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Posted 20 April 2012 - 06:40 PM

"what happens if a lightning storm approaches? "

There will be thunder , lightning, probably rain and maybe hail.


Thanks, that was very educational.
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#4 Guest_BillAdams_*

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Posted 20 April 2012 - 07:51 PM

Lightening BAD if it hits you or hits nearby. It's quite possible that a direct hit will run right through the coach wiring and into the ground frying most everything along the way. I have a coach without levelers and lightening struck nearby which sent a power surge through the campground electrical system and fried a bunch of stuff (including my inverter/converter). While all of that sounds bad, it's pretty unlikely that anyone inside the coach would be hurt as the electricity is looking for the most direct path to ground and it's highly unlikely that you are one of these. I would not be in the shower at the time and I would avoid playing with electrical devices, but if you are in your chair or otherwise isolated for the major metal and electrical systems I consider it very similar to being inside a Faraday cage. The charge should go around the outer edges and you should be snug as a bug in a rug (but not terribly happy about the aftermath!). http://en.wikipedia....ki/Faraday_cage

#5 hermanmullins

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Posted 20 April 2012 - 08:44 PM

Dewat, It concerns me that you have all but one tire off the ground and that its almost off the ground. Having the tire off the ground is a help with a flat tire, however a MH can sway a bit in the wind. Your are putting a lot of strain on the small 2 inch shafts and pads. If you are concrened about your tires being on the ground, raise each one off the ground, one at a time, and put a board under each wheel. Then lower them back down and level the coach. I hope the area you are parking your coach at your home is so unlevel that it requires the tires to be off the ground. If you dont have the fridge on you dont need to level the coach just to store it.
I dont want you to go out and find all of your jacks bent over from the wind.

Good Luck

Herman
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#6 DeWat

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Posted 20 April 2012 - 08:58 PM

Lightening BAD if it hits you or hits nearby. It's quite possible that a direct hit will run right through the coach wiring and into the ground frying most everything along the way. I have a coach without levelers and lightening struck nearby which sent a power surge through the campground electrical system and fried a bunch of stuff (including my inverter/converter). While all of that sounds bad, it's pretty unlikely that anyone inside the coach would be hurt as the electricity is looking for the most direct path to ground and it's highly unlikely that you are one of these. I would not be in the shower at the time and I would avoid playing with electrical devices, but if you are in your chair or otherwise isolated for the major metal and electrical systems I consider it very similar to being inside a Faraday cage. The charge should go around the outer edges and you should be snug as a bug in a rug (but not terribly happy about the aftermath!). http://en.wikipedia....ki/Faraday_cage


Thanks much Bill, this is the kind of information that I am seeking. Naturally, I know that in a direct stike, all bets are off... and maybe everything else as well. I'm just more concerned/curious as to if I would be a lightning rod. Your reference to Faraday Cages was also well understood as I having worked in the radio and cell phone fields since the 90's Thanks again...


Dewat, It concerns me that you have all but one tire off the ground and that its almost off the ground. Having the tire off the ground is a help with a flat tire, however a MH can sway a bit in the wind. Your are putting a lot of strain on the small 2 inch shafts and pads. If you are concrened about your tires being on the ground, raise each one off the ground, one at a time, and put a board under each wheel. Then lower them back down and level the coach. I hope the area you are parking your coach at your home is so unlevel that it requires the tires to be off the ground. If you dont have the fridge on you dont need to level the coach just to store it.
I dont want you to go out and find all of your jacks bent over from the wind.

Good Luck

Herman


Thank you as well Herman. I had a feeling that I would get a comment about my leveling, and was kind of hoping for it as an aside. Yes, the position bothers me, but this is the position that the LCI's auto-position always uses (the pad itself has a very slight forward left tilt). Because of this, I generally don't keep the levelers down, and I already have a series of questions about this in to Thor, but no response yet.

Again, thanks to you both!
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#7 DickandLois

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Posted 20 April 2012 - 09:42 PM

When there is a storm brewing and lightning in the area. I take the time to disconnect from shore power.
That separates the coach from the power grid,that if a lighting streaks close, the pathway to my power is open and inside we are isolated from the ground path.
Never say never,but I feel better with the metal and fiberglass cage around me and my feet 2 or 3 feet off the ground.

Rich.
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#8 wolfe10

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Posted 21 April 2012 - 02:53 PM

When there is a storm brewing and lightning in the area. I take the time to disconnect from shore power.
That separates the coach from the power grid,that if a lighting streaks close, the pathway to my power is open and inside we are isolated from the ground path.
Never say never,but I feel better with the metal and fiberglass cage around me and my feet 2 or 3 feet off the ground.

Rich.


Excellent advice. Just turning off the shore power or coach 120 VAC main breaker will not protect your coach from a lightening strike that comes in on the shore power grid. Lightening can travel on the neutral or ground wire as well as the hot wire/wires.

Chances of a direct hit are EXTREMELY low. Chances of a lightening strike near enough to be picked up by shore power wiring is LOT higher.

Brett
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#9 Briarhopper

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Posted 21 April 2012 - 11:41 PM

Interesting curious question. So much so, I inquired of the NWS to get their thoughts on motor homes in lightning storms. When I get a repsonse, I'll toss it in here.

In the mean time, the following thoughts drawn from some experiences and some conjecture.

Boondocking with jacks down may make the rig more visible to a bolt of lightning(visbile meaning the lightning detects a path to ground). If it makes the rig more visible, like a tree on the mesa, then yes, a strike would be more likely.

Metal body cars are considered safe shelters from lightning. Fiberglass shell cars are not considered safe shelters from lightning. Not sure if a rig with metal framing would act like a metal car body. However, a rig with no metal would be similar to a fiberglass shell car and likely not offer any personal protection.

Interesting fact: In Florida, lightning kills more people than all other storm-related weather events.
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#10 DickandLois

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Posted 22 April 2012 - 09:53 AM

Lightning like any form of electricity will seek the path of least resistance.

When one is in a car or any other enclosure that is off the ground plane. You are not the first choice, the pathway may make ones hair stand up though.
Hot bolts as many people call them, have a high current to voltage ratio and can split trees and do tremendous damage.

A personal observation, I have been so close to a lightning strikes (3 times) in my life that the hair on my arms was standing up. It is very much the same as an old physics static electricity generator.

Once when it hit the ground circuit of the power lines feeding the house. Once when a strike hit the free standing tower in my back yard and one time it came in on the phone line, bounced around the kitchen and grounded itself at the sink.

My father had a good friend killed by lightning when on the farm. Everybody was in the barn, but the man killed was standing in the open barn door. From dads description it struck the lightning rods and a finger of the strike hit the person in the doorway where it was wet from the rain and appeared to supply a ground path.

The thing is that if your caught out in the open doing an electrical storm get low, even lay on the ground and in no way near a tree or other tall object. When in the woods one hopes there is a taller tree away from where you are located. In my humble opinion it becomes just a factor of luck !!!

The leading edge of a storm is the most dangerous from what I have red over the years. One can be a mile or more away and still be the ground point. I have stayed low an taken getting wet over trying to out run one.

Rich.
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#11 phespe

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Posted 23 April 2012 - 08:31 PM

UHhhhhh
"I am one who has always heard, and believed that cars are gounded due to their rubber tires."

I think you got it backwards -- Rubber (and Rubber Tires) are far better insulators than conductors, i.e. as on Autos, the tires insulate the vehicle rather than ground it. Or as you said "I am reasonably assured that the tires are not grounding the MH." but because they are made of insulating materials - not because they are not in contact with the ground.

The leveling Jacks do ground your Motor Home

phespe



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#12 DickandLois

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Posted 24 April 2012 - 10:59 AM

phespe, Yes when the jacks are down the coach frame is grounded and the metal in the sidewalls of the Coach and the Steel frame will be the ground path.
When one is inside the coach and off the ground that person is not the primary ground path. the pathway is generally around you to ground.

Regarding the tires. They do isolate the vehicle from ground and should that vehicle get struck by lightning the pathway is around you, but your hair will most likely stand on end due to the electrical field around you.

Rich.
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#13 Briarhopper

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Posted 30 April 2012 - 03:19 PM

Response from NWS in quotation marks:

"FYI, I'm not aware of any incidents involving motor homes so I can't cite any examples.. The metal framing should provide protection, but it would not be as good as a complete metal shell. You would want to stay as far away from the metal framing and from any metal conductors as possible. As for leveling jacks versus the tires, it doesn't really matter."

I take his repsonse as being related to people protection and not neccessarily property, electronics, etc.
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#14 DeWat

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Posted 30 April 2012 - 06:37 PM

Thanks Briarhopper. I don't mean to sound cynical, but this looks more like the standard "I don't really know, but here's what I do know" type of response. :rolleyes:
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#15 DickandLois

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Posted 10 August 2013 - 06:39 AM

The power of nature !

This Video just showed up on the internet news and I thought it might be an interesting video for others to view.

 

http://news.yahoo.co...-162519853.html

 

It's the comment at the end by the reporter regarding the tires that kind of makes a point, the power a lightning bolt can pack.

 

Rich


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#16 TBUTLER

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Posted 10 August 2013 - 11:32 AM

For many years while I was teaching meteorology I subscribed to weather publications.  I can't cite the specific information for reference right now.  I tried searching the internet and haven't been able to come up with it for now.  There are two articles that are applicable here, both accompanied with wonderful photographic evidence of lightening strikes.

 

The first showed a car parked under a tree.  The tree was struck by lightening, from there the bolt went straight from the branches down to the roof of the car which was completely obliterated, a hole about 2 feet in diameter with burned edges.  The bolt continued straight to ground through the passenger seat and the floor of the vehicle, melting and destroying both.  Needless to say, the tires insulating the vehicle were ineffective.  So much for the protective nature of tires.  If lightening can pass through hundreds or thousands of feet of air which is an excellent insulator, a few inches of rubber won't stop it.  A car or motor home may feel secure but your safety is not guaranteed in any vehicle.

 

The second picture showed a golf green.  Lightening had stuck the flag stick in the cup on the green.  There was a pattern of dead grass on the green showing how the lightening had traveled across the surface of the ground as it dissipated.  In an even pattern around the hole were branching lines of dead grass.  It looked much like the roots of a grass plant pulled from the ground, evenly distributed in all directions.  The lesson from this picture was that you should not lie on the ground in a lightening storm, instead you should minimize your contact with the surface of the ground.  Stay away from tall objects and crouch low but stay on two feet. 

 

There is no absolutely safe place to be in a lightening storm but being inside a substantial building, staying away from electrical appliances and lines and also water lines and fixtures provides your best protection.  Lightening can strike miles from where the storm is so when you hear thunder you are at risk.  Distant thunder is your warning to seek shelter.  As the thunder becomes louder the storm is telling you to hurry to shelter.  If you are outdoors and can not reach shelter, head down hill, find the lowest place you can and shelter in place as described above.  Remember that lightening can strike miles from the storm.  Once the storm passes and the thunder is becoming more distant you are not our of danger.  Stay in place until the storm is well away and you can no longer hear thunder.


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#17 Wayne77590

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Posted 10 August 2013 - 10:53 PM

Every thing is a conductor. It is just that some things are poorer conductors than others.

 

Tom's example of the car brings to mind a long time ago, and long discussion regarding "grounding."  We are both Amateur Radio Operators, and one of the things that is taught is to ground the antenna system.  My theory is, that if you run an 8 foot copper rod into the ground and lightening strikes the ground near buy, then the copper becomes a potential conductor into the radio equipment.  The discussion went on and on with no definitive conclusion. 

 

With that said, a friend in Noxapater, MS had a 100+ foot HAM tower in his back yard.  His station was in his very organized basement of the house. Along one wall was a work bench with electrical connectors for testing equipment. Against a far wall was his HAM radio station.  In the middle of the basement floor was a 4 foot wide by 6 foot long wooden bench. There were not connections to this bench other than the four wooden legs on the floor. This bench was used only to dismantle the metal case of equipment he was working on and he would transfer the internal makings to the other work bench.  He had opened up a radio and laid the case next to the electronics, then left his house to go shopping.  When the came back the found that a storm had come through the area.  Lightening had struck his outside antenna, traveled down the RF wires into the house, through his radio. The radio suffered 1 blown resistor and a capacitor.  However, the radio sitting on the bench with nothing attached to it looked like an ARC welder had sliced right through the middle of it.  The lightening had then jumped the table, went inot an electrical plug on the wall, traveled up the wired and blew some components in his refrigerator.

 

I wonder why it didn't got to ground from his antenna which was grounded.

 

Lightening is the most unpredictable element in the world. 


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#18 Sdlineman

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Posted 13 September 2013 - 10:22 PM

 
With that said, a friend in Noxapater, MS had a 100+ foot HAM tower in his back yard.  His station was in his very organized basement of the house. Along one wall was a work bench with electrical connectors for testing equipment. Against a far wall was his HAM radio station.  In the middle of the basement floor was a 4 foot wide by 6 foot long wooden bench. There were not connections to this bench other than the four wooden legs on the floor. This bench was used only to dismantle the metal case of equipment he was working on and he would transfer the internal makings to the other work bench.  He had opened up a radio and laid the case next to the electronics, then left his house to go shopping.  When the came back the found that a storm had come through the area.  Lightening had struck his outside antenna, traveled down the RF wires into the house, through his radio. The radio suffered 1 blown resistor and a capacitor.  However, the radio sitting on the bench with nothing attached to it looked like an ARC welder had sliced right through the middle of it.  The lightening had then jumped the table, went inot an electrical plug on the wall, traveled up the wired and blew some components in his refrigerator.
 
I wonder why it didn't got to ground from his antenna which was grounded.
 
Lightening is the most unpredictable element in the world. 


Most likely, the vast majority of the lightning did go through his ground rod. By the old saying about electricity taking the path of least resistance is only partially true; it takes every path it can find. You can see this in your motorhome right now. If you have more than 1 light bulb on, the electricity doesn't just go to the one with the least resistance, it will go to all of them that are on. Lightning act the same way. Lets say that a bolt of lightning is 2 million volts ( I just pulled that # out of my a$$), and his ground rod had a very good ground with only 2 ohms of resistance, but the lightning found another path to ground though your buddy's work bench that had 20 million ohms(made that up, too) also.

 

Ohms law tells us that the ground rod saw 1 million amps, and his work bench got .1 amps at 2 million volts or a total of 200,000 watts, which was enough to fry his electronics. The hope of ground Protection is that the majority of the electricity will flow through it and the amount of amperage through other paths will be low enough to not damage anything, but with a direct lightning strike, all bet are off.


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