Lightning storm question

[Fyrzowt]

Originally Posted by Excella CM

One last thing you can do is to sacrifice a bull to Zeus now and then. I have have plenty extra

Does this mean that you're "full of it?"

[Excella CM]

No. It just means, that due to my charitable inclination and regard for my fellow beings, I'm willing to share what a I was blessed with by a bountiful nature with those less fortunate that see things perhaps too clearly.

[Buttercup]

Having parts of the trailer contacting the ground is not quite enough. it is for this reason that grounding rods are generally 6 to 8 feet long and pounded into the earth that great depth.

And with the grounded prong of the power cord bonded to the ground of the house or power-supply you can bet that it is a good solid ground and of lower resistance or impedance than the jack or stabilizer pads sitting on the ground. Plus, the type of ground is also a factor. Moist loamy ground will be able to carry current better than dry sandy or rocky ground. We put rocks that are low in metallic content in substations to act as a dielectric medium. They perform as an insulator and the grounding grid is located below the rocks to conduct any fault or lightning to the ground and away from anybody walking in the sub.

I still would expect that if a trailer is plugged in and gets hit, a healthy portion of that current will go through that cord. The place you don't want to be when the trailer gets hit is outside the trailer. Imagine that you are outside checking the trailer when it gets hit. Every part of the trailers metal skin will be energized and if you have one hand on the trailer AND any of your feet on the ground, you are going to get electrocuted.

[volvophile]

Hehe,
Well that shows what a 9th grade education got me

[Buttercup]

I used to have fun with this stuff in school. In fact, I brought home a Jacobs Ladder (why my teacher allowed me to do this I don't know) and was playing with it when my brother walked up and pointed at the device just as a spark jumped off one lead right to his finger. It hurt like hell and he went off to tell my parents. The Jacobs Ladder went back to school the very next day.

[john hd]

buttercup,

Imagine that you are outside checking the trailer when it gets hit. Every part of the trailers metal skin will be energized and if you have one hand on the trailer AND any of your feet on the ground, you are going to get electrocuted.

not to mention step potential, either way you are going to be on the ground doing the "crappie flop" as us linemen call it. (for those of you who don't know what that is, just imagine a "crappie" game fish flopping around on the ice when you catch one during an ice fishing outing!)

seems like you have a pretty good handle on substations, you must be an engineer.

just remember, there are two things you never want in a substation: linemen and squirrels!

for the rest of you, if you really want to protect yourselves and your trailer drive a 8 foot copper clad ground rod in. and connect it to the frame of your trailer with number 4 wire. anything less is just feel good stuff. having your trailer plugged in is the next best thing.

lineman john

[CanoeStream]

Sa-a-ay lineman john -- I moved from another part of the country and had friends laugh when I tried to pronounce the name of this fish. It looks strange in print folks, but pronounce it 'croppie' and you'll walk away with your yankee pride intact (didn't say this was going to be a win-win for you southerners... ). Here's a crappie pic.

You haven't lived until you see the tangle of graphite when a fisherman is hit during a cast...

[Excella CM]

Sounds like we're all getting a good grounding in electricty . I knew we had the potential if we could overcome our resistence and use our native capacity to learn by induction. Personally, I'm amp'd. They're coming! Gotta get back into my cage (Faraday) now albeit with some reluctance..

[markdoane]

Originally Posted by CanoeStream

. . . pronounce it 'croppie' and you'll walk away with your yankee pride intact . . .

Besides, if you say "crappy flop", it doesn't have the same poetic grace as "croppie flop".

[bigeasy63]

I am happy saying crappie like my pappy. Either way, they sure are good eatin'.

Thanks again everyone for all the nifty info.

[Buttercup]

{shop talk=on}
Ha! I love it! Linemen & squirrels! Yes, they do not last long. But the real pests here are the Starlings. Damned birds. In Nevada it rains once a month during the summer if you are lucky. And only enough to moisten the bird poop on every insulator. BANG! There goes a 120 kv circuit - one after another. Say? How do you bird guard that stuff anyway? We blast with the corn husk blaster because you can do it live, circuits off auto. But a month later, all pooped up again. Then we have our antquated 60kv system - a pole fire waiting to happen! old brown flowerpots that leak like sieves. Just waiting for that sprinkling of rain to moisten the dust that has built up on the pole and start tracking.

I am not an engineer but our company does require us to be knowledgeble in many areas of system operations and I have been working in operations for years. Substation switching is one job function I have performed and to be quallified to do that I had to go to classes in overhead and underground procedures as well as substation classes. However I have been a electricity/electronics hobbiest since I was a child. I know what a smith chart is and how to use one. And while I have never refused a cutout I probably could do it without blowing myself to pieces.
{shop talk=off}

Originally Posted by john hd

buttercup,

not to mention step potential, either way you are going to be on the ground doing the "crappie flop" as us linemen call it. (for those of you who don't know what that is, just imagine a "crappie" game fish flopping around on the ice when you catch one during an ice fishing outing!)

seems like you have a pretty good handle on substations, you must be an engineer.

just remember, there are two things you never want in a substation: linemen and squirrels!

for the rest of you, if you really want to protect yourselves and your trailer drive a 8 foot copper clad ground rod in. and connect it to the frame of your trailer with number 4 wire. anything less is just feel good stuff. having your trailer plugged in is the next best thing.

lineman john

[arodriguez60]

I asked the question at an electrical safety class and was told that the aluminum shell will work as a faraday box and will go around you and go to ground.

[Jammer]

I don't worry much. Airstreams are like a Faraday cage. While I suppose a direct hit could melt some of the pieces I would be surprised if it would result in injury for anyone inside.

If you're parked permanently you could put up a lightning rod on a 20' pole a few feetfrom the street side.

[Lumatic]

I'm no lightening expert but I think not being grounded makes a strike less likely. So would it be a good idea in a storm to have insulating material under the tongue jack and on any awning guy lines, etc? Unplug power hookups, cable TV, etc?

[aluminomad]

I don't think a weathervane on top of the trailer is a good idea, but other than that... wouldn't it be like being in a car if struck?

[Excella CM]

Make sure that either the hitch jack or the one of the stabilizers is in contact with the ground.

[bryanl]

Your major risk is going to be damage from debris, like stuff falling from trees or poles hit by lightning or stuff blown by the wind.

As a Farady cage, an RV has a lot of holes. Stay away from leaning on windows in lightning storms. Otherwise, stay inside!

Grounding to earth will make no difference. A few inches isn't going to matter squat to something that traversed a few hundred (or thousand) feet of empty air. (a big problem with intentional grounding is avoiding ground loops, which can be worse than incidental grounding and is why you crouch if caught out rather than lie flat.)

Do take care to be inside when lightning storms are around, and that can mean anywhere in sight as lightning can strike quite a ways from its cloud.

If you have a genset or other wires outside, it'd be good roll them up and get them stowed properly. Unplug any sensitive equipment inside if you can.

A lightning rod probably isn't going to help much either as these have to be installed properly at the right places with a good earth ground. Best bet is to be in the electrical shadow of something else but not too close so as to avoid falling debris and high ground currents.

[mandolindave]

But there were quite a few differences of opinions, all based pretty much on theory.
But I will share a story from first hand experience. My gal was visiting
at our friends campsite. The storm got stormy and she ran home to
my Airstream to be safe. A few seconds later..... BOOOM... lightning hit
big time. The lightning hit the tree right next to the camper where she was just visiting. It splintered a lot of the bark off the tree, leaving debree
everywhere. The bolt apparently went underground, came up under the
mat, melted the mat where the legs of the lawn chairs were, arcked ( sp ?) from one chair to another, melted the chairs where the arc happened.( right where they were sitting moments earlier ) Our friends SOBs electrical system was fried. On the other side of the rally a sound man watched as a blue glow danced along his speaker wires and zapped him big time ( apparently what they call St Elmos Fire ). Another camper was putting up his awning and was hit. He has a pacemaker and was hospitalized, just to be safe.
The smartest, most couragious, fearless, bad a$$ed imperial guard dog on the planet, climbs into my bed when he hears thunder.
Bottom line....you should take cover, and not in my bed, ...it's full!

[Aviator]

I think you would be fairly safe inside the trailer. I have been struck in aircraft (aluminum tubes) several times while airborne with only minor effects. I would, however, remove the lightning rod/weather vane from the top of your trailer. Electricity always seeks the easiest path to ground. If you are going to be there long term, the idea of a rod on a pole or in a tree away from your trailer has merit.

[Phil&Sher]

I don't know how relevant aircraft strikes are to RV's, but I too have been struck many times with only minor damage to the aircraft skin, mostly at the point of exit. My worst one was a bit of a doozy, however.

We were descending through 18,000 feet in clouds, circumnavigating a thunderstorm painting on the radar off our right wing about 25 miles away. It was around 10 at night over upstate New York in late summer and we were getting light St. Elmos fire on the forward windscreens. Suddenly we experienced the brightest flash and loudest boom any of the crew had ever experienced. I was instantly rendered blind and deaf.

The autopilot had been engaged prior to the strike, but I instinctively grabbed the yoke and could tell by the feel of the controls that the autopilot was history. I wondered if anything was left of the airplane forward of the cockpit. After what seemed like an eternity I began to hear the other pilot shouting at me, "Are you OK? Are you OK?" I shouted back that I was OK, and began to see the emergency instruments and floodlights on the instrument panel. Fortunately the airplane was still fairly close to the same attitude as before.

Both generators had been blown offline and we were able to reset only one. Many light bulbs in the cockpit were blown out including about half of the fault warning lights when we tested the panel.

As startled as we were up front, the passengers reported that they had seen what they all described as a fireball roll down the center aisle inside the cabin. Scared was an understatement for them.

We declared an emergency and landed without further ado at our destination about ten minutes later. On a postflight walkaround, there was a piece of aluminum missing from the trailing edge of the right outboard aileron - about the size of my little fingernail. Upon swinging open the fiberglass nose radome, which looked perfectly normal from the outside, we found it had literally been fried. All of the resin had been vaporized, leaving the entire inside of the radome just a mass of fibers about three inches thick.

I've been hit since, but ever since that night I've been a little more respectful of lightning.