Lightning & fiberglass van tops

[TrainChaser]

I can't help it -- I think of strange stuff. :dodgy:   (And I just watched Bob's new video about getting the fiberglass hightop put on his van.)

Anyone who has been doing much research on van dwelling probably knows that if lightning is striking nearby, the safest place to be is in a solid building with plumbing, or in your all-metal-shell vehicle.  "They say" that if your vehicle is fiberglass (or has a fiberglass hightop), you are in danger from a lightning strike.

Rubber tires are no protection against lightning.  The main protection of being in a metal vehicle is the Faraday Effect, where the electrical charge hits your roof or radio antenna, and zooms through the metal shell.  You're usually safe if you're not touching anything metal that is attached to the frame of the vehicle.  It will fry all of your vehicle electronics, and if you're using a corded (I assume) radio mic, you will get your lips or face fried (it's happened to cops).

Now, getting back to the fiberglass question.....

NOAA and the rest of the scientific community say that if you have a choice of vehicle, getting into a metal vehicle/van is safer than a convertible or a van with a fiberglass hightop.

Problem:  I can't find anything that indicates that a van with a fiberglass top has EVER been struck by lightning.  I can't find that a fiberglass Corvette has EVER been hit by lightning. 

What's going on here?  Is it a matter of the patch of metal called the 'roof' attracting the lightning?  If so, does that mean that the fiberglass DOESN'T attract lightning?  Does it mean that you're probably just as safe in a van with a fiberglass hightop as you are in a regular van?  Does it maybe even mean that you're safer, because if lightning doesn't strike fiberglass (and your electronics don't get fried), you won't have to walk down from the Rockies?

 

[John61CT]

You want the lightning to get to ground as directly as possible, but not through you.

If the fiberglass is transparent to the lightning, and your watery body is the highest thing in the area. . .

 

[bigsallysmom]

If you have a metal roof rack won't it go around?

 

[tx2sturgis]

ZAAAPPPP!!! BOOOMMM!


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[size=large][size=small][size=large][size=small]Sorry....couldn't help myself....ya'll go ahead....[/size][/size][/size][/size]

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[John61CT]

> If you have a metal roof rack won't it go around?

If that's a joke sorry, I'll assume not.

Lightning is heading to Earth ASAP, finds the most efficient path there in a nano-second, no side trips for the bulk charge.

And you don't want to be that path, hence not standing in wet, not being the highest thing around, not touching metal etc

 

[Spaceman Spiff]

. . .  does that mean that the fiberglass DOESN'T attract lightning?  Does it mean that you're probably just as safe in a van with a fiberglass hightop as you are in a regular van?  Does it maybe even mean that you're safer, because if lightning doesn't strike fiberglass (and your electronics don't get fried), you won't have to walk down from the Rockies?

I have seen lightning strike a fiberglass boat on shore.  Wasn't even the tallest thing around.

Every lightning safety source I have read warns that if you are in an RV that is not all metal or tent and around a lightning storm to get into a car with a metal roof (Faraday cage) and put your hands in your lap (don't touch anything conductive attached to the outside metal skin of the car).  If you can hear thunder you are around a lightning storm.

 -- Spiff

 

[TrainChaser]

Spiff: "I have seen lightning strike a fiberglass boat on shore. Wasn't even the tallest thing around."

But was it aiming for the fiberglass or the metal mast or the metal radio antenna?

 

[Spaceman Spiff]

But was it aiming for the fiberglass or the metal mast or the metal radio antenna?

Lightning is aiming for the ground and it will take the lowest resistance path to get there. I don't think anyone can predict what path it will take.  If your van is in the path the fiberglass roof offers no protection (a metal car body does).

The boat was an 16' open fiberglass runabout.  No masts, antennas, or fishing poles sticking up. Had a metal light stalk in back and an outboard motor higher than the boat, but that is not what the lightning hit.  Lightning hit the bow, blew a 12" hole in the top and bottom of the boat.  No metal in the path IIRC (it was ~ 15 years ago).  Trees not far from the boat.

Did a quick search on lightning hitting an RV and got a big nothingburger.  Lots of reports of secondary damage from ground currents.  Lots of links to lightning safety.  All of them suggest moving to a protected building or into a metal vehicle body.  Most fatalities seem to be from people standing out in the open or under trees.

 -- Spiff

 

[John61CT]

Yes, by far the biggest danger vanning is being out on the road.

Interesting as a theoretical exercise but not IMO something worth worrying about

 

[Scott7022]

I like how science is still arguing the why/how of lightning strikes.

Dynamat the roof with the silver sided dynamat. Good sound and temp insulator and bring it far enough down onto the original body of the van. Faraday cage restored and one in four billion Cat Ass Trophy averted.

 

[TrainChaser]

"...the fiberglass roof offers no protection ..."

YES, THAT'S WHAT EVERYONE SAYS. But people also used to assume that the world was flat, that Columbus discovered America, that the Vikings wore horned helmets, and that iodine was toxic. One parrot teaches another parrot, which teaches another parrot......

I don't know if it's just in this country, but lots of people can't seem to tell the difference between a fact, a theory, and an opinion. AND THEY'RE NOT THE SAME THING!

You can quote assumptions all day, but I still can't find where lightning has EVER struck a fiberglass hightop van! But what I want to know is... WHY NOT???

 

[tx2sturgis]

...... I still can't find where lightning has EVER struck a fiberglass hightop van!  But what I want to know is... WHY NOT???

Cause they're 'stealthy'?

 

[TrainChaser]

Not always: https://i.pinimg.com/736x/33/8a/7b/338a7b5bdae243d3a05127dd5c4c4ea9--hippie-love-hippie-chick.jpg

 

[Charlotte's Web]

Not "weird" to be concerned, or educated on the topic of safety in lightning storms!  Especially in the desert where one's vehicle (or one's self) could easily be the tallest thing around.

I did a search & found several sites with good info.  Below, I've posted one with lots of useful info.  I learned in my search of the importance of a proper Surge Protector.  This item can protect against thousands of dollars worth of damage.  There's a lot to read in this link; if you're serious about understanding the phenomenon, worth reading.

http://rvsandohvs.blogspot.com/2011/02/lightning.html

Charlotte

 

[Spaceman Spiff]

NOAA and the rest of the scientific community say that if you have a choice of vehicle, getting into a metal vehicle/van is safer than a convertible or a van with a fiberglass hightop.

"...the fiberglass roof offers no protection ..."

YES, THAT'S WHAT EVERYONE SAYS. 

Drat you TrainChaser.  I spent half the afternoon researching this :s

First to sort of answer your question:  "I still can't find where lightning has EVER struck a fiberglass hightop van! . . .  "
  
I could not find any direct evidence of lightning striking any RV (metal, fiberglass, wood, canvas, whatever).  I find references to RV damage due to lighting, mainly in compilations of insurance claims, but not very informative.  There is a lot of evidence of lightning striking boats (wood, metal and fiberglass).

To answer  "...the fiberglass roof offers no protection ..."  we need to understand two things: 1. how lightning gets from a cloud to ground and 2. how a car body (faraday cage) protects.

1. The VERY abbreviated cliff's notes version:  A charged channel of air (called a step leader) is developed from cloud to ground.  When this gets close to the ground a channel of positively charged air (called a streamer) develops from the ground.  When they meet lightning begins.  Why lightning picks one column of air over another is not understood.

A simplified explanation is here:  http://www.boatus.com/seaworthy/magazine/2015/january/lightning-facts.asp
A rigorous explanation here:  http://www.lightning.ece.ufl.edu/PDF/Published Journals/2014/Dwyer & Uman (2014)a.pdf[/SIZE]

2. A faraday cage protects because the voltage drop from the top of the cage where the lightning hits to the bottom of the cage is enough protection to keep the air inside the cage from ionizing and providing a path for the lightning.  A vehicle with a fiberglass top (or body or a convertible)  does not have this complete cage (no conductive top), so the charged column is free to develop inside your vehicle.  The thin layer of fiberglass does not afford enough insulation to make a difference.

https://en.wikipedia.org/wiki/Faraday_cage

Conclusions:  

If your van happens to be in the path of the charged column of air, an all metal van will protect by not letting the air inside ionize to complete the circuit through your van.  The lightning follows the charge on the outside of the vehicle.  A fiberglass top does not offer that protection.

I found no evidence that fiberglass protects from lightning.  On the contrary, fiberglass boats seem to be hit about as often as metal and wood boats.

And we see lots of Vikings wearing horns around here on NFL game day.

 -- Spiff

 

[Every Road Leads Home]

but I still can't find where lightning has EVER struck a fiberglass hightop van! 

Well they say there is nothing new under the sun, meaning if you've thought of it, it's happened before.  So yes a van with fiberglass high top has been hit by lightning before.  Did they live to tell the story?,  well that it seems we do not know.

 

[TrainChaser]

ERLH:  "... if you've thought of it, it's happened before."  There is a wide difference between thinking of something and having it actually happen.  I can think about flapping my arms and flying to the moon, but as for it happening...

"So yes a van with fiberglass high top has been hit by lightning before.  Did they live to tell the story?,  well that it seems we do not know."

I believe that you're assuming again.  If they DIDN'T live to tell the story, I suspect that there would have been physical evidence that indicated death by electrocution on their bodies, if not on the vehicle.  Bodies (even covered with hair, like livestock) are pretty good at showing they were hit by lightning, even if they survive. 

If anyone has any FACTS to add, please do.

Looking at info on boats, it seems that most boats that are struck by lightning are hit on the mast, antenna (which are often put on the mast because height improves the range) or bimini top.  Most boats probably use stainless steel, brass or copper antennae, because the cheap fiberglass ones break down quite badly, and they're not as efficient as to gain (your radio is only as good as its antenna).  Both are connected to wire.  Masts are either metal, wood or fiberglass; if they're wood or fiberglass, there's a reasonably good chance that the antenna is metal, and for certain the wire running down the mast is metal.  Bimini tops are framed with metal. 

From what I've found (and not found), I'm going to assume that the information being parroted about fiberglass-topped vehicles being less safe than full-metal vehicles is simply a theory, or even just an opinion, and isn't a fact.  However, I would disconnect from external power.

It could be that all the information isn't in yet, or that what info has been collected has been interpreted incorrectly.

 

[tx2sturgis]

If anyone has any FACTS to add, please do.

{snip}

Most boats probably use stainless steel, brass or copper antennae, because the cheap fiberglass ones break down quite badly, and they're not as efficient as to gain (your radio is only as good as its antenna).

Ok...some facts:

Most serious marine antennas (for ocean/salt exposure) are copper or stainless steel (with brass or aluminum hardware) inside a fiberglass casing, called a 'radome'....but small fresh water and recreational boats very often use stainless antennas.

Cheap fiberglass would probably break down over time and exposure, but good quality fiberglass will last for decades.

Generally speaking these antennas use a DC ground, so that if lightning hits them, it is shunted to the aluminum mast and delivered to the ocean water thru the steel hull, or a ground plate or the metal keel if it's a fiberglass or wooden hull.

 

[John61CT]

Do you mind me asking why you are so worried about lightning?

 

[highdesertranger]

tin foil hat. that's all you need. er, I mean for the van, cover your fiberglass top with tin foil. there is no such thing as a pure fiberglass antenna. there is either a metal core or a metal wire wrapped around the fiberglass. highdesertranger