Lightning Storm in RV

[carson]

Good stuff, Molaker. Appreciate your comments.

One more comment from me.... I moved into a gated community 14 years ago, all freshly built between 1998 and 1999.

  It didn't take long for lightning rod salesmen to solicit for an affordable house lightning arrester system.
Many of the newcomers fell for it and had them installed. A few little pointed things on the roof and wires going where?  A little ground stake ?

  I checked some of them and the wire was about a 8 gauge,  Give me a break.If you read up on lightning protection systems you will find that one needs super heavy wire to be somewhat effective to protect your home..

Well, I didn't fall for it, even though they offered me a cut-rate price when I hesitated.

My neighborhood has 118 homes and in 14 years not one lightning bolt anywhere, except in my neighbors yard, 60' from my backdoor.  The F-B time was almost zero.
I checked out his and my backyard and found that water leaking from his sprinkler system close to a 50' maple tree. Taller trees were next to it.
  He was an old fellow and wasn't home. I dug down with my hands in the now soft earth and found that his waterline was pouring out oodles of water.  A few neighbors gathered and we had to look for his main water shut-off valve. Hard to find..the lawn had overgrown it. We did find it and saved the day.

Later I learned from the owner that his garage electrical outlets had blown up, including his sprinkler timer. 

I believe the Empire State building has cables the size of your arm installed.

Don't ask me any questions,(unless you want to). I am not an expert,

An interesting topic just the same.

 

[Molaker]

For the most part, the size of the grounding cable and ground rods comes into play when the lightning rod has failed to prevent a strike.  So, if it's going to take a hit, it needs to be large enough to handle it.  But, as your tale implied and to quote another line from Forrest Gump, "Sometimes there just aren't enough rocks".  In the case of a lightning strike, sometimes there just aren't big enough ground rods.

 

[Jim Godward]

A good lightning detector is your CB radio.  You will hear "crashes", loud static way before the storm gets close to you.  IF there is a severe storm warning, tornado, thunderstorm, etc. a 2 meter Ham radio is able to hear the storm observers, weather watchers for NOAA.  You may have to scan to find them or you can get a repeater directory available from the ARRL

BTW, the comments have been  generally right on.  Current in a lightning strike can be in the range of 2000 amperes so even battery cables are too small.

 

[DonTom]

Water does not conduct electricity. It is the minerals in the water that does the conducting. Rainwater has very few minerals therefore it does not conduct electricity.

Try measuring distilled water with an ohmmeter. Or even rain water. I think you will be surprised. BTW, I have compared them all in an insulated  cup of water.

I first got some water from the pacific ocean and compared it to tap water. The tap water had about twice the resistance of sea water, per inch. Then I got some distilled water, it had about twice the resistance of the tap water, per inch. IIRC, the rain water measured just like the distilled water, no difference.

I cannot remember the ohms reading of each per inch as I did this experiment years ago. But you might try it yourself and try to explain why an ohmmeter doesn't agree with pure water doesn't conduct. But it wasn't all that high, even with distilled water. Several K-ohms per inch. That would be like no resistance at all to a few million volts of lightning.

Or is it that pure water doesn't really exist, except perhaps in a lab?

-Don-  Reno, NV

 

[Wavery]

Everyone seems to have an opinion on this one so I just let my common sense be the deciding factor.  Yes, antenna down during a lightening storm.  Satellite dish too and awning in.  This so much not for the possibility of a lightening strike but unexpected winds from a micro burst or other down drafts associated with stormy weather.  I have even been know to disconnect from shore power, water and cable during severe storms.  Slides in too if we really have to "hunker down".  Only if I have the option do I put my nose or my back into the wind.  More then likely I will leave the jacks down too.

^^ What he said^^

 

[John From Detroit]

tornado's love trailer parks, but I would be willing to bet the tornado would not know the difference between a trailer and an RV.

You are right a Tornado will not know the difference between a Trailer and an RV, however it may well know the difference between a Trailer Park (Lots of rather cool metal things and few trees) and an RV park (Warmer metal/plastic things Many trees and possibly some fires as well) which can make a BIG BIG difference.


Somone else commented "if you are hooked to shore power there is a direct path to ground: TRUE

But answer this: If you have a lightening bolt that travels say a mile through air, Do you really think six inches of rubber is going to slow it down?)

That said. Unpluging may protect your electronics.

Best advice I"ve seen.. DO NOT be the tallest thing around.

 

[Jeff]

As a satellite user the only time I like trees in a campground is during a lightening storm. :

 

[driftless shifter]

I was always grateful my stinkpot was moored amidst a forest of blowboats.

What's the purpose of the chains, hanging to the ground, from the undercarriage of rescue vehicles?
A solid path to ground in case of contact with power lines?
Might offer some protection to rescue guys in contact with equipment?
Lightening and power line hits travel through the steel tire bead and belts the rubber melts and burns. Most dump truck drivers and equipment operators know to stay in the vehicle, unless fire is involved. If you have to, you must leap as far as you can, off the vehicle. We hear of one every so often in this neck of the woods. It's a grim reminder, particularly when you know or know of the guy. We have 2 "in loving memory of" stickers around here. They are generally found on dump trucks and excavation equip. They commemorate 2 guys, 2 separate accidents. Dump trailer contact with power lines. They didn't leap, they jumped. These were maybe 15-20 years ago. Fresh stickers are still available.

Bill

 

[Tin man]

If the old rule is still true, "safest place is in your car" than leave your RV, and stay in your car till the storm passes.  You can also sleep on a rubber sheet, and if you get struck during the night you will save the mattress....

Jim

 

[Jim Godward]

Or is it that pure water doesn't really exist, except perhaps in a lab?

-Don-  Reno, NV

You have it, and lab water does not stay pure for any real length of time  A few hours at most.  We had to check for megohms of resistance before it could be used.

 

[SeilerBird]

Try measuring distilled water with an ohmmeter. Or even rain water. I think you will be surprised. BTW, I have compared them all in an insulated  cup of water.

In a cup of water there is only an inch or so of water between the contacts.

 

[PancakeBill]

When I was doing some consulting work at Intel I noticed overhead piping labeled Ultra Pure Water.  I commented that must be some good drinking water, but no it isn't.  They apparently use it to clean, the Ultra Pure water is essentially unbalanced, and when in contact with anythng, will draw the impurities out of the item, bringing the UPW into balance.  (pretty low down laymen explanation). 

As to the conductivity, I would assume pretty low.

 

[Thubbadubba]

> The function of lightning rods is not to absorb or divert a lightning strike necessarily, but to try to prevent it in the first place.

Molaker, thanks for a great post. You raised an important point, one that I have little understanding of. My previous understanding was that a lightning rod was typically just an arrester. It collects the lightning and safely grounds it. I have read about the dissipation of charge via the sharp edges and points. I have seen various pics of lightning preventers going back into the 1930's and maybe earlier. I don't believe that arrestors and preventers are the same thing. From an online ad (http://www.lightningprotection.com/lightning-protection/) "Unlike traditional lightning rods which are designed only to collect strikes, the LEC SDAT is designed to delay upward streamer generation, reduce the risk of direct strikes, and function as a highly efficient air terminal".  This company has a number of devices that dissipate electrical charge (as you described) and in one description, " eliminates the threat of lightning strike formation within a protected area by using charge transfer technology to keep the electrical field below lightning potential."

Does this sound right to you? It is true that an arrester can have both functions.

I cite the ad only as an example, not necessarily as a definitive source.

I was searching for info on RV lightning safety when I ran across this site. I just joined up- this is my 1st post. I am considering an extensive trip about the country in my 21' Ford E350 class C diesel. I drove the Nez Perce Trail Road [1] several times, thinking about doing it once more. Once in a Toyota PU with a Casita over-head camper. I spent the night inside a thunder cloud with lightning all about me for hours.

[1] Darby road, Montana rd, from Red River ID to Darby MT, 110 miles via a 100 yard wide corridor between four huge wilderness areas. Gotta be some good birding in there...

 

[WILDEBILL308]

Thubbadubba, welcome to the forum. You can find lots of good information in the library as well as doing searches. One thing you might want to be aware of is the dates on the post. While this is an informative post the last post was October 13, 2013.
Your trip sounds interesting.
Bill

 

[Gary RV_Wizard]

Semantics, I think. A lightning rod works by more-or-less continuously bleeding off the static charge in an area, thus reducing the probability that a major discharge will occur (at least not at that point). There might still be a strike a 100 yards away (or a mile away). It's not really a collector in the sense that it sits there waiting for a big bolt to hit - hardly anything would survive that anyway. Think of it more like a series of small strikes, mostly too small to produce visible light and sound see, that bleed off the charge imbalance in that area. But it still provides a conductive path to earth ground that will reduce or prevent damage in the vent the rod does take a sizable hit.

So yes, a "lightning prevention system" does both things, protecting a structure by reducing the likelihood of a damaging strike and also helping to carry the charge away in a less harmful manner.

 

[John From Detroit]

Semantics, I think. A lightning rod works by more-or-less continuously bleeding off the static charge in an area, thus reducing the probability that a major discharge will occur (at least not at that point).

Having been raised in an area where lightning rods are common, They taught us in school how they work.

And.. You are correct. that is how they work.

Fact: The cable that connects the lightening rod to ground can not survive a direct hit.

 

[blw2]

Being in an RV, because of it's metal cage, is, relatively speaking, a very good place to be in an electrical storm.  Now it's not the best in a tornado. 

This would be true in a  sheetmetal sided TT or MH, but I'm not so sure about my MH.  It has metal structure frame, but there's a lot of glass and other stuff between.  Not really what I think of as a Faraday cage.

Just my intuition, but I'd think the antenna might make a really attractive thing for lightning to jump to from a nearby tree.

 

[HappyWanderer]

What's the purpose of the chains, hanging to the ground, from the undercarriage of rescue vehicles?

It's an old post, but I'll answer the question. They're automatic tire chains that spin against the inside of the tire when you hit the switch in the cab. If you look closely, you'll see that they don't actually touch the ground unless deployed.  They're not as effective as regular chains, but are a whole lot easier to use.

 

[Deano2002]

Water does not conduct electricity. It is the minerals in the water that does the conducting. Rainwater has very few minerals therefore it does not conduct electricity.

I beg to differ with that statement, I got hammered standing in clean water. How long does it take rain water to gather up some minerals once it hits the ground?

 

[Lou Schneider]

Perhaps it would be more accurate to say perfectly pure distilled water doesn't conduct electricity. 

Any contaminants, minerals, dust, dirt, etc. added to that pristine distilled water will make it conductive.

Keeping the cooling water clean and pure is a major concern in liquid cooled high power transmitters, where there may be several thousand volts difference between one wet part and another.