# Thunderstorms - what do you do?



## 98316 (Mar 25, 2006)

Last week we were away during a really big thunderstorm right over head. The four caravans pitched opposite us had their electrics fried, litrally, with their fuses melting, someones TV blowing up etc after their bollard took a direct hit. This was at 2am in the morning, and the sound as it hit was like nothing i've ever heard before and had everyone leaping out of bed and looking out of their windows to make sure no one had been hit directly and there were no flames etc.

So we were wondering what should we do in a thunderstorm? I had dropped the TV aerial about 5 mins before the direct hit, but no one else had. Should we unplug from the bollard? What precautions can we take or does anyone else take. I spoke to another motorhomer the next day and they said they didn't do anything. We know we are on four rubber tyres but is this enough. Would appreciate some advice as we are a mother and daughter team travelling alone and this did scare us slightly (even the dog leapt out of bed and he's totally unphased by storms). Thanks in advance, TravelBug


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## 98585 (Apr 9, 2006)

I'm no expert, (I bet one will be along in a minute) But I would hazzard a guess that you are OK to do nothing. You have four (or more) rubber tyres incontact with the ground, and the caravanner has probably only two but will also have 4 metal steadys on the ground!. I think that the safest place to be in a storm is in a vehicle but do not stay under large trees that can fall on to you if they are struck, 

Anyway thats my tuppence worth, let's wait to hear what that expert says.


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## 96299 (Sep 15, 2005)

Just stay as you are.never touch anything electrical while a storm is overhead.and thats my two bobs worth.. :lol:


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## olley (May 1, 2005)

Hi travelbug you are perfectly safe as long as you stay inside. 
The motorhome or caravan acts as a faradic cage so even if the m/h is hit you should be ok. 

I think unplugging might be a good idea, but if its lashing down with rain it wouldn't be top of my list of prioritys. Certainly a direct hit on the ehu post is going to do some serious damage to the electrics in your van and give you a scare. You may be sitting on rubber tyres but they will be soaking wet so providing a good route to earth.

Olley


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## asprn (Feb 10, 2006)

Slightly different, but we lost power 8 times since last Thursday, including a 19-hour outage (for which they're paying us £100  ). When the skies darkened again last evening, I went round the house & powered everything off I could (pooter, Sky+ box, TVs etc) to reduce the risk of damage (the power went off as anticipated 10 mins later).

Powering off & unplugging devices inside the van may save the devices.

Dougie.


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## Snelly (Aug 20, 2005)

Its good practice to disconnect any antenna from devices and unplug everything.

Its also good practice to open the curtains and watch the show!! Sally and myself love to watch lightening, its awesome.


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## eddied (May 9, 2005)

*What do you do in a severe storm?*

:roll:

Unplug or switch off everthing!, or better still both.
saluti,
eddied


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## 94969 (May 1, 2005)

We have a early warning when storms are about, the Sky programmes and Digital TV start to go funny, freeze on the picture, then flash up 'no signal received'.   
And this is progress, at least with old system you could watch tele till the Power went off.   

Roy and Helen


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## mangothemadmonk (Aug 6, 2006)

Personally I would unplug and make myself as low as possible by reducing aerial height.

While we were out in France in may we were treated to an awesome lightening display in Avallon. Nature is a wondrous thing.

Johnny F


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## RichardnGill (Aug 31, 2006)

Top Gear did a test with a car a while ago, they put Hammy in it and then recreated a lightning storm striking the car. He was well frightened but as the lightning struck the car it just seemed to disperse over it. I would suppose a M/H would be the same. I would rather be in a M/H than a caravan with the steadys down.

I would make sure if you have steady they are not down and the mains and ariels are unplugged like already said.

Then watch the show!

Richard....


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## Detourer (May 9, 2005)

The advise we have always _lived_, by over many years of Sahara travel [severer storms on flat open land] was to stay in the vehicle. Been caught out a few times with lightening striking the ground all around like incoming mortar rounds. I would just pop out of MH and pull the plug an lob the cable away from van [if you don't want to run to your electric connection point.


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## Rapide561 (Oct 1, 2005)

*Thunder*

Hi

I lower the satelite dish and that's it.

Lightning will strike a "high" point and there are always trees on campsites etc etc.

Russell


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## annetony (May 1, 2005)

I would just unplug everything, and as we havent got a fixed aerial I would just unplug it and chuck it under seat, then make a brew and watch rhe show  
Anne


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## thehutchies (Jun 25, 2005)

The Faraday cage effect, as mentioned earlier, is what makes it safe to stay in a vehicle during a lightning storm.
Here's an interesting practical application:

Cool job!


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## altair (Mar 25, 2006)

Hi 
Can anyone say what the construction of a MH body actually is.
For example fiberglass outer layer with decorative gell coat, foam core, metalic foil layer, plywood inner skin, decorative inner finish.

Hamond was safe in the car because it was a faraday cage ie bonded metal skin at the same potential as the lightning bolt and able to withstand the current flow

I don't think MH manufacturers bother to electrically bond the foil layer if fitted as it is there for thermal protection/insulation. and also if struck the foil would probably fry 

Probably the best advice has already been given Aerials/dish down unplug from bollard and recover the cable and wait it out in a bar if possible
Tim


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## framptoncottrell (Jan 6, 2006)

Modern car tyres have carbon added to the rubber to make them good conductors of electricity - it's one way of trying to avoid static build-up. In fact the Faraday cage wouldn't work terribly well if the lightning strike couldn't escape to earth through the tyres. I don't know whether the GRP of modern caravans would work as a Faraday cage: I suspect that GRP is a good insulator and would be useless - full aluminium cladding certainly would work pretty well.

So: disconnect everything from the mains hook-up; unplug all mains operated equipment, if possible; lower the roof aerial(s). And, contrary to what was said above, leave the steadies down - these will help channel the current to earth as well as the two tyres should you suffer a direct strike. (In fact lightning strikes go upwards from the earth to the clouds, but I'm sure you understand)

Then sit back and enjoy the fireworks.

Dr (musical, not medical) Roy


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## Boff (May 10, 2005)

Hi,

sorry for the late response, but I was on a business trip on which my laptop got nicked. :evil:

Basically, four kinds of hazard arise from a lightning strike: Direct hit, the electric field of a nearby hit dispersing over the surface, flying debris from "exploding" trees that are hit, and finally voltage surges on electrical lines. Let us look at all four of them:


Direct hit:
Clearly the most obvious risk, however a direct hit to a person is an extremely unlikely event. Except, of course, if you are standing on top of a treeless hill during a thunderstorm, then the risk is significant! And do not rely on that lighning will always hit only the highest point. Most times it does, but sometimes it does not, and then you do not want to be in its way! It also happens sometimes that lightning does hit the highest point, but then from this point a second lightning bolt hits something else.

In case of a direct hit to a vehicle usually the Faraday cage effect provides perfect protection for all persons inside the cage. However, firstly a Faraday cage requires _metallic_ shielding, and secondly electronic equipment inside the cage can still be fried. Nowadays, more and more motorhomes come without any metallic materials in their walls and especially roofs. So the Faraday cage effect does not work here. However, as lightning bolts are extremely short lived, they correspond to a very high frequency, and this high frequency induces another protective effect, the so-called "skin effect". Which means that a high-frequency current will flow mainly at the surface of a conductor, not inside. This skin effect explains why many people who have suffered from a direct lightning hit actually _survive!_ It is less effective than the Faraday cage, but should still provide sufficient protection to people inside a non-metallic motorhome.
The heat at the point of impact could however ignite a fire. Therefore all owners of motorhomes with non-metallic outer hull should take extra precaution when settling down; and preferrably select a spot not exactly on a hilltop or treeless plain.

However, in case of a direct hit into a vehicle, the voltage is so high that the insulation from the tyres provides no protection at all.

Indirect hit:
If people or animals die from lightning, then in by far the most cases the indirect effect of a nearby strike are the culprit. Background is: When lightning strikes, then the point of impact is suddently exposed to a voltage of several millions, if not billions of volts above normal ground potential. This incredibly high voltage has to disperse into the ground, and this induces a strong electrical field around the point of impact. The extension of this field and the local field strength at each point varies with the composition and humidity of the ground. Typically the dangerous range of the field extends over a radius of about 30 to 50 metres around the impact point. The current that this field induces in a person or animal strongly depends on the distance of the "contact points" to the ground, so usually the feet. This is why it is recommended to put your feet closely together if you if you are outside in a thunderstorm. This also explains why large animals like cattle or deer are much more likely to be killed in a thunderstorm than e.g. rabbits.

In contrast to a direct hit, the rubber tyres of a vehicle provide fully sufficient protection against the electrical field in the ground.

Flying debris:
It is not very well-known, but occasionally a tree hit by a lightning bolt literally "explodes", making branches and parts of the bark flying around.

Voltage surges:
Voltage surges can occur even if lightning hits a power line several kilometres away. This depends on the effectivity of the protection measures applied within the power grid and the local installations. While a voltage surge causes no harm to the inhabitants of a motorhome (or caravan), even in case of a direct hit into the EHU post, it can fry sensitive electronics. So it is recommended to disconnect hookup cables during thunderstorms.

So, some general precautions: If thunderstorms are likely to occur, be careful when selecting your place. Avoid open hilltops (like the former Cap Blanc-Nez!) and treeless plains. But also avoid deep and narrow river valleys, because of possible flash floods. If possible, disconnect electric hookup and any TV aerials before the thunderstorm. And while the storm is over you: *Under all circumstances stay inside!*

Best Regards,
Gerhard


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## Grizzly (May 9, 2005)

That was interesting Boff. I'd not heard about keeping feet together. 
We've been in two lightning strike incidents; once when camping at Spion Kop near Mafeking and holding on to the metal poles of the tent to keep it from flying away ( yes, I know, dimwits!) and once in our house high on the watershed in Zimbabwe. At that time the lightning struck the telephone cables on the roof and burnt all the metal door frame among other things. 
The smell of cordite is something I shall never forget.

Would it be slightly safer in the cab rather than the body of the van if the storm was overhead ?

G


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## Sagedog (Jun 28, 2005)

Good post and thanks for all the advise.

Further to RichardandGill mentioning the Top Gear faraday cage experiment I have fond the footage!!

Hamster Farady Cage (not cruel to fluffy animals)

Enjoy the stormy weather


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## Grizzly (May 9, 2005)

What an interesting clip. Thanks for send that. Just as he was talking about being advised to not touch anything made of metal I noticed he was leaning back on the latch of his seat belt ! Amazing that the thing started and he could drive off.

G


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## vicdicdoc (May 14, 2005)

During severe thunderstorms & lightning I alway hide under the bed with my thumb in my mouth . . it works for me


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## JackieP (Oct 15, 2006)

thehutchies said:


> The Faraday cage effect, as mentioned earlier, is what makes it safe to stay in a vehicle during a lightning storm.
> Here's an interesting practical application:
> 
> Cool job!


That is an excellent video and explains the Faraday cage effect better than anything I've ever seen or read.

Thanks.


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## vardy (Sep 1, 2006)

- Cheers folks! - I've just read all this lot. I have a primal penchant for running around in the stuff. Very seriously, seem to be a bit of a storm-chaser with a thing about rain and it's accompaniments.
Going to definitely keep my feet together now. But won't be joining Vic and co under the bed.
Will certainly do what has been advised when in the van.
All this probably won't stop me though - so does anybody know how much rubber I have to wear? -H 8O


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## Sagedog (Jun 28, 2005)

It was obviously much better on the TV when broadcast but you tube does it justice...

Sorry for Hijacking your post slightly {offtopic}


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## thehutchies (Jun 25, 2005)

Excellent post from Gerhard - it reminds me just how much I've forgotten.

As an apprentice in a high voltage switchgear testing department about twenty years ago, we used to crank up the lightning strike simulator, turn on the rain machine and then dare each other to run naked across the 50 metre wide testing hall.
Ah, happy days, simple pleasures!


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## dwwwuk (Dec 31, 2005)

Very comprehensive and informative post from Gerhard - excellent reading.

A subject which has facinated me - a question I have is if you have roof bars/ladder is that better or worse?

I would think in theory (just a guess!) that if you put the ladder down in a thunderstorm it may be safer (obviously as long as you don't get struck whilst putting the ladder down) - but that could be completely wrong.

Looks like there are a few storms bubbling up around the country now - the met office has issued a warning for Durham / Northumberland - http://www.weatherxtra.com/observations/uklightning.asp. Looks like there is potential for thunderstorms tomorrow and saturday afternoon/evening also - Convective times.

I think I read that you have more chance of being struck by lightning in the UK than winning the lottery (4 times higher I think..) again could be wrong.


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## 98316 (Mar 25, 2006)

Thanks everyone, your replies have been great. We now know what to do in a storm. It has certainly put our minds at rest. Everyone on this site is helpful. Thanks once again.


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## 97984 (Mar 5, 2006)

Detourer said:


> The advise we have always _lived_, by over many years of Sahara travel [severer storms on flat open land] was to stay in the vehicle. Been caught out a few times with lightening striking the ground all around like incoming mortar rounds. I would just pop out of MH and pull the plug an lob the cable away from van [if you don't want to run to your electric connection point.


Not sure if chucking a live mains cable around in pouring rain is a sensible idea :?


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## Malc (May 9, 2005)

....and another site monitoring thunderstorms.
Malc

http://www.isleofwightweather.co.uk/live_storm_data.htm


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## jonnowycombe (Mar 2, 2007)

Firstly it does not really matter what a cage is made of and secondly if you are supported on tyres youre fine. Dont worry if your MH is wood or metal or GRP - you will be fine inside.

In lightening storms I just make sure the over equipped caravanners have ariels taller than mine - then Ill be fine  Oh and park away from trees.

And then I tell the girlfriend scary stories and enjoy the free cuddles !

Jonno


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## Suenliam (Mar 22, 2006)

So - I park away from trees, but not in the open. Stay in the MH, but don't rely on the Faraday effect. Don't put the steadies down, but if I do then it does not make much difference, unplug the cable, but don't touch it :? 

I'm with you Vicdicdoc -think I'll continue to put my head under the duvet and put my fingers in my ears. Second thoughts - think I'll sing. It's bound to go away then :lol: 

The real question is "Why don't thunder storms occur at a time of day when you can go to the bar and not risk frying in your own MH?" 

Sue


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## G2EWS (May 1, 2006)

Great thread and excellent answers.

The important thing to remember with lightning or surges caused by lightning (or electric supply) is they are looking for one thing - the best possible earth they can find!

That is why buildings have lightning conductors. So the strike can hit the conductor and run straight to an earth pit, which will if installed correctly be the best earth available.

We are one of the largest independent suppliers of lightning and surge protection equipment to the UK water industry and it still amazes me that some engineers miss this point.

With regards to MH's and caravans then the only real worry is a direct hit, which as has been pointed out is very rare and is still unlikely to cause a problem as the skin effect will come into play and take the strike to earth.

If you want to protect your valuable electronic equipment when you are in a storm then all you need is a good lightning protection device going to the best earth. As an example some of you are aware that we sell radio communication equipment to Water Companies that is used to take reservoir level information to nearby pumping stations. We need to look at three possible entries for lightning and surge:

1. Aerial
2. Power source/supply
3. Externally connected devices, typically a unit that is put in the reservoir to determine the depth (for those technically minded this is a transducer)

That is not the end of it however! Each protection unit which creates a short to earth once the surge gets to a certain level must have it's earthing point at exactly the same electrical level as the other two!

We where involved with the supply of a lot of protection equipment for a site on Bodmin Moor. When there was a storm and all the kit blew up, we where blamed. Further investigation showed they had not protected one aerial! It was enough!

Finally by way of example as to the best earth:

We where asked to protect a bunker for the MOD. Investigation showed there was no earth available! Simple we drove a stake through the concrete wall and even though it was not a perfect earth, it was the best available in the bunker so would be where any strike or surge would ultimately be looking for.

For those looking to read further here are four datasheets we give to customers:





































These come from one of our main suppliers Zymax.

Regards

Chris


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## sallytrafic (Jan 17, 2006)

With Boff and G2EWS's posts there is hardly anything to add but I suppose having survived a lightning strike I might add a little. A colleague and I were in a GRP hut next to a 100' mast when the strike occured - instantaneous flash bang which left both of us deaf for a while. We saw the flash though the green sides of the hut but it still 'burnt' the image on our eyes. It actually didn't hit the mast. As far as we could tell it hit the overhead mains supply cables but it could have hit cable tray on the outside of the hut which was burnt. The incoming mains surge arrestors (Bowthorpe) vapourised, all that was left inside the metal box was a little bit of din rail and the inside of the box was shiny where the vapourised metal had condensed. Most of the electronic equipment inside the hut was fried including a Fluke DVM (multimeter) that was switched off in its bag. However once we got mains back and replaced some fuses damage wasn't too bad for example a rack of radio equipment was uneffected apart from both 240V switch mode power supplies which were melted, when they were replaced the system worked fine. One other radio never got repaired although the fuse was intact the inside was just destroyed burnt circuit boards melted looms etc and it was in an aluminium die cast box! Of course its aerial some 80' up the mast could have also had a tickle (buzz words for a minor strike) at the same time.

Apart from the flash and bang we were not harmed, so the skin effect plus the abundance of direct paths to earth saved us. Mind you we had to go to the pub for the rest of the day 

My advice in thunderstorms is consider your options, if the storm is a fair way off disconnect hookup and move from under trees otherwise just stay in your van with electrical equipment switched off. >See here.<


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## lindyloot (May 20, 2007)

*lightening*

I found it very interesting reading all the replies on the subject, the old saying is true " you learn something new every day"


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## johnandcharlie (May 2, 2007)

sallytrafic said:


> My advice in thunderstorms is consider your options, if the storm is a fair way off disconnect hookup and move from under trees otherwise just stay in your van with electrical equipment switched off. >See here.<


I suppose that's where a panel van is best as it's all metal.


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## sallytrafic (Jan 17, 2006)

One thing I meant to say is that lightning obeys physical laws but often (apparently) in a chaotic way. So for example after a direct strike to a lighthouse everything seems to be working fine, all but one battery charger deep in the heart of the building. A change of a circuit board fixed it but we found several tracks in low current control circuits literally evaporated off the board. Then in a different incident everything ok except that some exposed hinges on a piece of racking were welded together. 
One cannot emphasise too much the extremely short time that the individual current pulses last (a single strike is made up of many such pulses) One result of this is that parts of the same lightning conductor a few feet apart will be at a different potential during the strike, the bend in a lightning conductor will be 'seen' as an open circuit whereas an actual gap will be no barrier at all.


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## JackieP (Oct 15, 2006)

*Re: lightening*



lindyloot said:


> I found it very interesting reading all the replies on the subject, the old saying is true " you learn something new every day"


Agreed. This is a superb thread and I too have learned such a lot. Thanks everyone for sharing your knowledge and experiences.


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## chrisjrv (May 7, 2007)

So basically, sit in the van and worry about it! :wink:


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## thesnail (May 1, 2005)

*just a thought for Vic*

Rosemary wants to know how you managed to get out of bed to hide under it, or are only talking about thunderstorms that occur in the afternoon.

Bryan


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## slamdunk69 (Apr 16, 2006)

Hey
Not wanting to put a spanner in the works, but a Faraday cage only works if you are inside it! Anyone (and that includes ourselves) with a coachbuit with an overcab which has a fibreglass roof AND sleeps above the cab, is actually sleeping above the metal roof of the van and therefore outside the Faraday cage. 
Fortunately the majority of vehicles have aluminium sheet somewhere within the skin of the vehicle and this is a far more suitable earth for any prospective lightning bolt to be attracted to, so you're probably safe......
On balance though, and not wanting to chance it I think in future I'm going to get out of bed, unplug the hook-up, disconnect all the appliances, and then sit in the cab with a Horlicks and enjoy the lightshow!
Cheers


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## sallytrafic (Jan 17, 2006)

slamdunk69 said:


> Hey
> Not wanting to put a spanner in the works, but a Faraday cage only works if you are inside it! Anyone (and that includes ourselves) with a coachbuit with an overcab which has a fibreglass roof AND sleeps above the cab, is actually sleeping above the metal roof of the van and therefore outside the Faraday cage.
> Fortunately the majority of vehicles have aluminium sheet somewhere within the skin of the vehicle and this is a far more suitable earth for any prospective lightning bolt to be attracted to, so you're probably safe......
> On balance though, and not wanting to chance it I think in future I'm going to get out of bed, unplug the hook-up, disconnect all the appliances, and then sit in the cab with a Horlicks and enjoy the lightshow!
> Cheers


Yes but due to the 'skin' effect at the high frequencies involved the wet grp skin can act in a similar fashion to the cage. Consider people who have survived a lightning strike to their body, it only takes around 50mA across the heart to stop it and kill them. They actually survive MegaAmps in part because the hi frequency current doesn't penetrate far although the body is an excellent conductor of dc and low frequency electricity.


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