# cross polarity



## TV175 (Jan 30, 2012)

Hi all
I've heard some stories about cross polarity on foreign sites and that it can mess up your van electrics? Can anyone tell me how to test for cross polarity on a site ? do i need to take a meter with me ? and what if the socket does not have an earth ? possibly taking the motor home abroad next year
Thanks
john+julie


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## Zebedee (Oct 3, 2007)

Hi J and J

It's your choice of course, but if I were you I would forget about it.

Your van will almost certainly have continental double pole switches anyway, so you haven't a thing to worry about.

Even if it doesn't, your van electrics will not be messed up in any way, and you will be in no danger unless you pull an appliance apart and start firtling about inside . . . without switching off at the mains *and pulling the plug out*. _(That's known as Darwinian Selection! :lol: )_

The subject has been done to death many times, so I won't go on. Suggest you do a quick search if you want more info - but be warned. Some of the "_expert opinions_" expressed are not very expert!!!

No earth connection is another matter altogether, and potentially far more serious. I would get a cheap meter, and if there is no earth go to another hook-up point and inform the management.

We have >> this one << and it's simplicity itself to use.

Dave


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## listerdiesel (Aug 3, 2012)

As Dave has said, nothing to worry about as European sockets generally aren't polarised in the same way as UK ones are.

As the supply is AC, the 'polarity' changes every 20ms at 50Hz, so polarity isn't an issue.

We are more conscious of the polarisation of plugs and connections in the UK as our AC supply Neutral is bonded to the Earth at the building entry point (Look up PME - Protective Multiple Earthing) 

Our Schuko 16A European plug for outdoor sockets will happily fit either way round when we are in Europe and we have never had any issues at all.

Peter


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## Zebedee (Oct 3, 2007)

Peter's post reminded me. :wink:

You will need an adapter like >> this one <<

Make sure the plug has a hole in it - this can clearly be seen in the images. It's for the earth pin, which may or may not be present. Some sockets use the pin, while others use a double edge band of metal for the earth contact.

You can buy plugs designed only for the latter, *but don't*!!! They are useless if you need to use a socket with an earth pin, 'cos they don't have a hole. :roll:

Dave


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## bognormike (May 10, 2005)

here's a detailed explanation from our members guides

http://www.motorhomefacts.com/ftopic-70164-0-days0-orderasc-.html

I spent alot of time fiddling about with changing over but gave up

:roll: I do have a tester similar to the one mentioned, and it's useful to check that everything is OK.


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## listerdiesel (Aug 3, 2012)

We have this one:

http://www.amazon.co.uk/outdoor-connector-hookup-Belgium-Germany/dp/B001T73LUY

on a long extension lead with 16A BS4343 socket.

The adapters with right-angle plugs can be a problem if you have closely-fitted sockets, the plug hangs down over the socket below.

Peter


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## emmbeedee (Oct 31, 2008)

Zebedee said:


> We have >> this one << and it's simplicity itself to use.
> 
> Dave


I bought what looks like the identical tester from Aldi recently. Price was about £2 IIRC.


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## Zebedee (Oct 3, 2007)

emmbeedee said:


> I bought what looks like the identical tester from Aldi recently. Price was about £2 IIRC.


You just ruined my day!!

Hope you are suitably ashamed of yourself!! 8O

Dave :lol: :lol:

P.S. I don't think it matters which one John gets - they all work the same.

I linked to one which shows the various read-out configurations fairly clearly on the image, in case he wanted to study them.


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## grizzlyj (Oct 14, 2008)

Hiya

I also have a short lead with a blue (male!) plug one end and a UK plug the other. If you find a pitch with a mains problem (or even no power at all!) its a lot easier to walk with a short lead than driving around!

If the campsite uses the Euro plug then you connect the one I've pictured to the one linked to above, so two sections and about 2' long, but covers all scenarios here and abroad for checking the mains on foot with the test plug.

Looking in a French DIY Leroy Merlin I found a Euro plug equivalent mains tester too! 

I've also found a UK tester with LEDs which often seems more sensitive and gives an earth reading when the one shown won't which is a bit odd.


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## Patrick_Phillips (Aug 17, 2006)

Another reason for having a little polarity tester - to find out if there is any juice in the socket at all.
Many campsites have multiple sockets for you to select. They are often not well maintained or the previous user has blown the trip and it hasn't been reset by the management.
So... a polarity tester in a socket on a short wire is magic for hunting down the working EHU.


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## TV175 (Jan 30, 2012)

thanks to all for your valued comments 
The stories of people ruining their van electrics are just that STORIES
THANKS ONCE AGAIN
J + J


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## Penquin (Oct 15, 2007)

Agree that it is not something to lose any sleep over, it will not muck anything up even if it is wrong....

our house works quite OK yet, according to the polarity tester it is not wired up properly 8O :roll: but everything we brought from the UK works OK, ev everything we have bought in France works OK and we are still alive.....

We do carry a polarity tester (hence how I know our house is not what we would expect) and a reversing connection "just in case" but that is because we have had that equipment for 20 years+ from caravan days.

There are much more important things to worry about (have we got a corkscrew, is there enough room for wine, how much French sausage is a reasonable portion.........) so don't worry about the physics of alternating current.........

As Dave said ages ago (well three pages) - you are only at risk if you decide to perform open heart surgery on an appliance that is still plugged in - unplug it and you are perfectly safe...... (exactly the same applies in the UK - don't tamper with the insides of things that are connected still.)

Dave


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## lesanne (May 1, 2008)

Have used all Testers for reverse polarity ,,but no earth bis diff ,,we used to carry a couple of metre legths of metal screw ,and wire ,to be sure we would make our own earth ..but havent bothered for some years now ,and were still here..Les


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## 100127 (Jul 20, 2006)

Zebedee said:


> Hi J and J
> 
> It's your choice of course, but if I were you I would forget about it.
> 
> ...


Dave, are you saying that reverse polarity on modern MHs is not a problem? My Sargeant box has a light which tells me polarity is reversed. I stick in my short Male/Female lead which I made up to reverse it back again. What your saying is I don't need it, correct?


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## Zebedee (Oct 3, 2007)

Blobsta said:


> Dave, are you saying that reverse polarity on modern MHs is not a problem? My Sargeant box has a light which tells me polarity is reversed. I stick in my short Male/Female lead which I made up to reverse it back again. What your saying is I don't need it, correct?


Hi Blobsta

It's not a problem on any motorhome if you unplug appliances before opening them up and delving inside - as has been explained in this thread and many others. :wink:

I was referring to Continental motorhomes in my first post. John has a Dethleffs, so that will almost certainly have double pole switches. No problem there then, even if appliances are not unplugged before being worked on. They will be totally isolated if the mains switch is in the off position. _(I would still unplug though - most definitely!!)_

My Sargent unit has the same indicator as yours, but I never bother with it. Continue to use your short lead by all means if you have any concerns. It won't do any harm and if it puts your mind at rest it's worth the minimal effort involved. 

Dave


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## bigtwin (May 24, 2008)

Blobsta said:


> Dave, are you saying that reverse polarity on modern MHs is not a problem? My Sargeant box has a light which tells me polarity is reversed. I stick in my short Male/Female lead which I made up to reverse it back again. What your saying is I don't need it, correct?


Correct! 
Unless you intend messing around behind panels etc WITHOUT taking all the precautions that Dave mentioned.


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## tonyt (May 25, 2005)

TV175 said:


> Hi all
> I've heard some stories about cross polarity on foreign sites and that it can mess up your van electrics? Can anyone tell me how to test for cross polarity on a site ? do i need to take a meter with me ? and what if the socket does not have an earth ? possibly taking the motor home abroad next year.Thanks john+julie


As has been made clear on this, and numerous other threads on the subject, the earthing check is far far more important than the polarity (polarisation?) check.

But don't kid yourself that it's restricted to foreign sites!

I've been to 2 CSs where there is no earth on hook up.

I would never hook up to any mains supply, in any country, without doing an earth check.


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## 100127 (Jul 20, 2006)

Zebedee said:


> Blobsta said:
> 
> 
> > Dave, are you saying that reverse polarity on modern MHs is not a problem? My Sargeant box has a light which tells me polarity is reversed. I stick in my short Male/Female lead which I made up to reverse it back again. What your saying is I don't need it, correct?
> ...


Thanks Dave xx

Bob :lol: :lol:


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## lifestyle (Apr 27, 2008)

Our control panel lights up red if reverse polarity,as already stated,not a problem unless you do something silly.

Les


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## bigcats30 (Aug 13, 2012)

I'd love to know who makes up these scare stories..........I would guess at whoever pockets it would benefit

Gas alarm anyone?


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## grizzlyj (Oct 14, 2008)

snipped


lesanne said:


> we used to carry a couple of metre legths of metal screw ,and wire ,to be sure we would make our own earth ..but havent bothered for some years now ,and were still here..Les


This I too used to carry, but have told here that it could potentially be very dangerous, so now don't  I don't know why though, sorry.


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## aultymer (Jun 20, 2006)

I would like some information on why no earth is a problem.


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## Penquin (Oct 15, 2007)

aultymer said:


> I would like some information on why no earth is a problem.


Good point and I hope someone will give both of us a clue; many French plugs do not have an earth connection as they are double insulated (whatever that means), the same applies in some things in the UK. I believe generators are also not earthed so I would also like to see a response to your point. If you are using a generator then presumably the earth connection on the electrical sockets would also say no earth connected but I have not tried it to see.

Dave


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## Scattycat (Mar 29, 2011)

Hmmm, I've never even thought about doing an earth check. 

I've just taken it for granted that there is one when we use mains hook-ups

Being a bit naive, I just assumed that while in the van we would be insulted via the tyres, providing it's not raining :roll: 

Anyway if there was a problem wouldn't the RDC(?) trip out?

Also many products, table lamps for instance, at home don't have an earth lead.

Should I be more concerned ?


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## tonyt (May 25, 2005)

Scattycat said:


> Hmmm, I've never even thought about doing an earth check.
> 
> I've just taken it for granted that there is one when we use mains hook-ups
> 
> ...


Yes, everything probably is as you say but I'm a belts-and-braces person and sleep well at night not wondering - what would happen if......... 

I wonder if I should apply the same approach to gassing?


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## Patrick_Phillips (Aug 17, 2006)

aultymer said:


> I would like some information on why no earth is a problem.


The original idea was that the earth would provide a better route for live lines to go rather than through you. Many electrical devices were made of metal so an escaping live wire would make the whole device live just waiting for you to come along, standing on the packed earth floor and give it a route home! Remember, earth and "neutral" are basically the same thing…

Then came plastics which pretty much took lamps and bulb holders out of the issue.
Then came the Earth Leakage Circuit Breaker - a device that killed the incoming live if any voltage appeared on the earth line. These would only work if the earth worked! So for vans with ELCB, the earth line was still important even though the tires kept us away from the ground.

Most modern vans have RCDs which measure the amperage between the live and neutral lines so that any "alternative" return route the live may have found will show as imbalance and switch off the live and neutral. This makes the earth pretty much redundant - unless the RCD fails!

So not as necessary for most as it used to be but, hey, its good to have if it is available, IMHO.

Patrick


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## Agilityman (Aug 17, 2009)

I'm glad this subject has just come up.

We're off to Germany in the next two weeks, so I've just checked that my polarity checker and polarity reversing lead are on board the van.

I'm a retired Electrical engineer, it dismays me that people advise to ignore the danger of reversed polarity. With reversed polarity it is possible for a metal clad appliance to be live to the touch, even though switched off. For this to be the case the earth must be faulty. So it is possible, probable? Well not very. Worth taking the chance? Well for a risk adverse person like myself - not at all, I will be checking the polarity at every hook-up.

If you want to risk it, it's up to you.


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## aultymer (Jun 20, 2006)

> With reversed polarity it is possible for a metal clad appliance to be live to the touch, even though switched off.


Would this metal clad appliance not therefore be live to the touch when switched on?


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## Zebedee (Oct 3, 2007)

aultymer said:


> Would this metal clad appliance not therefore be live to the touch when switched on?


Please don't ask awkward questions on MHF.

It upsets the natives!! :roll: :lol: :lol:


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## grizzlyj (Oct 14, 2008)

I know that French house wiring is quite often the wrong way round, but presumably they do something differently (as well as being 3 phase!?) to not make it an issue? The double insulated mentioned earlier???

Sometimes in the past I've had an earth in the van but not at the hook up plug! 

Is this thread going to remove all ongoing confusion?


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## Zebedee (Oct 3, 2007)

grizzlyj said:


> Is this thread going to remove all ongoing confusion?


Don't be daft Jason - this is MHF!! :roll:

Ponder on this though . . . how many people do you know who have been electrocuted, or even had a belt from the mains supply in their van - when they were *not *doing something stupid?

Further . . . how many do you know who *were *doing something stupid and got a shock?

You can bet your life it would have been reported on here straight away - probably blaming the dealer, motorhome builder, appliance manufacturer etc..!! :roll: 8O

Dave


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## aultymer (Jun 20, 2006)

> You can bet your life it would have been reported on here straight away - probably blaming the dealer, motorhome builder, appliance manufacturer etc..!!


or the Turkish traffic police!


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## Scattycat (Mar 29, 2011)

It's fun hear isn't it? :lol:


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## aultymer (Jun 20, 2006)

> It's fun hear isn't it?


no thats the other forum - the one that calls here! "the dark side"!!


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## listerdiesel (Aug 3, 2012)

tonyt said:


> TV175 said:
> 
> 
> > I would never hook up to any mains supply, in any country, without doing an earth check.
> ...


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## tonyt (May 25, 2005)

listerdiesel said:


> tonyt said:
> 
> 
> > TV175 said:
> ...


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