# Reverse Polarity Cross Over Lead?



## paul10june (Aug 7, 2007)

My Dad has a small length of hook up lead (about 2 feet long) where the live and neutral are reversed at on end in order to correct reverse polarity found on some foreign sites. He uses it if his polarity tester indicates a problem.

Like a fool I declined his offer to borrow it, saying I would buy one of my own - but there lies the problem!

No matter how I search google I can't seem to find one - can anybody help?

Paul


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## sallytrafic (Jan 17, 2006)

You'll have to make one (it would probably be illegal to sell in UK) You can do as I did buy the two ends and lop off a bit of your existing cable. Fit one of your new ends to the existing cable ensuring polarity is correct then fit the other end to your small piece you have lopped off ensuring the the earth is unchanged but live and neutral are swapped.


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## mangothemadmonk (Aug 6, 2006)

Just as frank has said. 

Just make sure you mark the patch lead up as revered polarity.

Johnny F


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## suffolkian (Jul 25, 2007)

If it's only 2 feet long I think you'll notice it's not the usual one.

Edited to say "sorry I didn't mean that to sound as rude as it does but you get my drift"


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## 100127 (Jul 20, 2006)

I made my own one and used a white cable so as not to get confused. Invaluable in France.


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## aultymer (Jun 20, 2006)

Have to agree with suffolkian.
Why would you mark it. 
There is also the school of thought that says "why bother?" If you do not intend working on any electrical equipment while hooked up some say it makes no difference.
Others say that if you do intend working on electrical equipment when hooked up then natural selection will work.


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## mangothemadmonk (Aug 6, 2006)

I have a selection of adapters that look similar, that's why.

Johnny F


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## aultymer (Jun 20, 2006)

> I have a selection of adapters that look similar, that's why.


It would be of interest to all, I am sure, to read what this selection does, in case we are missing something essential. I cannot think of another valid permutation involving a blue plug at one end and a blue socket at the other but I am not into elecktrickery.
A simple French/ German to UK adaptor plug is all I carry in addition to my standard lead for those few French sites still on old sockets.


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## Zebedee (Oct 3, 2007)

aultymer said:


> Others say that if you do intend working on electrical equipment when hooked up then *natural selection will work*.


_Love it. What a great quote. :lol: :lol: :lol:

I shall pinch it and use it everywhere except here (unless I forget) so thanks Aultimer.   _

Yes, I was puzzling about the various leads too?

I used to carry two or three, but only carry the French one now, and the plug end looks quite different so no confusion.

Johnny will no doubt enlighten us.


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## mangothemadmonk (Aug 6, 2006)

The top 2 on the left are the ones I use in France for EHU (2 pin). One is reversed the other one isn't. I use in conjunction with bottom right which is an ordinary plug socket and tester. I either use one or the other depending on which way round the +/-.

The back right is a rev pol patch lead (never used it)

The bottom left is just a plug for domestic if I park up at my Dads or friends and plug into garage etc.

Am I wrong? I don't know now I have a headache.

Johnny F


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## Zebedee (Oct 3, 2007)

Thanks Johhny.  

I think you probably are right, but I can't be bothered with all those leads.

No doubt I shall live to regret it someday soon!


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## sallytrafic (Jan 17, 2006)

Your top right is the one we always use for polarity reversal but then we don't tour France..

When you say two pin I think for the benefit of newbies you should stress that the earth is still made ie it may only have two pins but the earth is made by a strip down the side or a mating pin on the bollard.


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## 96706 (Nov 13, 2005)

We have all those leads as well. :lol: 
We just take all the reversed leads & the standard blue socketed adapter, when we hit Europe, we have found that we will use all /or some of them when abroad, as we use all grade of sites/aires.

Sod's law states: 
The one lead you need is the one lead you don't have. :roll: 

The english 3 pin ( bottom left in Johnny F's pic ) we use at home when hooked up on the drive. Or at a friends house :lol:


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## aultymer (Jun 20, 2006)

WOW, with that selection I am not surprised you need a labeling system but I would still question whether you are likely to forget why you have a 2ft long lead with a blue thing on each end, like no other in your extensive collection.

Can't the French plug be turned 'upside down' to give a reversal if you feel you must.

First time in France I corrected polarity every time, last time I only checked for Earth continuity. Nothing got damaged and I survived.
This is not a recommendation - only an observation.


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## Mandi (Jan 10, 2008)

We have two continental adaptors, one of which is wired reverse, but when the polarity light showed this year in Belgium I switched the lead to the reversed one and it still showed reverse polarity on the tester.

Can somone tell me why?

And yest I did get the right one 'cos I have written on it. Both continental adaptors look alike.

:roll:


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## jiwawa (Jun 22, 2007)

Is there something on the electric block that would tell you you have reversed polarity (2007 van - my instructions are in German)? Or do you need to buy a polarity tester?


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## mangothemadmonk (Aug 6, 2006)

Do you mean the charger in your MH or the EHU on site?

I don't think there is anything on your charger but you can get an add on which tells you/switches over if you plug into rerverse reverse polarity.

Switch over

There is usually nothing to say on a bollard that it is RP. Best get a tester. They are pretty cheap. Have a look ....

Tester @ Maplins

Johnny


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## sallytrafic (Jan 17, 2006)

Mandi said:


> We have two continental adaptors, one of which is wired reverse, but when the polarity light showed this year in Belgium I switched the lead to the reversed one and it still showed reverse polarity on the tester.
> 
> Can somone tell me why?
> 
> ...


Yes the supply was probably 'IT' (nothing to do with information Technology) the letter I " - indicates either that the supply system is not earthed at all, or that the earthing includes a deliberately-inserted impedance, the purpose of which is to limit fault current. This method is not used for public supplies in the UK."

The T " - all exposed conductive metalwork is connected directly to earth."

I have come across IT supplies twice, inside a UK hospital operating theatre and on a campsites in Norway - where IT supplies are still common in the far North. On the campsites my polarity indicator either indicated it was OK whichever way the plug was connected or reversed whichever way it was connected.


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## sallytrafic (Jan 17, 2006)

aultymer said:


> WOW, with that selection I am not surprised you need a labeling system but I would still question whether you are likely to forget why you have a 2ft long lead with a blue thing on each end, like no other in your extensive collection.
> 
> Can't the French plug be turned 'upside down' to give a reversal if you feel you must.
> 
> ...


If for some reason its impossible to put the plug in the opposite way around (it has an earth pin or the cover requires the cable to point downwards) there is a simpler method that works. P

Plug in the Two pin (+ earth connector) then plug the reverse changeover lead then plug in your ordinary cable. If your cables are really short the two joints are still off the ground.

If that arrangement is required its unlikely that you are on a 16A circuit so the extra connections are not a problem voltdrop wise.


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## sallytrafic (Jan 17, 2006)

I meant to give a plug to where I get my electrical quotes from its here:

>TLC<

This saves me keeping an up to date copy of the full British Standard Wiring Regs to prompt my memory. If you rely on this or other guide it is worth remembering that it can be out of date as unfortunately this one currently is 

His book is up to date though and can be ordered from the website.


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## jiwawa (Jun 22, 2007)

mangothemadmonk said:


> Do you mean the charger in your MH or the EHU on site?
> 
> Johnny


I meant the electric block inside the van. We use to be caravanners and on both the vans we had from 1993 there was some kind of trip switch that flipped if the incoming electrics weren't right - I assume it would have tripped with reverse polarity.

But the Maplin's thingy looks the business so I shall get one of those before we head off.

Do you have to go to a Caravan/Motorhome place to get the male/female plugs for motorhome electrics or are they to be found in Maplin's or B&Q?


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## sallytrafic (Jan 17, 2006)

An RCD or a MCB will not trip on reverse polarity


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## hilldweller (Mar 8, 2008)

JWW said:


> Do you have to go to a Caravan/Motorhome place to get the male/female plugs for motorhome electrics or are they to be found in Maplin's or B&Q?


http://www.marcleleisure.co.uk/CBE/CBE01.htm


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## mangothemadmonk (Aug 6, 2006)

JWW, the one in my picture came from B&Q a few years back. I think they still sell them. An electrical wholesalers would sell them as well.

Have a great trip whenever you go.

Johnny F


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## 110868 (Mar 26, 2008)

We tested our polarity tester recently using the 3-pin to blue (which came with the MH) from the house socket, then standard MH hook-up cable, the one we've been using for months to charge MH at home.......and it showed reverse polarity. 

After a lot of head scratching and an embarrasing thread on the forum, we discovered that the 3-pin to blue had reversed wires...are you following this?

So, we are guessing that reverse polarity doesn't seem to matter very much. Lack of earth would prob be very different?

Broadlady


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## sallytrafic (Jan 17, 2006)

Correct ac 'polarity' is just one safety net.

For those with double pole MCBs and double pole switching and who always unplug anything that isn't working before fiddling with it or never fiddle at all then for those people reverse polarity is not such an issue.

For an example of how reverse polarity could bite you I investigated the the following incident. A piece of toast caught in a toaster the guy switched it off and fished about inside with a fork. There was a flash and the bloke jumped a yard. They were in a portacabin and it had been connected up with reverse polarity. The wall switch which was single pole had turned off the neutral so the toaster was 'off' but the live potential of 230V was still present inside which he shorted out to earth with the fork. He was very lucky had the fork not been resting on the earthed frame he could have got fatal shock.

As it was he got a tickle but the rapid movement shot the fork across the table just missing someone's face.


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## AberdeenAngus (Jul 26, 2008)

That's right SallyTraffic. The other problem with reversed polarity is that you may have a short which blows the fuse, but the faulty bit of kit still has power to it !

Under normal circumstances reverse polarity on AC equipment has very little effect BUT it stops safety features working properly.

Bit like putting Paraffin in a fire extinguisher. It'll probably never matter, but when it does - you don't want to be around !!!!!!


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## aultymer (Jun 20, 2006)

AberdeenAngus - I like that one!!
Probably the best illustration ever.
Thank goodness the Germans fit double pole circuit breakers.


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