# Reverse Polarity



## Patsy (May 1, 2005)

Sorry about this but just to make sure I have got it right.

1. the 3 pin plug that goes into the site electricity box do I reverse the live and neutral on this one or the other end which goes into my own lead the other end of which goes into the motorhome.

2. If it is a 2 pin plug I presume it would be the same procedure to the answer to the above 3 pin query.

Thank you in anticipation.


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## GerryD (Sep 20, 2007)

Patsy,
It really doesn't matter which end you change as long as you remember which end it is and you only change one. With two pin, reverse polarity is not a concern.
Gerry


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## Patsy (May 1, 2005)

Gerry many thanks for your quick reply. This is probly a stupid question but i have to ask it If it doesn,t matter which end you reverse why do you have to remember which end you recversed.


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## GerryD (Sep 20, 2007)

Patsy,
You're right, senior moment brought forward. OOOOps!!!!!!!!
Gerry


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## CliveMott (Mar 10, 2008)

*EARTHING IS MORE IMPORTANT THAN REVERSED POLARITY.*

If you have a modern motorhome it will be equipped with an earth leakage current detecting main circuit breaker. (RCD) These breakers do this by accurately comparing the current flowing in the NEUTRAL wire with that flowing in the LIVE wire. If these currents are not almost identical (because some has flowed elsewhere - like via earth back to the transformer) then the trip will operate disconnecting both LIVE and NEUTRAL connections.

If you have an appliance with an earth leakage fault and the Mains hookup is connected correctly then the earth leakage trip will operate when you switch on that appliances ON/OFF switch.

If the mains hookup is connected with reverse polarity and you have an appliance with an earth leakage fault then the trip will operate as soon as you connect your hookup irrespective of the appliances ON/OFF switch (unless its double pole switching).

If you have an OVERLOAD situation then the circuit breaker supplying the circuit which has the overload will open irrespective of supply polarity. If this overload is because of an earth fault then the earth leakage trip will operate anyway.

So, I would not worry about reverse polarity unduly as faults will get picked up one way or another. Quite possibly sooner if the polarity is reversed!.

But what is important is good continuity between your Motorhome chassis and real earth via the earth wiring to and through the hookup. Who checks this?

But, 
The latest Autotrails, Autocruise, Kontiki, Bessacar and Timberland motorhomes include an indicator lamp to warn of reversed mains polarity. They can get confused in places like Norway though where the substation earthing is not necessarily the same as ours.

C.


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## Zebedee (Oct 3, 2007)

*Re: EARTHING IS MORE IMPORTANT THAN REVERSED POLARITY.*



CliveMott said:


> But what is important is good continuity between your Motorhome chassis and real earth via the earth wiring to and through the hookup. Who checks this?
> C.


I do Clive - every time.  

In fact that's all I use my polarity checker for! 8)

As I mentioned in another thread, I'm not bothered about reverse polarity, but a poor or non-existent earch connection is another matter altogether!!


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## Zozzer (Aug 13, 2006)

I once read that having no earth can dangerous in an all metal van conversion such as as our Autosleeper Symbol as you can end up being the earthing point for the entire site. Hence I've become paranoid about checking the supply, my lead, my reverse polarity lead before actually plugging into van. If there is no earth, then I'm using the vans leisure battery and not the site electrics

I recently came across a site in Lichtenstein that uses two pin plugs, however I couldn't get an earth. The site office sold me a Swiss adapter for 10 euro's. Well you learn something new every day.


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## tonyt (May 25, 2005)

*Re: EARTHING IS MORE IMPORTANT THAN REVERSED POLARITY.*



Zebedee said:


> In fact that's all I use my polarity checker for!


Likewise. 

During my last 8 week tour I drove out of 2 French municipals where I found no earth at several hook ups. And Im here to tell the tale


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## Patsy (May 1, 2005)

Thank you all for your response This is what I was dreading. Having read Garys reply I was contented Then other replies came in whitch totally confused me I fully appreciate what the intention was and do not wish to sound ungreatful but to a layman it all went over my head. Once again I really do appreciate your intentions


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## Rapide561 (Oct 1, 2005)

*Reversed polarity*

Patsy

I have a hook up lead that I made in order to deal with reverse polarity.

I used some "Tippex" to mark the end of the lead which had the reversed wires.

Russell


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## Zebedee (Oct 3, 2007)

Patsy said:


> Thank you all for your response This is what I was dreading. Having read Garys reply I was contented Then other replies came in whitch totally confused me I fully appreciate what the intention was and do not wish to sound ungreatful but to a layman it all went over my head. Once again I really do appreciate your intentions


Don't worry about it Patsy. 

I've got to go out now, but if someone else doesn't give you some easier guidance I'll do it tomorrow.

It can be very confusing, but can also be quite simple in practical terms. All you need is a polarity checker and test for "good earth".

If I forget tomorrow it will be senility (again!  )- so please DO send a PM or something to remind me.


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## oldun (Nov 10, 2005)

*Re: EARTHING IS MORE IMPORTANT THAN REVERSED POLARITY.*



Zebedee said:


> CliveMott said:
> 
> 
> > But what is important is good continuity between your Motorhome chassis and real earth via the earth wiring to and through the hookup. Who checks this?
> ...


The polarity tester is not a good tool to test earth connections.

It will show a good earth connection is only one strand of earth wire is connected. The only way to test it is to use a "mega" or the modern equivalent computer controlled device. However it is much better than nothing as it does show that there is some kind of earth.

The one thing modern van mounted equipment can do with reversed polarity is to put the plug fuse back into the positive line where it definitely should be - not in the neutral line.

If the plug fuse is small then with an overload this will blow (not the van fuse).

This will leave the device defective and LIVE.

If you don't mind this very dangerous condition existing in your MH then go on "not caring about reversed polarity".

To me safety is paramount and not something dreamt up by government spoilsports.

It takes only a few seconds to check for reversed polarity and correct.


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## Zebedee (Oct 3, 2007)

Hi Patsy

Sorry for the slow response, but my computer has been disconnected so we can put a lick of paint on the walls of the study. :evil: :evil:

*The polarity changer first.* Gerry is quite correct. You need a spare plug and socket just like the ones on your 25 metre hook-up lead, and a short length of cable - half a metre is plenty as the smaller it is the easier it is to store.

Then connect one end "correctly" and at the other end reverse the polarity of the blue and brown (live and neutral) wires.

Do be certain that the yellow and green *earth wire* is connected properly to the earth connection at both ends.

Then get a *Mains Polarity Tester* like this one. ::Click here to view::

They are all much the same, and come with a little diagram to tell you what the various lights mean. If it says the campsite polarity is OK, then hook up and get on with it. If it says the polarity is reversed, plug your short "reverser" lead into the hook-up lead - it doesn't matter which end, but it's probably more convenient to put the short lead in the hook-up supply post.

If the lights on the polarity tester tell you there is no earth connection - DO NOT USE that hook-up post, and inform the management of the campsite without delay.

There is some disagreement about how serious reverse polarity is, and the reasoning gets a bit technical. It's up to the individual to make their own decisions - assuming they have sufficient knowledge to do so.

As you quite openly admit, you don't have this knowledge so my advice would be to err on the side of caution. Do what Gerry and I have suggested and test the campsite electric supply every time you plug in your hook-up cable. (It should not be necessary in this country, but won't hurt to double check if you want to.) If the polarity is reversed you can fix that with your handly little cable. If there's no earth, disconnect, move to another supply bollard and report the fault.

I hope this is helpful to you

Regards


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## Patsy (May 1, 2005)

*Polarity*

Thanks Dave. Your advice is greatly appreciated. Simple and easy to understand just like Daves. It wuill be interesting to watch what will follow on the Forum.


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## Zebedee (Oct 3, 2007)

*Re: Polarity*



Patsy said:



> Thanks Dave. Your advice is greatly appreciated. Simple and easy to understand just like Daves. *It wuill be interesting to watch what will follow on the Forum*.


Probably nothing Patsy. :roll: :roll:

This topic comes up quite regularly, and members who have been around for a while will be fed up with it.

*I don't mean that in an unkind way*, but after responding to the same question several times on a monthly basis, one can hardly blame anyone for passing over the thread without making a contribution.  

That's why there is a search facility, and if you put in "polarity" and hit the button you will see what I mean!! 8O 8O  

Regards


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## Patsy (May 1, 2005)

*Polarity*

Re my last post I should have said Just like Gerrys and not Dave Sorry Gerry. To everyone else if I sounded anyway offensive please accept my apology it was never my intention


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## Zebedee (Oct 3, 2007)

*Re: Polarity*



Patsy said:


> Re my last post I should have said Just like Gerrys and not Dave Sorry Gerry. To everyone else if I sounded anyway offensive please accept my apology it was never my intention


No problem Patsy, and Gerry won't mind I'm sure.

Nothing at all offensive here. 

Wish everyone was as polite - I'd be out of a job!!


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