# Reversed polarity



## Poco Loco (Nov 2, 2010)

HI All,  Once again I need some help from you more experienced out there. I am due to pick up my first MH in Dec' and head back through France on route to Spain.  I understand about Reversed polarity, but I was wondering if it is still a problem with modern MHs i.e does the control panel automatically reverse the polarity if required?  

The link below to the caravan club website and the Reversed Polarity PDF gives some information about reversed polarity and suggests making a second connector with the Live & Neutral incorrectly wired in order to reverse the polarity back to the UK norm.  My question is how will I know if it is reversed as anything I plug in (TV etc) would automatically correct the polarity and work anyway.  I know that if the polarity is incorrect the earth could be the switch and the item left live, but thats only a problem if I'm working on it, in which case I'd just unplug the van and isolate it anyway.

Finally, and probably most important, what connection am I going to need for electric hook up in France?  Is it just a French 2 Pin Plug without an earth similar to the Spanish ones?

Thanks once again Thanks in advance for all our help and Tips.

Regards Poco Loco

Overseas advice leaflets | Planning your trip | The Caravan Club


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## vwalan (Nov 2, 2010)

the easiest way is never use ehu. ..i fitted it on mine used it while i was building the inside .but havent used it ever while travelling. big waste of money . well i think 50quid for a trip fuses box etc .


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## lebesset (Nov 2, 2010)

there is no such thing as reverse polarity 
all mains electricity is alternating current 

if you have a uk made motorhome it is possible the trip will be on the live connection only , otherwise there will be a trip on both live and neutral


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## Poco Loco (Nov 2, 2010)

*Connectors*



***** said:


> You need a reverse polarity tester (about £7 from caravan shops)
> and make up a short lead with the neg & pos reversed and you must clearly mark it accordingly so that it cannot be used when the polarity is normal.
> For France most electric hook ups are now the blue three pin round connector, but some of the older sited still use the two pin.
> Oh, most vans don't have automatic change over except for very new or expensive vans.


Thanks *****, Looks like I'll need a whole host of cable variations in order to connect the Tester and Cable to the van.  Might be easier to just start up the "Genny" LOL

What array of cables do you use or do you just not plug in?

Regards Poco


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## Kontiki (Nov 2, 2010)

What is your van? The reason being that continental motorhomes are usually protected by having dual pole trip relays. The only reason I see that 'reverse polarity' being an issue is that a British electric system only trips out on the live wire, this means that if the polarity is reversed then the neutral wire could still be live if the relay has tripped & even the fuse blown, the danger then is if you were to open the plug or appliance while still connected (can't see anybody doing this) then you could get a shock. I assume that having dual pole trip switches also means they don't need to fuse the plugs. I have a polarity tester I bought many years ago but my current van has dual pole relays so it doesn't matter.


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## Fleming (Nov 2, 2010)

lebesset said:


> there is no such thing as reverse polarity
> all mains electricity is alternating current
> 
> if you have a uk made motorhome it is possible the trip will be on the live connection only , otherwise there will be a trip on both live and neutral


I can only second that. We really do have alternative current everywhere on the continent (240 V) for about 60 years now . You really don't need a polarity tester. (your polarity will only change 50 times /second !)
You'll encounter practically everywhere the bleu EEC-socket. At some places there still are the french-belgian sockets with the neutre-pin (or german ones with side neutre, mostly they go together in one socket - have a plug with a neutre hole + side ones.) A GB-2 pin generally could be plugged in also, but without earth.


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## Airecraft (Nov 2, 2010)

I agree that reverse polarity is not relavant to AC. My van's control panel warns of RP when charging from a genny without an earth - presumably other RP warnings occur when the earth follows the neutral instead of the line.


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## Kontiki (Nov 2, 2010)

Another thing that the plug in polarity tester tells you is if the wiring is earthed.


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## Talbot Bertha (Nov 2, 2010)

> lebesset
> 
> there is no such thing as reverse polarity



Yes there is!!!

The biggest problem with reverse polarity on the AC occurs if a fault develops on a 240v circuit because the fuses are efficively in the neutral line, if a line (live) to earth fault develops and the fuse does blow a fault current will still exist because the neutral is now live and is not fused, this can lead to fires as the current could be in excess of the cables rating.
 On another note the polarity does not change 50 times a second this is confused with the phase angles rotating between 0 degrees and 180 degrees 50 times a second (50hz) which gives the AC waveform. 
So i would suggest using a plug in polarity tester and using a short lead with the brown and blue wires reversed to correct this.
Trust me on this as i am a qualified electrician.


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## syldale (Nov 2, 2010)

*reverse polarity*

hi poco loco depending on the make of the m/h on the control panel there is a warning light  telling you if the polarity is reversed on site also if you connect a generator up to the m/h  it will show reversed polarity which we don't pay any attention to . For the sites we have cables made up to suite  . happy camping


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## Kontiki (Nov 2, 2010)

Am I correct in thinking that as my van is built to a continental specification & the trips are dual pole then the reverse polarity isn't an issue as both live & neutral are protected? Would like to have it confirmed by a qualified electrician.

BTW I found the easiest way to sort out the 'plugs' issue is to buy them in the country you are in.


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## Talbot Bertha (Nov 2, 2010)

Fleming said:


> I can only second that. We really do have alternative current everywhere on the continent (240 V) for about 60 years now . You really don't need a polarity tester. (your polarity will only change 50 times /second !)
> You'll encounter practically everywhere the bleu EEC-socket. At some places there still are the french-belgian sockets with the neutre-pin (or german ones with side neutre, mostly they go together in one socket - have a plug with a neutre hole + side ones.) A GB-2 pin generally could be plugged in also, but without earth.


 
We have always had AC, DC was never really used domestically!!


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## Poco Loco (Nov 2, 2010)

Kontiki said:


> What is your van?



It is a 2003 Rapido 785F.  Thanks for you input.  Regards poco


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## Talbot Bertha (Nov 2, 2010)

Kontiki said:


> Am I correct in thinking that as my van is built to a continental specification & the trips are dual pole then the reverse polarity isn't an issue as both live & neutral are protected? Would like to have it confirmed by a qualified electrician.


 
If the outlets are protected via a dual pole trip then if this trip activates you are fine but if the fault just blows the fuse at the appliance (in the plug) then the fault could still exist at the appliance. Double insulated equipment such plastic kettles dont have an earth so would be fine but if its metal then it would be earthed so could potentially become live.


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## Tony Lee (Nov 2, 2010)

Those who maintain that there is no such thing as reverse polarity in mains supply may be correct according to some strict (and irrelevant) definition based on DC supplies, but it might be better if they kept their own council rather than suggesting that there is never a practical reason to worry about when hooking up to a pedestal with active and neutral conductors transposed.

And as for hooking up to outlets with no earth ......

{talking about normal  mains supplies, not generators or fully-isolated inverters. These last two are special situations and the earth may not even be connected so normal "rules" may not apply}

BTW - regardless of the advisability of connecting your van to an unearthed socket in a campground, those visiting Morocco may have a simple choice - unearthed outlet or nothing. Continental spec'd motorhomes with RCDs (earth leakage breakers) operating in both active conductors still provide some measure of safety, but I hate relying on safety gear as the first line of protection.


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## Talbot Bertha (Nov 2, 2010)

Tony Lee said:


> Those who maintain that there is no such thing as reverse polarity in mains supply may be correct according to some strict (and irrelevant) definition based on DC supplies, but it might be better if they kept their own council rather than suggesting that there is never a practical reason to worry about when hooking up to a pedestal with active and neutral conductors transposed.
> 
> And as for hooking up to outlets with no earth ......


 
Reverse polarity on DC does exist that is why problems occur on older cars (Read very old) with a positive ground chassis and modern equipment. Put the battery in backwards in any DC equipment and it shouldnt work. Either way always pay attention to the polarity of any connection be it AC or DC due to the fuses being on the live or positive leg.


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## Poco Loco (Nov 2, 2010)

*Polarity Warning Light on with a Genny*



syldale said:


> hi poco loco depending on the make of the m/h on the control panel there is a warning light  telling you if the polarity is reversed on site also if you connect a generator up to the m/h  it will show reversed polarity which we don't pay any attention to . For the sites we have cables made up to suite  . happy camping



When I get the hand over for the MH I will ask the question about the Reversed Polarity Warning light.  I didn't know that the warning light would illuminate with a "Genny".  Any idea why this is so? I thought 240v with the correct polarity is 240 with the correct polarity, whether from the mains or a generator?

Regards Poco Loco


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## Talbot Bertha (Nov 2, 2010)

Could be because the generator is not really earthed. Try using an earth spike connected to the generator chassis this may cure it.


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## lebesset (Nov 3, 2010)

you are correct , negative polarity does exist ,but  in DC

reversed polarity is correctly defined as when the positive cable is connected to the negative terminal and vice-versa 

as there are neither positive nor negative cables with A/C current , but phase and neutral , perhaps the expression reversed phase and neutral would describe what has happened 

but to fit a trip which operates only on the phase cable is illegal in most countries , can't say if it would still be permissable in the UK


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## Talbot Bertha (Nov 3, 2010)

lebesset, If the Line (Phase) and Neutral conductors are reversed in AC (Single phase 240v) it is still referred to as reverse polarity(Even though technically AC has no polarity). AS i stated in an earlier post this is a problem if a line to earth fault occurs on a load (appliance) the fuse locally in the plug can blow but due to the line and neutral being reversed this has no effect and the fault still exists causing fires electrocution, death, a rupture in space time and all other manner of events that make you wish you had observed the polarity of your supply......


Most circuit breakers fitted to domestic distribution boards only break the Line conductor, RCD's break both the Line and Neutral.

*****, mains wont overload on the neutral side only the line (live) side. Double pole breakers are used to disconnect the supply completely as this is safer just incase a reverse polarity situation exists.


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## Talbot Bertha (Nov 4, 2010)

Wouldnt know to be honest ***** my current van is an old express and has a zig charger and the 240v is on a normal distribution board, I'm picking up my new one on saturday an '05 Ducato with a mclouis conversion so i'll have a poke around a see what's on it. Besides a working heater comfy beds and the lack of a shower over the kitchen!


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## Deleted member 9215 (Nov 4, 2010)

hi there

i have a chausson van whitch is French, we are thinking of takeing it to france next summer and was going to get a suitcase genny to avoid the reverse polarity , but these give a fault to  now im not sure what to do)

dunk


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## Kontiki (Nov 4, 2010)

The Chausson being a French made van, made for the French to use on their electricity system  If your worried get yourself a polarity tester & make up a short cable with the live & neutral wired the opposite way on either the pug or the socket. Personally I think in reality unless you have a problem with any of your electrics having reverse polarity doesn't make any difference. It is only the British who seem to have this obsession with the polarity to the Europeans they don't care as they build their vans to cope with the EU electricity supply. As I said a polarity tester will also check that you have an earth on the system which is probably more of a concern.


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## Deleted member 9215 (Nov 4, 2010)

Kontiki said:


> The Chausson being a French made van, made for the French to use on their electricity system  If your worried get yourself a polarity tester & make up a short cable with the live & neutral wired the opposite way on either the pug or the socket. Personally I think in reality unless you have a problem with any of your electrics having reverse polarity doesn't make any difference. It is only the British who seem to have this obsession with the polarity to the Europeans they don't care as they build their vans to cope with the EU electricity supply. As I said a polarity tester will also check that you have an earth on the system which is probably more of a concern.


 


hi there i never thought about it before i read about the problem with a genny.
i think this is the way i will go anyway incase i need it for when im wilding sometime

p,s thanks for the reply.

dunk


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## Tony Lee (Nov 5, 2010)

Could I suggest that since mains electricity does involve potentially fatal outcomes if the RV system supply and protection fails or is incorrectly installed or modified, those giving advice to persons with unknown skills and experience might be taken more seriously if they state their relevant trade or professional qualifications and experience.

One assumes that since "polarity reversers" are considered essential equipment for UK RVs even when hooking up in the UK, there might be some deficiency in UK regulations governing installations within RVs and parks that either is not present in European RVs and parks, or perhaps has been rendered irrelevant by superior equipment installed in European-built RVs.


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## John H (Nov 5, 2010)

Tony Lee said:


> Could I suggest that since mains electricity does involve potentially fatal outcomes if the RV system supply and protection fails or is incorrectly installed or modified, those giving advice to persons with unknown skills and experience might be taken more seriously if they state their relevant trade or professional qualifications and experience.
> 
> One assumes that since "polarity reversers" are considered essential equipment for UK RVs even when hooking up in the UK, there might be some deficiency in UK regulations governing installations within RVs and parks that either is not present in European RVs and parks, or perhaps has been rendered irrelevant by superior equipment installed in European-built RVs.



I don't know anything about electricity and this point is not about eletricity - it is about assumptions. Who is it that "assumes" polarity reversers are essential equipment and could it be that these people making the assumptions are the same people who make and sell polarity reversers? I don't know but I do know there are plenty of people who are willing to tell you anything to make a quick sale. 
PS we don't have a polarity reverser and have never had a problem - even on some dodgy-looking campsites in eastern Europe. Maybe we are lucky or maybe the qualified electrician we met in Luxembourg on our first trip was right and they are unessential in any van built this century.


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## Talbot Bertha (Nov 5, 2010)

John i'd have probobly needed one in Bertha as how she was wired reverse polarity could have been a problem if a fault developed, however i doubt one would be required in my new van or indeed any modern van. Now to finish off removing any bits i may need from the old one before i get the new one tomorrow  .


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## mildred (Nov 5, 2010)

I'd better declare first off that I am not a certificated electrician, and my day-to-day work involves sub 230V installations (except where that then feeds inverters - which is a whole other can of worms in installations that also have "mains" inputs).

So far in this discussion of reversed polarity nobody (unless I've missed it - for which apologies) has talked about the potentially (!) lethal effect that appliances bring to the party.

There are at least two important considerations:

1) Appliances are often switched only on the "live" wire.  If you have a reversed polarity supply then you're switching on the neutral - and in the event of accident or failure the exposed parts of the appliance could well be "live" with respect to earth *even if switched off.  *

2) Appliances are only fused on the live supply side. (Through the plug top connection and any internal fuses there may be). Again a fault can result in the exposed parts of the appliance being "live" with respect to earth should there be a reversed polarity supply *even with a blown fuse.*

Given the damp, crowded, accident prone conditions in many vans, I would not trust any unknown supply, and carry both the test gear to check, and the necessary adapter to correct, any reversal.

MildRed


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## John H (Nov 5, 2010)

Talbot Bertha said:


> John i'd have probobly needed one in Bertha as how she was wired reverse polarity could have been a problem if a fault developed, however i doubt one would be required in my new van or indeed any modern van. Now to finish off removing any bits i may need from the old one before i get the new one tomorrow  .


 
Good luck with the new van - can't wait to see it when we get back in the spring.


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## NicknClair (Nov 5, 2010)

***** said:


> Hi Talbot....
> I know what a dual pole circuit breaker is, but someone said that all or most European vans would have this.
> I wonder if mine has?


 
In reply to your post *****, European Vans vairy all the time, there is never any consistancy with the builders. We are forever check/modifying/changing AC set-up in motorhomes on a daily basis, inc guys that are still importing from Europe and the States. It is worth noting that most pre 2001 Hymer's we've seen have been single pole MCB with no RCD fitted.

Bottom line is this....................... AC can kill - no question!! We work with an attitude that if it is installed in a manner of polarities being the same, it should have the correct input to suit it's correct operating proceedures.

You should be checking for reverse polarity especially if like some larger vans if transfer switches are used (like on Combi Inverter/chargers etc), sensitive electrical equipment etc etc.

The other thing that concerns us as well is when larger capacity inverters are not protected/installed with correct protection circuits and not integrated to ring main's of the motorhome's in the correct fashion. The worst we see is where the output of the inverter goes direct to the input of the mains on the motorhome, not only is this lazy but it doesn't issolate the mains sockets and keeps other AC equipment connected to the AC line of the van.

Basic protection has already been suggested by previous posts (Polarity Testers, different made-up leads etc, all methods I have used in the past). Bottom line is - do not guess if it will be safe, because one day it won't be and something will happen!! AC electrics are not to be fooled with.

FYI, Best continental socket adapter I found was at a Carreflour Hyper Market, made by CampingGaz of all people and had a quick release change to swap the pos and neg terminals once tested. Cost about 19 euros.

I'm afraid now I'm a bit lazy this day'n'age and got an Auto-Change-over system c/w Earth test built in. I just take a look at the lights to see what it's doing at the time just in case there is no earth present. Has been swapped on the last 2 vans now and is easy to fit, if the mains socket into the van is accessable.


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## bluepilot76 (Nov 8, 2010)

*How does it affect the charging of the leisure battery?*

Hi all.
If I plug my van into the wrong polarity will it damage the van / leisure battery? I have a tester, but when I went abroad I realised reversed might be correct (as my van is a carthago malibu ie german). It seemed ok in France recently (I think the supply was reversed polarity at that site), but then the leisure battery went flat quickly whilst plugged in in Switzerland (I think it was normal polarity there). However in the past I have plugged it in for days in the UK without noticing any ill effects. Then again since nobody is talking about leisure batteries in this discussion maybe it doesn't matter after all and I juust have a fault in my recharging circuit? Any ideas would be welcome. Thanks, Richard


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## Kontiki (Nov 8, 2010)

bluepilot76 said:


> Hi all.
> How does it affect the charging of the leisure battery?



As said before polarity is probably not the correct term as the current on mains hook up is alternating current AC & the charger in your van to your leisure battery is DC. The only issue with the reversed polarity is a safety one regarding the neutral wire can be live & not protected by a fuse or trip.


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## bluepilot76 (Nov 11, 2010)

Thanks Kontiki. 
In that case I think maybe there was something wrong with the power supply at the Swiss campsite I was at, as the L battery seemed to charge well before that and has done ever since. I hope so anyway!


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## Byronic (Nov 11, 2010)

As has been stated many British M/caravans were fitted with isolation on the live side only, perhaps they still are. To overcome the potential problems,many owners fitted a changeover switch (named RYD) just before the circuit breakers if red warning light came on you just flicked the switch and green safe light came on.


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## lebesset (Nov 11, 2010)

there isn't either negative or positive with A/C by definition 
there is phase and neutral


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## Mick H (Nov 11, 2010)

Talbot Bertha said:


> We have always had AC, DC was never really used domestically!!



You young un's!!!
It was used domestically, not far from where you live yourself, in many Derbyshire pit villages, but that was  a long time ago, before the national grid.


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## Talbot Bertha (Nov 11, 2010)

Mick H said:


> You young un's!!!
> It was used domestically, not far from where you live yourself, in many Derbyshire pit villages, but that was  a long time ago, before the national grid.



Yeah, I realised that after i posted.


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## Byronic (Nov 12, 2010)

***** said:


> But to the layman such as me why do we see Pos (+) and neg (-) on many appliances and instruction manuals
> Why a red wire, sorry now brown, with a plus sign and a blue, now black with a neg sign.
> Surely everybody refers to them as neg and pos
> Well, I do anyway
> ...


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## Tony Lee (Nov 12, 2010)

The important thing is that some of the problems associated with getting active and neutral back the front in a system that either has no RCD or no double pole switching may only arise when other parts of the protective equipment fail, and even if qualified people explain what the problems are, those not qualified may not appreciate all the ramifications and if they carry out any changes or enhancement based on advice given on a forum like this one, the situation may end up becoming more dangerous.

The result of this is that any professional engineer or qualified tradesman should be very wary of giving such advice to those who may not be able to interpret or implement it correctly and safely.


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## Byronic (Nov 12, 2010)

Agreed, thats why a changeover switch would appear to me to be essential, at least you're sure thats what's coming into  your van, and have no control over is easily corrected, if not correct.


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## Tbear (Nov 12, 2010)

It would seem to be sensible to always check polarity and make a simple change over devise ie a short extension with wires crossed over, which is very well marked as having reverse polarity! that way if its not a problem you have done very little harm, perhaps a little more resistance on the earth. but if you have single pole switching it could save your life - Fires and Electric Shocks.


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## Talbot Bertha (Nov 12, 2010)

While i am a qualified electrician i am not qualified in the wiring of motorhomes/caravans etc, While in one post i did mention the use of a short lead made to reverse the polarity i would actually seriously suggest an automatic changeover device that is  installed by someone who is qualified to do so. Never take electrical safety lightly as i have seen many bodge jobs that while they may work could cause electric shocks or even fires in the right (Wrong?) curcumstances. 

And as Byronic says the fuse should always be in the Live, Line or Phase (Never heard of it referred to as active before) side. I would also say make sure the polarity is correct even with double pole breakers just to be safe.


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## NicknClair (Nov 16, 2010)

Tbear said:


> It would seem to be sensible to always check polarity and make a simple change over devise ie a short extension with wires crossed over, which is very well marked as having reverse polarity! that way if its not a problem you have done very little harm, perhaps a little more resistance on the earth. but if you have single pole switching it could save your life - Fires and Electric Shocks.


 
In regards to the gear fitted in my Swift, we ran a test to see if reversed polarity would harm any of the equipment just so we were armed with the correct info for our customers when fitting similar equipment (the last thing I want is a call from someone in Spain saying their unit had gone bang!!!).
The Combi Inverter/Charger Blew the moment it was engaged to mains supply and switched on, this was due to the switching relays leading to the charger and the mains sockets not matching in terms of input/output, basicly the system got confused and gave up!!.
Due to the expense of this unit (plus the minor detail of my van going up in smoke  ), then I want to know that whatever the circumstances, I has a set-up that can deal with all situations and I have the correct protection (i.e Auto Switch, RCD's including the inverter output etc etc). As the van is used in all situations (Bit like Ian Botham being a good all-rounder all year), I am covered whatever the situation but do not want to have the hassle of messing with leads etc.
It is worth knowing guys n gals that some european vans (did mention this earlier and at the moment there is a Burstner Delphin 2008my in the Workshops as a UK spec) not fitted with an RCD trip, only a MCB's. I know that most UK posts have RCD's, but it is still recommended that an RCD is fitted in the van as back-up. Most electrical posts abroad do not have the same passion as us Brits when it comes to electrical protection.


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## AndyC (Nov 16, 2010)

nickjvanbitz said:


> In regards to the gear fitted in my Swift, we ran a test to see if reversed polarity would harm any of the equipment just so we were armed with the correct info for our customers when fitting similar equipment (the last thing I want is a call from someone in Spain saying their unit had gone bang!!!).
> The Combi Inverter/Charger Blew the moment it was engaged to mains supply and switched on, this was due to the switching relays leading to the charger and the mains sockets not matching in terms of input/output, basicly the system got confused and gave up!!.
> Due to the expense of this unit (plus the minor detail of my van going up in smoke  ), then I want to know that whatever the circumstances, I has a set-up that can deal with all situations and I have the correct protection (i.e Auto Switch, RCD's including the inverter output etc etc). As the van is used in all situations (Bit like Ian Botham being a good all-rounder all year), I am covered whatever the situation but do not want to have the hassle of messing with leads etc.
> It is worth knowing guys n gals that some european vans (did mention this earlier and at the moment there is a Burstner Delphin 2008my in the Workshops as a UK spec) not fitted with an RCD trip, only a MCB's. I know that most UK posts have RCD's, but it is still recommended that an RCD is fitted in the van as back-up. Most electrical posts abroad do not have the same passion as us Brits when it comes to electrical protection.


This is a bit worrying, I don't really understand why 'reversed polarity' of the incoming mains supply should cause an inverter/charger to go bang. I'd very much like more detail about what you think the cause was and how you overcame the problem.

AndyC


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## Tony Lee (Nov 16, 2010)

AndyC said:


> This is a bit worrying, I don't really understand why 'reversed polarity' of the incoming mains supply should cause an inverter/charger to go bang. I'd very much like more detail about what you think the cause was and how you overcame the problem.
> 
> AndyC




ditto


...


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## NicknClair (Nov 16, 2010)

The Combi itself runs a CPU (which includes a power sharing device), plus 2 x relays. One to transfer the AC supply input to the ring main of the van, the second engages the output from the charger, but this is where it gets tricky. 
Due to the units ability to suppliment AC supply (i.e when on low current sites abroad), the unit takes power from the leisure batteries to increase it's output e.g I ask for 8A mains but only 6A site supply, the unit gives me the extra 2A from the leisure batteries if sufficent power is available. Once this high demand is finished, it simply goes back to full charge mode to recover what was used providing I am still not asking for more than the 6A the site electrics can give me.
Our conclusion is that with the CPU trying to process the transfer, plus the mix of AC in and out, somewhere and somehow the system's CPU failed. 
The engineer's report when returned after repair confirmed "Incorrect polarity input to output". 
Please do not ask HOW they can test for that!!! We can only guess that they have had a few units returned and can recognise what happens when this kind of failure takes place!


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## AndyC (Nov 16, 2010)

nickjvanbitz said:


> The Combi itself runs a CPU (which includes a power sharing device), plus 2 x relays. One to transfer the AC supply input to the ring main of the van, the second engages the output from the charger, but this is where it gets tricky.
> Due to the units ability to suppliment AC supply (i.e when on low current sites abroad), the unit takes power from the leisure batteries to increase it's output e.g I ask for 8A mains but only 6A site supply, the unit gives me the extra 2A from the leisure batteries if sufficent power is available. Once this high demand is finished, it simply goes back to full charge mode to recover what was used providing I am still not asking for more than the 6A the site electrics can give me.
> Our conclusion is that with the CPU trying to process the transfer, plus the mix of AC in and out, somewhere and somehow the system's CPU failed.
> The engineer's report when returned after repair confirmed "Incorrect polarity input to output".
> Please do not ask HOW they can test for that!!! We can only guess that they have had a few units returned and can recognise what happens when this kind of failure takes place!


Ah, I understand a bit better now. Even though AC effectively has no 'polarity', for safety devices like RCDs to work there must be a 'reference point'. I think in UK domestic supplies this is achieved by bonding the incoming 'neutral' to earth, although I don't think this is allowed on campsite supplies so I don't know how they work. I wonder if in the case of your combi inverter charger the reversed polarity meant that there were two different reference points (the incoming mains one and and on-board one created in the combi) resulting in the unit trying to effectively trying to connect 'live' and 'neutral'.

Of course I might be talking b*****ks  Where's a IEE engineer when you need one....

AndyC


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## NicknClair (Nov 16, 2010)

AndyC said:


> Ah, I understand a bit better now. Even though AC effectively has no 'polarity', for safety devices like RCDs to work there must be a 'reference point'. I think in UK domestic supplies this is achieved by bonding the incoming 'neutral' to earth, although I don't think this is allowed on campsite supplies so I don't know how they work. I wonder if in the case of your combi inverter charger the reversed polarity meant that there were two different reference points (the incoming mains one and and on-board one created in the combi) resulting in the unit trying to effectively trying to connect 'live' and 'neutral'.
> 
> Of course I might be talking b*****ks  Where's a IEE engineer when you need one....
> 
> AndyC


 
Gave up trying to understand it myself!! lol. From what I understood from the engineer's report, the power share ability (using the charger/AC input etc) can be overwelmed somehow and cause the unit to fail.

I guess the point that I am making is really that a majority of equipment will not be effected by reversed polarity say 80% of the time (kettles, toasters etc), but with equipment like the Combi, there may be different issues in it's abilities when in opertation that can be effected.
For anyone looking at this thread, I did come across an article (Caravan Club) on the Web that may prove usefull, but I would still put my experience in with the issues of my Combi fitted and the returned engineer's report.
I don't trust electrics - plain fact. Therefore will always carry on with the way I make sure the van is connected, being a Safety freak and all. At the end of the day it boils down to your own attitude towards safety. Your call at the end of the day!!

Here's that link anyway;
http://www.caravanclub.co.uk/media/19098/Reversed Polarity complete.pdf


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## Tony Lee (Nov 16, 2010)

I assume they recognised their device was poorly designed and not fit for purpose and gave you a new one free. If not, they certainly should. There is NEVER going to be any guarantee that the phase and neutral conductors are in any particular order and I don't know of any devices that require it. 

My understanding of these load sharing devices is they have no direct connection between the incoming mains and any inverter output so how does "polarity" cause a problem. More likely to be a timing problem in the operation of any changeover relays.

That engineers report doesn't hold much water. True, if there was some timing problem during the changeover, then it is possible that the main semiconductors in the inverter might have failed, but that should never be reflected back into the CPU causing that to fail. 

I would be surprised if the power share device created its own neutral to earth connection point when in power share mode (unless the mains supply was completely isolated from the van circuitry at that time)  because that would certainly cause problems with any RCD anywhere in the supply chain.


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## NicknClair (Nov 17, 2010)

It is funny you should say that Tony as there was no service charge, however I am not going to reverse the polarity just to prove that theory .

When I spoke to FIL (Father in Law, an Electrical Engineer of 45 years), he did mention timing of the switch-over and it should have also been fitted with a protection/rectification circuit IF something were to happen but like I said in a previous post, I gave up trying to understand it. 
Since this episode was over 8 months ago and I re-fitted my Auto-Switch back on the van, i've gone past caring.

For them to replace the CPU FOC, it makes me a tad suspicious I must admit.


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## lebesset (Nov 17, 2010)

this discussion could only take place on a british forum

I have all sorts of electronic equipment with 2 pin plugs ; as the plugs can be put in either way round it must be able to work in that manner ...anything that cannot is not fit for purpose ...I don't understand how you could make it so anyway with A/C

is it still permitted in the uk to fit equipment that only trips the live and not the neutral ?
I have been in france for more than 20 years and it was illegal when I arrived !


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## Tony Lee (Nov 17, 2010)

> When I spoke to FIL (Father in Law, an Electrical Engineer of 45 years), he did mention timing of the switch-over and it should have also been fitted with a protection/rectification circuit IF something were to happen



Great minds think alike. Maybe he had similar problems as I did many years ago - several thousand dollars of high power SCRs blowing up at random intervals - sometimes weeks apart. Turned out to be a slight drift in the timing control that very occasionally placed a short across the mains by switching forward and reverse circuits on together. Not altogether different from what happened to your gear.

At least they did the right thing by you and I do understand your reluctance to experiment.

As for the UK being the only place it could happen - plenty of countries have good rules but they rarely make them retrospective so there is always a lot of non-compliant gear around.

Speaking of introspectiveness - here in Oz, all RVers will soon have 6 months to fit smoke alarms in their RV. Houses was several years ago.


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## NicknClair (Nov 17, 2010)

Tony Lee said:


> Speaking of introspectiveness - here in Oz, all RVers will soon have 6 months to fit smoke alarms in their RV. Houses was several years ago.


 
I think the NCC (National Caravan Council) insisted on having detectors in all leisure vehicles some time ago, but not all Motorcaravans are governed by them (British built only I think). I would always have one, plus Monoxide in a Motorhome (bought at B&Q for about £39.00). Have also fitted an LPG detector as precaution as am always on the gas for the fridge and cooking.
Goes to show, as we have had to do a few LPG Gas detectors on some US RV's, as they were fitted as standard to comply with Federal Law. Amasing the different attitudes


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## oldosc (Feb 17, 2011)

*oldosc*

Being a wilder, I dont have much problem with polarity
on the occasional times I go to a site, (Like paris beceause of the beautiful ride along the Seine to Champs, and the night ride back thro Bois de Boloune shouting "bon nuit,mamselle vous est tres jolie " to the lady boys, who respond with "merci monsieur vous aussi"
  I use a wire stripper, and some tooth pics.
  But I do not endorse this stupidity...


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## Brian Evans (Feb 17, 2011)

Poco Loco said:


> HI All,  Once again I need some help from you more experienced out there. I am due to pick up my first MH in Dec' and head back through France on route to Spain.  I understand about Reversed polarity, but I was wondering if it is still a problem with modern MHs i.e does the control panel automatically reverse the polarity if required?
> 
> The link below to the caravan club website and the Reversed Polarity PDF gives some information about reversed polarity and suggests making a second connector with the Live & Neutral incorrectly wired in order to reverse the polarity back to the UK norm.  My question is how will I know if it is reversed as anything I plug in (TV etc) would automatically correct the polarity and work anyway.  I know that if the polarity is incorrect the earth could be the switch and the item left live, but thats only a problem if I'm working on it, in which case I'd just unplug the van and isolate it anyway.
> 
> ...


 
My advice to you would be to contact a qualified electrician face to face . Perhaps there may be one working at you motorhome dealer, or your dealer could direct you to a person with the relevant knowledge .I would be vey carefull of listening to some of the advice given on such forums regarding a very lethal power supply same goes for gas .As reading some of the threads it is obvious to me that some of the advice is incorrect , and could be very dangerous .


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## Tbear (Feb 17, 2011)

Brian Evans said:


> My advice to you would be to contact a qualified electrician face to face . Perhaps there may be one working at you motorhome dealer, or your dealer could direct you to a person with the relevant knowledge .I would be vey carefull of listening to some of the advice given on such forums regarding a very lethal power supply same goes for gas .As reading some of the threads it is obvious to me that some of the advice is incorrect , and could be very dangerous .


 
Hi Brian,

As much as I agree that Expert advise is well worth getting, I do think if you are going to rubbish what the very well meaning people on this site advise then you should at the very least say what you disagree with and why.

Richard


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