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A couple of Reversed Polarity points
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userspospe
Posted: 3 November 2015 2:43 PM
Subject: A couple of Reversed Polarity points
 


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The following two observations of mine concern the problem of 'Reversed Polarity' and I am offering them in an attempt to show that it does matter and it is not a matter to be contemptuously ignored..

The Eberspächer Airtronic heater will not provide heat using mains electricity with reversed polarity, it will only operate on diesel under this condition (our MK7 Duetto showed this problem).

The Thetford Caprice Mk III electric hot plate 'on', warning light glows dimly, even when not switched on (this phenomenon is present in our current Warwick Duo).

My conclusion is that if you want a simple, trouble free time when out and about in you motorhome; make sure that your polarity is correct, as the consequences of it being wrong may be quite puzzling at times.
userCaddies104
Posted: 3 November 2015 4:49 PM
Subject: RE: A couple of Reversed Polarity points
 


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Hi
Sounds good advice... We Always check the polarity
userEJB
Posted: 4 November 2015 3:02 PM
Subject: RE: A couple of Reversed Polarity points
 
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Good post assuming you are technically correct

Have never had reason to check it in my life.
userCharles
Posted: 4 November 2015 3:39 PM
Subject: RE: A couple of Reversed Polarity points
 
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Maybe your hot plate on indicator light (neon?) is using the appliance earth instead of neutral. The current, when reversed, will be flowing through the element and down to earth through the lamp. the resistance of the element will make the light dim... and it would go off when the element is on.

userspospe
Posted: 4 November 2015 5:15 PM
Subject: RE: A couple of Reversed Polarity points
 


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Charles - 2015-11-04 3:39 PM

Maybe your hot plate on indicator light (neon?) is using the appliance earth instead of neutral. The current, when reversed, will be flowing through the element and down to earth through the lamp. the resistance of the element will make the light dim... and it would go off when the element is on.



When the element is switched on, the light is at full brilliance no matter which way the polarity is connected.

When the element is switched off, the light glows dimly when polarity is reversed and not at all when polarity is correct.
userCharles
Posted: 4 November 2015 6:20 PM
Subject: RE: A couple of Reversed Polarity points
 
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oh I don't know then, was just an idea. I've done some back of a fag packet calcliations and the way I was thinking it's wired it's not possible for the light to be on when polarity is reversed and element is on.. Anyway that's a handy reverse polarity indicator you've got there.
userCharles
Posted: 4 November 2015 6:33 PM
Subject: RE: A couple of Reversed Polarity points
 
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You'd think all vans would be compatible with reverse polarity, I know ours is as we've just spent 6 weeks in Benidorm with reversed polarity.

None of our vans sockets have switches on them and everything worked as normal. I only knew it was reversed because I made a gadget to test it (out of curiosity)

Edited by Charles 2015-11-04 6:35 PM
userspospe
Posted: 4 November 2015 9:46 PM
Subject: RE: A couple of Reversed Polarity points
 


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Charles - 2015-11-04 6:33 PM

You'd think all vans would be compatible with reverse polarity, I know ours is as we've just spent 6 weeks in Benidorm with reversed polarity.



Mostly vans work OK with reversed polarity, but my point is that you can never be 100% sure for all vans in all cases, so it is best to test and if needed, correct matters. The first time I tried using the heater on reversed polarity and it would only work on diesel, I really thought that there was an equipment failure and that it was going to be expensive to repair!

Edited by spospe 2015-11-04 9:47 PM
userlennyhb
Posted: 5 November 2015 9:04 PM
Subject: RE: A couple of Reversed Polarity points
 


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spospe - 2015-11-03 2:43 PM

The Eberspächer Airtronic heater will not provide heat using mains electricity with reversed polarity, it will only operate on diesel under this condition (our MK7 Duetto showed this problem).


I find it hard to believe that a large German company would produce a product that can only be used in the UK. Germany like most European countries does not differentiate on polarity with it's wiring like most countries (except for the UK) it is unnecessary due double pole switching on all circuits.
userGram
Posted: 5 November 2015 9:57 PM
Subject: RE: A couple of Reversed Polarity points
 


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I can vouch for the fact that the Eber Airtronic does not operate on reverse polarity mains.

I've tried it on my Symbol.

G
userlennyhb
Posted: 5 November 2015 10:26 PM
Subject: RE: A couple of Reversed Polarity points
 


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Gram - 2015-11-05 9:57 PM

I can vouch for the fact that the Eber Airtronic does not operate on reverse polarity mains.

I've tried it on my Symbol.

G

Surely it's not fit for purpose if it can only be guaranteed to work in the UK.
userGram
Posted: 5 November 2015 11:16 PM
Subject: RE: A couple of Reversed Polarity points
 


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I suspect we're in danger of going over old ground here.

See http://forums.outandaboutlive.co.uk/forums/Motorhomes/Hints-and-Tips/Reverse-polarity-points/33356/

G
userkeninpalamos
Posted: 15 November 2015 11:06 AM
Subject: RE: A couple of Reversed Polarity points
 


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well blocked Gram. I have carried a plug-in tester for years and a lead with a reversible plug on it not that I use hook-up .
usersteve00136
Posted: 16 November 2015 7:53 AM
Subject: RE: A couple of Reversed Polarity points
 
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I always use a reversing lead to correct any reverse polarity hook ups as I was under the impression that although most electrical appliances are safe and tested under eu regs to be safe with reversed polarity (not sure about some stuff imported from china via eBay) . Also that the main safety cut out / rccd in the control panel may not work correctly under reverse polarity conditions if a fault developed in an appliance.
Does anyone know if this is correct?
userrupert123
Posted: 16 November 2015 11:27 AM
Subject: RE: A couple of Reversed Polarity points
 
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steve00136 - 2015-11-16 7:53 AM

I always use a reversing lead to correct any reverse polarity hook ups as I was under the impression that although most electrical appliances are safe and tested under eu regs to be safe with reversed polarity (not sure about some stuff imported from china via eBay) . Also that the main safety cut out / rccd in the control panel may not work correctly under reverse polarity conditions if a fault developed in an appliance.
Does anyone know if this is correct?

No it is not.
userBrian Kirby
Posted: 16 November 2015 12:53 PM
Subject: RE: A couple of Reversed Polarity points
 


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rupert123 - 2015-11-16 11:27 AM

steve00136 - 2015-11-16 7:53 AM

I always use a reversing lead to correct any reverse polarity hook ups as I was under the impression that although most electrical appliances are safe and tested under eu regs to be safe with reversed polarity (not sure about some stuff imported from china via eBay) . Also that the main safety cut out / rccd in the control panel may not work correctly under reverse polarity conditions if a fault developed in an appliance.
Does anyone know if this is correct?

No it is not.

Too quick, Henry. Steve asked two questions. The answer to the first is that it is correct. Only the second is incorrect.

Edited by Brian Kirby 2015-11-16 12:53 PM
userrupert123
Posted: 16 November 2015 10:21 PM
Subject: RE: A couple of Reversed Polarity points
 
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Brian Kirby - 2015-11-16 12:53 PM

rupert123 - 2015-11-16 11:27 AM

steve00136 - 2015-11-16 7:53 AM

I always use a reversing lead to correct any reverse polarity hook ups as I was under the impression that although most electrical appliances are safe and tested under eu regs to be safe with reversed polarity (not sure about some stuff imported from china via eBay) . Also that the main safety cut out / rccd in the control panel may not work correctly under reverse polarity conditions if a fault developed in an appliance.
Does anyone know if this is correct?

No it is not.

Too quick, Henry. Steve asked two questions. The answer to the first is that it is correct. Only the second is incorrect.

Maybe, but it looked to me as if he is only asking a question in the second sentence of his post, Anyway he now has the answer to both.
usersteve00136
Posted: 16 November 2015 11:38 PM
Subject: RE: A couple of Reversed Polarity points
 
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Thanks
userEJB
Posted: 17 November 2015 9:54 AM
Subject: RE: A couple of Reversed Polarity points
 
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Presumably the very many customers who have never heard of 'reverse polarity' have had their faulty heaters replaced or repaired by the manufacturers?
userDerek Uzzell
Posted: 17 November 2015 11:46 AM
Subject: RE: A couple of Reversed Polarity points
 
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EJB

I assume you are referring to the Eberspacher “Airltronic/Airlectric” peculiarity spospe mentions.

This was explored in some depth in the forum discussion Gram gave a link to in his posting above of 5 November 2015 11:16 PM.

The issue was (in my opinion) never satisfactorily resolved, but as the Airtronic/Airlectric combination seems rare as hen’s teeth (it may be that it has only been used in Auto-Sleepers motorhomes) the likelihood is that few motorcaravanners would have had that heating system. Even if they did have it, the problem would only become apparent when the mains power-supply was reverse polarity and the motorcaravanner had not ‘corrected’ the polarity before the heater was switched on.

The problem probably would not rear its head in the UK - where a reverse-polarity hook-up would be unusual - and as UK caravanners/motorcaravanners are encouraged to ‘correct’ reverse polarity (as steve00136 does) if it is encountered abroad, it may be that someone with an Airtronic/Airllectric system may never become aware of the Airlectric’s (apparent) requirement for a UK polarity-norm mains supply.

(I understand what you are getting at, but when I researched this I could find no evidence that anyone other than spospe and Gram was aware of the Airlectric issue, nor any indication that anyone else had complained about it.)

Edited by Derek Uzzell 2015-11-17 11:49 AM
userEJB
Posted: 18 November 2015 4:29 PM
Subject: RE: A couple of Reversed Polarity points
 
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Most continentals normally use extension reels for hook ups which are inevitably the usual 2 pin/ reversible Shuko plugs.
So, I estimate that 50% of those with the specific system under discussion have a real problem?
Over the years I've spoken to many Germans and Dutch and 'reverse polarity' is not a subject they have usually heard of!
userDerek Uzzell
Posted: 18 November 2015 6:51 PM
Subject: RE: A couple of Reversed Polarity points
 
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Non-UK caravanners/motorcaravanners are oblivious to reverse-polarity and, even if a reverse-polarity 230v campsite service-pillar were encountered and it were possible to use a Schuko plug to ‘correct’ the polarity (not always practicable on French campsites that still have the French domestic-norm type of outlet) nobody (except some UKers) bothers to do this.

Spospe first mentioned this Eberspacher-related issue in December 2013

http://forums.outandaboutlive.co.uk/forums/Motorhomes/Hints-and-Tips/Reverse-polarity-points/33356/

If you wade through the discussion you’ll see that, for anyone with an Airtronic+Airlectric heating system, it was well recognised that there was the potential to have a ‘reverse-polarity’ problem when travelling abroad. Logically this system should not be polarity sensitive and, despite Eberspacher have told me that "...it is correct that the Airlectric needs to know the live and neutral connection to ensure correct polarity” I’m still not 100% convinced that all Airlectric heaters are polarity sensitive. I fully accept that the Airtronic+Airlectric heating systems fitted to spospe’s and Gram’s Auto-Sleepers motorhomes have proven to be polarity sensitive, but that doesn’t necessarily mean that all Airtronic+Airlectric heating systems react similarly.

Spospe also mentioned the problem on the Auto-Sleepers Owners Forum in 2014

http://www.autosleeper-ownersforum.com/t10261-erberspacher-heater

but it did not produce a storm of interest.

If it were known how many Airtonic+Airlectric systems were sold and in which vehicles they were fitted, it might be possible to establish if reverse-polarity sensitivity is universal for the system or (perhaps) relates just to a batch of Eberspacher units that happened to be fitted by Auto-Sleepers. Spospe has warned Auto-Sleepers owners about this peculiarity and mentioned it twice here, and that’s about the best that can be done as far as I can see.

userGram
Posted: 18 November 2015 11:22 PM
Subject: RE: A couple of Reversed Polarity points
 


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I present a theory why Continental consumers are not concerned about reverse polarity.
It is a theory which is completely unfounded and not backed up by any factual information or research.

The phenomena of the UK supply having a polarity originates from the 230V being derived from a 415V three-phase transformer, the star output having its centre point (the neutral conductor) connected to earth at the substation. The line voltage becomes effectively above ground potential and is considered to be, if you like, the positive conductor.

Now, if the secondary output of the substation transformer were to be a centre-tapped winding, and the centre-tap were connected to earth, then neither supply conductor would be at a potential higher than the other - both conductors would be at the same potential relative to earth. 230v RMS would be maintained between the conductors by virtue of the fact that the voltages at each conductor are in anti-phase.

The supply would then not be polarised as we know it.

So, is this the manner of Continental supplies?

I am quite happy to be shot down in flames. A good talking point though, eh?

G
userEJB
Posted: 19 November 2015 12:31 PM
Subject: RE: A couple of Reversed Polarity points
 
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All we need now is a sub station engineer or higher
userDerek Uzzell
Posted: 19 November 2015 2:26 PM
Subject: RE: A couple of Reversed Polarity points
 
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The vast majority of UK inhabitants will be completely unaware of and unconcerned about ‘reverse polarity’. This is simply because the present UK-norm for domestic electrical wiring involves electrical appliances having a fused 3-pin plug cabled to a standardised format and socket-outlets to accept that type of plug and similarly cabled to a standardised format. Essentially, a UK inhabitant expects a socket-outlet or 3-pin plug always to be cabled to comply with the UK-norm.

I began motorcaravanning with no caravanning background. At that time I was comfortable with UK domestic wiring to the extent that I could (and had) wired up house extensions, fitted electric showers, ovens, etc. I didn’t really care (and still don’t much care) what happened ‘upstream’ of the mains power supply prior to it reaching my house. I had also travelled a fair bit in Continental Europe and was aware that domestic plugs, sockets and wiring norms differed overseas.

When I bought my first motorhome (a Herald Templar in 1998) I also obtained John Wickersham’s book “The Motorcaravan Manual”. This included a section about motorhome mains electrical systems and explained that the differences between UK-norm and Continental-norms for mains wiring could result in campsite hook-ups having reverse polarity and this could be potentially dangerous for UK travellers. JW’s advice was to cease using a hook-up found to have reverse polarity, or to ‘correct’ the hook-up’s polarity via a changeover adapter-lead. There were also numerous UK magazine articles offering the same advice.

It was obvious that swapping round the live and neutral cables in a UK domestic socket-outlet or 3-pin plug would ‘reverse’ the outlet’s/plug’s polarity, and it seemed credible that the potential effect of doing so could be problematical. The Herald was fitted with ordinary UK switched socket-outlets and it seemed logical to me that, when the motorhome was connected to a hook-up, the electrical supply at the outlet should be to the UK-norm. So I used to test Continental hook-ups and, when I found one with reverse polarity, I would correct it as JW and the magazine articles advised. It needs emphasising, though, that if I hadn’t read JW’s book or the magazine articles I would never have done this.

I don’t believe Continental Europeans are anymore clued up about the technicalities of their mains power supply than the UK man/woman-in-the-street. Why Continentals won’t be concerned about reverse polarity is because their domestic electrical norms obviate potential problems this might cause and, as a consequence, nobody bothers to mention it to them.



Edited by Derek Uzzell 2015-11-19 2:28 PM
userBrian Kirby
Posted: 19 November 2015 4:39 PM
Subject: RE: A couple of Reversed Polarity points
 


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Derek Uzzell - 2015-11-19 2:26 PM................................... Why Continentals won’t be concerned about reverse polarity is because their domestic electrical norms obviate potential problems this might cause and, as a consequence, nobody bothers to mention it to them.

I obviously don't know if Derek checked this on his previous (Hobby) and/or present (Rapido) vans, but the electrical consumer unit mounted inside a continental made van will have circuit breakers (basically, resettable fuses) at both the line (supply) and neutral (return) terminals, the sockets are unswitched, the plugs are unfused, and continental (CE marked) appliances are double-pole switched.

Our van has this. It is therefore "blind" to polarity, in that whichever way round the current flows the circuits are protected.

A bit more reading here if anyone is interested. http://tinyurl.com/o6yerop (The Institution of Engineering and Technology was, until 2006, the Institution of Electrical Engineers. It is the body responsible for drafting the regulations that govern how electricians must carry out electrical installations - The IET Regulations, published as BS 7671).
userDerek Uzzell
Posted: 19 November 2015 6:54 PM
Subject: RE: A couple of Reversed Polarity points
 
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Brian

I’m pretty sure the Hobby had one of these

http://leisurelines.net/cbe-ds120-s-mains-consumer-unit-double-pole-13a-2040-p.asp

My Rapido 640 also has CBE electrical equipment, but the consumer unit is a bit different to the DS-120S. The Rapido User Manual describes it as “an electrical protection box containing one 16A twin-pole thermal-magnetic circuit breaker and a 30mA differential safety switch”.

I’ve been inside the Rapido’s consumer unit in order to add cabling for a couple of extra socket outlets. (What fun that task was - not - but the 640 left the Rapido factory with just a single socket outlet above the hob and masked when the hob’s glass lid was raised, so something had to be done.)

My Germany-purchased LHD Hobby had Schuko unswitched socket outlets (lots of them) while my LHD Rapido (presumably because I bought it from a UK dealer) came with a UK-norm unswitched socket outlet. As you say, both the Hobby and Rapido are ‘blind’ to polarity, but I’m doubtful that the Herald was.

Nowadays I may test a hook-up to check that it’s ‘live’ or (if it looks iffy) what its state is, but I don’t bother to ‘correct’ reverse polarity if the test reveals its presence.
userBrian Kirby
Posted: 20 November 2015 12:00 PM
Subject: RE: A couple of Reversed Polarity points
 


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Hello Derek. Can't remember what our French supplied Burstner had, but our German supplied Hobby Van had, and the present van has, double pole RCBOs (which are basically MCBs combined with RCDs into a single unit). I suspect that is what you have been looking at.

There is a main, combined, RCBO rated at 16A, with a single low Amperage circuit (5A from memory) wired from it through a DP MCB to feed such items as fridge, cooker hob igniter, and I think the power 12V pack/charger unit. So, polarity is irrelevant, circuit overload is catered for by the MCB functions, and an earth fault is catered for by the RCD function of the main RCBO switch.

The only thing I now check for if the site wiring looks a bit old or abused, is an earth. Truth to tell, with a residual current type device that trips if the outflowing current doesn't match that flowing in, I'm not entirely sure that the earth connection is still that critical to safety. Obviously better if it is there, but it seems to me not significantly more dangerous if it isn't.
userDave225
Posted: 21 November 2015 5:25 PM
Subject: RE: A couple of Reversed Polarity points
 
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I am not a qualified electrcian but would make the following comments.

I agree that the majority of outfits these days will have EU certified systems which mean that the mains circuit is protected on both live and return so polarity is not such an issue. I have noted that some mains units are rated at 20 amp for the mains circuits which is high so do not really use this as a primary safety device. However, I would take issue withe comments regarding earthing. Even Schoko plugs all have earth connections and if there is none then if an item is faulty it is possible that by touching it you will become the earth path with disastrous effects. I know we have 13 amp fuses in most items here in the UK but do note it takes a huge surge to blow it, which if you are in the path, will revert to you. If your polsrity teste shows no earth to the mains bollard then please do not use it. If it just shows reverse polarity but still has earth, then there should be no problem at all.

If you have any concerns at all then use a safety trip socket between the socket in the van and your electrics. Always remember electricity is an invisible killer. It has no sound, smell or visual identity. 230 volts at 13 amps will fry you.

userspospe
Posted: 21 November 2015 5:43 PM
Subject: RE: A couple of Reversed Polarity points
 


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There is an inherent danger with all double pole switches and that is, they can fail on one pole. If such failure occurs, there is a 50 - 50 chance that it could happen on the neutral leg and thus leave the live leg still connected. I have seen this happen twice.

The system used in the UK normally switches just the live leg and so when the switch is operated, the appliance either switches on or off. If the appliance is switched off, then it is off; no doubt about it.

The UK system with single pole switching relies on all the mains wiring being installed correctly. The continental system makes no assumptions about compliance.

You can take your pick as to which you think is the safer system, but in the UK, wiring polarity is important and switch functioning is not so important from a safety point of view. Abroad, with double pole switching, wiring compliance is not so important, provided that the switch works properly 100% of the time.

As I have said, you can take your pick as to which you think is the better system, but for a UK spec installation, if you want a smooth, trouble and surprise free life, make sure that your polarity is correct at the van.
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