Reversed polarity

[Tbear]

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.

 

[Talbot Bertha]

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.

 

[NicknClair]

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.

 

[AndyC]

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

 

[Deleted member 3011]

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


...

 

[NicknClair]

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!

 

[AndyC]

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

 

[NicknClair]

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

 

[Deleted member 3011]

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.

 

[NicknClair]

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.

 

[lebesset]

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 !

 

[Deleted member 3011]

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.

 

[NicknClair]

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

 

[oldosc]

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...

 

[Brian Evans]

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

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 .

 

[Tbear]

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