Brian Kirby Posted November 19, 2015 Share Posted November 19, 2015 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). Link to comment Share on other sites More sharing options...
Derek Uzzell Posted November 19, 2015 Share Posted November 19, 2015 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. Link to comment Share on other sites More sharing options...
Brian Kirby Posted November 20, 2015 Share Posted November 20, 2015 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. Link to comment Share on other sites More sharing options...
Dave225 Posted November 21, 2015 Share Posted November 21, 2015 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. Link to comment Share on other sites More sharing options...
spospe Posted November 21, 2015 Author Share Posted November 21, 2015 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. Link to comment Share on other sites More sharing options...
Brian Kirby Posted November 21, 2015 Share Posted November 21, 2015 Dave225 - 2015-11-21 5:25 PM 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. Apologies Dave, but as another non-electrician :-), I think you may be confusing two things. The fuse to which you refer (be it an actual fuse as in a plug, or an MCB as in all consumer units), is not your protection against electrocution. It is there to protect the wiring from overload, not the person from electrocution. Fuses/MCBs are to eliminate the risk of overloaded circuits overheating, possibly to the point at which they catch fire. Your protection against electrocution lies at the mains switch which, since the 1970's, will incorporate some form of earth trip. These are Residual Current Devices (RCDs), which compare the current flowing in to your system (on the line, or live wire) with that flowing out (on the neutral wire). The logic is that if there is a difference between the two currents, the difference must be flowing to earth (possibly via an external conductor, such as that person), and the supply should be interrupted, so providing protection against electrocution. They respond in milliseconds and, with their sensitivity usually set at about 30mA, they should interrupt the supply before you are aware of much more than a tingle. They are mechanical devices, but are easily tested via the test button on the switch, which simulates a fault (how many of us, I wonder, do that regularly?), though I understand anyone with a pacemaker may still be at risk under certain circumstances. But, they are infinitely safer than any of the electrical systems most of us will have grown up with, with individually wired fuses and only an "on-off" switch alongside the fuseboard. I agree, as I said above, that it is sense to check for an earth - but an earth alone does not protect against electrocution. It will provide a partial belt for the wiring, but that far more important braces against electrocution are provided by the RCD. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted November 23, 2015 Share Posted November 23, 2015 Returning to the Eberspacher Airtronic+Airlectric system’s reaction to a reverse-polarity power supply, I’ve now emailed a UK firm advertising the system about this. I said "Your website advertises the Eberspacher Airlectric 230V unit that can be added to an Airtronic D2/D4 heater. I have been given to understand that the Airlectric unit fitted with the automatic diesel/230V switching option is polarity sensitive and requires a UK-standard 230V power-supply to function. Users of the Airtronic+Airlectric system have said that If the power-supply has 'reverse-polarity' (ie. the supply's live and neutral cables have been swapped over as is commonly found to be the case at campsites outside the UK) the system will not switch automatically from diesel to electric heating. Experiments have shown that, if a reverse-polarity 230V supply is encountered and the system will not switch from diesel to electric heating, using an adapter that modifies the supply's polarity to the UK-norm causes the system to switch automatically between diesel and 230V. Are you aware of this reverse-polarity limitation, please?” The very prompt reply was “...I have spoken to Eberspacher technical and they have said that if you were to plug into a supply with reverse polarity then nothing would happen at all and it wouldn't switch over. So they said to carry another lead that is the opposite just in case.” Link to comment Share on other sites More sharing options...
Charles Posted November 23, 2015 Share Posted November 23, 2015 You could install a 230v relay (coil) between neutral and earth to automatically correct the polarity. But the van would fail an earth leakage test. Better (but still not perfect) would be a solid state high impedance circuit... I can look into it if if anybody's interested Link to comment Share on other sites More sharing options...
Derek Uzzell Posted November 24, 2015 Share Posted November 24, 2015 A commercial product to ‘correct’ a reverse-polarity mains power-supply (and check the supply’s general functionality) has been marketed in the UK for a good many years, and a GOOGLE-search on “mains polarity changeover switch” will show that versions are available (for £40-£50) from several suppliers. Examples are here http://www.homesteadcaravans.co.uk/accessory-shop/caravan-motorhome/electrical/230v-electrics/nova-mains-polarity-changeover-switch.htm http://www.marcleleisure.co.uk/store/mains-polarity-changeover-switch-with-audible-alarm-p-3419.html?osCsid=6dc43ec764c57a462c662a38723c36f5 http://www.marcleleisure.co.uk/store/pdf/polarityswitchinstructions-02.pdf?osCsid=6dc43ec764c57a462c662a38723c36f5 with the last link providing fitting guidance. The changeover switch (apparently the asking-price was cheaper then) is mentioned by Dave Newell in this 2009 forum discussion http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Reverse-polarity-adaptors/14639/ I’ve no idea how many of these switches are sold nowadays, but an owner of a motorhome with an Airtronic + Airlectric heating system who travels a lot abroad might find the switch a useful, safer modification to his/her vehicle rather than needing to use the traditional cable reversing adapter. Link to comment Share on other sites More sharing options...
George Collings Posted December 18, 2015 Share Posted December 18, 2015 Mains sparks are not really my subject although like Derek I have in the past installed ring main in a dormer conversion.( I had a full test and eventual professional rewire four years a go and the only part that was up to scratch was my work). About 6 years ago I was in an electrical factors where three near retirement sparkies were talking about the latest Electrical Regulations. One said they are falling into line with continental practice and some of the changes lower UK standards. all three intended to work until retirement without requalifying on the principle that they had not killed anyone so far and could not afford the four figure sum for the required course and test. Personally having an 18 year old van that had its mains wiring rattled about for 80,000 miles I always test for polarity and correct if necessary but above all never use a post with no earth. HU is became quite rare since fitting a 150w solar panel. Link to comment Share on other sites More sharing options...
aandncaravan Posted March 2, 2016 Share Posted March 2, 2016 The fact that an appliance like a Kettle has a reversed polarity plug, is not a danger in itself. Only should you carry out maintenance while it is still plugged in and switched on. There is no real danger with mains 230v electrics being reverse polarity, unless you remove the cover to an appliance and stick a metal object into the wiring, which clearly most sensible people are not going to do. Therefore the risk is, and has always been, almost zero. The primary issue is with Electronics. Some of the older British Caravan and Motorhome Charger electronics did not work on reverse polarity, and some popped. As late as early 2000's British Motorhome builders were pressing the need to check for reverse polarity rather than build reverse mains polarity protection into the units. This preservation of the 'Electronics Warranty' by the industry led to some statements which were at best, exaggerated. Most of the Continental built charger units (indeed almost all continental built electronics) from 30 + years back are generally ok. Most of the stuff coming out of China is also ok, because they design and build for a World market, which includes the Spanish. Better explanation here : http://www.aandncaravanservices.co.uk/reverse-polarity.php Link to comment Share on other sites More sharing options...
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