sshortcircuit Posted July 5, 2009 Share Posted July 5, 2009 No Given a combination of fixed wiring faults then a situation could arise. Link to comment Share on other sites More sharing options...
Dave G Posted July 5, 2009 Share Posted July 5, 2009 Not necessarily. If a piece of equipment developed an earth fault anything might happen - electrocution just from touching any electrical appliance or even a sink tap fed from your electrically heated water supply. An electrical fire caused by an earth fault is not uncommon either. I would rather be safe than sorry. Link to comment Share on other sites More sharing options...
rupert123 Posted July 5, 2009 Share Posted July 5, 2009 Syd - 2009-07-05 9:04 AM So!! To me, from all of thid debate, it seems that the only real danger from reverse wireing will come from anyone dismantleing electrical equipment while it is still plugged into the supply. Is that correct?? Correct. The combination of other wiring faults mentioned has nothing to do with it and would cause problems anyway if this was the case. If your wiring is so bad that it has a lot of faults then get it sorted out. The original post was a simple question about reverse polarity and lack of an earth on the supply not whether your van has a multiple of faults in the first place. Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 5, 2009 Share Posted July 5, 2009 rupert123 - 2009-07-05 10:25 AM Syd - 2009-07-05 9:04 AM So!! To me, from all of thid debate, it seems that the only real danger from reverse wireing will come from anyone dismantleing electrical equipment while it is still plugged into the supply. Is that correct?? Correct. The combination of other wiring faults mentioned has nothing to do with it and would cause problems anyway if this was the case. If your wiring is so bad that it has a lot of faults then get it sorted out. The original post was a simple question about reverse polarity and lack of an earth on the supply not whether your van has a multiple of faults in the first place. Incorrect! Any dismantling of electrical equipment while it is connected to the supply is dangerous, whatever the polarity.The original post was not a question about reverse polarity and lack of an earth, it was about whether the poster needed to re-wire (presumably his plug) if his mains tester (of unspecified type) displayed an abnormal light configuration. He was correctly advised to make up a reverse polarity lead and use that to correct polarity problems, and not to use the connection point if an earth problem was indicated. This is a simple routine, and is fail safe.Rupert123's answers ignore the potential variables: in the site supply (presumed safe), in the on-board installation and equipment (presumed in good condition and RCD/DPMCB protected), and in portable electrical equipment (presumed in good condition and DP switched and double earthed) that may be carried by the poster, so his "it'll probably be OK" type replies are not safe to follow.I'm not questioning his electrical knowledge (though I note he is not an MIEE), just that his assessment of the potential risks, and their possible consequences, is too narrow. The probability that any such risk event may arise is, admittedly, quite low, but the risk itself - of possible shock or fire - is serious, and is easily and cheaply avoided, so avoid it. Link to comment Share on other sites More sharing options...
tonyishuk Posted July 5, 2009 Share Posted July 5, 2009 If you are not happy with checking , rewireing etc maybe fitting a polarity change over switch would be a better . Have aq search in the archives for advice, cost and fitting. Rgds Link to comment Share on other sites More sharing options...
rupert123 Posted July 5, 2009 Share Posted July 5, 2009 Brian read the question and answer properly before you come out with your answers. I said DISCONNECTED. The question was about green lights, what else could it be but about revesre polarity and earth connections. Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 5, 2009 Share Posted July 5, 2009 rupert123 - 2009-07-05 10:25 AM Syd - 2009-07-05 9:04 AM So!! To me, from all of thid debate, it seems that the only real danger from reverse wireing will come from anyone dismantleing electrical equipment while it is still plugged into the supply. Is that correct?? Correct. The combination of other wiring faults mentioned has nothing to do with it and would cause problems anyway if this was the case. If your wiring is so bad that it has a lot of faults then get it sorted out. The original post was a simple question about reverse polarity and lack of an earth on the supply not whether your van has a multiple of faults in the first place. So that you can read both the question, and your reply, again, I have quoted them above. Syd concludes that the only risk from reversed polarity is if fiddling with the electrics while still connected - and you responded correct. The simple truth is that fiddling with any electrics while still connected is potentially dangerous, whether or not polarity is reversed. Secondly, reversed polarity carries some risks to users of vans with older electrical installations. If the polarity is corrected, these risks are eliminated. Why obscure this simple truth?My tester has amber lights for all conditions, but they light in different combinations. So, to me, green lights could indicate anything from a healthy supply (which I would expect from green), to imminent death, depending on the type of tester being used - which was not stated.Look, it is all quite simple really. You can insert the tester, then correct reversed polarity if necessary, and reject any connection with a poor earth in the process. This takes only a few seconds, and eliminates any resulting risk. Please, why do you insist on advising people to do otherwise? Link to comment Share on other sites More sharing options...
Syd Posted July 5, 2009 Share Posted July 5, 2009 Hi Brian Yes of course you are right to say that any plugged in equipment is equally dangerous to fiddle with, but can we please leave out everything else but the actual physical reversed wireing situation. What I am trying to get out into the open is exactly what are the dangers that we face from the reversed wireing situation from the electrical equipment that we use in our motor homes/caravans. Do we face electricution or not and if so why or why not. It seems to me that if everything on the vehicle is being maintained correctly and equipment is in good servicable condition then reverse wireing is no more dangerous than non reverse wireing, under the same conditions. Is this correct Incedently we are totally non 240volt in our caravan other than for the microwave oven but this subject bugs me, it's like the gassing thread all over again Link to comment Share on other sites More sharing options...
sshortcircuit Posted July 6, 2009 Share Posted July 6, 2009 Syd Previous posts "So!! To me, from all of thid debate, it seems that the only real danger from reverse wireing will come from anyone dismantleing electrical equipment while it is still plugged into the supply. Is that correct??" "No Given a combination of fixed wiring faults then a situation could arise." Recent post "Do we face electricution or not and if so why or why not. " Yes you face electrocution "and if so why or why not." I'm lost on this bit "It seems to me that if everything on the vehicle is being maintained correctly and equipment is in good servicable condition then reverse wireing is no more dangerous than non reverse wireing, under the same conditions." Correct, in an ideal world, but it does not happen and faults can occur. Its amazing how such a simple common sense test brings out such negative responces Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 6, 2009 Share Posted July 6, 2009 As far as I can see, anxiety about reverse polarity is a fixation only with UK caravanners/motorcaravanners, and the main reason for this is because they can easily and cheaply check for it! The type of inexpensive domestic plug-in mains tester available to UK caravanners/motorcaravanners is (as far as I'm aware) not marketed outside this country. Our Continental cousins can't easily test for 'reversed' mains power supplies and, consequently, the issue of reverse polarity doesn't arise. Risk-wise, I've never read of anyone coming a cropper because of reverse polarity and I believe the real-world likelihood of anyone being harmed by to be minimal. It would be interesting to see what the UK attitude to reverse polarity would be if a tester cost several hundred pounds rather than just a few quid. Link to comment Share on other sites More sharing options...
Syd Posted July 6, 2009 Share Posted July 6, 2009 Hi shortcircuit Thanks for your reply but in my last post I did clearly say and you replied "It seems to me that if everything on the vehicle is being maintained correctly and equipment is in good servicable condition then reverse wireing is no more dangerous than non reverse wireing, under the same conditions." Correct, in an ideal world, but it does not happen and faults can occur. I suspect no one takes 240volts supply, equipment and wireing lightly and I suspect most people do take more care of them than they are given credit for. So under the previously stated conditions just what faults can occur, the crux of the matter is. What exactly are we at risk from. I'm really not trying to be some kind of smart Alec but I really would like to know the answer Link to comment Share on other sites More sharing options...
sshortcircuit Posted July 6, 2009 Share Posted July 6, 2009 Syd Its all a matter of Ifs If the site RCD is faulty If the earth is faulty from site to vehicle If the vehicles RCD is faulty, if fitted If you have a fault neutral to earth If you touch the vehicles earthed (now live)metalwork with you on tera firma All if,s, but that's what the protection devices are for and the wiring regulations. A simple polarity checker can indicate a problem Link to comment Share on other sites More sharing options...
Syd Posted July 6, 2009 Share Posted July 6, 2009 Hi Again shortcircuit Yes I know it is all a matter of If, if, if, but that what I am trying to get at is exactly what is the extra risks, that are not presant with non reverse wireing, that we might face from reverse wireing if we use our electrical gadgets in our motorhomes and caravans assumeing that all other things are ok Do we face any extra risks. Link to comment Share on other sites More sharing options...
duetto owner Posted July 6, 2009 Author Share Posted July 6, 2009 thanks again for all the detailed replies got a bit lost on some of them too technical for me. I will get a spare reversed socket made up for any occasion where the 3 lights do not illuminate. Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 6, 2009 Share Posted July 6, 2009 Syd - 2009-07-06 10:11 AM Hi Again shortcircuit Yes I know it is all a matter of If, if, if, but that what I am trying to get at is exactly what is the extra risks, that are not presant with non reverse wireing, that we might face from reverse wireing if we use our electrical gadgets in our motorhomes and caravans assumeing that all other things are ok Do we face any extra risks. OK Syd, I'll try, but it’s a bit of an essay!Domestic 230V cabling comprises three wires, usually called live, neutral, and earth. Standard UK practise is to always insert a circuit breaker into the "live" feed to a circuit (at the consumer unit, sometimes called the fusebox), and to always place a switch at a socket, and at an appliance. In most cases these switches will also affect only the "live" wire. In addition, all plugs contain a fuse. The neutral is generally left unswitched and unfused, so that there can be no break in the return path for the current once it has done its work. The earth is, in effect, an alternative, more direct, path back for the current, which comes into play if the neutral becomes defective. How all this is arranged in practise will depend on the age of the installation. In older installations fuses may be present where modern practise would install Miniature Circuit Breakers (MCBs). Because all this is installed into the live feed only, it is called single pole (SP) switching.In relatively recent (say the past 20 years) installations there will be some additional form of safety device at the consumer unit, either an Earth Leakage Circuit Breaker (ELCB), or more recently a Residual Current Device (RCD). These will operate the main switch, which cuts both the live and the neutral supplies. This is called Double Pole (DP) switching.So, what are they all for?The circuit breakers/fuses in the consumer unit are rated for the load the circuits can carry, and they cut supply to a circuit if it is overloaded. This is because overloaded cables to get hot, damaging their insulation, and also creating a fire risk. Circuit breakers are there to protect wiring, not people. The switch on a socket is there to prevent inadvertent contact with the live contact inside. The plug fuse is there to prevent overload of the flexible cable connecting an appliance. The switch on an appliance is to cut the circuit before the appliance is dis/connected.The bit that protects people is the ELCB/RCD. An ELCB works by detecting current flowing on the earth wire, and tripping the main switch, an RCD works by comparing the current flowing on the live and the neutral wires, and tripping the main switch if there is an imbalance. RCDs are better, because if it is you that is connected to earth an ELCB may not react, whereas an RCD will.Now, what is different in Europe?First, the MCBs/fuses in their consumer units switch both live and neutral (so are double pole switches), so isolate the supply whichever way the current is flowing. Second, sockets are not, generally switched. Third, plugs have no fuse. Fourth, appliances generally are DP switched. The presence of ELCB/RCD main switches, as in UK, depends on the age of an installation. This applies also to site feeder pillars, where the most modern have both RCD and MCB protection, but the most ancient may have only fuse protection on a main distribution board. The latter are being eliminated, but the pace varies from country to country, even from district to district, partly dependent on the inspection regime prevailing (i.e. annual, biennial quinquennial, etc).So, what is the risk to UK travellers with reversed polarity supplies? If installations are modern, with RCD and MCB protection at both supply pillar and van, actually, very little. However, because all our UK installations are SP fused/switched, all the neutrals have now become the live feeds, and are by-passing the consumer unit MCBs to connect unprotected to appliances and sockets. Still, provided all the circuits, fixed equipment and appliances are in good shape, no danger will arise. The proviso, however, is important. Since motorhomes (and caravans) are driven around, they are subject to vibrations that fixed installations do not encounter. Connections can, and do, work loose, with wires dropping from their terminals. Van electrics frequently rely on junction boxes to ease final connections to fridges, cookers, hobs, battery chargers etc. Within these junction boxes, several differently rated circuits may connect with their respective appliance feeds. Should a low capacity feed drop onto a higher capacity circuit, the low capacity wiring could effectively end up carrying too high a current. This creates the risk of overheating. So, there is a possible fire risk. What is the danger from poor/faulty earths?Provided your installation has a working ELCB/RCD installed (and by now the great majority will have), any leakage current should immediately isolate the supply, so any shock will be very brief, and the consequent danger very small. On the other hand, if there is not a working ELCB/RCD mains switch at either pillar or van, there a risk of shock should a wiring fault cause metalwork to become live. Overall, with modern installations, all working correctly, the risks are negligible. The potential risks lie in the variability, and condition, of site and on-board installations, and the condition of user appliances. The greatest danger is vibration while travelling, which can cause connections to loosen, and wiring or components to break free, resulting in unforeseeable and unseen faults developing during journeys. We used to carry a small 230V fan. The last time I tried using it, it hummed, but did not turn. When I tried spinning the blades manually, they resisted, so out came the toolbox. Once inside, I could see that the motor shaft bearings had collapsed due to the vibrations from travelling, rendering the fan unusable. I also discovered that even in the short time it had been on and humming, it had become surprisingly hot! Had that been a less obvious fault, in a built-in item, I guess fire would have been possible. Electricity is a good, but potentially dangerous, servant. Taking precautions each time you connect to an unknown supply eliminates most of that danger. Simples! Link to comment Share on other sites More sharing options...
Syd Posted July 6, 2009 Share Posted July 6, 2009 Thanks Brian, no arguments there then. I already knew what you said about how our supply is protected at home but simply couldn't work out what the special danger was that made everyone view reverse wireing with such horror. It is how I thought it was and now we know. PS You shouldn't carry any fans cos they can be dangerous Link to comment Share on other sites More sharing options...
Guest Tracker Posted July 6, 2009 Share Posted July 6, 2009 Syd - 2009-07-06 7:34 PM You shouldn't carry any fans cos they can be dangerous Unless they are all plastic with no metal parts touchable - or, as in our case - 12 volt! I still remain to be convinced how dismantling any electrical appliance that is NOT connected to the mains can be dangerous - unless it has a capacitor inside it - but that's another story! Surely nobody is daft enough to take any electrical item apart whilst it is still plugged in and/or live - or are they? Link to comment Share on other sites More sharing options...
rupert123 Posted July 6, 2009 Share Posted July 6, 2009 Well thanks for all that Brian, if you refer to my very first post on this it confirms what I stated in the first place, which you disagreed with. Nice to see you have changed your mind. Link to comment Share on other sites More sharing options...
rupert123 Posted July 6, 2009 Share Posted July 6, 2009 Brian Kirby - 2009-07-05 10:39 PM So that you can read both the question, and your reply, again, I have quoted them above. Syd concludes that the only risk from reversed polarity is if fiddling with the electrics while still connected - and you responded correct. The simple truth is that fiddling with any electrics while still connected is potentially dangerous, whether or not polarity is reversed. Brian either I am reading this wrong or you are. Syd states fiddling with electrics while connected is not the thing to do I said correct, what is wrong with that after all in your first sentence you agree. Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 7, 2009 Share Posted July 7, 2009 In response to both Rupert, I can only say that what you now say you meant, is not what I originally read your comment as meaning. Whether that is my fault for not reading it right, or yours for not writing it right, others will have to judge. However, if one person (me) can misunderstand, I dare to assume others may also misunderstand, so if we have now cleared away the misunderstandings, we have presumably done a good, if lengthy, job. Amen! Link to comment Share on other sites More sharing options...
JohnK Posted July 7, 2009 Share Posted July 7, 2009 Thanks for your explanation, Brian. I have just bought a Continental adapter which is the blue socket with a continental 2 pin plug on the other end. Does this mean that if I have to use this, there won't be an earth? Using previous comments I have wired up (and tested) a reverse polarity adapter as notwithstanding other comments, it seems easier to be safe than sorry! John Link to comment Share on other sites More sharing options...
Guest Tracker Posted July 7, 2009 Share Posted July 7, 2009 JohnK - 2009-07-07 1:05 PM Thanks for your explanation, Brian. I have just bought a Continental adapter which is the blue socket with a continental 2 pin plug on the other end. Does this mean that if I have to use this, there won't be an earth? Using previous comments I have wired up (and tested) a reverse polarity adapter as notwithstanding other comments, it seems easier to be safe than sorry! John Most continental plugs have a metal strip on their sides. This strip is the earth and makes contact with the earth contact on the side of the socket - always assuming that the socket has an earth wire attached to it! To reverse polarity simply pull the plug out, turn it through 180 degrees and shove it back in again. Link to comment Share on other sites More sharing options...
JohnK Posted July 7, 2009 Share Posted July 7, 2009 Thanks Tracker - simple but only when you know how! Link to comment Share on other sites More sharing options...
Guest Tracker Posted July 7, 2009 Share Posted July 7, 2009 Forgot to mention - turning the plug over is easier if you have a plug where the cable exits parallel to the pins as opposed to the more usual cable exit at 90 degrees to the pins - and it also helps avoid the ingress of water by not having the cable facing 'downhill' as it enters the plug. I don't know about you but nothing frightens me more than wet live electicals! By the way these plugs are readily available, and cheap, at supermarkets in the countries that use this system. Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 7, 2009 Share Posted July 7, 2009 Tracker - 2009-07-07 2:03 PM JohnK - 2009-07-07 1:05 PM Thanks for your explanation, Brian. I have just bought a Continental adaptor which is the blue socket with a continental 2 pin plug on the other end. Does this mean that if I have to use this, there won't be an earth? Using previous comments I have wired up (and tested) a reverse polarity adaptor as notwithstanding other comments, it seems easier to be safe than sorry! John Most continental plugs have a metal strip on their sides. This strip is the earth and makes contact with the earth contact on the side of the socket - always assuming that the socket has an earth wire attached to it! To reverse polarity simply pull the plug out, turn it through 180 degrees and shove it back in again. These side mounted earth contacts are not, so far as I know, used in France - at least I have never yet encountered them. The French version of the two pin socket (and I seem to remember the Italian), has a single male earth pin mounted top dead centre, with the female live/neutral contacts at 3 O'clock and 9 O'clock. The plug has male live/neutral pins, and a single female earth, and cannot therefore be rotated 180 degrees and re-inserted. All the two pin plugs I have seen for sale in UK on "continental" adaptor leads incorporate both the single French female earth contact, and the side contacts for the German socket at top and bottom dead centre. You can safely use them rotated in the German pattern sockets, but not in France.I have not yet encountered European supply pillars that will not accept ether this type of adaptor plug, or the blue CEE type. However, we have not yet got to Scandinavia, where I gather things get a bit special! Link to comment Share on other sites More sharing options...
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