# Another Theoretical versus Practical?



## johnsandywhite (May 9, 2005)

8O Another Theoretical versus Practical?

Quite a few use a Polarity reversal connector when they find that an on-site the hook up is reversed. The point is this. Does it really make any difference? The reason I ask is because in some European countries they have a twin plug or a twin plug and earth that will plug in either way. A Schuko plug is one kind. I know what regulations state that if a short occur's? It must we wired in order that it makes it's path to earth. But this doesn't apply in a Motorhome. Does it?


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## DABurleigh (May 9, 2005)

This is my understanding, so in these MHF days of endless debate of angels on pinheads, I shall state from the outset that if someone wants to shoot me down in flames I shall not be upset.

The issue I always thought was that on the continent, both live and neutral lines are switched, so reversal doesn't matter, but that in the UK, the trend is for just the live line to be switched. Thus for UK produced vans, IF there is a certain type of fault in an applicance, there is a greater risk of injury or worse if the polarity is ALSO wrong.

Dave


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## 88724 (May 9, 2005)

Hi Dave

Pretty much spot on its not just vans produced in the UK though many produced FOR the uk are so equiped too.

For American and UK type vans its a potentiall very serious issue.

Hi John 

On the further point of earthing yes its very important, when on hookup also with certain types of genny and Invetor.


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## johnsandywhite (May 9, 2005)

GeorgeTelford said:


> On the further point of earthing yes its very important, when on hookup also with certain types of genny and Invetor.


I am aware of that *George*. But in practice how many people earth their RV while using the on-board Generator or the invertor for that matter?


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## 88724 (May 9, 2005)

Hi John

In the original question you asked about the shuko earth

*It must we wired in order that it makes it's path to earth. But this doesn't apply in a Motorhome. Does it? *

that is the question I answered.

Now to your further question of how many people?, not many, if any actually use an earth spike.

For most this is OK due to the way the genny and invertor work it would make an earth spike a decoration rather than any practical use, but even those that should have an earth spike are ignored. Most people ignore the manual unless anything goes wrong.


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## johnsandywhite (May 9, 2005)

Hi *George*. I didn't ask about the schuko plug. I mentioned it as a type of twin plug and earth. I am well aware of how they are wired having spent time in the Army in Germany and have wired plenty. The point is that in practice how many people actually follow the Regulations, quide lines call it what you will. Has anyone actully got proof of people being electrocuted while not following the Rules/Regulations/Guide lines? Does a light bulb know which way it screwed into the light holder? Does it work no matter whether Live is Nuetral. or visa/versa? Does a Microwave or a washing machine work the wrong way round. I would say a definite NO.


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## 88724 (May 9, 2005)

Hi John

your questions follow in bold text

*Has anyone actully got proof of people being electrocuted while not following the Rules/Regulations/Guide lines*

Yes I have while working on an inccorectly wired van in Belguim

*Does a light bulb know which way it screwed into the light holder? Does it work no matter whether Live is Nuetral. or visa/versa? Does a Microwave or a washing machine work the wrong way round. I would say a definite NO. *

Light bulb of course not, but it gets interesting when you mention Microwave and washing machine etc, in the very first post you talk about reversed polarity does it really matter and the Shuko plug that will go either way round and yet you think these two items would not work.

Now think about what you have said logically, do you see the answer?


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## johnsandywhite (May 9, 2005)

Sorry I didn't quite put the theoretical question correctly.

What I meant to say was. Will the Microwave or the Washing machine turn the worng way because the polarity is reversed? Not would it work or not. :roll:


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## 88724 (May 9, 2005)

Of course John we all know what you meant

Bye John


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## RainDancer (May 24, 2005)

Hello Everybody

I have just read all the comments by everybody and I thought I would make mine. In the situation of wrong polarity should a fault to earth occur and an rcd or rcbo be fitted in the circuit each pole would sense the imbalance be it the live pole or the neutral pole thus causing the rcd or the rcbo to operate therefore isolating the piece of equipment. However should NO protection be in the circuit to prevent earth leakage such as an rcd or rcbo and you was connected to a reversed polarity supply a dangerous state could exist if the equipment was switched off it would be possible that live parts would exist within the piece of equipment. Should anyone dismantle that equipment whilst it was still connected even though it was switched OFF they could make a circuit between the (phase conductor) live and earth and this could result in DEATH. Therefore if you have an rcd or rcbo within the circuit you will be better protected from shock. Sorry it's so long


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## 88927 (May 10, 2005)

Hi JSW
Following your theory, if the washing machine went the wrong way would it make our clothes more dirty??? And what about the reversed microwave, would this refreeze the food very quickly, I guess that would depend on the wattage of the microwave eh???
:lol: :lol: :lol: :lol: :lol: :lol: 
Keith


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## johnsandywhite (May 9, 2005)

Hi *Keith*. The question I asked was 'would it work the wrong way round?'. For instance. If you take a simple 12 volt motor (DC)(i use these in model aerploanes) and reversed the positive and negative. It would run in reverse. If you did the same with a Washing machine or Microwave (AC) would in then run in reverse or the correct way. (I know the answer - read my signature). :wink:
Does any AC appliance know the difference between postive and negative?


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## 88724 (May 9, 2005)

Hi John

I think we all understood what you really meant.

In the first part of the paragraph you ask does a light bulb work when the polarity is the wrong way round, the answer of course is yes. You then go on to ask would the Microwave and Washing machine work (if the polarity was the) wrong way round, sadly at this point you achieved a defered correct answer, if I was reading it right.

John we all suffer from brain fade at some point mine was obviously misreading what you meant.


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## johnsandywhite (May 9, 2005)

Hi *George*. I think the thread got screwed up along the way to a different path. Quite a few people worry (perhaps rightly so) about reversed polarity. I raised the question to basically ask. Does it make any difference? Electric appliances will still work the way they are supposed to work. The only potential problem is with a shorted circuit. Surely you must agree with that?


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## 88724 (May 9, 2005)

Hi John

Shorting? I cannot see were reversed polarity makes any difference to a short. A short circuit is basically live and neutral meeting, live and neutral coming down different wires is a problem why exactly?


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The potential danger is that any switched off apliance is still live, changing a light bulb could then become dangerous as the neutral pin as been switched off, But the potentially highley dangerous Live pin is still ready to kill you.

Any non double insulated appliance could also prove fatal.

Of course the RCD should still save you.


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## johnsandywhite (May 9, 2005)

Many sockets in Europe and the US are not switched. In many the plug can be plugged in either way round. Some motorhomes have no RCD fitted on any circuit except in the bathroom. So what you are saying is that everyone travelling abroad should have a reverse polarity tester and cable to correct the problem. Which is why the question was raised. I myself am quite happy to continue as I have always done. Other's will have to decide for themselves.


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## Bazbro (May 9, 2005)

My understanding of this Continental reversed-polarity business is not any problem with the supply, but with our UK/USA appliances/motorhomes.

We use switches that only disconnect "our" live wire whereas Continentals use a "double-pole" switch which disconnects both live and neutral, whichever way round they may be. The problem is therefore within our appliances/motorhome switches, etc. Our appliances could remain live, even though turned off.

We could negate the problem by exchanging all our "single-pole" switches in the motorhome and our appliances with "double-pole" ones.

That's my understanding of the problem.


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## 88724 (May 9, 2005)

Hi John

Let me get this right, *you cannot grasp the basics and cannot see the dangers so therefore there are none?* You are quite happy to await a Darwin award, but worse still you try to persuade othes its safe too.

Americans sockets are polarity secured










Here is a French/Belguim socket note it is set position










German Shuko










Were they are changeable the circuits are protected via both poles, double poled switching.

Over and over you demonstrate you have not got a clue and yet you are prepared to pretend and try to persuade others to follow your dangerous path, If you want to risk your life go ahead, but do you think so little of Sandy? Stop playing games

Sorry if this post seems harsh, *but lives are at risk here*


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## 88724 (May 9, 2005)

HiBarry,

spot on, sorry I took a while to formulate my post and you beat me to it.


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## johnsandywhite (May 9, 2005)

8O George. I do understand the basics of electicity and circuitry. I have been playing with electricity one way or another since I could stick my finger's in a plug to see what it did. Please don't confuse the question I raised with me not having the Knowledge. I will say again what I have already said. I raised the question so that other's can see why they require a polarity tester and reversing cable. The question pops up quite often. But the fact remains that some people do not and never have used these items. :roll:


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## Road_Runner_644 (May 9, 2005)

Hi All

Just so i can get my head around this.

If i miswire my hook up lead, live and neutral reversed, and plug it in. What differances will i see when i try the TV, charger, lights, microwave etc.

Is there anything that mh'ers take along with them that won't work, or will something like the electric kettle work as soon as it is plugged in, rather than when it is switched on. (depending on whether it is single or double pole switched)

I'm not arguing the point either way, just interested.

Dave


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## 88724 (May 9, 2005)

It as been explained why

So now it was only a rhetorical question and you knew all along?

As I say your reasons for asking questions/baiting are getting more and more implausable.

Yes and it was all a dream until Bobby got out of the shower one morning.

Fin


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## johnsandywhite (May 9, 2005)

Hi *Road_Runner_644*. They will ALL work just as intended. AC doesn't know one from the other. :wink:


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## Scotjimland (May 23, 2005)

There is no 240v AC appliance I know of that wouldn't work with reversed polarity, by it's very nature AC it is changing polarity 50 times per sec (50hz) 
As previously stated it is only a safety concern as our sockets are only single pole switched. 
Thinking about it, if someone wants to open up a toaster or whatever with it still plugged in they must be crazy 8O


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## 88724 (May 9, 2005)

Hi Dave

Yes they will all work (even John admits this now), but they could prove dangerous in a uk or american specced van. Due to our lack of double pole switching and protection.


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## johnsandywhite (May 9, 2005)

GeorgeTelford said:


> Hi Dave
> 
> Yes they will all work (even John admits this now), but they could prove dangerous in a uk or american specced van. Due to our lack of double pole switching and protection.


 8O *George*. Who is the one being crass and baiting now. I will say for the last time. I myself am aware of the potentiial problems. The point its that things will continue to work the way they were intended to be used. Other's like myself choose to ignore reverss polarity for whatever reason. By the way US is 60hz. Now that and our 50hz does have an effect on appliances.


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## Road_Runner_644 (May 9, 2005)

Ok - Thanks all - I see - I Think

Strange really, but my improvements to the van on the socket side have perhaps introduced a slight danger. I replaced all the german unswitched sockets with uk 3 pin switched sockets. I should have perhaps used unswitched, or got some with lights.

So the danger is there when instead of unplugging from the old unswitched socket with convertor. We switch something off with the switch on the uk 3 pin socket. (If we are on a dodgy french site).

Whatever is plugged into the socket will still be live.

I'm racking my brains to find something really dangerous, but i suppose if you had a fan heater plugged in and went off for the day, and then something falls onto the heating element.

I just put the meter on one of the plugs i put in, and it is only switched on the live side. I wonder if you can get Uk 3 pin double switched sockets, and would this cancel the potential danger.

Are there any electrical items out there that are turned on by only switching the live side.

Very interesting

Dave


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## Bazbro (May 9, 2005)

> "Whatever is plugged into the socket will still be live. "


Whatever is plugged into the socket MAY still be live (50/50 chance)



> "Are there any electrical items out there that are turned on by only switching the live side. "


Most (all?) UK appliances are switched like this, I believe (only switching off the UK live side). But all Continental appliances have both live AND neutral switched. Caveat - I think this correct - check other sources too.


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## 88724 (May 9, 2005)

Hi Dave

its the polarity thats the problem, simplist solution is to check the polarity and then if its incorrect use a short adaptor that as been wired with the Live and Neutral crossed (make sure this short adaptor is clearly marked)


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## Road_Runner_644 (May 9, 2005)

Hi All



> Hi Dave
> its the polarity thats the problem, simplist solution is to check the polarity and then if its incorrect use a short adaptor that as been wired with the Live and Neutral crossed (make sure this short adaptor is clearly marked)


Yep - got me again George - I said i'd converted all my plugs, but forgot i'd put a convertor from the continental plug in the kitchen to a strip of four uk plugs below it.

And because its the german type, you can put the convertor in either way round.

Guess what - it's live/neutral reversed, I didn't even have to go to France to experience it :?

Thats easily fixed - turn the convertor plug around.

I've had no nasty experiences with that plug being wired that way, but feel better now that whole van is wired the same way.

It still begs the question if there is any appliance out there that if plugged into a reversed live/neutral plug would cause grief. As there are lots of vans like mine where folk have simply put adaptor plates over the german sockets and have a 50% chance of having live/neutral reversed.

Does PME come into the equation? - all to much for my brain at the moment :wink:

Cheers

Dave


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## johnsandywhite (May 9, 2005)

Hi *Dave*. I seem to remember that I mentioned that many are in the same position as myself. They don't bother to check or even think about it. The only time I check the polarity Is when I am working on anything connected to any electicity supply of any denmomination ie. 12/110/240. :wink:


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## 95405 (Jun 10, 2005)

Converted non-switched outlets to uk switched ? Not all are single-pole. Many ranges of uk domestic socket outlets are dp as standard. CEF do a range. You can't tell the difference once they're fitted.

"by it's very nature AC it is changing polarity 50 times per sec (50hz) " (from scotjimland)

Hmmm. There must be more to it than this. Otherwise, with a correctly polarised single pole installation, we will still get half of the cycles down our finger if we touch the neutral terminal - which I can tell you, you don't feel a thing usually.


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## johnsandywhite (May 9, 2005)

8O Now the other problem with a US RV is the AC runs at 60hz so it must be hitting you faster. :wink:


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## Scotjimland (May 23, 2005)

LordAtManor said:


> "by it's very nature AC it is changing polarity 50 times per sec (50hz) " (from scotjimland)
> 
> Hmmm. There must be more to it than this. Otherwise, with a correctly polarised single pole installation, we will still get half of the cycles down our finger if we touch the neutral terminal - which I can tell you, you don't feel a thing usually.


Tis true tis true, unless your connected to a dodgy French supply with reverse polarity :wink:

Live will always be live, cycling between pos and neg potential at 50hz .. The neutral is (should be) at earth potential, hence poses no shock risk when touched.


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## johnsandywhite (May 9, 2005)

8O I think I should just mention this. There is a potential for shocks if you touch 2 seperate lines of Neutral at the same time. 8O


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## Scotjimland (May 23, 2005)

Hi John , could you explain this a bit more, how can you get potential between two neutrals ? Unless you are talking about genies and mains neutrals in the same vehicle.


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## 95405 (Jun 10, 2005)

"Live will always be live, cycling between pos and neg potential at 50hz"

Ah, yes, positive and negative - but the thread is about whether live and neutral may be reversed, not the same thing at all. Neutral as I understand it is always at earth potential, in fact somewhere between the socket outlet and the power station neutral is connected to earth.

Just that you've posted this bit about the cycling wave in the same breath as reversed polarity which is the bit I found confusing.


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## Scotjimland (May 23, 2005)

Hi LordAtManor 
Sorry, I didn't mean to confuse you by throwing in the cycling bit, the thread is about reversed polarity and whether there are any inherent risks. I think this has been explained quite eloquently by previous posters. 

Jim


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