Reversed Polarity

[Paul Batchelor]

Hi everyone we are currently driving down through France and at two Airs had the use of power but both have had reverse polarity. Have never had this issue before in UK or France. Is this just a coincidence two in a row or could I have a problem.

 

[Happy Jim]

It’s not a problem for the 240V devices (they’ll still work happily), I got a cheap polarity tester from flea bay and use a crossover cable if I come across it (in theory it renders single pole trip switches a bit useless, in practice I’ve never actually found a problem!)

Jim

 

[Odd-no-more]

If your van has single pole mcb's then there's a small (very small) extra risk, if it has double pole mcb's then no risk at all

 

[Paul Batchelor]

Thanks Jim my van is a 2010 and has a warning light on the Sargent controller so I have unplugged and not used hook up both times. Didn't want to cause any damage.

 

[Lenny HB]

Hi everyone we are currently driving down through France and at two Airs had the use of power but both have had reverse polarity. Have never had this issue before in UK or France. Is this just a coincidence two in a row or could I have a problem.

You don't have a problem, they don't worry about which way they wire sockets as in all their circuits breakers & switches are double pole.

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[bigalw35]

We stopped off at a site in charvile mezziers (Mont Olimpe) a couple of years ago on the way down through France, that pitch was reversed polarity, no problem installed the switchover cable, stopped at the same site on the way back, different pitch, perfect

 

[Odd-no-more]

Because in France all the posts have double pole isolators, polarity doesn't matter, reversed or not.

 

[The Wino]

I bet you wouldn't find any Europeans with a changeover cable and yet they all seem to manage perfectly well. Just don't dismantle any of your electrics while plugged in although you'd have to be pretty daft to anyway.

 

[Paul Batchelor]

Thanks folks we very rarely use hook up when touring so it won't make problem but at least I now understand what is going on.

 

[bigalw35]

I installed two neon lamps, one green and one red, good or bad, subject to the result I now just fit the switchover cable and then all is good

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[bigtwin]

I’m surprised that after so many threads where the non-issue of reverse polarity is discussed that folks are still carrying ‘corrector leads’ for something that has no material impact on the user. But then, fear has always been a significant weapon in the armoury when it comes to persuading folks to purchase items.

Ian

 

[autorouter]

I bet you wouldn't find any Europeans with a changeover cable and yet they all seem to manage perfectly well

Because they all have double-pole circuit breakers and plugs without fuses. The UK fused 3-pin plug is the one thing we can't do anything about, unless they are all changed to Schuko '2-pin' plugs and sockets.

 

[bigtwin]

Because they all have double-pole circuit breakers and plugs without fuses. The UK fused 3-pin plug is the one thing we can't do anything about, unless they are all changed to Schuko '2-pin' plugs and sockets.

Indeed, but why would you consider delving behind the covers on ac kit without disconnecting the EHU cable?

You wouldn’t? In which case it makes no odds which way round the Live and neutral are connected.

Ian

 

[Richard n Ann]

I always think the small risk of having extra ehu connections with the changeover lead is more than the risk from reverse polarity.

 

[bigalw35]

Hi Ian, the last thing I would want is to try and get people to buy items that are not required, but lets let people know the implications of reverse polarity.
When the polarity is reversed in a camper/motorhome ANYTHING that is metallic is LIABLE/POSSIBLE to become a problem as the metal work will be connected to the LIVE and NOT the NEUTRAL, so when people think that appliance is dead it could actually be LIVE

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[bigtwin]

When the polarity is reversed in a camper/motorhome ANYTHING that is metallic is LIABLE/POSSIBLE to become a problem as the metal work will be connected to the LIVE and NOT the NEUTRAL, so when people think that appliance is dead it could actually be LIVE

That is simply UNTRUE.

You are confusing Neutral and Earth.

Ian

 

[bigtwin]

I always think the small risk of having extra ehu connections with the changeover lead is more than the risk from reverse polarity.

Agreed, I always think that folks who don’t understand the non-issue of reverse polarity should leave things well alone rather than meddle with things they don’t understand.

Ian

 

[two]

You could always turn your van around, if that makes you happier.

Like your position to the peg, it'll make little difference in practical terms.

 

[autorouter]

Indeed, but why would you consider delving behind the covers on ac kit without disconnecting the EHU cable?

You wouldn’t? In which case it makes no odds which way round the Live and neutral are connected.

Just because you can't imagine any scenarios where reverse polarity could be dangerous doesn't mean there aren't any. If it's dangerous to delve into ac kit without disconnecting it, it is also dangerous to knock the toaster into the washing up, for example. The fuse blows, but it is still live, because the fuse is on the neutral side.

 

[bigtwin]

Just because you can't imagine any scenarios where reverse polarity could be dangerous doesn't mean there aren't any. If it's dangerous to delve into ac kit without disconnecting it, it is also dangerous to knock the toaster into the washing up, for example. The fuse blows, but it is still live, because the fuse is on the neutral side.

Of course one can imagine scenarios where risk may be increased but, frankly, driving your MH to a campsite is more dangerous than connecting to a ‘reverse polarity’ EHU bollard. It’s about perspective!

Ian

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[autorouter]

Agreed, I always think that folks who don’t understand the non-issue of reverse polarity should leave things well alone rather than meddle with things they don’t understand.

It has only become a non-issue because hookup posts and motorhomes are nearly all fitted with an RCD (Residual Current Device), which protects against electric shock, whether due to reverse polarity or anything else. Older motorhomes and some self-builds may not have an RCD.

To see if your MH has an RCD, look for a mains trip that has a 'Test' button. Some of them (MCBs) don't. There should be an RCD and also an MCB. There's no harm in fitting a 'polarity reversal' lead, but make sure there is an RCD.

 

[bigtwin]

To see if your MH has an RCD, look for a mains trip that has a 'Test' button. Some of them (MCBs) don't. There should be an RCD and also an MCB. There's no harm in fitting a 'polarity reversal' lead, but make sure there is an RCD.

Indeed, there’s no harm in doing so but there’s no real point in doing so either.

Ian

 

[Jonno1103]

99% motorhome sockets aren't switched so they remain live on hook up anyway. Every appliance you use has it's own fuse in it's 3 pin plug. The only users which seem to have a problem are those with hook up in a tent or trailer tent. The wiring in their extension sockets won't work with reversed polarity so a crossed over connector is required.

 

[bigtwin]

The only users which seem to have a problem are those with hook up in a tent or trailer tent. The wiring in their extension sockets won't work with reversed polarity so a crossed over connector is required.

How so? Are you able to explain?

It shouldn’t make any difference to the operation of anything connected to it.

Ian

 

[pappajohn]

it is also dangerous to knock the toaster into the washing up, for example. The fuse blows, but it is still live, because the fuse is on the neutral side.

But of course, the double pole RCD at the post would have tripped so all you have is an aquatic toaster.

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[Trevor Wbm]

As I alluded to in another thread, it's Alternating Current, operating at 50hz, which means the supply is reversing polarity 50 times a second, so AC kit doesn't care which way it starts. The only risk is if you start buggering about with cables or go to fish the toaster out of the sink without disconnecting the EHU. Ideally, don't put the toaster in the sink.

 

[The Wino]

It has only become a non-issue because hookup posts and motorhomes are nearly all fitted with an RCD (Residual Current Device), which protects against electric shock, whether due to reverse polarity or anything else. Older motorhomes and some self-builds may not have an RCD.

To see if your MH has an RCD, look for a mains trip that has a 'Test' button. Some of them (MCBs) don't. There should be an RCD and also an MCB. There's no harm in fitting a 'polarity reversal' lead, but make sure there is an RCD.

But if anyone hasn't got an RCD fitted wouldn't they be better fitting one rather than a reverse polarity lead as it would then give better protection under all circumstances.

 

[Reallyretired]

I have toured sur le continent for best part of half a century without a changeover lead and I am still here.
The only problem I have had is a disconnected earth in the plug.

 

[autorouter]

But of course, the double pole RCD at the post would have tripped so all you have is an aquatic toaster.

That's why I said IF it is dangerous. The two situations are equally dangerous. Both can be guarded against by a double-pole RCD.

But if anyone hasn't got an RCD fitted wouldn't they be better fitting one rather than a reverse polarity lead as it would then give better protection under all circumstances.

Yes. Every motorhome mains inlet should have an RCD. It is a necessary safety item. They are cheap and easy to fit. There's no excuse for not having one.

 

[pappajohn]

The only users which seem to have a problem are those with hook up in a tent or trailer tent. The wiring in their extension sockets won't work with reversed polarity so a crossed over connector is required.

It's make no difference what the situation is.
Electric cable has 3 wires, live, neutral and earth.
Live and neutral can be either way round.....they still transmit electrical current
So whether it's a boat, a tent, a motorhome or a garden extension lead is irrelevant.