Reverse polarity

[Wellington]

Given that we plan to venture Abroad this summer, I am trying to prepare for all the confusing things I will encounter. So, what IS reverse polarity, what will it damage, how do I know if an EHU has it, and how do I stop it doing whatever it does?! I even have reverse polarity thingy, but I don't know how you tell if it’s reverse polarity or the forward kind!

(See later for more threads on What is an Aire? How do I avoid getting gassed/burgled/murdered in my bed? What hose connectors do I need? Can you drink the water these days and Where the hell is France anyway?!!! )

 

[Richard n Ann]

It up to you but we don't worry about reverse polarity. It's reversed half the time in Spain, doesn't make any difference. In fact I'll just check it now........

 

[Richard n Ann]

No, it's not reversed today, but see? You'd never know

 

[The Wino]

We never bothered we have a French made m/h so as I understand it the electrics are double poll switched and it isn't a problem also as there are loads of m/h exactly like ours in France and they all seem ok the odds are we will be too!. Aires vary a lot some just car parks that allow overnighting some almost like sites (mostly fairly cheap). If its your first trip there why not find a nice site with pools/the sea etc for most of the trip and aires for a few nights there and back. Do remember when looking that France is BIG you can travel a few hundred miles and feel like you haven't got very far if you like UK summer weather the cote opal is close and normandy both with weather a bit like ours but french food etc.

 

[SIFTA SAM]

Some inverters don't like reverse polarity I am informed.

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[autorouter]

Reverse polarity is the popular term for when the live and neutral poles of the mains supply are interchanged. It causes no damage, and appliances operate perfectly normally, so most people never even notice that the polarity is reversed. The problem is that the protections that you normally expect with a British-wired motorhome are compromised, and can be dangerous in the event of a fault.

The most important protection is to make sure you have a Residual Current Device (RCD) fitted on the incoming mains box. An RCD can be recognised by the 'test' button. Other devices, called MCBs, do not have a test button. If in doubt, post a pic of your mains control box.

Most modern MHs have an RCD, but some older ones don't. It's worth checking. They are inexpensive and easy to fit.

Once you have an RCD, you can mess around with a socket tester to check the polarity, and fit a reverse polarity lead to bring it back to correct polarity. That's what I do, but most people don't bother - the risk is small.

 

[WillH]

We never worry about it, not for thirty years, no problems.

 

[Jonno1103]

Never worried about it. Yes it'll keep a switched socket live even when turned off but most Moho's don't have them so when on 230v a plugged in kettle, microwave or toaster is always live anyway and unlike Euro plugs a U.K. 3 pin is fused so that will blow and protect your gadgets.

Just be sure to check that all your fused 230v stuff and tech has the correctly rated fuse installed... you don't want a 13a in a 5a rated product etc.

Also I'm sure you don't go prodding your sockets and playing with wiring whilst it's still live at home if you think you have a power problem with your telly etc so I assume your not about to start doing it in your van.

As for being gassed, trust me it's myth, you'd need a 40ft tanker of the stuff and have really well sealed windows, doors and vents, i'm talking submarine type sealed... It would be far heavier than air and would trigger any fitted gas alarm. If there was a product around that could knock you out so quickly and deeply every hospital in the world would be using it as an anaesthetic and even then you'd still need to be wearing a mask. It would also be very expensive, a cost which would easily negate anything pinched from your van.

 

[WillH]

What hose connectors do I need?

You, don't need any if you use a watering can, they fit everything!

 

[Richard n Ann]

Some inverters don't like reverse polarity I am informed.

Non of them do but that's DC. This 'reversed polarity' we're talking about is actually reversed Live - Neutral

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[pappajohn]

The non technical way to explain it.
It doesn't work this way but for simplicity look at it as electric comes in through the live wire and goes out through the neutral.

230v mains has 3 wires... Live... Neutral... Earth.
For now forget earth.
In normal circumstances Neutral wire on its own is relatively Harmless, you need to touch live and neutral (or earth) to get a shock.

The live wire in your van connects to the switch in sockets and light switches.
The neutral wire connects directly to the socket or light fitting.
The live and neutral wires from the mains hookup connect to corresponding live and neutral in the van.
When you switch off a socket or light you break the live wire which disables that socket or switch.
Reverse polarity works in exactly the same way except the mains hookup live wire is connected to the vans neutral wire and mains hookup neutral to the vans live wire.
Switching off a socket or light switch still turns it off but instead of the live wire being broken the neutral is broken leaving the live wire still... Well... Live,
so if you turn off a socket and stick a knife in the toaster to get a teacake out you may well get a shock because the vans neutral wire which isn't switched is connected to the mains live wire
So, providing you have an RCD and decent earthing, don't poke anything in any electric outlet and don't dismantle anything without unplugging the hookup lead and inverter if you have one, there is nothing to worry about.

 

[Bognor Saint]

On our last motorhome a warning light on the sargent control panel lit up when reverse polarity was detected. At the time not knowing much about it worried me as I saw it as a fault.
Anyway since then I have made up a couple of connecors to reverse the reverse polarity.

 

[The Wino]

The non technical way to explain it.
It doesn't work this way but for simplicity look at it as electric comes in through the live wire and goes out through the neutral.

230v mains has 3 wires... Live... Neutral... Earth.
For now forget earth.
In normal circumstances Neutral wire on its own is relatively Harmless, you need to touch live and neutral (or earth) to get a shock.

The live wire in your van connects to the switch in sockets and light switches.
The neutral wire connects directly to the socket or light fitting.
The live and neutral wires from the mains hookup connect to corresponding live and neutral in the van.
When you switch off a socket or light you break the live wire which disables that socket or switch.
Reverse polarity works in exactly the same way except the mains hookup live wire is connected to the vans neutral wire and mains hookup neutral to the vans live wire.
Switching off a socket or light switch still turns it off but instead of the live wire being broken the neutral is broken leaving the live wire still... Well... Live,
so if you turn off a socket and stick a knife in the toaster to get a teacake out you may well get a shock because the vans neutral wire which isn't switched is connected to the mains live wire
So, providing you have an RCD and decent earthing, don't poke anything in any electric outlet and don't dismantle anything without unplugging the hookup lead and inverter if you have one, there is nothing to worry about.

Or if your switches switch off both live and neutral no problem

 

[SIFTA SAM]

Non of them do but that's DC. This 'reversed polarity' we're talking about is actually reversed Live - Neutral

I'm referring to inverters that have the A/C switch over circuits built in.

 

[SandraL]

Our last van had an eberspacher diesel wet heating system that would not run if the mains polarity was reversed.

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[mitzimad]

we had cbe spurs in our self build and when on reversed polarity the neons glowed dimly even when switched off
but apart from that everything worked its really only a problem if your going to work on the electrics

 

[autorouter]

Most proper camp sites in Europe have the standard blue 3-pin sockets, as you find on British camp sites. However some places, like Aires, small sites and marinas etc may have the domestic sockets for the country you are in. For this situation you will need and adaptor. There is a previous thread with information about the adaptor for French, German and Spanish sockets. Switzerland, Italy and Denmark are different again.
https://www.motorhomefun.co.uk/forum/threads/what-adapters-to-take-to-germany.190454/

 

[Camping Gaza]

Dont worry about reverse polarity, but you probably need one of these adaptors. euro plug to blue socket to your blue plug on your hook up cable.

PS. The water in France is better quality than the UK. And France is the bit you stand on when you get off the boat or through the tunnel.

 

[Silver-Fox]

As for being gassed, trust me it's myth, you'd need a 40ft tanker of the stuff and have really well sealed windows, doors and vents, i'm talking submarine type sealed

No it’s true you can get gassed.
As @The Dotties will back me up on this.
We were talking to a bloke that works in the builders merchants I use.
He was gassed in France, no really he was

 

[pappajohn]

Or if your switches switch off both live and neutral no problem

That's fine on Johnny Foreigner vans but in the UK they still haven't grasped that concept in domestic installations let alone mobile ones.

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[The Dotties]

No it’s true you can get gassed.
As @The Dotties will back me up on this.
We were talking to a bloke that works in the builders merchants I use.
He was gassed in France, no really he was

Every word is true, he had his baby with and was really swearing on her life.
Think he got a bit upset when we didn’t wholeheartedly agree with him though!

 

[Lenny HB]

Gee Wiz, 3 Toilet Threads & Reverse Polarity in a week.

@hilldweller I could be on for a Full house.

 

[Wellington]

Gee Wiz, 3 Toilet Threads & Reverse Polarity in a week.

@hilldweller I could be on for a Full house.

Soooorrreeee

But if you don’t ask, you don’t find out!

I will cross it off my list of things to worry about, and worry about the Alps instead. (I was only joking about the gas, I promise)