# Reverse Polarity Switch



## Huckleberry (Oct 18, 2008)

We found it our thanks to all those who had some great ideas. The price of this one (and peace of mind) is around £35

Found it on http://www.conrad-anderson.co.uk/power/switches-accessories/reversed-polarity-switch.htm
Waudbys sell it
Ebay sell it too
I just put in the wrong description originally

Reversed Polarity Switch - Live/Neutral Changeover

When hooking up to mains power in foreign marinas it is important to check that the live and neutral wires are in the right order.

The two pin plug system can have live and neutral either way round.

The Live/Neutral Changeover is wired into the electrical system and monitors the polarity giving a visual indication of the polarity. If it is incorrect an alarm is sounded along with a visual indication you can then switch to correct the polarity before turning on the power to the boat.

Permanent installation.

Supplied complete with glands.

Full colour coded fitting instructions.
Reverse Polarity Changeover - article from MMM magazine.

First recommended by MMM in 1991, the Live/Neutral Changeover switch is still sold in its hundreds every year at home and abroad. Mounted in a box the size of a domestic, surface-mounted light switch, the device has an LED, which shows green if the live neutral wires incoming from the mains to the 'van are the right way round. If they are reversed, the LED is red and the buzzer sounds continuously. Operating the switch on the box reverses the connection if necessary. The device can draw attention to other faults in the supply, such as absence of an earth connection. The switch is inserted in the mains cable before the RCCD and consumer switches, so that the polarity can be checked before any mains supply is fed round the 'van. The wiring must, of course, be carried out or verified by a qualified electrician.

Never having used a forum before it's nice to know there humans at the end of these computers ready to help!

Thanks again Happy Motorhoming - Lets hope the weather gets better!

Huckleberry


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## 101405 (Oct 15, 2006)

It will not make one bit of a difference to how your appliances work in your van , most are only 2 wire so you either switch off the neutral or the live , so why not just reverse your + - in your van when you cross the channel . with our 2 pin or 2 pin and earth-(2prongs) there is no right or wrong way to plug in , but then people don't fiddle, they call the man ,


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## Ian_n_Suzy (Feb 15, 2009)

silversurfa said:


> It will not make one bit of a difference to how your appliances work in your van , most are only 2 wire so you either switch off the neutral or the live , so why not just reverse your + - in your van when you cross the channel . with our 2 pin or 2 pin and earth-(2prongs) there is no right or wrong way to plug in , but then people don't fiddle, they call the man ,


Hi,

Is this the same for the battery charger?

Cheers


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## Don_Madge (May 1, 2005)

I would think twice about having one of these fitted, under certain circumstances they can cause a lot of damage to your electrical wiring.

Don


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## Ian_n_Suzy (Feb 15, 2009)

Hi Don,

Could you please expand a little on what you mean by this?

Would I be better to stick to the "crossed over hookup" to rectify the Reverse Polarity?

Thanks in advance.
Ian


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## aultymer (Jun 20, 2006)

First year in France we checked every hookup and used crossover lead as required. Did some more reading and from then on left the crossover lead at home.
Since I never work inside any appliances when on hookup there appeared to be no point worrying which way round the plugs are wired. If something goes faulty it is removed to storage to be serviced by someone qualified back home.
This works for me but it is up to everyone to make up their own mind on the subject.


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## brightsparkretired (Sep 26, 2008)

*changeover switch*

If the incoming supply is reversed then that means the neutral(solid bar in the consumer unit is live so if u think that switching the mcb off has isolated the supply it hasn,t. Also if u have switched sockets in your van & they are not double pole switched it also means that u still have a live supply into the appliance . Imagine an electric heater, the element would have 240v on it up to its control switch. Always unplug, is the motto.
Tel :!:


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## 101405 (Oct 15, 2006)

*reverse polarity*

Neutral bar? well firstly you sould keep your fingers out of the Distribution box! and switch off - unplug if you do? secondly this does not exist in a euro Installation all negs are joined in Insul /connectors lose in the box so no live terminals ,same with earths, you can remove your own N/ bar and replace with strip connectors , I would think this is not fitted on new Installations in the uk , all Heaters, oil ect ,have dp switching to comply with eu regs. no metal appliances should be used in a motor home. but you all should have respect for Electricity !230 volts kills!!


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## Don_Madge (May 1, 2005)

Ian_n_Suzy said:


> Hi Don,
> 
> Could you please expand a little on what you mean by this?
> 
> ...


Hi Ian,

I should have put a full explanation last night but it was late and I don't feel to great these days.

An acquaintance had one of the devices fitted to his motorhome and one day on a camp site in the UK while hooked up to the mains he was demonstrating to some friends how the switch worked.

Not realising that his wife had switched on the water heater and the electric kettle he operated the change over switch and it promptly blew up destroying the switch and doing quite a bit of damage to the wiring.

I have since heard of another case of this happening and I think it was a member of facts that it happened to.

I had one of the switches fitted when they first came out and I've not had any problems but I do disconnect from the mains if I need to operate the change over switch.

With hindsight I should have stuck with my old cross over adapter.

I hope this helps.

Don


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## sallytrafic (Jan 17, 2006)

I am suspicious of auto change over units for both polarity reversal and earth swapping (see inverter thread).

When I was designing such things it is amazing what pitfalls there can be.

I was designing in a fixed environment and still there were so many 'what ifs.'

When you are designing for a mobile application the problems multiply.

What if (for example) you plug in to a IT earthing system (found in some campsites in Scandinavia - Norway for certain) has the designer designed in a 'fail safe (in which case you are without hook up), is it capable of sensing that it is an IT, does it 'fail run' and if it does can it cater for a faulty IT installation.

(note for non-electricians IT is to do with earth systems not computers and has polarity as well as earth implications).

So such a system has to be able to cope with anything you throw at it and everything that can go wrong, a tall order for something not built into a 19" rack.

Its the UK wiring regs that are the problem I just hope I live long enough to see complete harmonisation to the continental system (and to the back of ring circuits and single pole switching).


PS Sorry you're not feeling top form Don.


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## Ian_n_Suzy (Feb 15, 2009)

Hi Don,

Sorry to hear that you don't feel too great. Whatever the reason I wish you well.

Many thanks for letting me know the negative points of the switch - it did cross my mind on what would happen if the switch was "inadvertantly switched" at the wrong time.

Thanks again.

Ian


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## twinky (Aug 11, 2008)

I understood the issue with reversed polarity was the rcd wouldnt operate as designed - in addition to the problems already mentioned.


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## sallytrafic (Jan 17, 2006)

No rcds don't mind, they are double pole for sensing and operation. However not sure about the rcbo's that might replace them under the 17th ed I think they are single pole.


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## twinky (Aug 11, 2008)

RCBO's are single pole.

RCD's still comply fully with 17th - if there are 2 and they are used to protect a split load board.


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## sallytrafic (Jan 17, 2006)

I'll have to look into it but a split board on a motorhome doesn't sound likely does it.


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## twinky (Aug 11, 2008)

sallytrafic said:


> I'll have to look into it but a split board on a motorhome doesn't sound likely does it.


LOL no not unless you have an upstairs with the need to separate lights from sockets.....and smoke alarms, cooker, immersion heater etc.

Then we'd need sites with 100A hook ups  .

What would the solar panels be like to supply 100A when wild camping?


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## oldun (Nov 10, 2005)

One problem with reversed polarity is that the plug fuse will be in the neutral so if it blows the current will be cut off but the appliance left live.

To avoid any danger you should always cut off the power by unplugging the device or by switching off at the mains.


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## hilldweller (Mar 8, 2008)

sallytrafic said:


> I am suspicious of auto change over units for both polarity reversal and earth swapping (see inverter thread)


Although this is a manual change over using a crappy looking rocker switch.


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