Reverse Polarity - What is it?


A lot of 'scaremongering' surrounds the topic of Reverse Polarity on Caravan/Motorhome websites based on data that is no longer current.


Reverse Polarity is a term usually used to describe where a 230V device, like a household appliance, e.g kettle, has been wired incorrectly at the plug so that the Live/+ power travels down the Neutral/- wire of the 3 wire cable.

Normally the Live/+ voltage would pass down the Brown wire which is where most Appliances have the On/Off switch. 

The Blue wire is used for Neutral and the Yellow/Green wire for Earth. 

It is not an uncommon situation in the UK where somebody fits a 13A plug to, for example, a toaster they have purchased and accidently reverses the wiring so that the 230v Live/+ comes in down the Blue neutral wire in the cable. 

This is reversed Polarity.

Something like a Kettle or toaster will continue to function if connected this way.

However, even when the device works correctly there can be a 'perceived' safety issue as the On/Off switch is sometimes located in the +/Brown cable.

If the Polarity is reversed much of the cable in the device would still be 'live' when 'switched off'. If someone then opened the Case and put their fingers into the wiring, they might be injured. 

Which is why 'standard practice' suggests removal the power supply plug from the wall socket before opening a 230v device and putting your fingers into the wiring. 

Much is made of this 'danger', yet it quite clearly isn't a safety risk as few sensible people are going to open up any 230v device while it is still connected to the wall 230v socket and put their fingers on the bare wires!! 

Almost every appliance going now has labels warning about the Danger of opening the casing of any device while powered with 230v.

To combat this issue of 13A plugs being incorrectly fitted in the Home, new UK regulations were introduced (around 1990?) that specified all Appliances being sold in the UK, had to be pre-fitted with a 13A plug so that purchasers are less likley to fit a 13A Plug with wires/Polarity reversed

Around the same time Appliances began to be 'Double Insulated' and 'double pole' switched, i.e. a switch in both the Live wire AND the Neutral wire. 

UK quality Electronic devices (from say 1999 onwards) began including features to cope with Reverse Polarity by having Double Pole switches and Polarity protected Electronics, following the mainland Europe practice started many years before.   

In France and Spain, they had long ago realised that even when good standards were in place, people did not always follow them in the home. So the majority of French and Spanish manufactured 230v Appliances of the 1970's and 1980's took account of Voltage Polarity reversal and generally worked/were safe on both.

Any Camping Site Electric Hook-Up (EHU) bollard should follow the European 230v wiring standards on all camp sites.

But in the 1980's some French and Spanish camp sites were slow to adopt the more rigidly enforced standards. It had never been a problem before, so some viewed it as unnecessary bureaucracy.

The situation is now very different. Double Insulated, Double Pole switched and Polarity Reversal proof appliances are the norm. 

A modern, quality Motorhome like Auto-Trail, Burstner, Hymer, Dethleffs, N&B, Knaus, etc will happily function on any Polarity and has for about 15 years.  

So while the issue in the 1980's with 'Reverse Polarity' was significant, it is now not the problem it was with a quality, modern Motorhome/Caravan. 

Much of the advice you will read will be old and no longer so relevant.

A Kettle used on the wrong polarity in a Motorhome is no more dangerous than one in the House with the 13amp plug wired incorrectly. 

The risk of using it is zero in real terms.



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