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Portugal/Spain and reverse polarity


timandjen

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We are planning a trip to Portugal and Spain next month for the first time. Somewhere I read concerns about reverse polarity, which I have come across before in several other contexts. I don't really understand what it is and wonder if it is a problem that I need to get to grips with. If so, could someone explain it all in easy to understand terms! Apologies if this has been covered ad nauseam in these forums - I did a quick search but didn't come up with anything.
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timandjen - 2021-09-15 5:01 PM

We are planning a trip to Portugal and Spain next month for the first time. Somewhere I read concerns about reverse polarity, which I have come across before in several other contexts. I don't really understand what it is and wonder if it is a problem that I need to get to grips with. If so, could someone explain it all in easy to understand terms! Apologies if this has been covered ad nauseam in these forums - I did a quick search but didn't come up with anything.

All of the above is sound advice. However, motorhomes tend to stay in use for many years, so vans over 20 years are not that uncommon. It might help, therefore, if you could give some details of your van: at least make, model, and year.

 

Much of Europe has reliably adopted the blue CEE marked, weatherproof, EHU connector, but parts (the more rural bits of Portugal, for example, seemed a little "behind the curve") still lag behind the rest. Electrical supply pillars on sites can still be found with two pin type sockets in such locations, and if your van is an older one, especially if UK built, there is a possibility that its electrical system may be single pole, meaning that any fuses/MCBs will be installed into the +/positive side of the "consumer unit" (which will also include the mains on/off switch) only, leaving the -/negative circuits unprotected.

 

This still raises a possible risk. First, if a circuit is subjected to overload due to an earth fault in an item of installed equipment, or in an item plugged into a socket in the van, the supply will not be cut until the wiring itself fails. The purpose of the fuse/MCB is to protect the circuit under these circumstances (not to protect the person from shock/injury). As Allan explains in the linked article, in the absence of that fuse/MCB, which would be the case if the supply from the site pillar has reversed polarity, with the current running to earth rather than returning down the -/neutral wires, the circuit wiring has no protection and would, under those circumstances rapidly overheat until the actual wires melt, possibly starting a fire.

 

So, if your van is UK manufactured and more than five or so years old it would be prudent to equip yourselves with a polarity tester and a polarity reversing cable to insert into your EHU cable between supply pillar and van. That way you can be sure your van's electrical system gets its electricity fed to it in the way it was designed to receive it, and will be as safe as any other.

 

OTOH, if your van is newer and UK manufactured, or especially if manufactured in the EU within the past 15 or so years, it will almost certainly have double pole switching/MCBs and will be "polarity blind". If unsure it would be worth either asking whoever sold it, (assuming it was not a private purchase) if they can confirm whether it wiring is polarity sensitive, or getting an electrician to look at it to confirm.

 

This is not a high risk as Allan points out, and it requires a several build, age, and electrical supply characteristics to be present for it to exist at all but, if you want peace of mind, a simple check/enquiry plus polarity tester etc. should completely eliminate your doubts.

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