Mains electric "polarity"

[Transporter]

[Disclaimer: This is my first-ever post, and I'm completely new to the caravan game.]

I just bought a caravan (2006 Swift Charisma 540), and I've been making sure that I'm equipped to get household mains AC in both the UK and the continent. So I bought a UK mains adaptor and a "continental" adaptor.

The adaptor instructions -- and the dealer, and an experienced friend -- warn me that I need to watch out for "reversed polarity", mostly in France.

But the "continental" adaptor can obviously be plugged into a household Dutch or German (at least) socket either way. And -- strangely enough -- not a French one (they usually have an earth pin which prevents that).

Someone -- please interpret this confusion and put my mind at rest. Thank you.

 

[JohnM20]

Hi Transporter

French electric wiring is different to that in the UK inas much as it is safer, both the live and neutral wires are switched and not just the live as in UK. This means that it doesn't matter, from a safety point of view, which wire goes to which terminal. This means that it is possible and indeed quite probable that the neutral will be to the live terminal and vice versa.

When connecting up in France first of all plug in a polarity tester. If this shows a fault, don't switch anything else on but insert a reversed polarity link into your EHU cable. This can be easily made using a blue UK plug and socket but wire them 'wrongly', ie the live wire at the plug goes to the neutral terminal in the socket and the neutral wire in the plug goes to the live terminal in the socket. The earth goes to the earth in both. When this is connected in, (best at the caravan end), the polarity is reversed and the safety restored in the caravan. Everything can then be switched on.

Most caravan accessory places sell adapters with a French plug on one end and a UK blue socket on the other. No-one seems to sell the polarity reversers possibly because it is probably illegal to sell something which is deliberately wired incorrectly.

Hope this helps but get back if you need more help.

PS In France beware of low ampage on pitches, most are 6 amp, a few 10 and very few up to 16 (as we usually get in the UK). Some pitches may have as little as 2 amp supply and some offer a choice, but at varying prices.

John M

 

[Transporter]

Thank you very much, John.

But I'll not be going to France very much. I have family in the Netherlands, and will be touring mostly northern Europe, including Scandinavia.

You'd think the Germans (and the Dutch) would have a logical AC supply, but the fact is that you can plug an earthed plug either way into any socket, earthed or not. Yet you can't plug an unearthed plug into an earthed socket. Beats me.

Are you any the wiser in this department?

 

[Lutz]

Standard German (and Dutch) plugs have two earth terminals, on the outside and a right angles to the two pins. That's why they get an earth connection whichever way round they are inserted into a German or Dutch socket. However, these plugs cannot be inserted into French sockets unless they have provision for the French earth pin.

Low wattage electrical equipment on the Continent often have a flat two pin plugs without any earth connection. These, of course, can be inserted either way, even in France.

 

[Transporter]

Standard German (and Dutch) plugs have two earth terminals, on the outside and a right angles to the two pins. That's why they get an earth connection whichever way round they are inserted into a German or Dutch socket. However, these plugs cannot be inserted into French sockets unless they have provision for the French earth pin.

Low wattage electrical equipment on the Continent often have a flat two pin plugs without any earth connection. These, of course, can be inserted either way, even in France.

Thanks, Lutz.

I know all that, and it obviously means that the Dutch and the Germans don't worry about "polarity". But caravan people keep telling me that I should worry about it.

Judging by the way the Dutch and the Germans run their countries, compared with the way ours is "run", they must know something we don't know. So do I really need to worry?

Sorry I didn't make myself clear in the first place.

 

[Lutz]

There are two reasons why polarity isn't an issue on the Continent:

1. The main circuit breakers act on both live and neutral leads.

2. The housing of electrical equipment which is not earthed must be fully isolated so that there is no chance of touching anything capable of carrying a current even if there is a short circuit inside.

By the way, you'd be surprised how many electrical goods in the UK aren't earthed, either. The earth pin on the plug is often a dummy, provided only so that you can insert the plug into the socket.

 

[rob_jax]

Hi,

I work in Rotterdam and although outsiders view the Dutch as easy going, bike riding, etc... but in truth and as you'll know, they love rules and regulations...

A part of the "problem" is the term "polarity reversal" - this implies the sort of problems you'd get by inserting a battery the wrong way round in a remote control - it wouldn't work...

Mains is AC power distribution - and the "polarity" reverses 50 times a second - and it doesn't matter which way round the live and neutral wires are connected - the appliance always works.

The European dual switched system is inherently safe, whereas the UK system only achieves safety by people correctly wiring the system... You may want to check your house out with the polarity tester...

The possibility of a problem occurs when single switched systems (an old UK caravan) is connected to a dual switched supply (random wiring of live and neutral) - then there is a 50% chance that the power to a kettle or TV or whatever is only "cut" after it leaves the appliance. And this only becomes a problem if you start poking about inside with the plug still inserted...

Robert

 

[Lutz]

Yes, like Robert says, reversal of polarity is only a potential problem if you start poking around inside. If you use electrical equipment intelligently, it will work perfectly even if connected the "wrong" way round and you won't get a jolt if you touch it, either.

 

[Transporter]

Yes, like Robert says, reversal of polarity is only a potential problem if you start poking around inside. If you use electrical equipment intelligently, it will work perfectly even if connected the "wrong" way round and you won't get a jolt if you touch it, either.

"Yes, like Robert says, reversal of polarity is only a potential problem if you start poking around inside. If you use electrical equipment intelligently, it will work perfectly even if connected the "wrong" way round and you won't get a jolt if you touch it, either."

That's what I thought. Thanks to everyone for the background information, which is exactly what I needed to know.

 

[ProfJohnL]

I concur with Rob-Jax' description. The confusion arises because of the common misuse of the word polarity in respect of mains AC supplies.

Polarity should only be used to describe a DC electrical supply such as 12V system in a caravan where you have a positive and negative conductors with respect to each other or a another reference potential.

The AC supply should more correctly be described as Phase and anti-phase, but as anti-phase side of the supply is normally tied to the earth potential it can be called neutral.

The Phase conductor may be called Live.

The incidence of so called reversed polarity should be really referred to as crossed, 'reversed' or 'out of' phase supply.

 

[KeithJ]

Hi Transporter

I agree with what Lutz and Rob-jax are saying, and with your conclusion.

Most of the mains voltage electrical equipment in my 'van has been purchased on the continent. This includes Kettle, Vacuum Cleaner, Television Set, Satellite Tuner box, Portable Fan, Portable Electric Grill; I plug them into the UK sockets via short adapter leads. Some of the appliances have two pin plugs, ie. double insulated as in the UK, that can be inserted either way round in the socket, and others with double earth contacts can also be inserted either way. So it doesn't matter which way round the mains supply plug is inserted in the site supply socket if the appliance plugs can be inserted the opposite way.

None of this equipment has double pole switching, as many people seem to think it has, so it must rely on being electrically safe whether live or not. Having said that you obviously have to use common sense when using it, following the safety advice given with the product, but nowhere will it say it can only be plugged in a certain way in the socket.

There is a lot of "talk" about so called "reversed polarity", but I think many people are just repeating what they have heard, and don't really understand the subject.

Keith

 

[WatsonJohnG]

http://www.caravanclub.co.uk/NR/rdonlyres/E50748C8-D9E7-4890-86C3-CEFD5A13B134/0/ReversedPolaritycomplete.pdf
this is what the CC say on the subject

The C & CC have a similar fact sheet

 

[WatsonJohnG]

http://www.caravanclub.co.uk/NR/rdonlyres/E50748C8-D9E7-4890-86C3-CEFD5A13B134/0/ReversedPolaritycomplete.pdf

this is what the CC say on the subject

The C & CC have a similar fact sheet

http://www.campingandcaravanningclub.co.uk/FAQ.asp?id=SX7ABD-A77F7DC5

 

[rob_jax]

Hi John,

I'm surprised at that article from the CC, and written by John Wickersham too - it contains a smattering of misleading information and a flawed example trying to illustrate the safety implications...

Like the CC review of 13 pin car-caravan connectors in this months CC magazine, which also has it's fair share of inaccuracies, I'd really expect better from the CC or their technical writers...

Regards, Robert

 

[Reg]

I'm a bit confused about the description given of the german plugs.

Do they differ from the standard blue plug or those found on some french sites ie the 16amp 3 pin (usually white)?

 

[rob_jax]

Hi Reg,

Across Europe, household mains power sockets and plugs comply with similar, but different, versions of the CEE requirements.

One thing they all agree on is the pin spacing for the live and neutral, so a two pin CEE plug (the sort of thing fitted to a radio or electric razor) will fit in any CEE socket.

But the earthed ("three pin") plugs and sockets are different:

The French / Belgian plug that you are familiar with - has a pair of live and neutral pin connectors, and the earth is an off centre socket. The Dutch / German plug has the same pin spacing for the live and neutral connectors, but the earth is a pair of side contacts.

The universal plug found on a "continental adaptor" has both the "French" earth socket and the two "German" side earth contacts.

The IP44 rated blue plug (used on UK camp-sites) is a totally different animal...

Robert

This image may help:

 

[Reg]

Many thanks for the explanation Rob_jax

Am I likely to see this plug/socket on campsites as we are going over to Germany via Belgum in a few weeks.

 

[rob_jax]

Hi Reg,

Possibly yes - Belgium has the French style socket, Germany and Holland has the other (CEE 7/4 or Schuko) type - and yes, I've seen them on camp-sites - and you probably stand more chance of seeing the blue IP44 type than in, say, France.

But - if you already have a universal "continental" adaptor - the plug looks like the CEE 7/7 image in the lower left - then that will fit any French, Belgian, Dutch or German household socket...

Robert

 

[Lutz]

The sockets that Robert refers to are no longer common for EHU's on campsites in Germany. A few small old sites off the beaten track may still have them though. In general, though, most posts accept the same blue plug that you are familiar with. However, you will encounter such sockets elsewhere such as in the washrooms.

 

[Reg]

Many thanks Robert & Lutz,

I don't think I'll create another lead but I'll have an adaptor handy just in case.

Regards

Reg

 

[Lutz]

If you are going to create another adaptor, it would be best to use a CEE 7/7 plug, as shown in Robert's pic above, as this will work and give you an earth connection both in French and German (North European) sockets.

 

[WatsonJohnG]

This is the one to get

http://www.towsure.com/product/349-Continental_Mains_Converter_Lead