Electric Hookup

[cookwatty]

Just returned from a great 2 weeks in France with my other half and 2 kids. First time on a long trip in the van and we thoroughly enjoyed it.

I have an electrical question which I hope someone can advise on. My van hasn't got a Zig unit, but the hookup goes through what looks like a domestic fuse box with 1 main and 2 socket trip switches. On one camp site when hooked up, a light lit up on the the fuse box. Underneath the light it read "Polarity reversed when lit. Do not use when lit." As the fuse box is closed away in a cupboard we didn't notice it for 3 days, by which time we'd been using electrical equipment with no worries, so we continued using it. As an electrical novice, first of all what is polarity, and why shouldn't you use it when reversed?

Oh, and has anybody else ever driven off while still hooked up? Stupid I know, but I did it and luckily only pulled he wires out of my hookup cable which was easily fixed. First time I'd used hookup, and won't be repeating that trick!

Looking forward to Bestival next Friday. Anyone else going?

[Andyvandy]

Mains power has polarity - Neutral and Live. Electrical equipment which has an on / off switch always has the switch in the live line so that when the switch is off there is no voltage present then in the appliance. The neutral line is effectively at earth potential i.e. tied to ground at the electricity substation.

So, mains equipment will work quite happily if the polarity is reversed but would pose a hazard if opened up/worked upon if switched off by its switch as the live would still be present and ready to bite!

Hope that explains you query.

Andy

[cookwatty]

Thanks AndyVandy, I think I understand. Basically the internal electrics will always be live in a device even if switched off. Luckily we only used mains for charging phones, cameras and the fridge so hopefully any risk was minimal.

[Dan Wood]

For historical reasons, the French electricity supply developed in a way in which they don't care which is live and which is neutral. (All their stuff is double-pole switched!)

Make up a short hookup socket and plug 'adaptor' with live and neutral reversed. (Clearly mark it, and don't use it as an extension lead!!)

If you get this problem again when in France, you can add your adaptor to the end of your hookup cable to swap live and neutral back to where they should be...

[dbroada]

I do as Dan has suggested. I have also ignorned it as you did. It is really only a problem if you go investigating deep in the electics or if you have a fault. There is (normally) no problem during usual use.

Hopefully your "main" trip is an RCD. (residual current device) which will break in the event of an earth fault. I consider these VITAL in a motor caravan. Have an (domestic) electrician look at it if you are uncertain.

[DiscoDave]

not only vital but a legal requirement for an rcd! polarity is not usually important, unless you are using electronic equipment, such as tvs micro waves etc otherwise fine!

and yes i have driven off while hooked up too! very immbarrasing, i can't work out why i didn't get a nomination for axelnut!!

[dbroada]

not only vital but a legal requirement for an rcd!

but only if done professionally! However if "self builders" continue to ignore such requirements I can see a goverment ban on any vehicle modifications.

[DiscoDave]

not only vital but a legal requirement for an rcd!

but only if done professionally! However if "self builders" continue to ignore such requirements I can see a goverment ban on any vehicle modifications.

regardless of weather done by a profesional or a self builder the regs are still a legal requirement!

[dbroada]

regardless of weather done by a profesional or a self builder the regs are still a legal requirement!

I have to admit to not realising that. What regulation does that come under?

[DiscoDave]

technically it's the building regs that are law! they state that the 16th edition wiring regs (bs7671) must be adhered to, thus making it law. so it don't matter if you are a sparky or a muppet ( think i fall in to both of those categories ) you still need to follow the letter, not that all do tho!