12S & 12N question

[mealsonwheels]

Just wondering if someone can answer my queryThe.
The caravan reversing lights are wired through the 12S plug, but why do I need both 12S & 12N to be plugged in for them to come on, when the indicator/side lights/brake lights all work with just 12N plugged in?

 

[SirRogerFFS]

Only a guess but maybe reversing light is picking up the earth from your 12S
Sir Roger

 

[Gagakev]

Why would you not want to plug it in?????????
I am presuming you mean when you are travelling, apart from the fact the cable would be loose and you wont have any reverse lights!!!! And I do beleive the fridge works off the 12s as well, please correct me if I'm wrong.

 

[marlot]

The earths on the 12s are dedicated for the battery and fridge. The earth for the reversing lights is on the 12n

 

[Steve L]

I have never used my 12 S plug in the near 30 years I've been caravanning. So long as you run the van on EHU with the fridge running at it's coldest it will remain cold for a good 12 hours, which is usually plenty of time for you to of got to your destination. The advice is correct that your reversing lights (if fitted to your van) run via the 12 S socket and complete their circuit via the 12 N earth wire. Again I have only just (2008) got a van with a reversing light. I usually use my hazard flashers if reversing and I get my OH to act as banks person to guide and guard the rear of the caravan.

When I started caravanning we were living on a shoe string as all newly wed home ownwers do, then the kids arrived and were a drain on resources ( wouldn't change them for the world though), and finally as we'd always made do I just haven't bothered with the expense of adding the charger relay, wiring and socket, as most my cars came with a tow bar already fitted.

I have got my auxilary plug stowed in the A frame storage position and secured with a short elastic strap so that it can't move.

 

[mealsonwheels]

Thanks all for the replies.
Gagakev - Not being electrically minded, I was just intrigued why it was that both 12S & 12N had to be plugged in to get the caravan reversing lights to come on (I wouldn't have towed without both being connected).

steveinleo - thanks for explaining that the reversing lights run via the 12S socket and complete their circuit via the 12N earth wire.
All is revealed!