Caravanning Guide - Trailer Plug Wiring Diagrams | Caravan Trailer Plug Wiring Diagrams Use the correct size cable for the plug/socket - most standard plugs will accept up to a 4mm auto cable easily. The 12-pin flat plug have a second row of 5 larger points which will accept up to 6mm auto cable. CaravansPlus: Traditional Electrical Installation Guide I have recently removed the caravan from the caravan yard and stored it at my cousins farm. When we plugged the caravan into the mains, we tripped the fuse between the transformer and the batteries. We changed the fuse (from a 30A to a 40A) and the wires started to smoke. We took the fuse out and checked the batteries to find they had drained.4.5/5(95) Caravan Electrical Systems - Without A Hitch Thirty or 40 years ago, when we were all towing Viscount and Millard caravans with Holden Kingswoods, just about all caravans and motorhomes had very simple electrical systems – 230V mains supply for a few powerpoints and those very elegant fish bowl-style lights. Elite Caravans - Luxury and Off Road Caravans Elite Caravans is delighted to have one of Australia's biggest caravan dealers as our representatives in South Australia. They also have Australia's largest indoor display showroom at 64 Grand Junction Rd, Kilburn, so, it’s like a caravan show every day.