The Eriba Touring vans are fitted with a complete 12V system, and looking at my Eriba Triton I see:
1. A BIP battery charger / multi stage conditioner to keep the 12V battery fully charged if connected to site power
2. In our case a 110AH 12V battery
3. Next to the battery live terminal a set of 12V in-line fuses correctly rated for the proposed appliance use - one fuse for the 12V lighting, another fuse for the 12V power points, another for the 12V fridge circuit, etc. The fuses are the normal car type plug-in fuse mounted in a small holder.
4. Wiring of the correct amp grade for the task in mind - this is a German van so the wiring is specified at 2 X the maximum current. Single core copper wiring is better than multi-core ina fixed installation
5. The wiring is laid in trunking, either a flexible plastic tube or a small square section with removable top
6. Correctly rated sockets - Eriba use the nicely engineered DIN sockets, but the UK 12V sockets and plugs can be obtained from most caravan shops
None of this should be a problem for an experienced DIYer.
We use the 12V supply to power a Sony World Band Radio, a Sony hard disc MP3 player and HK On-Tour amplified speakers. One of Eriba friends also uses the 12V supply to power a flip down 8" wide screen LCD TV.
Robert