So called Towbar fitting experts.
Here are pictures of the electrical installation on my car by towbar fitters recommended by the car dealer.
The install :-
Crappy scotch locks, signs of where the wrong cable was selected to start, scotch locks used to extend a cable by 100mm, loads of tape, quite a mess.
The main power connection:-
So how do you make your main power connection?, clearly in this case the preferred approach is to strip the insulation a bit and wrap your wire round it followed by a good dose of tape. This connection supplies the fridge electrics, charge for the leisure battery and the canbus lighting module so many tens of amps! (read potential fire risk).
The fix was to re-make all connections using solder and heat shrink (self amalgamating tape around the main power wires so as to avoid cutting them)and then loom tape around the wiring to make it a lot neater and hence more reliable.