Electrics - Planning the Crafter's electrical needs

To work out what cables needed to go where in the van I planned them out on paper so I could see clearly how many cables I needed, the type of cable, the length and how they needed to be installed  to work properly with all of the other cables. 

I created a document on my computer to help illustrate the van layout and plan this installation. (wiring panel PDF download)

First of all I needed to understand what sort of loads would be going on the cables. I searched online for each appliance that I am installing to find their respective installation manual. The manuals usually state the current that the appliance will draw. For example the Dometic fridge I want to install is powered three ways, gas, 12v and 240v. The 240v current is 2amps and the 12V current is around 10amps. The 12V current of 10amps is a high amount of current and as such the cable will need to be sufficiently suited in core size to handle that load. I chose a cable rated to 25amps which will easily take that load. This is slightly higher than needed but I like to make sure I have plenty of room in case of spikes etc. I used the same cable for all similar current appliances. 

For the lower current draw appliances such as the control panels, and single LED lights that don't need such a high rated cable I used a cable that was suited to handle up to 10amps. 

The mid range current appliances; LED strip lights, 5v chargers and fans etc I used a cable rated to 17.5 amps which would allow plenty of extra current draw should it be required. 

For the 240v systems I used Artic Cable which is designed to withstand rugged and harsh conditions including low temperatures. This cable is more than sufficient to handle the largest current that will be drawn from the appliances in the van. 

With all the cable types now worked out I planned for them all to run back to the same location which is where the battery box will be along with the main switch panel. I am going to design the panel myself with two switch panels, 240v and 12v. The switch panel will contain the trip switches should an over current load be applied to the respective line. (More on this in part two). 

Now for the practical side of this installation; laying the cables in place. I used 20mm plastic conduit tubes to run the single core cables through to protect it from rubbing on any of the van. The tubing has to go through a few bulkhead holes so it needs to be protected.