The 12 volt system had to accomodate a number of appliances including the lights, the water pressure pump, the fridge and the ignition for both the gas cooktop and the hot water system.
Because I had to get the power down from the solar panels on the roof and the 12 volts back up from the battery to the lights etc, I needed to run wiring up the side of the bus. I though of many ways of doing it in a way that it was hidden and eventually gave up in favour of this system using flexible mains ducting. I think it looks OK and will be hidden by the curtains anyway. I might paint it, not sure.
I used 15 amp 2 core automotive cable from Jaycar because it was both heavy enough and has insulation on the wire and a heavy plastic cover encasing both wires. With the lights, the simplest thing to do was to start from the battery, go up the wall to the underside of the overhead cupboards and run the wiring around all of the cupboards. Where I wanted a light, I put in a terminal block and ran two wires to go to the light. This means that all of the lights are in parallel, hopefully getting at least 12 volts right the way to the last light. (the outside light) All of the lights are going to be very low wattage LED lamps. They are way more expensive than any others, but when you are relying on batteries to run light, fridge etc, the lower the wattage the better. We are all going to be using them in our homes soon anyway.
The pic below shows how I've run the lighting wiring under the overhead cupboards. The orange cables hanging down will be shortened once the underside of the cupboards have been panelled. The lights will all have switches on them. I've also put the fan for the rangehood on the same circuit.
This is the rangehood in its final position ready to be wired in and have the panelling either side of it. Not much stainless steel for $250.00 though. I decided to have the rangeood which flumes to the outside because there is nothing worse than cooking smells in a caravan/motorhome.
The pic below is of one of the kitchen cupboards which I've decided to use as the mounting place for the power supply for the fridge and the battery charger. I didn't want to put these units in the battery box (under the right side dinette seat) mainly because of the possibility of overheating. Both of these units only work when the bus is plugged into the mains. The one on the left is the unit that came with the fridge and connects to the fridge and the battery. It works by sensing when 240 volts is present, and then automatically disconnecting the fridge from the battery. Of course when the mains are connected the 'smart' battery charger (on right) will also begin charging the battery. A power point will also go into this cupboard.
The pic below is the panel that I made for the solar regulator and the fuse box. The regulator is a little upmarket from some available and of course cost a little more, but it does more. Unlike some regulators this little box has an LCD screen and not only regulates the charging rate of the batteries from the panels, but it also constantly senses the voltage of the batteries and cuts out the supply to appliances when the voltage falls below a pre-set level. This is to prevent the deep cycle batteries getting too flat which will damage them. The regulator also has 4 stages of charging and is designed to maintain the batteries at their optimum charge at all times so that the motorhome is always ready to roll. Daily and current charging rates and usage from the batteries are also monitored and can be viewed at any time on the LCD screen. Jaycar sell this unit for about $170.00, however I was lucky and found it on eBay for $109.00. If you are going to use absorbed glass mat (AGM) batteries this is a must. Other regulators can overcharge your batteries and greatly reduce their service life - these batteries are not are not cheap.
On the right is a 6 circuit fuse box. Each of the circuits go though this box with the appropriate fuse installed. It even comes with little lables that go on the clear plastic civer to show which fuse is for what.
I have deliberately kept the 12 volt system independent from the body earth of the vehicle. This means that it is completely separate from the vehicles 12 volt system. To do this I had to run negative wiring to all appliances instead of simply running one +'ve wire and earthing everything back though the body, which means less chance of problems. If a wire rubs through it cannot short out on the body of the vehicle. Any short circuit can only result from the +'ve and -'ve wires in the system shorting together. This is why I have used plywood for the panel.
For safety reasons, I have installed a 60amp dual circuit breaker (pic below) which all power from the battery will flow through. These units are designed for high power car audio, but will do the job nicely. These are available from Jaycar for $30.00. If there is a fault anywhere in the system this will disconnect the batteries from the circuit and minimise damage. Two 120 amp batteries in parallel provide enough energy to weld metal and could easily cause a fire. One of the circuit breakers is for all of the applicances. The other one will be for a dedicated output to my amateur radio which draws up to 23 Amps on transmit. Again this will provide a safety measure if there is a short in the system.
240 Volt Wiring
I have completed the wiring for the 240volt system. I have run the wiring in purpose made flexible conduit. I had to do this so that I could move on with the conversion, however I will not be attempting the connection of the power points, the residual current device or the circuit breakers. That's a job for a licensed electrician. All power points in the motorhome must be double pole switches. This means that both the active and neutral lines are disconnected by the switch. In normal house wiring only the active line is cut by the switch. These are all for reasons of safety if portable generating systems/inverters are being used.
The pic below gives an idea of how the wiring is placed in conduit. The RCD and circuit breaker box will go on the outside of this cupboard.
