I also added a lot of new wiring and lights fed from a blue sea fuse box. So I upgraded to LED 12V and eliminated basically all the 120VAC or dual voltage lighting. In spite of being in excellent shape, it’s ~40 years old. My camper came with relatively small wire for its 12V lighting and appliances. Spend a little time up front and you can optimize your wire runs. But in my opinion that’s wasteful and in a van every pound counts against your available payload capacity. You can just skip all that and use 12 gauge for almost everything. You can get away with a smaller wire for devices that have higher surging current such as fans and pumps with a smaller wire as long as the running current meets your voltage drop requirements. It doesn’t affect the voltage drop but it does affect how much current you can draw for a short amount of time and affects the fusing requirements. Common wire might only have 75C temperature rated insulation. Second consideration is the wire utilized. Don’t rely on simple charts without knowing the assumptions. You can find calculators online for this. For example, your solar PV cabling should maximize efficiency. For high power loads you might even want to keep it to <1% if possible to maximize efficiency. Some devices don’t care if there’s as much as 10% voltage drop but at that point you’re just loosing efficiency in the form of heat. Typically you want to stay under 3% voltage drop for critical devices and maybe 5% for non-critical. This is determined by the current draw, wire gauge and round trip distance if you have positive and negative conductors.

There are multiple considerations when selecting wire. If someone needs more info, especially about the appliances, by all means ask me, and I'll do my best to provide more info as to help you, help me. That is my goal: to get the appliance wire and fuses here so I officially have everything ready. Knowledge is power, literally in this case, and I'm certainly open to more, however I've been making this a little harder than need be and rather prefer someone take the above list of appliances, copy and paste into a reply, with merely the corrections to my fuses and appliance wiring. Everything (except appliance wiring and fuses)is sitting on the table in front of me, right now, waiting to go together.My plan was to do as I wrote above, use the appropriately calculated fuse for the appliance, use 12 gauge for everything, even on the outlets.

(May seem unnecessary but I've spent the money for the solar, and why by batteries). I'm using (3) cigarette lighter outlets for the two Road Pro's and my Fridge that come with 18 gauge wire that has inline fuses.All of these appliances will be less than 13 feet, even under 10 feet away, from the battery (almost right beside the bank inside my van, a small Chevy G10, not a huge Sprinter or bus).(1) single zone dimmer switch that from what I've learned by other customers, has no led on it and draws no additional current, rated for 8 amps 25 amps each (that will have to be wired in parallel so I'm assuming 1 amp total, could be wrong- if not 1*1.25 = 1.25 (2 amp? 5 amp fuse?) 5 (2 amp fuse? 5 amp fuse?-how small do they really make them?) So here is what I have going on as far as 12v DC: So the way I'm interpreting my 12 v DC appliance install, as a 'newb', is, 'don't over think it, do the appliance math for the fuses, get said fuses, and use 12 gauge wire to wire everything up to the fuse block. Below that there's a chart in case I'm using longer wire, but it does specify that for 0 - 20 amps, all the way up to 13 feet circuit length, it references using 12 gauge wire. Prowse specifies: if the appliance is 240 watts or less and less than 13 feet, 12 gauge will be sufficient. I've taken the amp draw of the appliance and multiplied it by 1.25 for fuse size.

Out of trying not to overthink it, I took it for face value. What I've done is simply gone off what Will's two sections on 'Selecting Wire' and 'Selecting Fuses' say to do.

I understand that different gauge wire has different current capacity.

My puck lights for instance, come attached to 22 gauge wire.

I understand that not all my devices require me to go as large as 12 gauge wire.

I do realize that wire needs to be large enough to carry the current to blow the fuse.

It's dragging on and I need to get to work.įirst I'll tell you what I do understand, or think I do: Maybe I'm just timid and don't trust myself, beats me. I've read Will's book and have taken as far as I can. For one reason or another I've been having trouble understanding what I need in regards to the wire and fuses for my 12 volt DC appliances.

12 2 wire for 12 volt dc