How-to Wire 12v Accessories in a DIY Camper Van Electrical System

Affiliate Disclaimer: As an Amazon Associate, earns from qualifying purchases..

The electrical system in a DIY Camper Van is a bit pointless if you don’t have anything to power, so let’s learn how to hard-wire plugs, fans, and other accessories into your camper.

Quick note before we get started.  This is just one part of an overarching “How to Install a DIY Camper Van Electrical System” series.  If you’ve just stumbled on this article directly without seeing that, there are likely some things we’ve already covered.  If you want to check out that step by step guide, you can do that here:

Also, we have interactive solar wiring diagrams that are a complete, A to Z solution for teaching you exactly what parts go where, what size wires to use, fuse size recommendations, wire lug sizes, and all kind of other stuff to help save you time and frustration.  You can check that out here:

12v Distribution Block

We already know that all positive wires need to be protected with a fuse. A 12v Distribution Block makes a nice, organized spot to make all of your accessory runs originate from:

12v Distribution Block

The 12v Distribution Block connects into your busbar and the one I like has enough spaces for 12 circuits and can power a max of 100 amps at a time combined between all the branch, or accessory circuits.

12v Wire Color

Power, Positive, and Hot (these all mean the same thing and can be used interchangeably) wires in 12v setups are typically red. Since you are likely starting this from scratch, I recommend keeping it consistent and going with red for the positive wires.

Negative and neutral (again, same thing) in 12v systems are commonly EITHER black or sometimes yellow. Keep it easy and consistant here and go with black for your negative wires unless you have a really good specific reason to choose otherwise.

Wiring 12v Plugs in a DIY Camper

12v Plugs will power any of your plug in devices such as camera battery chargers, phones, drones, and in some cases: Refrigerators.

Standard 12v Plug

On the back of the Standard 12v Plug, there will be 2 pins that you’ll attach your wires to with spade connectors.

Chaining Multiple 12v Outlets

If you want to chain multiple 12v outlets on the same citcuit, you’ll want to wire them like this:

If you decide to wire multiple 12v outlets in the same circuit, please stay aware of how many total amps you anticipate using in their ENTIRE cicuit and size your fuse and wire size appropriately.

I actually don’t like wiring multiple 12v outlets in series, personally. I prefer running 1 x 12v outlet per fused circuit from the distribution block.

Wiring 12v DIY Camper Van Accessories:

Most 12v Accessories can be wired using the exact same methods as described above. Fans, refrigerators, 4g booster, etc..

12v accessory wire

I’m a big fan of 12ga duplex wire for 12v circuits. It’s big enough for 95% of accessory circuits and when installed in lengths consistent with being installed inside a camper stays within the 3% voltage drop range even though, most of the time it isn’t necessary. It’s a red and black wire with high-grade, 105°C insulation contained inside of a white protective sheath

Now that you’ve learned how to wire 12v accessories and a distribution block, it’s time to learn how to wire lights and things that require switches.  In this next lesson we are even going to talk about wiring in 2-way switches so don’t miss it. Check that out here:

Everything that you are learning here is put to use in our FREE Interactive Solar Wiring Diagrams.  If you haven’t yet, check them out as they are a complete solution for a camper van electrical system.  Check them out here:

Remember, this is just one part of a full camper van electrical educational series.  To see all of the individual guides, click here:

Finally, If you found this guide helpful, It’d truly mean the world to us if you’d share it with somebody who can use it, pin it to pinterest for later reference, or share it to a facebook group when somebody has a question about this subject.  Click the bubble in the lower right corner to subscribe to be notified of future updates and as always, leave any questions you’ve got in the comments below.

23 thoughts on “How-to Wire 12v Accessories in a DIY Camper Van Electrical System”

  1. I have been researching electrical system from my Sprinter build for weeks but learned more on your site in a couple hours than I have ever before. Do you recommend having all wiring in any kind of wire looms and use grommets? I’m worried with the wires rubbing on the metal and shorting out. Also how do I best know on which fuse to use on the distribution blocks for my runs?

    1. Having wire inside of loom and using grommets is a good idea, especially in areas where it looks like rubbing can occur. For picking your fuses on the distribution block, if you’re using 12ga wire for the runs like recommended, 15 amp fuses are a good blanket statement, but if you want to get more detailed or verify that’s correct, I’d highly recommend this post:

  2. Nate, love you guys and the info you provide. Awesome.

    Can you possible in the near future update the diagrams to show the connectors ie butt connectors, spade connectors, etc – like you did above for the 12V outlet?

    Also, please show how to wire an outlet to a switch.

    It would be so helpful as most sites usually show just the wires from one or multiple items but not the connectors which is just as confusing when you have never done it before. Thanks.

  3. Can you have multiple connections that have switches wired to the same fuse? For example: a set of pot lights and a LED strip- each on their own switch, but connected to the same fuse?

      1. Hey Nate! Thank you so much for the amazing guides and diagrams and all of the time you’ve put into this site (and your YouTube channel!). It’s been immensely helpful to my husband and I in planning our van’s electrical system.

        I was wondering if it would suffice to use 12 gauge wire when multiple loads are on the same DC circuit. For example, we’ve got two Fantastic Fans installed in our van and are planning to run them in the same circuit. We’ve got a Sprinter 170″ Ext so the van is very long, therefor all our wires will be a bit longer. Should we just go with 10 gauge or 8 gauge to be safe? Both fans operating at full speed at the same time won’t pull more than 8 amps (from what I’ve read) but the distance of the wires is what I am worried about- in total from battery to fans will be around 16-18′. I know your guide specifies that 12 gauge is sufficient to handle most DC loads but I wasn’t sure if it accounted for multiple loads on the same circuit (and at a further distance that most van builds)?

        We will likely run into the same issue with our lights- very low draw (0.25 amps) but we will have a dozen lights and the distance from batter to all the lights will be quite long (we’re not putting all 12 on the same circuit, but still…)

        Better safe than sorry, right? Maybe we should just run 8 gauge to all our circuits containing multiple loads?

        Thanks so much!

        1. For a circuit that has 2 loads (such as your dual fan example), you’d simply add the amps together (8A in your case) and figure the wire size based on the furthest load. That’s the simplest way to do it. 8ga wire is pretty big, so I wouldn’t recommend making a blanket statement to use 8ga wire for all of your small DC loads. I think you’d end up regretting that decision. 8AWG at 40′ would put you within the 3% voltage drop range, but you COULD use as small as 14 AWG and stay within the 10% voltage drop threshold (which is still totally safe; but if your batteries get nearly empty; your fans may shut down)

          1. What type of connections were used to wire both fans onto one circuit? I’ve been looking for an example and haven’t found anything

  4. Hey Nate!

    Question about chaining usb charging sockets together. The USB charging socket I’m looking at has 2 charging ports each port says 5v 2.1a. With two charging ports that gives me 4.2 amps at 5v. Do I have to convert that to 12v to figure out how many amps my circuit is and multiply that by however many I want on my chain?


  5. Hi Nate,

    Thanks for this guide. Which cable gauge and fuse size would you use to connect the battery to the fuse block?


  6. Hello Nate,
    I have decided to use the electrical system layout you have created for solar/inverter/shore power. For now I only want to install wire to 12v ports, and lights on ceiling. Next year after the walls and ceiling are in, I will install major electrical; solar panels, charge controller, batteries, inverter, isolator, monitor. I plan to install the solar gland in the roof now before the ceiling goes in, and place conduit and wire before walls are in. Are there other things I should do now?

  7. Can you wire three DC switches to a series of lights? A three way or four way depending on who you talk to.

    1. Yes, but it would require a 4-way-switch where the poles swap contactors when switched rated for 12V DC current, which I’m struggling to find. A diagram and explanation is somewhat useless when we can’t source the products to make it work. lol I’ll update the post if/when I find a source.

  8. Hi, thank you for this amazing website. I’m just getting started on the wiring part of my bus build and I’ve run into a dilemma. Both the dimmer switch and the junction boxes take 3 wires (hot, ground, neutral) but my fuse block (Blue Sea Systems) only has space for 2 wires (hot and ground) what would I do with the neutral wire in this situation? Do I just ditch neutral altogether?

Leave a Comment

Your email address will not be published. Required fields are marked *