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Campervan Wiring: Best Wire Sizes for a Camper Van Conversion

Choosing the correct wire sizes you need for a camper van electrical system is complicated because there is no “one size fits all” solution. An RV with significant electrical demands may need different wire gauge sizes than a simple camper van conversion.

In this post, however, we aim to recommend ideal wire sizes appropriate for ‘most’ DIY camper van electrical systems. The wire gauges we recommend will be appropriate for electrical systems with a:

  • Standard 12V system
  • Inverter/charger (2000W max)
  • Solar system (440W max)
  • DC-DC charger (40A max)

If your electrical system is within these parameters (as ours is), the wire sizes below will work for you. We’ll also note when you want to jump up a wire size if you use a larger system (e.g., a larger inverter or solar array).

In this post, we aim to keep the number of wire sizes you buy to a minimum to save money and simplify the wiring installation.

Note: All our wire recommendations are pure copper, stranded wires. We ignore the cheaper copper-clad aluminum (CCA) stuff to ensure your cables can safely handle the correct amount of electrical current.

If you’re ready, let’s get to it.

Is There a Camper Van Wire Size Calculator?

We don’t provide a wire sizing calculator because we don’t believe using them is safe. This is because calculators are not only confusing and time-consuming but – assuming you calculated correctly – also get you that perfect, ‘dialed-in’ wire size for your present needs only. They do not allow you to expand or grow your electrical system in the future. If you add more devices to your electrical system later on but keep the wire sizes the same, you risk overheating those wires and causing a fire.

If you want to upgrade your inverter or add additional solar panels, you may need to buy new wires and redo your installation to keep your system safe. Also, when using a wire size calculator, you might buy lots of different wire sizes when it would be cheaper to consolidate them into smaller but larger wire gauges.

Our approach in this post will better help you arrive at the wire sizes you need for your camper van’s electrical system while also future-proofing yourself in case you want to make any minor additions later.

If this sounds like a good plan, keep reading.

Wire Size for the 12V System

The 12V section of a camper van electrical system comprises multiple pieces. Different sections will require different wire sizes. We break down this 12V section into five parts.

  1. Combining batteries
  2. Batteries to bus bars
  3. Bus bars to fuse panel
  4. Fuse panel to 12V devices
  5. Ground wire

In each part, we provide detailed wiring diagrams and wire size recommendations so that you understand which wire gauge goes where.

Part 1: Combining Batteries (2/0 AWG)

If you plan to install a power inverter rated up to 2000W, use a 2/0 AWG wire to combine multiple batteries. For most camper van conversions, this is more than sufficient. Refer to the below diagram to see how this looks.

Note: Use a 4/0 AWG wire to connect your batteries if you will install a 3000W-rated inverter.

Three Redodo lithium batteries wired in parallel.
Three batteries wired together with 2/0 AWG wire

We recommended the 2/0 AWG wires from Windynation because of their unmatched flexibility for their thickness. This wire comprises hundreds of tiny copper strands, making it easy to bend the wire to connect all your components in a tight space. The wire jackets are water, oil, and UV corrosion-resistant, making them ideal for camper vans.

Windynation | 2/0 AWG Wire

100% pure copper wire. Perfect for battery and 12V wiring when used with 2000W inverters.

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Our YouTube video below reviews the 2/0 AWG wires from EWCS, which we use in our camper van. However, we later bought the Windynation wires and discovered they are the exact same build and quality but significantly cheaper.

EWCS 2/0 AWG Wire Review

Part 2: Batteries to Bus Bars (2/0 AWG)

For this section, we recommend using the same 2/0 AWG wire you used to connect your batteries. This is because these wires will transmit the same high amperages to supply all areas of your electrical system. Review the below diagram to see how this looks.

Note: If using a 3000W inverter, remember to use a 4/0 AWG wire, like in the previous section.

Wiring diagram connecting 12V leisure batteries to bus bars
Wiring 12V batteries to bus bars

Lug terminal size: The wiring diagram above shows how a 2/0 gauge wire connects to every component via lug terminals. Different components, however, require different lug terminal sizes. Some require 5/16″ lugs (pink), and others require 3/8″ lugs (orange). We list both of these lugs in the table below.

Complete install tutorial: Read our camper van 12V installation guide.

Complete 12V system product checklist: Head to our 12V parts list

Part 3: Bus Bars to 12V Fuse Panel (4 AWG)

The next step is to connect the batteries to the bus bars. You can do this by referencing the wiring diagram below.

Wiring diagram connecting bus bars to 12V fuse panel
Bus bars to 12V fuse panel

If you intend to use the same Blue Sea Systems fuse block that we use, the manufacturer recommends using a 4 AWG wire to connect the fuse block to the bus bars. This is because the block has a 100A current rating, and the 4-gauge wire we recommend below will safely transmit that level of continuous current.

Windynation | 4 AWG Wire

100% stranded copper wire. Rated for 150 Amps of continuous current and is ideal for connecting the bus bars to the 12V panel. Resists UV, water, oil, and salt corrosion.

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Our YouTube video below reviews the Windynation 4 AWG wire. We strip away the insulation to expose the bare copper strands and explain why we recommend this wire for your build.

Windynation 4 AWG Wire Review

Lug terminal size: You will need more lug terminals to connect the 4 AWG wires to the 12V panel. These lugs are color-coded in dark and light green in our wiring diagram. To save you money, we recommend buying the below lug terminal set. It includes lugs for four different wire sizes and will also be helpful for other parts of your electrical system build.

Sanuke | Lug Terminal Set

Save money with this convenient lug terminal set. It covers 12 different lug sizes from 2-8 AWG wires and M6-M10 ring diameters. Heat shrink is also provided.

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Our YouTube video below reviews the Sanuke lug terminal set and shows you how to crimp one of these lugs onto a 4 AWG wire.

Sanuke Copper Lug Terminal Set Review

Part 4: Fuse Panel to 12V Devices (14 AWG)

This section connects the fuse block to every 12V device (i.e., the fan, LED lights, & fridge). We recommend using 14 AWG wires to complete this wiring section. Refer to the following diagram for more info.

Wiring diagram connecting the 12V fuse panel to individual 12V devices
12V fuse panel to 12V devices

In particular, we like the 14/2 AWG twin wire from GS Power. ‘Twin wire’ means two 14-gauge cores (red and black wires) are packed together inside a tough outer insulation layer.

Note: If you plan on wire runs longer than 20′, we recommend upgrading to 12 AWG wire instead to combat issues with voltage drop.

GS Power | 14 AWG Wire

The #1 seller on our site. Get this 14AWG wire for all your 12V device connections. We like the tough outer jacket that protects the inner wires from the constant vibrations when driving. These tinned copper wires are 'marine grade' for superior resistance against corrosion.

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Our YouTube video below reviews the 14 AWG twin wire from GS Power, and we explain why we love this wire when connecting it to each 12V device.

GS Power 14 AWG Wire Product Review

Part 5: Ground Wire Size (4 AWG)

According to the National Electric Code (Article 250, Table 250.66), the ground wire’s gauge depends on the cable sizes you use in other parts of your electrical system. Check out the ground wire chart.

Because we recommended 2/0 AWG wire in a previous section, 4 AWG wires should connect the negative bus bar to a ground point on your vehicle’s chassis. Refer to the diagram below for more info.

Note: If you used 4/0 AWG wire for the battery and bus bar connections, you should use 2 AWG wire to ground your system.

Connecting the negative bus bar to a ground point on vehicle chassis with 4 gauge wire.
Grounding 12V system

Lug terminal size: You can still use the Sanuke lug set we recommended earlier. You must confirm the bolt size on your camper van’s chassis to know which lug to use, but the Sanuke set should have it.

12V Wiring Summary

When completed, the wires you select for your 12V section should resemble the wiring diagram below. For a complete list of products used, download our electrical wiring ebook.

Complete camper van 12V wiring diagram connecting leisure batteries to 12V devices
Complete 12V wiring diagram for camper vans

Wire Size for the Power Inverter System

This section reviews the wire sizes you need to install a 110V power inverter in your van. We separate this section into four parts and provide detailed diagrams for each part.

  1. Inverter to batteries
  2. Wiring to outlets
  3. Wiring to shore power (for inverter/charger models only)
  4. Ground wire

Part 1: Inverter to Bus Bars (2/0 AWG)

Instead of wiring the inverter directly to the leisure batteries, we recommend wiring to the bus bars since the bus bars are already connected to the batteries, which we completed in the previous 12V section.

Refer to the diagram below for more information.

Wiring diagram connecting the inverter to the bus bars
Wiring inverter to the bus bars

For inverters rated up to 2000W, we recommend using the same 2/0 AWG wire size from the previous 12V section to connect the inverter to the bus bars. This is because the inverter will demand large amounts of 12V DC power from the batteries to convert to 110V AC power. And you want thick, durable wires to handle the high current load.

Windynation | 2/0 AWG Wire

100% pure copper wire. Perfect for battery and 12V wiring when used with 2000W inverters.

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Lug sizing: In most cases, you will need 5/16″ lugs to connect the 2/0 AWG wires to the inverter. But you should double-check the bolt size on your inverter, just in case.

For a complete product list for your inverter installation, read our camper van inverter installation guide.

Part 2: Wiring the Inverter to Sockets

Some inverter models have built-in power outlets, like this AIMS-branded inverter pictured below. This is a convenient feature since you do not have to worry about additional wiring. You can directly power your household appliances by plugging directly into these sockets.

Green AIMS Power 2500 watt inverter/charger
AIMS Power 2500W inverter/charger

If your inverter does not have built-in sockets, you must connect electrical wire from your inverter’s ‘AC Out’ to the power outlets. We had to do this with our Victron 2000W inverter/charger.

When wiring an inverter to the power outlets, there are two sections to be aware of.

  • Section One: Between the inverter and the breaker box (bulk feeder circuit).
  • Section Two: Between the breaker box and the individual power outlets (branch circuit)

Usually, there is only one bulk feeder circuit, but there can be multiple smaller branch circuits to the individual sockets.

Refer to the below diagram to locate these two sections. In the graphic, the first section uses 10 AWG wire, and the second section uses 12 AWG wire. The thickness of the cables for these two sections will depend on the wattage rating of your selected inverter.

Wiring diagram connecting the inverter to the power outlets
Wiring inverter to power outlets
  • 1000W inverter (& smaller): Use 12/3 AWG wires for sections one and two.
  • 2000W inverter: Use 10 AWG wires for section one and 12 AWG wires for section two.
  • 3000W inverter: Use 8 AWG wires for section one and 12 AWG wires for section two.

Part 3: Wiring to Shore Power (10 AWG)

If you have an inverter/charger model, you can connect the inverter to shore power to charge the leisure batteries. For inverters rated up to 2000W, we recommend using 10/3 AWG triplex wire. For larger 3000W inverters, you should upgrade to 8/3 AWG triplex wire.

Wiring diagram connecting inverter to shore power in a camper van
Wiring inverter to shore power

Part 4: Ground Wire (4 AWG)

Following the same NEC chart earlier in this post, we recommend using 4 AWG wires to ground your system for inverters rated up to 2000W. For larger 3000W inverters, use 2 AWG wires.

Wiring inverter to ground point on vehicle chassis

Lug size recommendation: You can still use the same Sanuke lug set we recommended earlier to connect the wire to the inverter and ground point.

And that’s it! The below diagram encompasses the four different parts of the inverter wiring system.

Wiring leisure batteries to the inverter
Complete inverter wiring diagram

Wire Size for Solar Systems

This section covers the wire sizes you need to build your camper van solar system. We break up this solar wiring section into two parts.

  1. Solar panels to charge the controller
  2. Charge controller to bus bars

Our wire size recommendations will work for a solar array of up to 440 Watts, assuming multiple solar panels are connected in series (and NOT in parallel). Where appropriate, we will provide alternative size recommendations.

Part 1: Solar Panels to Solar Charge Controller (10 AWG)

Assuming a max solar array size of 440W, we recommend using a 10 AWG wire to connect the solar panels to the charge controller. Refer to the diagram below for more info.

Wiring the solar panels to charge controller with wire size recommendations
Wiring solar panels to charge controller

Why 10 AWG? We follow National Electric Code (NEC) guidelines to protect your solar wiring. Assuming you wire two 220W panels in series, the maximum theoretical current produced is 13.41 amps. When we multiply 13.41A x 1.56 (NEC safety factor), we get 20.9A. And 10 AWG wires are safe for up to 30A of current.

When connecting solar panels to the solar charge controller, parts of the wire will be outside the camper van and exposed to harsh weather elements, such as UV light, water, dirt, and salt spray. That’s why we recommend selecting ‘marine grade’ wires from Ancor. The rigid insulation jackets of these wires resist corrosion and exceed most international standards for wire construction.

Ancor | 10 AWG Wire (Red)

We love Ancor's 'marine grade' wires for solar installations. The insulation jackets are UV & salt water resistant (good for rooftop installations).

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Part 2: Solar Charge Controller to Bus Bars (8 AWG)

If using our recommended Victron 100/30 charge controller, use 8 AWG wires to connect the charge controller to the bus bars. Refer to the diagram below for more information.

Wiring solar charge controller to bus bars & indicating wire size.
Wiring charge controller to bus bars

Why 8 AWG? This is because the max amp output of the charge controller is 30A. In keeping with NEC safety standards, we multiply 30A * 1.25 to get 37.5A. Round this up to 40A, which corresponds to 8 AWG wires.

8 AWG Wire (5' Red & Black)

We like WindyNation wires for their ultra flexibility (high strand count) and tough EPDM rubber insulation. We use these 8-gauge wires for wiring the solar charge controller to the bus bars.

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Upgrade to 6 AWG? If you use a larger 40A or 50A charge controller, you will want to upgrade to a 6 gauge wire.

Check out our camper van solar install guide for more specific solar info, including recommended parts & components. You can also download our free solar eBook.

Wire Size for Alternator (DC-DC) Charging

You will need a DC-DC charger if you want to charge the leisure batteries while driving. Most camper vans install an 18A, 30A, or 40A charger. We recommend using 6 AWG wires for these chargers to make all the connections.

Refer to the diagram below for more information.

DC-DC charger wiring diagram (final) connecting the vehicle starter battery to the leisure battery.
Complete DC-DC charger wiring diagram

Lug Sizing Guide: If following our wiring diagram, there are two sizes of lugs you will need to crimp on the 6 AWG wires: 5/16″ & 3/8″. You can find these lug sizes in the Sanuke lug set we recommended earlier.

Check out our DC-DC charger install guide for more specific information on installing a DC charger with recommended components.

Camper Van Wire Size Summary

Below is a quick table summarizing the wire sizes we recommend when converting a camper van.

Campervan Wiring Tips

Use Split Wire Loom

Regretfully, we did not do this. But putting your electric wires in a split wire loom is critical in protecting the cables.

Alex Tech 1/2" Wire Loom

One of our van build regrets was not protecting our wires with wire loom, which prevents cuts and abrasions to the wires due to the constant friction experienced while driving. Keep you van safe from short circuits with wire loom.

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This is important in a camper van because you’ll create lots of vibration throughout the vehicle while driving. And if your unprotected wires are resting next to another object, constant vibration can cut through the wire’s outer jacket and expose the bare copper wires inside.

This is a fire hazard.

You can also hold these wire looms in place along the van’s metal frame with these 3M adhesive mounts. This is a popular solution to ensure that electrical wires are not just jangling around behind your wall and ceiling boards!

3M | Cable Zip Tie Mounts

The perfect solution to hold wire looms and electrical wire in place behind the ceiling and wall boards.

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Final Thoughts: Campervan Wiring Is Just the Beginning!

Thank you for making it this far in our campervan wiring post! We hope you learned something about the best wire size and placement for your van conversion.

But buying the right size wires and laying them in your van is just the first step. For more information, read our DIY van electrical guide or download one of the many free resources we provide to aid your van conversion.

If you have any questions, please comment in the below section.

Happy building!

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