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 huge 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 that are 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 (ours is), the wire sizes we recommend below will work for you. If you will be using a larger system (e.g. a larger inverter) we’ll also note when you may want to jump up a wire size.
Lastly, we DON’T believe in using wiring calculators. That’s because not only are calculators confusing and time consuming, but – assuming you calculated correctly – they also get you that ‘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 want to upgrade your inverter or add additional solar panels, you may need to buy completely new wires and redo your entire installation in order to keep your system safe. Also, you may end up buying lots of different wire sizes when it would be cheaper to consolidate them into fewer, but larger wire gauges.
In this post, we aim to keep the number of wire sizes you buy to a minimum to save you money and simplify the wiring installation.
Best Quality Wires: All our wire recommendations are pure copper, stranded wires. We ignore the cheaper copper-clad aluminum (CCA) stuff to ensure the wires you have can safely handle the correct amount of electrical current.
If you’re ready, let’s get to it.
Camper Van Wire Size Summary
Before we get into the wire size details, below is a summary table. We’ll go into more detail in the next sections.
Section | Wire Size |
12V System | 2/0* & 4 AWG |
Inverter System | 2/0* & 12 AWG |
Solar System | 10 & 8 AWG* |
DC Charger System | 6 AWG |
* 2/0 AWG wire is recommended when using up to a 2000W inverter. Use 4/0 AWG when paired with a 3000W inverter.
**Solar wire size depends on seeral factors, but our recommendation is good for solar panels up to 440W. But read our solar wire size guide to double check.
Download our FREE PDF to help build your van's electrical system; from batteries, to solar, to inverter, and more. 38+ pages of detailed diagrams, product recommendations, and links to additional resources.
Section 1:
Wire Size For 12V System
In this first section, we discuss all the different wire sizes you will need to build a 12V system in a camper van. This section is broken down into five parts:
- Combining batteries
- Batteries to bus bars
- Bus bars to fuse panel
- Fuse panel to 12V devices
- Ground wire size
In each part, we’ll provide detailed wiring diagrams and wire size recommendations so that you understand which wire goes where.
1. Combining Batteries: 2/0 AWG
If you are wiring multiple batteries together (in parallel), go with 2/0 AWG wire. You will want to use this thick battery cable size because these wires will be handling the most current (Amps) in your electrical system.
Size Note: 2/0 AWG wire is great if you plan to install an inverter rated for up to 2000W. Look for 4/0 AWG wire if pairing with a 3000W inverter.
We recommended 2/0 AWG wires from EWCS because of their unmatched flexibility for their thickness. This wire is made up of hundreds of tiny copper strands, making it easy to bend the wire to connect all your components in a tight space.
(Watch our product review on YouTube)
The wire jackets are also water, oil, & corrosion resistant, making them ideal for use in camper vans.
Safety is a top priority. This ultra flexible, premium copper cable is wrapped in tough EPDM insulation and handles 175+ Amps of 'continuous' current. This is PLENTY for most camper vans. Get peace of mind with this wire.
By the way, you’ll also need lug terminals. Most batteries use 5/16″ terminal posts (though you should confirm what your batteries use). If you are using 2/0 AWG wire, these lug terminals from Wirefy will be what you need to connect the wire to the batteries.
Additional reading: If you haven’t yet finalized your battery set up, check out our related posts for additional info:
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 together. That’s because these wires will be transmitting the same high levels of current to supply all areas of your electrical system.
If using a 3000W inverter, remember to upgrade to 4/0 AWG wire just like in the previous section.
In the above wiring diagram, you can see how 2/0 gauge wire is used to connect every component between the leisure batteries and the bus bars.
Good to know: Some components in the above diagram have 5/16″ terminal posts while others use 3/8″ posts. We color coded our lugs (dark & light orange) to help you identify which ones you’ll need.
For a complete product list, read our camper van 12V installation guide.
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.
If you intend to use the same fuse block that we use, the manufacturer recommends using 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.
100% stranded copper wire. Rated for 150 Amps of continuous current and ideal for connecting the bus bars to the 12V panel. Tough EPDM insulation to resist UV, water, oil, and salt corrosion.
Watch Our YouTube Review: Click the button in the above display to watch our review of this 4 AWG wire.
Lug recommendation: To save money, we recommend getting the Sanuke 120PCS lug set. This set contains 12 different lug sizes that WILL be useful for other parts of your electrical system.
Another Money Saving Tip: There is no problem using a larger wire size than what we recommend. If you still have 2/0 AWG wire leftover from the previous section, you can use this cable to complete this wiring section.
4. Fuse Panel To 12V Devices: 14 AWG
In this last 12V section, we connect the fuse block to every individual 12V device (i.e. the fan, LED lights, & fridge). We recommend using 14 AWG wire to complete this wiring section and you can refer to the following diagram for more info.
In particular, we like this 14/2 AWG twin wire, meaning two 14-gauge cores are packed together inside a tough outer insulation layer. This is a flat-wire design, making it more space efficient behind your walls and ceiling boards.
In a 12V system, these 14-gauge wires will support devices running up to 240W.
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.
Lug recommendation: To connect 14-gauge wire to the fuse block, you will need these #8 ring connectors.
Do You Need 12 AWG Wire Instead? If your wire runs will be longer than 20 feet (6 meters), you may want to consider using 12 AWG wires to combat voltage drop. However, we use 14-gauge wires in our van and it works just fine.
5. Ground Wire Size: 4 AWG
According to the National Electric Code (Article 250, Table 250.66), the size of the ground wire depends on the size of the wires you used in other parts of your electrical system. Check out the ground wire chart.
Because we recommended 2/0 AWG wire in a previous section, this means 4 AWG wire should be used to connect the negative bus bar to a ground point on your vehicle’s chassis. Refer to the diagram below for more info.
Luckily, we used 4 AWG wire to connect the fuse block to the bus bars (part 3), so you should still have some leftover 4-gauge wire to make the ground connection.
Lug size recommendation: You can still use the Sanuke lug set we recommended earlier. You will need to confirm the bolt size on your camper van’s chassis to know which specific lug to use, but the Sanuke set should have it.
And that’s it for 12V wiring! The wiring diagram below is a complete overview of everything we talked about so far. If you’re looking for wire size recommendations for other parts of your camper van, like for your inverter, solar system, and DC charger, we’ll talk about these next.
Section 2:
Wire Size For Inverter System
In this section, we’ll go over the wire sizes you’ll need to complete the camper van’s inverter installation. We separate this section into 4 parts:
- Inverter to batteries
- Wiring to outlets
- Wiring to shore power (for chargers only)
- Ground wire
Just like in the previous 12V wiring section, we’ll provide detailed diagrams to help you identify which size wires you’ll need to complete each part.
1. Inverter To Batteries: 2/0 AWG
For inverters rated up to 2000W, we recommend using the same 2/0 AWG wire size that you used for the 12V system in section 1 & 2. That’s because the inverter will demand large amounts of 12V DC current from the batteries to convert to 110V AC power. Refer to the below diagram for more info.
Why 2/0 AWG? For inverters rated up to 2000W, it’s possible for this unit to experience surge/peak power up to 6000W for several seconds. This is potentially ~450A of current at a standard 13.3V. That’s why we wouldn’t trust any thinner wire to handle this current, even if it’s just for a short amount of time. The EWCS 2/0 wire we recommend is rated up to 450A in “welding applications”, which is short bursts of high amperage power.
Safety is a top priority. This ultra flexible, premium copper cable is wrapped in tough EPDM insulation and handles 175+ Amps of 'continuous' current. This is PLENTY for most camper vans. Get peace of mind with this wire.
Lug recommendations: In most cases, you’ll need these 5/16″ (M8) lugs to connect the wires to the inverter. But you should double check to bolt size on your inverter.
Wires included with your inverter? Some inverters already come with battery cables, but they’re usually thinner and not 100% pure copper. We wouldn’t use them. If you have remaining 2/0 AWG wires from the previous section, you’re much better off using these high quality wires instead.
For a more complete product list for your inverter installation, read our camper van inverter installation guide.
2. Wiring To Outlets: 10 & 12 AWG (Triplex)
When wiring the inverter to the outlets, there are two sections to be aware of.
- Inverter to breaker box
- Breaker box to outlets
Refer to the below diagram to locate these two sections.
Section 1: We use 10/3 AWG triplex wire for the mains line connecting the inverter to the breaker box. We use a thicker wire here just to ensure that the wire stays safe during any peak/surge power from the inverter.
Section 2: We use 12/3 AWG triplex wire to connect the breaker box to the individual outlets.
Perfect for all 110V wiring. This 'marine grade' wire is perfect for all AC Out connections from the inverter to standard 15A outlets. The tough outer jacket resists cuts & abrasions and like that the copper wires are tinned to resist corrosion.
Using a 3000W inverter? Consider upgrading your section 1 (10AWG) wire to either a 6 or 8-gauge triplex wire.
3. Wiring To Shore Power: 10 AWG
If you have an inverter/charger model (rated up to 200W), then you will be able to connect the inverter to shore power to charge the leisure batteries. For this situation, we recommend using the same 10 AWG triplex wire. Refer to the below diagram for details.
Using a 3000W inverter/charger? Consider using 6-gauge triplex wire instead.
4. Ground Wire (4 AWG)
Following the same NEC chart, we recommend using 4 AWG wire to connect the inverter to a ground point on the camper van’s chassis.
Luckily, if you followed our section 1 (12V system) wiring recommendations, you can use the 4-gauge wire that you already bought for this ground connection. Refer to the below diagram for more details.
Lug recommendation: You will still be able to 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 4 different parts of the inverter wiring system.
Next, we’ll tackle the wire sizes you will need for the solar & DC-charging systems.
Section 3:
Wire Size For Solar Systems
In this section, we go over the wire sizes you’ll need to build your camper van solar system. We break up this solar wiring section into two parts.
- Solar panels to charge controller
- Charge controller to bus bars
Safety Caution: Solar wire sizing depends on the total wattage of your solar array AND how you wire your panels together (series or parallel).
The wire size recommendations that we provide will work for a solar array size of up to 440W (panels connected in series). Where appropriate, we will provide alternative size recommendations for different and larger arrays.
1. Solar Panels To Charge Controller: 10 AWG
Assuming you have a max solar array size of 440W, we recommend using 10 AWG wire to connect the solar panels to the charge controller. Why 440W? Because this is the maximum wattage for the Victron 100/30 charger controller.
Refer to the diagram below for more info.
Why 10 AWG? We follow National Electric Code guidelines to keep your solar wiring safe. Assuming you wire two 220W panels in series, the max current produced is 13.41A (short circuit current). When we multiply 13.41A x 1.56 (NEC safety factor), we get 20.9A. And 10 AWG is (conservatively) safe for up to 30A.
Upgrade to 8 AWG?
If you are connecting multiple large panels in parallel, and the total Amps produced * 1.56 is greater 30A, you may want to consider upgrading to 8 AWG wires.
We love Ancor's 'marine grade' wires for solar installations. The insulation jackets are UV & salt water resistant (good for rooftop installations).
Is ‘Marine Grade Worth It?’
Our solar wires take quite a beating on our van’s roof. Though the wires that came included with our solar panels are faded (from UV exposure), our marine-grade cables still look like new. So we think these wires are worth the extra cost.
2. Charge Controller To Bus Bars: 8 AWG
If using our recommended Victron 100/30 charge controller, we recommend using 8 AWG wires to connect the charge controller to the bus bars.
Refer to the below diagram for more info.
Why 8 AWG? This is because the max 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 wire.
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.
Upgrade to 6 AWG?
If you are using a larger 50A charge controller you will want to upgrade to 6-gauge wire.
For more specific solar info, including recommended parts & components, check out our camper van solar install guide. Or you can also download our free solar eBook.
What’s Next? Now that the solar is complete, we’ll move on to recommending the wire size you need to connect your leisure batteries to the alternator.
Section 4:
Wire Size For Alternator (DC-DC) Charging
If you want to charge the leisure batteries while you drive, then you’ll need a DC-DC charger. Most camper vans choose to install either a 18A, 30A, or 40A charger. For these chargers, we recommend using 6 AWG wire to make all the connections.
Refer to the diagram below for more information.
Why 6 AWG? This is the maximum wire size that Victron DC chargers accept. We recommend going with the maximum size to combat against voltage drop because you will need long wire runs to connect to your vehicle’s starter battery. (If using Renogy’s 40A charger, you can use 4-gauge wire if the connection is longer than 20′)
For more specific information on how to install a DC charger, with recommended components, check out our DC-DC charger install guide.
Building a camper van? Download our free e-Books with intuitive electrical, solar, and plumbing diagrams.
Bonus:
Campervan Wiring Tips
1. Use Split Wire Loom
Regretfully, we did not do this. But putting your electric wires in a split wire loom plays a critical role in protecting the wires.
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.
This is important in a camper van because you’ll be creating lots of vibration throughout the vehicle while driving. And if your unprotected wires happen to be resting next to another object, constant vibration can work to 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.
Final Thoughts: Campervan Wiring Is Just The Beginning!
Thank you for making it this far in our campervan wiring post! We hope you learned a thing, or two, about best wire size and placement in your own van conversion.
But buying the right wires and laying them in your van is just the first step. This blog has so many more posts to get your campervan electrics up and running. Check out these posts below for more information.
- Camper Van Conversion Guide
- 12V Installation Guide
- Inverter Installation Guide
- Solar Installation Guide
Happy building!
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Building a camper van? Download our free e-Books with intuitive electrical, solar, and plumbing diagrams.
