Campervan Wiring: Diagrams, Wire Gauges & Safety (2025)
Getting the wiring right in your campervan wiring diagram is the difference between a safe, reliable system and a potential fire hazard. This guide covers everything: wire gauges, fuse sizing, colour codes, and UK safety standards.
This is part of our complete campervan electrical system guide. If you want your wiring diagram generated automatically, our free calculator does exactly that.
Get a custom wiring diagram
Our calculator generates a complete wiring diagram with every wire gauge and fuse rating calculated for your specific system.
Wire Gauge Sizing
Using the wrong wire gauge is the number one cause of campervan electrical fires. A wire that's too thin for its current load will overheat, melt its insulation, and potentially cause a short circuit.
For an interactive tool, see our wire gauge calculator. For a complete reference table, see campervan cable sizes.
The Calculation
Wire gauge depends on two factors: current draw (amps) and cable length (metres). Longer cables need thicker wire because of voltage drop.
At 12V, a 3% maximum voltage drop is the standard target. Our calculator handles this automatically.
Common Wire Sizes
| Connection | Typical Current | Typical Length | Recommended Size |
|---|---|---|---|
| LED lights | 2A | 3m | 1.5mm² |
| Fridge | 5A | 2m | 1.5mm² |
| Water pump | 5A | 3m | 2.5mm² |
| USB sockets | 3A | 2m | 1.5mm² |
| MPPT to battery | 25A | 1.5m | 6mm² |
| DC-DC to battery | 30A | 1.5m | 6mm² |
| Battery to fuse box | 40A | 1m | 10mm² |
| Battery to inverter | 170A | 1m | 35mm² |
Fuse Sizing
Every wire must be protected by a fuse. The fuse protects the wire, not the appliance. See how to size fuses for your campervan for the detailed guide.
The 125% rule: Size your fuse at 125% of the expected continuous load, but never exceed the wire's maximum current rating.
Never skip fuses
A short circuit on an unfused wire connected to a LiFePO4 battery can deliver over 1,000 amps — enough to instantly melt copper and start a fire. Every wire needs a fuse at the power source end.
Fuse Box & Distribution
Your fuse box distributes power from the battery to all your 12V circuits. See campervan fuse box wiring for the complete guide with diagrams.
Bus Bars
Bus bars simplify your wiring by providing a common connection point. You'll need a positive bus bar and a negative bus bar. See campervan bus bar wiring for setup options including the Victron Lynx Distributor.
Earth Bonding
All exposed metal parts must be bonded to a common earth point. This is essential for safety, especially if you have 230V circuits. See campervan earth bonding for the full requirements.
Connections: Crimping vs Soldering
For campervan wiring, crimping is always preferred over soldering. Solder melts under heat (exactly when you need the connection to hold), while properly crimped connections maintain integrity. See crimping vs soldering for the detailed comparison.
Wiring Best Practices
Cable Routing
How you route your cables matters for both safety and aesthetics. See campervan cable routing for best practices on hiding cables, protecting them from chafe, and maintaining accessibility for future changes.
Colour Codes
Following standard colour codes makes your system understandable to anyone who works on it later. See campervan wiring colour codes UK for the full UK and European standard.
Wiring Order
There's a specific order you should connect components to avoid sparks and accidents. See campervan wiring order for the recommended sequence.
Testing
Once installed, test every circuit with a multimeter before connecting the battery. See testing campervan wiring with a multimeter for the step-by-step process.
Specific Circuits
LED Lighting
Wiring LED lights is one of the simplest circuits and a great place to start. See how to wire LED lights for the 12V circuit guide.
Anderson Plugs
Anderson plugs are useful for portable solar connections and easily-disconnectable circuits. See Anderson plugs for campervans.
Related Guides
- Campervan electrical system guide — the complete overview
- Campervan battery guide — what you're wiring to
- Campervan solar setup guide — solar cable routing and sizing
- Campervan charging guide — charger wiring requirements
- Campervan inverters guide — high-current inverter wiring
FAQ
What wire size do I need for a campervan?
It depends on the current and cable length. LED lights typically need 1.5mm², a fridge circuit needs 1.5–2.5mm², and the main battery-to-fuse-box feed needs 10–16mm². Use our wire gauge calculator or free system designer for precise sizing.
Do I need to use automotive-grade wire?
Yes. Household cable (1.5mm² twin and earth) is not suitable for campervans. You need flexible, tinned-copper automotive or marine grade cable that can handle vibration and temperature changes.
Can I do the wiring myself?
The 12V DC wiring is absolutely DIY-able with proper research. You'll need a ratchet crimper, wire strippers, and a multimeter. For 230V AC circuits, have a qualified electrician inspect your work at minimum.