“The complete wiring guide for campervan electrics in the UK. From basic 12V systems to advanced solar setups — everything a DIYer needs to wire their van's electrical system.
Table of Contents
- Basic Electrical Concepts
- Main Components
- Wiring Layouts
- Fuse Sizing
- Cable Sizing
- Common Issues
- Tools Needed
- Safety Tips
Basic Electrical Concepts
Voltage, Current, and Power
- Voltage (V): Electrical pressure. UK = 230V mains, 12V van, 24V some vans
- Current (A): Flow of electricity. Your battery provides current
- Power (W): Volts × Amps. How much work you can do
Key Relationship
Power (W) = Voltage (V) × Current (A)
For example: A 100W light at 12V draws 8.3A.
Main Components
Battery Bank
The energy store. Options:
- AGM – cheap, heavy, 50% usable
- LiFePO4 – expensive, light, 90% usable
- Lead-acid – budget, short lifespan
Inverter
DC to AC converter. Runs mains appliances from 12V battery.
- Pure sine – £150-£300, best quality
- Modified sine – £50-£100, noisier, less reliable
Solar Charge Controller
Regulates power from solar panels to battery.
- PWM – cheap (£30-£50), less efficient
- MPPT – efficient (20-30% more), £100-£400
LED Lighting
Low-power, long-lasting, great for vans.
Wiring Layouts
Simple 12V System
Battery → Fuse → Switch → Load
Solar + Battery + Inverter System
Solar panels → Charge controller → Battery → Inverter → Mains outlets
→ 12V loads (LEDs, fridge)
Multi-Bank System (Advanced)
Chassis battery (engine) → Isolator switch → Leisure battery
Solar → Charge controller → Leisure battery
Alternator → Charge controller → Leisure battery
Fuse Sizing
| Wire Size | Max Fuse |
|---|---|
| 1mm² | 10A |
| 1.5mm² | 15A |
| 2.5mm² | 20A |
| 4mm² | 30A |
| 6mm² | 40A |
| 10mm² | 60A |
Rule: Fuse size should be 125% of the load current.
Cable Sizing
For 12V systems:
- 1m cable run at 10A: Use 2.5mm²
- 2m cable run at 10A: Use 4mm²
- 3m cable run at 20A: Use 6mm²
Always use higher gauge than minimum – it's cheaper than replacing burnt cables.
Common Issues
- Fuses blowing – short circuit or overload
- Batteries not charging – check solar connections
- Flickering lights – loose connection
- Inverter overheating – poor ventilation
- Draining battery – parasitic drain from unused devices
Tools Needed
- Multimeter
- Wire strippers
- Crimping tool
- Cable cutters
- Soldering iron
- Heat gun
- Panel cutters
Safety Tips
- Always fuse – every cable from battery
- Use marine-grade cable – tinned copper, doesn't corrode
- Secure all cables – use cable ties and conduits
- Label everything – future-you will thank you
- Check connections – test with multimeter before closing up
Updated June 2026. Questions about wiring your van's electrics? Contact us.
