A proper electrical system is the backbone of any campervan conversion. Whether you're building a simple sleep-and-cook setup or a full RV-style kitchen, getting the wiring right is essential for safety, reliability, and performance. This guide covers everything from planning and component selection to installation and troubleshooting.
Benefits of a Good System:
- Reliable power for lighting, cooking, and heating
- Safety — proper wiring prevents fires and electrical shocks
- Longevity — correct installations last for years
- Flexibility — ability to add more devices as needs grow
- Peace of mind — knowing your system is wired correctly
Common Mistakes to Avoid:
- Using automotive wire for house circuits
- Skipping the fuse on every positive lead
- Mixing AC and DC systems without proper isolation
- Not using proper crimping tools and heat-shrink
- Running cables through sharp edges without grommets
- Ignoring the earth connection
System Planning — Know Your Power Needs
Day-to-Day Power Requirements:
- LED lighting: 10-20W per fixture (1-2A per LED)
- 12V fridge: 3-5A running, 15-30A compressor cycle
- Water pump: 5-10A per minute of use
- Phone charging: 2-5A per device
- Laptop charging: 3-5A per device
- Fan: 1-2A per fan
- Total daily consumption: 100-200Wh
Monthly Power Consumption:
- Daily average: 200Wh
- Monthly total: 6,000Wh
- Solar panels needed: 200W panels (for UK conditions)
Wiring Diagrams — Basic vs Advanced
Basic System (Entry Level):
- 1x 100Ah leisure battery
- 1x DC-DC charger (UK Battery Master or Victron)
- 2x 100W solar panels
- 1x 30A inverter (pure sine wave)
- 1x AC socket (Type G)
- 1x 12V distribution board
- Wiring: 10mm battery to DC-DC, 4mm to inverter
Advanced System (RV Level):
- 2x 200Ah lithium batteries
- 1x 50A MPPT charge controller
- 4x 200W solar panels
- 1x 3000W inverter (pure sine wave)
- 1x AC distribution board
- 1x DC distribution board
- Wiring: 25mm battery to inverter, 6mm to DC distribution
Component Breakdown
Battery Options:
- Lead-acid (AGM/Gel): £200-400, 50% usable capacity
- Lithium (LiFePO4): £400-800, 90% usable capacity
- Hybrid (Hybrid AGM): £300-600, 70% usable capacity
- Capacity: 100-200Ah recommended for UK van life
Inverter Types:
- Pure Sine Wave: £50-300, clean power for sensitive electronics
- Modified Sine Wave: £20-100, cheaper but can damage electronics
- Power: 500W-3000W depending on needs
- Switch: Manual or automatic (senses AC presence)
Charge Controller:
- PWM: £20-60, cheaper, less efficient
- MPPT: £60-200, more efficient, best for UK conditions
- Current: 30A-60A depending on solar array
- Features: Bluetooth monitoring, remote control, multiple inputs
Wiring Specifications:
- Battery to DC-DC: 10mm² for up to 15A
- Battery to inverter: 25mm² for up to 200A
- DC distribution: 4mm² for individual circuits
- AC wiring: 2.5mm² for standard socket circuits
- Cable type: 100% tinned copper, flexible
- Crimping: Use proper crimping tool and ferrules
Step-by-Step Wiring Process
Step 1: Install the Battery Box
- Choose a ventilated area near the front of the van
- Ensure the box is secured and not near heat sources
- Line the box with rubber matting for vibration damping
- Add a battery vent if using lead-acid batteries
Step 2: Wire the DC-DC Charger
- Connect the input to the vehicle's alternator
- Connect the output to the leisure battery
- Fuse the positive lead within 300mm of the battery
- Add a fuse near the alternator input as well
Step 3: Install the Inverter
- Mount the inverter near the battery
- Connect the positive lead first, then the negative
- Fuse the positive lead within 300mm of the battery
- Connect the AC socket to the inverter output
Step 4: Wire the Solar System
- Mount the solar panels on the roof
- Run the cables through the roof into the van
- Connect the cables to the charge controller
- Connect the charge controller to the leisure battery
- Add a DC-DC charger for alternator charging
Step 5: Wire the DC Distribution
- Install a DC distribution board
- Wire each circuit with its own fuse (1-10A for lighting, 10-15A for fridge, 10-15A for water pump)
- Use 4mm² cable for all circuits
- Add a main fuse near the battery
Step 6: Wire the AC Distribution
- Install an AC distribution board
- Wire each socket with its own fuse (10-15A per circuit)
- Connect the inverter to the AC distribution board
- Add an earth cable to all AC circuits
- Test the system with a multimeter before turning on
Installation Tips and Best Practices
Wiring Tips:
- Use proper crimping tools and ferrules
- Label every cable at both ends
- Use conduit or cable ties to prevent chafing
- Route cables along the same side of the van where possible
- Avoid running cables through sharp edges without grommets
- Use a multimeter to verify each circuit before powering up
Safety Tips:
- Always disconnect the battery before working on the system
- Fuse every positive lead within 300mm of the battery
- Use a 10A fuse for lighting circuits
- Use a 15A fuse for fridge circuits
- Use a 15A fuse for water pump circuits
- Test each circuit with a multimeter before turning on
- Add a main isolating switch for emergency power-off
Troubleshooting Common Issues
Common Problems:
- Inverter not turning on — check battery voltage and fuse
- Fridge not cooling — check power and voltage
- Solar panel not charging — check connections and charge controller
- DC distribution board not working — check fuse and connections
- Battery draining — check for parasitic drain and wiring
Quick Fixes:
- Inverter not turning on — check battery voltage and fuse
- Fridge not cooling — check power and voltage
- Solar panel not charging — check connections and charge controller
- DC distribution board not working — check fuse and connections
- Battery draining — check for parasitic drain and wiring
DIY vs Professional Installation
DIY Installation:
- Cost: £200-400 for components
- Time: 1-2 days for basic system
- Pros: Save money, learn valuable skills
- Cons: Risk of wiring errors, may void insurance
Professional Installation:
- Cost: £1,000-3,000 for full system
- Time: 2-5 days depending on complexity
- Pros: Expert wiring, warranty, insurance compliant
- Cons: Higher cost, less control over components
Hybrid Approach:
- DIY battery, wiring, and solar installation
- Professional installation of inverter and AC distribution
- Cost: £500-1,000 for components
- Time: 1-2 days for DIY, 1 day for professional
- Pros: Best of both worlds — cost savings and expert wiring
Campervan Electrical System Final Thoughts
A proper electrical system is the backbone of any campervan conversion. Whether you're building a simple sleep-and-cook setup or a full RV-style kitchen, getting the wiring right is essential for safety, reliability, and performance. With careful planning, proper components, and correct wiring, your electrical system will last for years and power everything you need for van life in the UK.
