Choosing the correct cable size in a campervan electrical system is essential for safe operation, reliable charging and stable appliance performance. Undersized cable can cause voltage drop, overheating and poor equipment behaviour, while oversized cable increases cost and installation difficulty.
This guide explains what cable sizes are typically used for common campervan circuits including lighting, fridges, water pumps, USB sockets, DC-DC chargers and inverters. It also links to MKGT cable size calculators so you can check exact values for your own installation.
Open all MKGT cable size calculators →
Typical Campervan Cable Sizes by Circuit Type
The correct cable size depends on current, cable length and acceptable voltage drop. The table below shows typical ranges used in many campervan installations. Always confirm final cable size using a calculator.
| Circuit | Typical current | Typical cable size |
|---|---|---|
| LED lighting | 1–5 A | 0.75 – 1.5 mm² |
| USB sockets | 2–10 A | 1.5 – 2.5 mm² |
| Water pump | 5–15 A | 1.5 – 2.5 mm² |
| 12V compressor fridge | 4–8 A | 2.5 mm² (often recommended) |
| Diesel heater | 2–12 A | 2.5 mm² typical |
| DC-DC charger | 20–60 A | 10 – 25 mm² |
| Inverter (1000–2000 W) | 80–200 A | 25 – 50 mm² |
Cable Size for Campervan Lighting Circuits
LED lighting circuits usually draw relatively low current but can suffer from voltage drop if cable runs are long. For most campervan lighting installations:
- 0.75 mm² works for short runs
- 1.5 mm² is a safer standard choice
- use larger cable for long cable routes
Use the calculator below to confirm your exact cable size:
Open Cable Size Calculator →
Cable Size for Campervan Fridges
Compressor fridges are sensitive to voltage drop and often require larger cable than expected. Even though many draw only 4–6 amps during normal operation, manufacturers frequently recommend:
- 2.5 mm² cable minimum
- larger cable for longer runs
Stable voltage helps prevent fridge shutdown errors and improves efficiency.
Cable Size for Campervan Water Pumps
Water pumps draw moderate current but also create startup surge loads. Typical cable sizes:
- 1.5 mm² for short runs
- 2.5 mm² recommended for reliability
Always fuse water pump circuits correctly close to the distribution panel.
Cable Size for DC-DC Chargers
DC-DC chargers transfer significant current between starter battery and leisure battery. These circuits normally require dedicated battery cable rather than 2-core flat automotive cable.
Typical cable sizes:
- 20 A charger → 10 mm²
- 40 A charger → 16 mm²
- 60 A charger → 25 mm²
Actual size depends on cable length and installation layout.
Cable Size for Campervan Inverters
Inverters are among the highest-current circuits in a campervan electrical system. Cable sizing must be calculated carefully based on inverter power and cable length.
Example typical ranges:
- 1000 W inverter → approx. 25 mm²
- 1500 W inverter → approx. 35 mm²
- 2000 W inverter → approx. 50 mm²
Always confirm inverter cable sizing using a proper voltage drop calculation:
Open Voltage Drop Calculator →
Why Voltage Drop Matters in Campervan Wiring
Low-voltage DC systems are sensitive to cable losses. Even small voltage drops can affect fridge performance, charging efficiency and inverter stability.
Typical targets:
- Lighting circuits: 3–5%
- Charging circuits: 2–3%
- High-current circuits: up to 10%
Choosing the Correct Fuse Size
Every positive cable leaving the battery should be protected by a fuse sized to protect the cable. Fuse size depends on:
- cable rating
- circuit current
- installation length
Use the MKGT fuse calculator here:
Open Fuse Size Calculator →
Plan Your Campervan Electrical System Properly
Cable sizing works best when planned together with battery capacity, solar charging and system load calculations.
Use the full system builder here:
Open Campervan Electrical System Calculator →
FAQ
What cable size should I use in a campervan?
Cable size depends on current, cable length and acceptable voltage drop. Interior circuits often use 1.5–2.5 mm² cable, while battery and inverter circuits usually require much larger battery cable.
Is 2.5 mm² cable enough for a campervan fridge?
In many installations yes, but longer cable runs may require larger cable. Always check voltage drop calculations.
What cable size is needed for a 2000W inverter?
Typically around 50 mm² depending on cable length and system voltage.
Do campervan cables need fuses?
Yes. Every positive cable connected to the battery should be protected with an appropriately rated fuse.