Choosing cable for a camper van's DC circuit means checking the equipment, cable run and installation conditions together.
Start With The Equipment Instructions
Record the circuit voltage, equipment model and documented current requirements. Use the manufacturer's cable and protection instructions before a general chart. Do not size an inverter's battery cable from its AC output current.
Victron's DC Wiring Guide explains cable selection, connections and protection. Its product-specific recommendations need the matching model and installation conditions.
Measure The Complete Circuit
For a calculation requiring total conductor length, include the positive and return conductors. Two four-metre cable runs make an eight-metre total. Check the calculator's definition: entering that total into a tool requesting one-way distance would give the wrong input.
Check The Chart's Assumptions
The preserved chart below belongs to the marine approach described in Blue Sea Systems' Wire-Selection Brief. That brief uses round-trip circuit length and assumes 105°C-rated insulation. Its marine 3% and 10% circuit categories are not a blanket voltage-drop allowance for every van appliance.
Confirm the voltage drop the equipment permits and the cable's current capacity under its actual installation conditions. Check conductor material, insulation rating, temperature and routing.
Select Protection With The Cable
Cable selection and circuit protection need to agree. Check the fuse or breaker's DC voltage rating, interrupt rating, holder and placement as well as its amperage. The Blue Sea Fuse-Selection Guide explains those checks. Do not increase a fuse simply to stop nuisance trips without finding the cause.
For the components I used in my van, see my distribution and protection page alongside this wire-sizing reference.
Keep A Circuit Record Before Buying
- Equipment Model And Installation Instructions
- System Voltage And Required Current
- Positive And Return Cable Lengths
- Cable Specification And Routing Conditions
- Permitted Voltage Drop And Calculation Inputs
- Specified Protection And Compatible Terminations
The Build Resources and MOSFET And Relay Guide provide related project context.