In this video, I walk you through how to build a safe, reliable 12V electrical system for a campervan, from laying out the components through to the first power-up and system test.

Rather than simply explaining a wiring diagram, I show you how the system is physically connected, which order to wire everything in, and how to avoid some of the most common mistakes made by first-time van builders.

You’ll also see my temporary electrical board method, which allows you to assemble and bench test the complete system before permanently installing it inside the van.

In this 12V electrical walkthrough, I cover:

• How a combined DC-DC and solar charger works

• How to arrange your electrical components

• Where circuit protection should be installed

• How to select the correct fuse or circuit breaker

• How to calculate cable size using a 3% voltage-drop chart

• Why automotive and marine-grade cable should be used

• How to make secure large-cable crimp connections

• The safest order for connecting the system

• How to complete the first power-up and bench test

This type of system can power the essential appliances found in most small campervans, including a fridge, lights, water pump, roof fan, wall fan and USB outlets. It can also be designed to support an inverter later if your power requirements increase.

If you’re building your first van and feel confident reading a diagram but unsure about the actual wiring process, this walkthrough will help turn the theory into a practical system you can understand.

👉 Use the accompanying 12V wiring diagram and cable-size chart while following the video, and visit the full product list to see the components used throughout my builds.

Important Safety Note

I’m not a licensed electrician. This video is intended to help you understand the principles behind a campervan 12V electrical system. Always confirm cable ratings, fuse sizes, equipment instructions and installation requirements for your specific system.