Free tool
Draw your wiring
Starts from your power plan if you made one in this browser, or from a sample van. Drag, connect, set cable lengths, and download a PNG with every gauge and fuse on it.
Scroll the diagram sideways to see all of it. A tablet or computer makes editing easier.
Add a part
How it works
- Drag parts to arrange them.
- Tap Connect two parts, then tap two parts.
- Tap a cable to set its length. Gauge and fuse update as you go.
- Tap a part to change its label or rating.
- Each line is a pair: red positive, black negative. Brown lines are 120 V AC; green are solar panel wires.
Nothing is saved: download a PNG when you're done.
What this tool is, and isn't
It's a block diagram: one box per part, one line per cable pair, with a label you can trust for gauge and fuse. It isn't a schematic of every terminal, it doesn't know your parts' manuals, and it doesn't replace an installer's eye on anything 120 V.
New to the parts? Start with how a van electrical system fits together, which has a diagram you can download.
Questions people ask
How does the tool pick the wire gauge?
From the current on that cable and its length. The current comes from the part's rating (a 40 A charger, a 2,000 W inverter) or, for battery cables, from everything that can run at once. The fuse is 125% of the current; the wire is the smallest that can carry that fuse in a bundle (ABYC E-11) with under 3% voltage drop.
Can I save my diagram?
The free tool doesn't save projects. Download the PNG when you're done. If you want to keep, edit and redraw systems, that's what DrawWire is for.
Why is each line drawn as two wires?
Every DC run is a pair: a positive (red) and a negative (black) of the same size. The negative carries the same current back, so it gets the same gauge.
Can I draw the AC side?
You can add an outlet or appliance after the inverter and a shore inlet before the charger, and the tool labels them with the usual breaker and wire size. Any 120 V wiring should be done or checked by a qualified electrician.