Free Tool

Wiring Diagram Builder

Pick your battery, charging, and gear. Get a custom 12V wiring diagram with every wire size, every fuse, and a parts list — updated as you go.

⚙ Your Setup

12V systems. The diagram updates as you change things.

House Battery
Charging
Inverter (for wall-plug gear)

Bigger than 2000W? That's a job for a 24V system.

Fuse Block Circuits

Check what you'll run. Amps are typical — use the number on your gear's label if you have it.

Wire Run Lengths (feet, one way)

Measure the path the wire will really take (around corners, under trim), then add 20%.

Extras
See My Diagram ↓

⚡ Your Wiring Diagram

12V system

Dust & Watts — 12V Wiring Plan (dustandwatts.com/wiring-diagram)

Positive (+) Negative (−) Fuse

Each label on a wire is its size. 8 AWG and thicker: use cable rated 105°C (it's printed on the jacket). Solar controller and DC-DC charger: run a black (−) wire from each to the negative busbar, the same size as its red wire.

Cut List

Every Wire & Fuse

Parts List

What To Buy

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    Before You Crimp

    Wiring Rules That Keep Rigs From Burning

    🔥 Fuse at the power source

    A fuse protects the wire on the battery side of it. Put each fuse as close to the battery or busbar as you can, never at the gear end.

    🔧 Crimp it right

    Big cables need copper lugs and a proper lug crimper (hammer or hydraulic), not pliers. Seal every lug with adhesive heat shrink.

    ⚪ Negatives matter too

    Every black wire carries the same current as its red wire. Use the same size, and run it to the negative busbar.

    🚗 Newer trucks: smart alternators

    Many newer vehicles drop alternator voltage while driving. Hook up your DC-DC charger's ignition (D+) wire so it knows the engine is running.

    🌡 Heat and rub points

    Use loom or split tubing, grommets through metal, and keep cables away from exhaust. Wire near heat should go one size bigger.

    📝 Label everything

    Label both ends of every wire and every fuse slot. Future you, at night, on the trail, will thank you.

    Planning tool, not a certified design. Sizes here use copper wire (cables 8 AWG and thicker must have 105°C-rated insulation; lower-rated cable needs a bigger size), 3% voltage drop (5% on the DC-DC charger's input, which chargers are built to handle), and fuses about 25% above the load. Your gear's manual wins: if it calls for a different fuse or wire, follow the manual. Lithium batteries can push huge current in a short circuit, so never skip the main fuse. Not comfortable with high-current DC? Have a pro install it. See our Terms of Use.