Fuse box · bus bars · main fuse

Fuse box and power distribution wiring

In a custom harness, a race car or a camper, every circuit should start at one fuse box: one heavy feed from the battery, one fuse per circuit, and a clean ground. Here is how to lay it out.

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Layout

Battery + → main fuse at the battery (rated for the feed cable) → fuse box input.
Each output channel gets its own fuse, sized for its own wire and load.
Heavy loads go through relays fed from the fuse box; the relays sit next to it.
A negative bus bar collects the grounds and connects to the body or the battery − with a cable as thick as the feed.

Sizing the feed

The main feed carries the sum of everything that can be on at the same time, not the sum of all fuses. Size the feed cable and the main fuse for that current; the channel fuses then protect each thinner wire after the box.

Plan it in WireForge

Use the Power bus component: up to 10 channels, each with its own fuse.
Add Positive and Negative distribution blocks for the bus bars.
Simulate with everything switched on: click the main feed to see the total current.

Questions

Do I need a main fuse before the fuse box?

Yes. Without it, the feed cable from the battery to the box is unprotected — a short there has nothing to stop it.

How many circuits per fuse?

One circuit per fuse is the clean way: a fault then takes out only that circuit, and each fuse matches its own wire.

Where should grounds go?

To a negative bus bar or a few solid ground points on bare metal, joined to the battery − with a heavy cable.

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