CAD package for wiring diagrams

[eSteve]

Does anyone know of a good piece of software for drawing wiring diagrams?

I realise it could be done with any CAD package or SketchUp but would like to remove the tedium of drawing switches, fuses etc and have the package to have these items available within it so I can concentrate on the layout and function.

Any ideas?

Open source preferred.

PS Don't be thinking I've made an enormous leap in progress, and I'm on the wiring now, just thinking ahead, whilst I continue welding.

PPS: Just found a thing called SmartDraw which says it is good for automotive wiring diagrams, anyone used it? Just realised it's only free for 30 days