3D wiring diagrams

Is there a standard for doing wiring diagrams in 3D,
I'm not sure on the PartP law on rewiring my own house
but surely I could help by doing a diagram of what's where,
but as the wires go on lots of levels is there 3d software around?

I'm looking at
http://www.blender.org/
and
http://sketchup.google.com/

but is there a standard with templates anywhere?

george

and ditto for water pipes!

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