I also use Visio, for no other reason than I know the software already,
and CAD software would be overkill. I then cut and paste to a word
document, before I send to the yard or other members of our yahoo
group, so they can view it.

I have made some extremly complex wiring diagrams. You can move the
blocks around, and the wires and labels follow, which make it all worth
while.

Dan