How about AutoCAD??
I use AutoCAD r 14 exclusively for just about everything related to an Engineered project [along with Excel for Panel Schedules, calcs, etc.].
If ACAD is out of your price range, try Turbocad, by IMSI. I have that program [an older version prior to obtaining a rock solid AutoCAD version"14"], and it has a nice library of components plus the power of a CAD program. It is a little easier to learn than ACAD, but it still requires somewhat a large learning curve.
Lastly, try Visio. I have version 4 and it is very versitile.