Please look into providing a tool pallet consisting of typical electrical symbols that are used to develop a single line diagram.
Perhaps, these could be used inside a Detail View, or they could be used in a Legend.
It could also be under a different view altogether, exclusive and specific for drawing single line diagrams.
Revit 2017 has been out for a few months now, and it still does not offer this capability. Without such a tool, electrical engineers who still use AutoCAD would be extremely skeptical to make the move to Revit.