The 'Out of the box' (OTB) Duplex Receptacle.rfa family REVIT supplies is as good a place as any to start to investigate just how a typical REVIT electrical family works.
First of all you can host it to a wall in a linked architectural model, but most interesting is the fact that there is a 'nested' annotation family within the 3D family.
When in a Plan view all you see is the correctly scaled annotation symbol (as shown on the left) but in a 3D or Elevation view you see the physical 3D elements on the right.
View the CADclip below for a breakdown and introduction to dissecting this interesting little family.
Once you get the just of it, modifying these electrical families will become much less of an issue.