EPLAN Electric P8 - CAE software solution for project planning, documentation and administration of electrotechnical automation projects.
FreeCAD - An open-source parametric 3D modeler
QElectroTech - QElectroTech is a free software to create electric diagrams.
SketchUp - 3D for Everyone
AutoCAD Electrical - AutoCAD Electrical design software is electrical engineering software for electrical CAD.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.