DOC is described as 'software dedicated to the design and calculation of single-line diagrams of electrical systems in low and medium voltage, allowing the user to choose switching devices and security, and for verification and coordination of protective devices'. There are more than 10 alternatives to DOC for a variety of platforms, including Windows, Online / Web-based, iPhone, Self-Hosted solutions and SaaS. The best alternative is Catia. It's not free, so if you're looking for a free alternative, you could try BetterDocs or EKTS (Electrical Control Techniques Simulator). Other great apps like DOC are See Electrical (Paid), EPLAN Electric P8 (Paid), SolidWorks Electrical (Paid) and ETAP (Paid).
CATIA (Computer Aided Three-dimensional Interactive Application) (in English usually pronounced /k?'ti?/) is a multi-platform CAD/CAM/CAE commercial software suite developed by the French company Dassault Systèmes.
SOLIDWORKS Electrical schematic design capabilities simplify development of embedded electrical systems for machines and other applications, with single-line and multi-line schematic tools for planning your electrical systems.