In this work we present a specialized software that should be used in the bidding or design phases for the optimal choice of the equipment that make up the automatic switching system from the base source to the backup source. The use of the software does neither require wide electric engineering knowledge, design knowledge nor electric circuit sizing know-how, and can be used by the bidding and supply staff. The advantage of using this software is the possibility to quickly select the necessary technical equipment in order to obtain a technically competitive automation system at a convenient price. The software we propose in this work is based on sizing calculations and predefined lists of standardized equipment provided by various producers and suppliers. Upon inputting variable values, the software outputs a price estimate and a list of electric gear, including the life-size equipment dimensions. The software application allows the sales engineer to draw up the necessary documentation, without the assistance of the design engineer, in order to establish a correct price estimate.