Electrical system design plays a major role in modern building construction. Electrical system design deals with analysis and application of Power transmission and Distribution, Lighting systems, telecommunication, fire alarm systems . It helps to reduce cost and time to fulfill client needs. In electrical system design we have to calculate the total load used by commercial building, residential building and industrial buildings. Also find out the selection of switch gears and conducting system, fault level detection, transformer & generator selection, Earthing and protective measures . In Electrical system design our main aim is to ensure electrical safety and maintain energy efficiency