The electrical installation play vital role in the utilization of building, constructed for different use, e.g. residences, offices, hotels, shopping complexes, theatres, sport stadiums, auditoriums, especially multi-storied buildings. The basic electrical installations are, lighting i.e. providing illumination both inside and outside buildings exhaust fans, use of portable and non-portable electrical machines or appliances and their wiring network, including sub-main wiring, cable, O.H. lines etc, including control panel and switches. The earthing is very common and essential electrical installation. The other electrical installations like air conditioning, various sound systems, protection against lightning and fire, lift, diesel generating sets, computer networking are various optional installation in various buildings. Protection against lightning and fire are mandatory in buildings as per building manual. Stage lighting, sound systems are essential in building used for various conference hall, auditorium, places of worship, studios and audio video broadcasting stations. Telecommunication and networking has become very useful electrical installation now-a-days. The book describes these optional electrical installations necessary for the buildings and useful for occupants. Lift is useful for accessing high floors and shifting of essential commodities. D.G. sets are essential for alternate source of energy at time of failure of the power supply from the powers stations. The book will be of interest for architects, engineers associated with building projects, students studying electrical engineering at polytechnics and architecture to provide in-depth understanding on estimating and costing.