In accordance with the Development plan of Riga city the purpose is the thorough development of economy, using the geographic location of the city, natural possibilities and traditions for strengthening the economic independence of the city as well as improve the quality of people life efficiently applying the natural resources. It is not possible without the development of electric power engineering and development of the safe system of the city power supply. For its realization it is necessary to define the basic principles of the network organization, order of the building of new system elements as well as the opportunities of interaction of new and old elements of the system. The growing of communal consumers number in large cities, increasing of the number of storey of dwelling houses and administrative buildings, large amount of point load and separate regions with a high load density results in the necessity to introduce higher level of voltage in the power supply system. These tendencies are typical for Riga city - the capital of Latvia and main administrative, industrial, financial, business and cultural center. The introduction of higher level of voltage should be justified by the economic and technical possibilities and advantages in comparison with the existing power supply system.