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Abstract. The cost of energy has increased significantly for the industrial enterprises over the recent years, due to an increase in the electricity tariffs and the changes in the rules of the electricity market. Tariffs for electricity sold to consumers, differentiated according to various parameters, one of which is the voltage range. The higher the voltage range, the lower the tariffs, and thus, the consumer pays less for the supplied energy. Currently only for big consumers made energy supply "direct input" through the construction of an overhead line (OL) with a nominal voltage of 110 kV or 220 kV. However, it is advisable to consider the issue of power supply efficiency of big and medium-sized industrial enterprises based on the "direct input". The questions of voltage level study based on empirical formulas are considered in the article, expressing the dependence of the voltage from the transmission distance and the amount of transmitted power. It was proven that these formulas give a large spread, so intermediate voltage classes 35 kV and 110 kV, which compared with the traditional option of power supply on the basis of the cable line 10 kV, have been selected. Based on the technical and economic calculations it has been proved the value of the transmit power and length of the line at which the power supply of industrial enterprise on the basis of " direct input" with a nominal voltage of 110 kV becomes effective.