The introductory part explains which electrical properties are contained in electric power lines. Also, the advantage of overhead in relation to underground lines was explained, as well the most commonly used types of conductors in transmission lines. The third chapter describes the resistance, and its change with increasing temperature. The fourth and fifth chapters describe the inductance and capacity of power lines, and their calculation in relation to types of line, the number of bundle conductors, and whether the line is transposed or not. The method of mean geometric distances used to calculate capacitance and inductance is also described. At the end of the work, typical examples are shown for 110-kV, 220-kV, and 440-kV lines used in Republic of Croatia, and their solutions in the Matlab.