The task of this thesis was to analyze in detail the effective length of the simplest version of a type A grounding system according to HRN EN 62305 during a lightning strike in the center point of the grounding system. In the thesis, the observed grounding system comprises of two horizontal elementary grounding rods connected in one point and oriented opposite one another. In the second chapter the main characteristics of type A grounding system according to HRN EN 62305 are described. Also, the simplest version of that grounding system which is observed in this thesis is described. The simplest version consists of two opposite horizontal grounding rods. In the third chapter impulse impedance of the observed grounding system is defined as well as the effective length of the observed grounding system. In the fourth chapter a description of the program package EMGround is given which is used to obtain accurate values of effective length of the observed type A grounding system. In addition, the iterative procedure of computing the effective length of the grounding system is described. In the fifth chapter a detailed analysis of the effect of electrode depth on effective length of the grounding system is performed for different values of front duration of the wave of the imposed impulse current and for different values of homogeneous ground resistivity. For eight different values of ground resistivity, ten different values of front duration and five different values of burial depth of the grounding system a total of 400 simulations were performed in EMGround software. In each simulation the effective length of the grounding system has been iteratively sought. Analyzing the obtained effective lengths, a pattern was found indicating similar reduction in effective length as the burial depth increases regardless of the values of ground resistivity and front duration. This effect was described by an effective-length-reduction-factor due to burial depth relative to the effective length of the grounding system when it is buried at a depth of 0.1 m. The approximation formula describing this effect was developed in MATLAB Curve Fitting Toolbox and its accuracy was verified in the same chapter. In the sixth chapter a set of ten values of ground resistivity and ten values of front duration were selected and by using EMGround the effective length for all cases has been found for a burial depth of 0.1 m. It was shown in the previous chapter that the obtained effective lengths can be reduced to any burial depth using the developed approximation formula. By analyzing these 100 effective lengths, four approximation formulas are proposed using which one can quickly and accurately calculate effective lengths of the observed grounding system type for any combination of the given parameter within the prescribed limits. In the seventh chapter two numerical examples are provided which depict the usage of the developed approximation formulas for different values of parameters.