## 1 Introduction
The current trend of using materials with non-negligible internal resistance such as carbon steel or others for the electrodes of a grounding system makes it necessary to study their effect on the parameters of the system. After setting a calculation model for the electrodes that takes into account their internal resistance, the here called Resistive Driven-Rod method (RDR), which takes into account the internal resistance of the rod will be applied both to synthetic and real soils. Figure 1: Outline of the RDR method. A direct method to determine the resistivity as a function of the depth is known in literature as normal resistivity logging (NRL) [10]. This is a geophysical method for determining the rock's conductivity by studying the drilling geological profile in a well. However, this technique requires the drilling of a well of a section large enough for the probes to be introduced. Resistivity is measured with a four-pin device taking a short electrode separation so that the well walls can be tested. To complete this brief review of several of the methods used to investigate the electrical structure of soils, mention should be made of the magnetic field-based eddy-current methods (ECM), framed in the transient electromagnetic methods class. By means of a coil near the soil surface, a variable magnetic field is produced. Eddy-currents are generated in the conductive soil, producing magnetic fields that depend on the layer structure. Although they are based on very different principles from those of the methods described so far, ECM are clearly non-invasive methods with high resolution at shallow depth [11]. From the apparent resistivity data obtained with the indirect methods described above, the soil resistivity profile can be obtained by posing an inverse problem. Starting from semi-analytical expressions for the grounding resistance as a function of the parameters of a multilayer model, an optimization algorithm is implemented to find the set of parameters of the model that minimizes the squared differences between the values of the resistance measured in the field and those calculated with the theoretical expressions that contain the parameters. However, the techniques used in the inverse problem with the measurements made with the Wenner array cannot be extended when the measurements come from a driven-rod logging. Apparent resistivity has a different meaning depending on the type of measurement. The main objectives of this paper are, firstly, to establish a systematic procedure to include the internal resistance of conductors in the calculation of the grounding resistance of buried electrodes, and secondly, testing the feasibility of the RDR method to determine the parameters of a multilayer soil model from grounding resistance measurements, pointing out its limitations. To achieve these goals, the paper is structured as follows. After the present introduction, the backgrounds section is intended to introduce the foundations of the proposed method. In the next section, some tests are carried out on synthetic soils in order to test the method relevance. In the same section some real examples are also studied. Finally, the conclusions of the work are collected in the last section.