scope:

The earth potential rise (EPR) that can occur in power systems and that can be transferred to telecommunication systems is potentially dangerous to the people working in the telecommunication plant; damage to the plant itself can also occur. The impedance to earth of earthing systems of a power installation is one of the key parameters affecting the magnitude of the EPR. This Recommendation aims to provide methods of different complexities for measuring the resistance to earth of earth electrodes or complex earthing systems. Techniques for calculating the resistance/impedance to earth of isolated, as well as interconnected earthing systems are also included.