Earth fault in a power system causes earth currents which raise the earth potential where the fault current leaves and enters the earth. The magnitude and extension of the EPR depends on the fault current level, the earthing resistance, the soil resistivity and the layout of the earthing arrangement. The duration of an earth fault depends on the type of power network.

This Recommendation gives information about:

a) locations where EPR may occur;

b) duration of EPR in different types of power networks;

c) "safe distance" between telecommunication cables and power installations;

d) measures to be taken if the safe distance is not achieved.