This Recommendation specifically addresses the magnitude of transferred earth potential rise (EPR) to telecommunication systems due to faults in AC power systems, and how to mitigate these effects. The intent of this Recommendation is to provide a good source of information for engineers who need guidance on how to assess the magnitude of transferred EPR to telecommunication systems due to faults in AC power systems, and how they can mitigate such effects. The main objective of this Recommendation is to identify situations where the transfer of EPR to telecommunication systems may cause problems.