The presence of ac power supply systems or of a.c. electric traction systems (in this standard also indicated as a.c. power systems) may cause voltages to build up in pipeline systems,(in this standard indicated as interfered systems) running in the close vicinity, due to one or more of the following mechanisms:¿ inductive coupling,¿ conductive coupling,¿ capacitive coupling.Such voltages may cause danger to persons, damage to pipelines or connected equipment or disturbance to the electrical/ electronic equipment connected to the pipeline.This European Standard deals with the situations where these effects may arise and with the maximum tolerable limits of the interference effects, taking into account the behaviour of the ac power systems both in normal operating condition and/or during faults.NOTE In the worst case, the pipe may not disperse current to ground. As a consequence, the prospective touch voltage coincides with the interference voltage.This European Standard applies to all metallic pipelines irrespective of the conveyed fluid, e.g. liquid or gas, liable to be interfered by high voltage a.c. railway and high voltage a.c. power supply systems.The objective of this standard is to establish:¿ the procedure for evaluating the e.m. interference;¿ the interference distance to be considered;¿ the types of coupling to be considered for operating and fault conditions of the high voltage a.c. electric traction systems and high voltage a.c. power supply systems;¿ the configurations to be considered for both metallic pipeline and high voltage a.c. electric traction systems or high voltage a.c. power systems;¿ the limits of the voltages due to the electromagnetic interference;¿ information on interference situations, calculation methods, measuring methods, mitigation measures, management of interference.This European Standard is applicable to all new metallic pipelines and all new high voltage a.c. electric traction systems and high voltage a.c. power supply systems and all major modifications that may change significantly the interference effect.This European Standard only relates to phenomena at the fundamental power frequency (e.g. 50 Hz or 16,7 Hz).This European Standard does not apply to:¿ all aspects of corrosion,¿ the coupling from a.c. railway and power supply systems with nominal voltages less than or equal to 1 kV,¿ interference effects on the equipment not electrically connected to the pipeline.