EN 50122-2:2022/prA1:2024

This document specifies requirements for protective provisions against the effects of stray currents, which result from the operation of DC electric traction power supply systems.
As several decades' experience has not shown evident corrosion effects from AC electric traction power supply systems, this document only deals with stray currents flowing from a DC electric traction power supply system.
This document applies to all metallic fixed installations which form part of the traction system, and also to any other metallic components located in any position in the earth, which can carry stray currents resulting from the operation of the railway system.
This document applies to all new DC lines and to all major revisions to existing DC lines. The principles can also be applied to existing electrified transportation systems where it is necessary to consider the effects of stray currents.
This document does not specify working rules for maintenance but provides design requirements to allow maintenance. The range of application includes:
a)  railways,
b)  guided mass transport systems such as:
1)  tramways,
2)  elevated and underground railways,
3)  mountain railways,
4)  magnetically levitated systems, which use a contact line system, and
5)  trolleybus systems,
c)  material transportation systems.
This document does not apply to
a)  electric traction power supply systems in underground mines,
b)  cranes, transportable platforms and similar transportation equipment on rails, temporary structures (e.g. exhibition structures) in so far as these are not supplied directly from the contact line system and are not endangered by the electric traction power supply system,
c)  suspended cable cars,
d)  funicular railways.