This part of IEC 62128 specifies requirements for protective provisions against the effects of stray currents, which result from the operation of d.c. traction systems. As experience for several decades has not shown evident corrosion effects from a.c. traction systems and actual investigations are not completed, this standard only deals with stray currents flowing from a d.c. traction system. This standard 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 standard applies to all new d.c. lines and to all major revisions to existing d.c. lines. The principles may also be applied to existing electrified transportation systems where it is necessary to consider the effects of stray currents. It 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) trolleybus systems, and 5) magnetically levitated systems, which use a contact line system, c) material transportation systems. This standard does not apply to: d) mine traction systems in underground mines, e) 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 traction power supply system, f) suspended cable cars, g) funicular railways. This standard does not specify working rules for maintenance.