BS EN 50122-3:2022+A1:2025

This document specifies requirements for the protective provisions relating to electrical safety in fixed installations, when it is reasonably likely that hazardous voltages or currents will arise for people or equipment, as a result of the mutual interaction of AC and DC electric power supply traction systems.

It also applies to all aspects of fixed installations that are necessary to ensure electrical safety during maintenance work within electric power supply traction systems.

The mutual interaction can be of any of the following kinds:

• parallel running of AC and DC electric traction power supply systems;

• crossing of AC and DC electric traction power supply systems;

• shared use of tracks, buildings or other structures;

• system separation sections between AC and DC electric traction power supply systems.

The scope is limited to galvanic, inductive and capacitive coupling of the fundamental frequency voltages and currents and their superposition.

This document applies to all new lines, extensions and to all major revisions to existing lines for the following electric traction power supply systems:

1. railways;

2. 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,

   5. trolleybus systems, and

   6. electric traction power supply systems for road vehicles, which use an overhead contact line system;

3. material transportation systems.

The document does not apply to:

1. electric traction power supply systems in underground mines;

2. cranes, transportable platforms and similar transportation equipment on rails, temporary structures (e.g. exhibition structures) in so far as these are not supplied directly or via transformers from the contact line system and are not endangered by the electric traction power supply system for railways;

3. suspended cable cars;

4. funicular railways;

5. procedures or rules for maintenance.

The rules given in this document can also be applied to mutual interaction with non-electrified tracks, if hazardous voltages or currents can arise from AC or DC electric traction power supply systems.