Whether it is maintenance or fault rectification, it must be ensured that the electrical overhead contact line with its 15,000 volts does not pose a threat to workers or deployed personnel working in the track area.
Therefore, the specification of Deutsche Bahn (the German railway company; or DB for short) is that overhead contact lines must be isolated from the power supply according to the five safety rules. Merely switching off the current in the control room will not suffice.
Only additional earthing measures will guarantee that overhead contact lines are in a dead condition.
Protecting people working in the track area – that is the central task of mobile traction system earthing.