scope:

This specification applies to earthing and bonding systems installed on Network Rail 25kV a.c. electrified lines.

Bonding required exclusively for signalling purposes is outside the scope of this specification.

Purpose

This specification states the requirements for the design of earthing and bonding systems for 25kV a.c. electrified lines to ensure a continuous return circuit for traction load current and a continuous return path for fault current, and to ensure that accessible and touch voltages in excess of the values quoted in Appendix A do not occur.

The document is to be read in conjunction with the relevant project design remit.