The Background to the Book

Many public domain standards and company documents exist to guide the design of the earthing and bonding of AC railway electrification systems but in practice there remains both gaps, overlaps and conflicts between them. Therefore, it is not uncommon for the designs to follow discipline specific scope rather than being holistic in their approach.


The complexity of integrating the earthing of a 25kV electrified railway with various electrical distribution systems and exposed conductive parts, means that it is impossible to prescribe one earthing and bonding design solution that addresses the needs of every railway. Therefore, this creates different earthing designs for individual railways.


 The Scope of 25kV Railway Earthing and Bonding Requirements

This guide aims to assist infrastructure owners, railway designers and installation contractors in adopting a harmonised approach towards E&B design philosophy for 25kV railway infrastructure. The guide implements a common earth system formed by bonding lineside assets and structures to the traction return system, effectively forming a low impedance meshed earth network.


Electrical safety is required to minimise the potential difference between all exposed conductive parts and systems sharing the system earth. The guide will therefore undertake to explain the principles of a ‘common earth’ system (traction and non-traction) which is able to provide a robust and low impedance path to earth.


See the attached guide for more information.