200811 – Blakeley-Smith & Neilson – Earthing and Bonding: Emerging Australasian Practices

Earthing & Bonding is an essential element in an a.c. electrification environment to ensure personnel and property safety. It is a highly interdisciplinary and iterative activity in the design process of a new 25kV a.c. railway system and many of the fundamentals are not widely understood – yet the underlying principles do not require much more than a basic appreciation of Ohms Law. Personnel hazards resulting from induction and earth potential rise (EPR) are, in practice, very rare events however care must be taken when focussing on the strict numeric requirements of standards that we do not lose sight of the big picture, both in terms of immediate and consequential hazards. These can only be avoided by a top down approach to earthing and bonding, and therefore compromises in design are inevitable.

This paper aims to ensure that all key aspects of this cross-disciplinary subject are understood,
reviewing some past historical practices adopted by different rail authorities and sets out parameters for good design and installation practices applicable to both Australia and New Zealand in alignment with contemporary international practice. This paper builds on the paper [1] presented by the authors at the CORE 2008 conference in Perth.