Introduction: Previous research efforts have concentrated on the better characterisation of major aspects of practical earthing systems. Both experimental and computer simulation investigations have helped to clarify some performance aspects including determination of safety voltages. However, it is now recognised that little work has been performed to improve the understanding of the conduction mechanisms that control the performance of large/extensive earthing systems. This deficiency in accuracy of knowledge of earthing systems is particularly significant for the control of safety voltages around electrical installations.

Presently, several computation tools exist but their comparison with practical systems is not always possible because the computer models assume uniform layer structures of the soil surrounding the earth electrodes. Therefore, it is proposed to conduct an experimental programme using a large scale test electrode system, and investigate the effects of electrode shape, magnitude and shape of applied voltage/current, and assess the accuracy of existing simulation tools.

Objectives: The proposed programme aims to:

• Understand better the conduction mechanisms following current injection at earth electrodes

• Develop and test new mitigation techniques suitable for the control of safety voltages

• Develop a model for the characterisation of earth electrodes subjected to different magnitudes and shapes of fault current

• Check validity and accuracy of existing earthing designs which were based on most popular computational tools through a comparison of experimental results with predictions.