Distribution Earthing: Standards, Methods and Procedures - A Case Study

Distribution earthing design covers a very broad area of considerations, which in other plant and system earthing designs are usually covered by multidisciplinary teams. Distribution Earthing often encompasses overhead lines, underground cables, UGOH transitions, transformers, substations and entire multiply earthed neutral systems. Any individual earthing study may contain many or all of these elements.Further compounding the difficulty of distribution earthing design is that broad consensus in Australia does not exist with regards to the application, interpretation and enforcement of standards, particularly by different utilities. Often the standards themselves are combined with a utilities own specifications and guidelines, resulting in widely varying approaches to distribution earthing throughout Australia.The purpose of this case study is to provide a systematic review of distribution earthing practices, the applicable standards as well as how the standards ought to be applied to the distribution earthing problem. The engineering question investigated is-“For a distribution earthing design, what engineering designs and practices lead to a negligible risk distribution earthing design”. It is intended that this case study will inform engineers and designers about engineering design and practices which results in negligible risk distribution earthing designs.