Performance evaluation of series impedance insulation used as earthing system safety mitigation measures

High resistivity surfacing materials such as crushed rock and bitumen, are often used to limit electric shock hazards for utility operators and maintenance staff, as well as the public. Certain safety codes also make allowance for the likelihood that utility operators and the public will be wearing footwear. This paper evaluates the performance of series impedance insulation used as earthing system safety mitigation measures. Data gathered as part of a detailed R&D programme, undertaken by the Safearth Engineered Solution team within Energy Australia, is discussed with respect to the performance of surface layers and footwear, and their effect upon electrical installation safety profiles under earth fault conditions. Guidelines for improved performance specifications are developed based upon test results and application requirements.