Development of risk profiles associated with electrical power substation earthing systems

Electric shock safety criteria and earthing system design methods should provide a level of safety that appropriately reflects the probability of a hazard occurring. This paper provides a risk management framework for the process of hazard identification. It also develops a methodology for modelling the probability of death from a wide range of hazards associated with the electrical power network. The case studies examine the level of shock hazard associated with people moving in or around a substation, and determines the sensitivity of the risk to a range of parameters which might be expected to have significant impact upon that particular shock scenario. The methodology is illustrated using actual case studies, coordinated with a combination of analytical computer modelling (as distinct from simplified empirical techniques) and field current injection test results.