Electric Security Fences for Power Substations: Electrical Safety of Induced Potentials

Attempted copper theft from power stations causes many fatalities and is an increasing concern. There is a trend towards using electric security fencing to protect power stations. However, capacitive and inductive coupling into fence wires from the power lines above has not been studied previously. Therefore, we calculated the capacitively and inductively coupled voltages and currents for different power line heights, angles, voltages, and currents. We restricted the analysis to 3-phase power grids. Varying levels of current imbalance between the 3 phases were included. We concluded that under typical fence placements (i.e. angled with respected to power lines) the induced voltages were less than 15 V, the human perception threshold at AC frequencies. This level is much lower than the AC magnitudes expected to raise cardiac safety concerns. As a result, the use of electric security fences around power substations is safe. We recommend that fence lines should be temporarily connected to ground during installation. The grounding should be removed only after the connection to the low-impedance output of the electric fence energizer.Clinical Relevance- This study addresses the electrical safety of fence wires placed around power distribution lines.