The high potential incident occurred recently after a shuttle car ran over its own power supply cable, damaging it and causing a short circuit between two live phase conductors and the earth conductor.

Not only did the fault cause a power surge in the local distribution system, it also led to two miners seeing visible sparks from the continuous miner, working nearby, and the mine's rib mesh.

Fortunately no injuries or shocks were reported after earth leakage protection tripped at the distribution control board.

The incident has sparked a warning from the Queensland Mines Inspectorate which said the use of a neutral earthing reactor - as opposed to a resistor - can contribute to high inrush currents in some system configurations and should be checked against the Australian Standards outlined for electrical equipment.

The inspectorate urged all mining companies to test their electrical systems in relation to the guidelines and consider possible hazards from low power factor neutral connected current limitation when planning a mine's safety and health management plan.