According to the NSW Department of Primary Industries the electrician and plant operator was given the task of isolating the motor of the surface conveyor belt prior to receiving the electric shock, to allow an electrical contractor internal access to the 3300 volt slip ring conveyor motor for fault diagnostics.
To access the motor, the electrician isolated a switch fuse inside a switch-fuse unit. As part of this isolation an interlocked earth had been applied to the load side of the switch fuse.
After examining the conveyor motor, the motor repair contractor advised the electrician there could be a loose connection on the mains supply to the motor.
The electrician opened the door to the switch-fuse unit and assumed the bottom of the switch was isolated from before. He did not "test for dead" before touching the electrical conductors.
Placing his left hand on the bottom of the unit, the electrician placed his right hand on the switch. The electric current travelled up his right arm, through his chest and out through his left hand.
Earth leakage protection located on the neutral of the supply transformer operated and disconnected the 3300 volt supply by tripping off the transformer primary (11,000 volts) circuit breaker via a shunt trip.
The man was taken to hospital where he received treatment.
DPI has released recommendations as part of an ongoing investigation into the incident, stating that more planning is needed when high-voltage work is to be carried out to avoid future accidents.
This includes a formal risk assessment to examine any possibility of people coming into contact with an energised conductor, and a detailed high-voltage work plan with provisions for verification at each step.
DPI said electricians involved in high-voltage switching and isolation must be trained and retrained periodically, and all planning for high voltage work should be carried out by qualified people.
Finally, when performing high voltage work, DPI recommends every step be clearly communicated to all involved in supervision and work.
