Two recent electrical incidents at separate underground mines have flipped the switch on potential risks and consequences of cutting live power and conducting hot work in unsafe conditions.
The first incident occurred at an underground coal mine, when a mining supervisor cut through a live high-voltage cable while a crew was rehabilitating a drift.
The supervisor used a battery-powered reciprocating saw to cut the cable, which carried an 11kV feed supplying surface compressors. The line ran from a trench, across the portal and into another trench on the opposite side of the drift.
Severing the cable triggered a high-voltage earth leakage fault that tripped multiple protection relays across the mine. While no workers were injured and there were no visible signs of arcing, the incident highlighted the risks posed by unidentified or unverified electrical infrastructure during rehabilitation work.
According to the NSW Resources Regulator, high-voltage cables identified for removal must be isolated and confirmed to be de-energised before removal. Supervisors should also ensure that an electrician has confirmed de-energising before cutting any cables.
In a separate “dangerous incident” at an underground metals mine, a worker received an electric shock while carrying out electric arc gouging in a workshop.
At the time, water was spraying in the workshop, and the ground around the work area was wet.
The circumstances, the resources regulator said, suggested the combination of electrical equipment and water created an unsafe environment, leading to the electric shock and highlighting deficiencies in hazard awareness, work area inspection, and adherence to safe welding and gouging practices.
Following the incident, the regulator is urging operators to inspect the work area and ensure that it is suitable for the task before undertaking welding activities.
Mine operators are also being advised to ensure portable electrical equipment has appropriate electrical protection and that leads are regularly tested and tagged.
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