In the incident, an excavator on site hit an under-slung earth wire on a three-phase aerial supply.
The excavator then applied tension to the earth wire, which caused the phase conductors to clash, arc and trip, before the earth wire snapped.
The regulator said the potential for interaction between mobile plant and fixed structures such as overhead power lines, must always be assessed.
Controls should also be in place, in accordance with Work Health and Safety Regulation 2017 hierarchy of control measures.
Under these measures, mine operators must minimise risks, so far as is reasonably practicable, by either substituting or isolating the hazard, or by implementing engineering controls.
