Sibanye-Stillwater miners were trapped underground in Randfontein due to a power supply interruption caused by powerlines that collapsed after being weakened by the vandalism of cable thieves.
According to Eskom, the pylon structures were weakened by the theft of "tower members" and unstable ground caused by digging around their foundations.
Eskom spokesperson Amanda Qithi said the incident happened on Monday, and that they had dispatched a team of technicians to restore supply to the mine.
Qithi said a number of "132kV lines fell during the storm", compromising their "integrity".
"The pylon structures were weakened by the theft of the tower members and the unstable ground caused by digging around the foundation," she said.
She added:
Production in the gold-extracting mine came to a grinding halt while Eskom worked to restore supply at significantly high costs.
Qithi added that the theft of tower members resulted in the instability and collapse of the pylons that carry high-voltage power lines, which posed a severe safety risk to members of the public.
It had an additional devastating impact on the economy and on Eskom's ability to sustain the provision of electricity, she said.
Qithi said Eskom was spending a fortune on the replacement of stolen pylon parts and other network equipment.
She added that power had been restored to most of the shafts and that Eskom technicians were still working around the clock to restore power to a shaft in Kagiso.
Mashangu Xivambu, Eskom's maintenance and operations senior manager in Gauteng, said vandalism and theft had extended to include pylons whose tower members were often stolen by "unscrupulous criminal elements", resulting in the steel structures collapsing.
"It is disturbing that this incident happens a week after we raised a concern about incidents of theft and vandalism of pylons," he added.
Xivambu also appealed to the members of the public to "partner" with Eskom by reporting illegal connections, theft, and vandalism of electricity infrastructure to the utility's crime line number, 0800 112 722.
Technicians were on Wednesday still at the mine to restore power in the remaining shaft.