Oberholzer said there had been no cameras in the facility, adding that “you don’t expect your own people to be up to mischief”.
“To have cameras all over the show, it was never believe to be necessary.”
He said there had been other incidents of sabotage but he did not want to disclose the details.
“But it wasn’t when we previously load-shedding. That is what I would like to say.”
He said Eskom had taken action and installed two cameras at two power stations. They would also be “more visible”.
On Wednesday, President Cyril Ramaphosa and ministers Pravin Gordhan and Gwede Mantashe met Eskom bosses about the power crisis plaguing the country.
It was promised at a briefing after the meeting that there would be no load-shedding between mid-December and mid-January.