Johannesburg - Construction on Medupi power station resumed on Thursday, with 12,000 workers back on site, Eskom said.
"We have adopted a phased approach to the return to work," spokesperson Hilary Joffe said.
Five thousand more workers would return to the site in due course.
Construction at Medupi stopped on January 16 after a dispute about the payment of year-end bonuses.
Forty-six workers were arrested on February 15, following violent protests.
Joffe said Eskom had been concerned about violence and intimidation at the site after protesters damaged an Eskom vehicle and a police vehicle last month, but on Thursday the situation was quiet.