The loss of 700MW of power from the unit would not, on its own, result in load-shedding, Mantshantsha said.
Eskom said the accident occurred while technicians were displacing hydrogen with carbon dioxide and air to detect an external leak in the system.
“Following the power station’s preliminary investigation, it appears that while performing this activity, air was introduced into the generator at a point when hydrogen was still present in sufficient quantities to create an explosive mixture, which ignited and resulted in the explosion,” Mantshantsha said.
Six Eskom employees have been suspended pending an investigation into whether they had deviated from the required maintenance procedure.
Trade union Solidarity said some of its members were among the suspended employees. The union agreed with Eskom that the explosion was not due to sabotage, as some reports have speculated.