Eskom managers do not listen to low-level workers according to the National Union of Mineworkers.
The union says this is contributing to the energy crisis.
It says there is a culture of fear at the utility, where workers are threatened when they try to speak out.
The union addressed Parliamentary Committees visiting Megawatt Park.
Parliamentary committees are on a 2-day visit to Eskom.
On Thursday, they met unions, including Numsa, Num and Solidarity.