More than 4000 Eskom employees will take to the streets of Johannesburg on Wednesday in a bid to stop the parastatal from using labour brokers.
The National Union of Mineworkers (NUM), which is organising the march to the electricity giant's offices in Braamfontein, say the use of brokers encourages the exploitation of workers.
The union's latest move follows the handing over of a memorandum by branch members to Eskom management at head office in Megawatt Park, north of Johannesburg, last week.
The memorandum, among other things, demanded that Eskom stop outsourcing its "corporate commercial services" such as its college, postal services, canteen and other such services.
"We want to stop a situation where over 60 percent of personnel are temporary," said NUM spokesman Lesiba Seshoka.
In addition, the unions insist that no jobs are lost when the parastatal disposes of what is known as the Eskom Finance Company soon.
NUM say those working for the company were, in effect, seconded by Eskom and should therefore be allowed to return and not lose any benefits.
The workers are also demanding that Eskom stop its new, monthly bus card system until such time they have been consulted.
When asked about the possibility of NUM's latest action turning into a protracted dispute, Seshoka said they would be affording management the "opportunity" to respond once they hand over a new memorandum.
"We will intensify our efforts towards bigger industrial action if there is a failure by management to respond," said Seshoka.
Eskom's Fani Zulu said the company was aware of the planned march and promised it would "deal with the issues raised".
If NUM emerge victorious they will become the second major union to successfully rally against the use of labour brokers by a parastatal.
Last month the South African Transport and Allied Workers Union (Satawu) won a similar battle against national airline carrier South African Airways.