Johannesburg - Eskom's latest wage offer of 5.6% is a disappointment, trade union Solidarity said on Tuesday.
"It is worrying that Eskom's offer is still below the current inflation rate," the union's metal, engineering, and electrical industry section head Deon Reyneke said in a statement.
"Bearing in mind that the CPI inflation rate may increase by the end of the year and given that fuel and food prices have risen sharply, Solidarity had no choice but to turn down Eskom's wage offer."
Eskom's wage negotiations stalled on Monday and were referred to the Commission for Conciliation, Mediation, and Arbitration.
Solidarity said the unions wanted to keep negotiating, but Eskom claimed the talks had reached deadlock.
The union wanted a 12% wage hike, but would submit "any fair offer" to its members for consideration.
The National Union of Mineworkers and National Union of Metalworkers of SA (Numsa) also represent Eskom workers.
On Monday, Numsa rejected the 5.6% offer as a "spit in the face".
Eskom spokesperson Hilary Joffe said: "Eskom had raised its offer to 5.6%, which is the percentage which the national energy regulator allowed us in terms of its recent tariff determination."