Around one quarter of homes will be affected by power cuts if an ESB strike goes ahead on Monday week.
Unions and management at the ESB are currently attending talks with the Labour Relations Commission over a hole in the workers' pension fund.
The Energy Minister Pat Rabbitte says the pension scheme will be fully funded by 2018 - and he says a strike by staff would be 'out of proportion' with the scale of their dispute.
Juliette Gash reports;