The ESB workers' union has authorised the serving of notice for strike action.
The Energy Services Union said it is calling on the company management to "accept its obligations to staff and their pension fund with regard to any deficit, thus averting an all-out power strike in ESB."
The notice period will expire on Monday, December 16, at 8am in the morning.
It is expected that power outages could occur in the weeks running up to Christmas. It would be the first such strike in 21 years.
Unions and management have been invited to talks later this week in the row over the pension deficit at the company. However, the Union claims the company has yet to accept the invitation.
Retail Excellence Ireland issued a warning earlier today that its members will withdraw, en-masse, all business from the ESB in the New Year if a strike is held.
"Our members want to deal with companies that live in the real world," David Fitzsimmons of REI said.
"ESB seem to operating in a vacuum - in a different economy, an economy of opulence, and our members are saying if a strike proceeds, they'll withdraw all support for that company."
Chief Executive of ISME, Mark Fielding, also said it would be ironic that the lights could be out at the very time Ireland is at the centre of world attention, just one day after the Troika leave town on December 15.