The ESB Group of Unions has formally served strike notice on the company.
The industrial action, which is due to commence at 8am on Monday December 16th, could result in power cuts.
The row centres on a dispute over a €1.6 billion hole in the ESB pension scheme.
Talks between management and unions, aimed at averting the strike, were held yesterday but no deal was reached.
Arthur Hall is the acting General Secretary of the Technical, Electrical and Engineering Union:
Both sides say dialogue will continue in an effort to reach a resolution before December 16th.
Aruthur Hall says the unions have yet to decide what format the industrial action will take if no deal is arrived at: