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 16, could result in power cuts, but the unions have said that it won't.
The row centres on a dispute over a €1.6bn hole in the ESB pension scheme.
Talks between management and unions, aimed at averting the strike, were held yesterday but no deal was reached.
Both sides say dialogue will continue while the unions say the format of the industrial action has yet to decided.