Trade unions at the state-owned ESB have started balloting members for industrial action as a row over the status of a group pension scheme rumbles on unresolved.
Shop stewards at the semi-state voted unanimously last month in favour of a motion to ballot for industrial action, up to and including strike action.
The dispute centres on a union claim that the ESB switched a staff pension from a defined benefit scheme to a defined contribution scheme. The ESB says it has not changed the nature of the scheme.
Balloting of members of the Unite union began yesterday and will continue until November 18.
Four workers at the ESB have also taken a case to the High Court in relation to the pension scheme.
The ESB said it will fully defend the action.
"On the basis of advice obtained to date, ESB believes that the plaintiffs' claims will not succeed and intends to fully defend the proceedings," the ESB said.