The Technical Engineering and Electrical Union (TEEU) has served strike notice on the ESB and two sub-contractors at Moneypoint, Co Clare.
The notice comes over a dispute surrounding the nonpayment of wages to 200 Polish workers working on the construction of a new power plant.
Union officials met ESB management today but the talks failed to find any resolution to the row and strike notice was served.
However, the Labour Relations Commission has since intervened and has invited both sides to talks at 11am tomorrow.
TEEU general secretary designate Eamon Devoy, who met ESB management today, said the contractor and sub-contractor involved in the dispute had failed to show up for today's meeting.
He added that the ESB was "taking no responsibility" for the actions of the contractor and sub-contractor. "There was no satisfactory outcome [to the talks], and as a result of that we expect to proceed with placing pickets from tomorrow."
Mr Devoy said the union will first consult with all members who are permanently employed at Moneypoint tomorrow morning.
The dispute threatens to disrupt the national power supply if the meeting fails to result in assurances sought by the TEEU that the workers will be paid.
The workers, some of whom have not been paid since the beginning of September, have been told their employer, a Polish sub-contractor, has lost the business. They were instructed to clear out their lockers at Moneypoint today, the union said.
Workers voted last night to hold a public protest at the plant today if the ESB fails to give assurances over pay and job security. This did not go ahead.
An ESB spokesman said yesterday that the company had made considerable efforts to secure the rights of the workers by "leaning" on the contractor. He also said ESB pays its turnkey contractors sufficiently to ensure they could pay their sub-contractors properly.
Moneypoint is the largest supplier of electricity to the national grid, at times contributing up 40 per cent of national demand.