ESB staff in strike threat over wages.
Now Electricity Service Board employees are threatening to go on strike over a 16.5 per cent pay claim.
They are expected to be the first to challenge the government's pay policy this winter.
The threat to strike comes as ESB management seeks 2,000 redundancies and radical changes to working practices without any pay rise.
The company said it has little room to manoeuvre because of rising fuel costs and a price freeze on electricity by the government.
However, the white-collar union, the ESB Officials' Association, gave the company until last Wednesday to make a "serious offer'' on a pay increase.
General Secretary Willie Cremins said the union had now served ESB with a 30-day notice on its plan for industrial action.
Union members have voted by 84 per cent for strike action, he added.
"It is my belief that management is seriously underestimating their strength of resolve,'' added Mr Cremins.
It is claimed there was deep anger among ESBOA members after senior ESB staff received huge pay rises.
The strike threat by the ESBOA also has the support of the largest ESB union, the Amalgamated Transport and General Workers' Union.
ATGWU secretary Denis Rohan said his members were contemplating an even higher pay claim than the ESBOA.