All ESB energy will be taken off the grid if workers follow through with threatened strike action over pensions.
The ESB unions' strike dispute committee warned an all-out stoppage would kick in from 8am on Monday December 16.
They said there will be a full withdrawal of manpower and pickets organised.
All power generated by the ESB will be off the grid when the strike kicks in.
Detail of the threatened walk-out was revealed as talks open at the Labour Relations Commission in a hostile dispute with management over the company's pension fund.
Union leaders claim a 1.6 billion euro black hole in the retirement pot has been put on the shoulders of workers in a revised accounting scheme.
The committee said, however, that workers are giving due regard to public, staff and environmental health and safety if the strike goes ahead.
"Therefore, where applicable and to be decided by the committee, emergency cover for fault and repair services will be provided," the committee said.
The Department of Communications, Energy and Natural Resources said the state-owned electricity operator EirGrid will try to minimise any disruption caused by a potential strike.
"Every effort will be made to keep as many customers supplied as possible, particularly vital services and infrastructure," the department said in a statement.
"In respect of this morning's announcement by the ESB Group of Unions, EirGrid and ESB Networks will now put into effect plans which are aimed at carefully managing the power system to mitigate the impact of supply disruption."
It confirmed ESB will publish details of arrangements in advance of any event and that EirGrid will keep customers informed on a national basis should a strike take place.