Union representatives at ESB are warning the Government against any sale or break-up of the company.
An expert group has been appointed to examine the value of all semi-state companies - such as the ESB, Bord Gais and the Dublin Airport Authority.
But Brendan Ogle of Unite trade union said it is not acceptable
He is warning the Government they'll "turn the lights out" rather than let it happen.
Meanwhile the Communications Workers Union will hold a meeting later to discuss concerns about job losses at Eircom.
According to weekend reports, up to 2,000 jobs are at risk at the telecoms firm.
The Minister for Enteprise and Trade Batt O' Keefe has already said he is aware of the restructuring plans at the company, but not of the job losses.