Staff at the ESB have voted overwhelmingly to take industrial action, up to and including strike action, if any structural or organisational change is imposed without prior agreement with the unions.
The result of the vote was announced at a meeting of the ESB group of unions.
It is not yet known how many staff members took part in the postal ballot, but it is thought that five out of every six respondents supported possible industrial action.
The unions say they have notified ESB management of the result of the ballot.
