6,000 members of the Psychiatric Nurses Association will refuse to work overtime today and tomorrow, in their dispute over pay and staffing.
The union says its members have been left with no option but to engage in industrial action.
It comes as the first in a series of 24 hour strikes by members of the Irish Nurses and Midwives Organisation ended this morning, but a further five stoppages will begin next Tuesday.
There’s no sign of any breakthrough in the dispute between their unions and the Government.
General Secretary of the PNA, Peter Hughes, says today’s action is an overtime ban and not an all out strike.