Unite and GMB workers, are due to walk out on this morning.
Urgent and emergency services are not being targeted, unions said. Healthcare workers from across Belfast are to protest at Stormont at 1 pm.
Unions want a 1% pay rise to be implemented for all staff, but the NHS has said this will cost too much.
Among those taking strike action in Northern Ireland are office workers, laboratory and pharmacy staff, community nurses and catering staff.