Strike action will be taking place at hospitals across the region today.
Stewards from Unite have signalled their members' unease over controversial plans to outsource Wrightington, Wigan and Leigh NHS Foundation Trust support roles to an arms-length third party.
Union leaders say 81 per cent voted in favour of striking, amid proposals to transfer hundreds of employees to WWL Solutions, a subsidiary company brought into being earlier this year.
Just under 60 per cent of eligible members of Unite, representing electricians, plumbers, fitters, porters and cleaners, turned out for the ballot.
Workers say they fear that the move by the hospitals trust would leave staff vulnerable to cuts to their pay, and terms and conditions.