Hospital porters at Exeter's R D & E are planning a 24-hour strike next week in protest at the introduction of 12-hour shifts.
Their union UNISON says the management argue that the longer shifts will improve efficiency.
But UNISON's regional manager Helen Willis says the existing eight-hour shifts are tiring enough, and the increase is unacceptable.
The R D & E say they have been working with their staff and UNISON to find a solution to the dispute and hope to continue negotiations, with the support of a mediation service if necessary.
They also say if the strike goes ahead it won't affect the acute medical unit or A&E, and contingency plans are in place to ensure that normal services continue.
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