Wendy's staff may turn to industrial action if negotiations over lieu days break down.
The move follows Lyttelton port workers striking over wages and rosters, and nurses saying strike action is likely after they rejected a pay offer from district health boards.
The fast food workers' move comes after a three-year battle over lieu days, prompted by Hornby Wendy's staff member Rose Williams.
She went to the Ministry of Business, Innovation and Employment with the lieu day issue after she had been working at the Hornby restaurant for a year.
Williams said Wendy's staff were not being given a lieu day after working on a public holiday.