Hundreds of St John paramedics and ambulance staff are set to walk off the job following more failed pay talks with between their union and management.
First Union members will go on strike for 24 hours from 6am on Wednesday and are set to do the same again on Saturday.
First Union national ambulance organiser Sarah Stone said the union was "unfortunately ... in protracted bargaining with St John".
"What we are faced with is they only applied for funding that would result in workers getting a wage cut in this round and where they are receiving full funding, they are cutting pay to those roles anyway," Stone said.
But St John deputy chief executive of ambulance operations, Dan Ohs, said: "The key discussion point is over the payment of penal rates. And whether or not it's a .25 or 25 percent penal rate, which is what First Union, or whether it's a .15 or 15 percent penal rate, which is what St John offered. Which is in line with the findings of the independent pay review."
A penal rate is paid in recognition of ambulance officers working nights and weekends, and the impact that has on their health and wellbeing.
Ohs said the amount of funding allocated to St John would allow a .25 penal rate but only if the base pay rate of ambulance personnel.
"It's kind of one or the other. We're not able to raise the base amount of ambulance personnel and also pay a premium penal rate which is in excess of what was recommended to us by the independent review."
Ohs said St John was surprised that one of the three unions was striking.
The issue of the 1.15 or 1.25 penal rate would be heard by the Employment Court next year, Ohs said.
"If the Employment Court finds that the rate of 1.25 must be paid then St John will of course honour it."
Stone said all unions were under the same collective agreement but claimed St John had worked to undermine First Union.
She claimed First Union had provided a "cost-neutral" alternative for the pay negotiations, but that it had been turned down by St John last night.
Stone said the union wanted a commissioner to come in and run the St John "so that it's safe for the workers there and safe for New Zealand".
The plan for the strike
Ohs said St John had a comprehensive plan to ensures the public would be safe during the strike.
"We have managed to fill the majority of the rosters which is really good. The striking union represents about 37 percent of our paid personnel and none of our volunteers.
"We have people in other roles that aren't predominantly front line that hold ambulance qualifications."