Almost 3000 intellectual disability care workers are striking after mediation with their employer, IDEA Services, failed.
E tū union members who work for IDEA, a branch of IHC New Zealand, are seeking better pay, and are unhappy about contractual terms to do with their safety at work.
A union delegate, Nicholas Corrigan, said striking staff felt overworked and undervalued.
Additionally, he said IDEA were trying to erase all mention of "challenging behaviour by service users" from their collective agreement.
He said that involves removing a clause that acknowledges staff are vulnerable to assault and threats of assault from those they care for.
E tū industry coordinator Alastair Duncan told Morning Report that violence in the workplace is part of the day to day.
Mr Duncan quoted one of his delegates who said "we'll put up with it, we'll deal with it, but we need to know our employer has our back".
Mr Duncan said the employer turned up with up a series of clawbacks, taking things off workers that had been agreed on.
"It's a lack of respect for the workforce," he said.
"Initially they wanted to reduce sick leave, and in fact people who work with people with intellectual disabilities have high rates of infection and cross infection."
Mr Duncan said IDEA wanted to make other changes but the one that "really rocked" them was the one trying to erase all mention of "challenging behaviour by service users" from their collective agreement.
IDEA Services said it remained committed to trying to achieve a collective agreement.
Chief Operating Officer Joan Cowan said: "We have listened to our staff ... We have been carefully considering all demands, either financial or otherwise, and are continually balancing staff remuneration with other quality improvement priorities."
Mr Duncan said they've been bargaining now for five months and that most of the workers were paid under the equal pay settlement that Equal-pay advocate Kristine Bartlett led the charge for.
However, he said with the cost of living going up they now wanted to talk about the restoration of weekend rates and some recognition for people doing a senior role.
"Initially our claim would have been for $22 million ... in five months of bargaining we've reduced that down to $6 million and the employer hasn't moved beyond $100,000," he said.
The four-hour strike began at 7am. It involved pickets and protests throughout New Zealand.
IDEA said it had put "careful plans in place to ensure the safety of people with intellectual disabilities during strike action".
Although there would be some disruption in some services it had put coverage in place to ensure people's safety, Idea said.