NZ Professional Firefighters Union president Steve Warner told NZPA the partial strike action started at 8am today after the union gave two weeks' notice last month.
"We are still answering all emergency calls, nothing's changed there.
"It's early days yet, but we have done this before, unfortunately, every time we go for a pay rise we have a real fight with our employers, even for a reasonable pay rise.
"It does hurt the employer but it takes a wee while to kick in and for them to notice the effects."
Mr Warner said the Fire Service had retaliated in a "nasty and petty" way by cancelling and refusing to extend sick leave. Anyone on injury leave was not allowed to carry on rehabilitation work -- affecting about 30 staff around the country.
"It's not a lot compared to the 1800 members, but for them it's pretty drastic."
Fire Service chief executive Mike Hall told NZPA firefighters were still responding to emergency calls.
"We accept the fact they won't be providing the information they normally do. We have taken some measures to take the firefighters out of the loop and we will be collecting some of the information, but by and large they won't be providing the normal levels of information."
The strike action would not have an immediate effect, but there would be a "very slow and gradual decline" of services, he said.
The Fire Service believes the risk to the public will rise the longer the industrial action goes on.
Firefighters are also refusing to train -- resulting in a degradation of their skills and of the volunteers that they also train, the service says.
They are also refusing to carry out equipment maintenance, install smoke alarms and work with young fire-lighters to change their behaviour. Firefighters install around 1200 homes per month.
"We know that smoke alarms save lives so there is a very real concern that stopping this work will increase the risk to the New Zealand public," Mr Hall said.
He said the union had no give at all in negotiations so far and he was not optimistic there would be any flexibility in the near future.
The union had made a "ridiculous" pay claim and there would be no dialogue unless it came back with something more reasonable, he said.
The Fire Service has to operate within the limits set by the Government, he said. "It's not something the Fire Service has the ability to budge on, given current government policy.
"We won't be moving at all unless the Government takes a broader view of pay rates within the public sector."
Fire Service figures showed firefighters' wages were keeping pace with inflation, and were, in fact, doing better than the private sector and the service's offer was better than that for primary and secondary school teachers, Corrections Department staff, nurses and police.
Last year's tax cuts, coupled with a offered pay rise, would mean firefighters pay would have increased by in excess of 6 per cent - above the projected CPI of 5.3 per cent.
Mr Hall rejected the accusation it was being petty and nasty by refusing sick leave and rehabilitation. If firefighters were only responding to emergencies, there was no point in having anyone on light duties.
"We are simply working to rule like the firefighters are."
- NZPA
