A union leader says a strike could leave the country without enough firefighters for an hour.
Firefighters are set to strike in two-weeks time, after the Union rejected the latest pay offer from Fire and Emergency.
The one-hour strike will take place between 11am and 12pm on the morning of 19 August, and again on August 26.
"That is a possibility that for an hour FENZ will have a very limited ability to respond to fires" - Professional Firefighters Union secretary Wattie Watson
Professional Firefighters Union secretary Wattie Watson told Morning Report they might not have enough volunteer firefighters to cover the strike period.
"We are hoping in mediation next week that we will be able to resolve the situation but that is a possibility that for an hour FENZ will have a very limited ability to respond to fires," Watson said.
The strike would be the first of its kind as while firefighters took similar action 25-30 years ago this would be the first nationwide strike, she said.
"This is a really serious situation and it's taken a lot for the members a lot to get to this point," she said.
FENZ had issued a statement saying there would be contingency plans available to cover the lack of firefighters on call during the strike, Watson said.
However, Watson said she was not sure what FENZ had planned as the strike applied to all members of the Professional Firefighters Union.
While pay was the not the only issue, FENZ's current offer was not good enough, Watson said.
"The pay offer is too low... FENZ has removed any offer to pay a base wage increase for 2021 and instead is offering to pay from 1 July 2022.
"It's essentially a three-year deal and for a lot of our members for that three years that will be between eight and 12 percent."
Firefighters and all of the union's members had last received a pay rise on 1 July 2020, she said.
The firefighters also wanted safer systems at work, she said.
While she understood members of the public would be concerned by the risk posed by the strike, Watson said FENZ had failed to keep firefighters safe for too long.
"Absolutely they'll be worried but they should also be worried about the level of protection they are getting now, we've had repeated and it's almost daily in some areas where trucks are off the run and stations are closed because FENZ has not employed enough firefighters."
The stress the country would feel for an hour during the strike was being felt by firefighters everyday, she said.