The Professional Firefighters Union has admitted the industrial action its members are taking may harm the public.
Union members have been carrying out partial strike action since Friday after failing to reach a pay agreement.
They will attend only emergency callouts and won't record data, offer training or maintain equipment.
National president Steve Warner says that includes not installing fire alarms in people's homes and not helping young arsonists identified as a risk.
Mr Waner says the action is not about harming the public, but he accepts it could leave some people without protection.