The vote was overwhelmingly passed today, which means retained firefighters in the Dublin area are poised to go on strike if the plans to decrease crew numbers go ahead.
Siptu represents about 1,700 part-time, retained firefighters who work for local authorities across the country. Their vote was passed with 95% in favor of industrial action.
Full-time firefighters are also in opposition to the changes, and balloted on strike action yesterday. The results of this ballot will be known next month.
Siptu has previously expressed concern that reducing crew levels will put both firefighters and the public at risk.