N.J. Stat. § 40A:14-45
In any municipality where an examination is scheduled to determine appointments to the paid or part-paid fire department and force, any qualified fireman having served in the volunteer fire company or force of the municipality for at least 2 years next preceding such appointment shall be entitled, in addition to his earned rating, to service credits of not less than 3 nor more than 10 points as may be determined by the governing body of the municipality or the authority in charge. Said appointee shall be over 21 but not more than 40 years of age at the time of the appointment.
Nothing herein contained shall establish a preference over a paid fireman temporarily dismissed or on leave of absence for reasons of economy, or the appointment of a paid fireman to a superior position at the time of promotion in said fire department or force.
N.J.S. § 40A:14-45