N.J. Stat. § 43:16A-20
The provisions of this act shall apply in such municipalities as at the effective date of this act there shall have been established a pension fund for policemen and firemen and in such counties as there shall have been established a pension fund for county police officers, and in any fire district located in a township in which there shall have been established a pension fund for firemen; which pension funds have been established under chapter sixteen of Title 43 of the Revised Statutes or under article four, chapter ten, of Title 43 of the Revised Statutes.
The provisions of this act shall apply to the policemen and firemen of any county, municipality or political subdivision thereof on and after January first following the adoption of this act by the voters of such county, municipality or political subdivision thereof as hereinafter provided.
N.J.S. § 43:16A-20