N.J. Stat. § 19:18-4
Every municipal clerk to whom the ballot boxes shall be delivered shall thereupon keep the same, with their contents, but shall not have the keys thereof in his possession until required for the next ensuing election, and shall not open or permit to be taken or opened any ballot box for the space of three months after the same has been so deposited, except when he shall be called upon by some court or other tribunal authorized to try the merits of such election or to take testimony regarding the same; and after such trial or investigation the clerk shall have such box or boxes returned to be held for any purpose within the time that same are required to remain in his custody.
After the space of three months the municipal clerk may remove the contents thereof and preserve the same for two years, and permit the ballot boxes to be used at any election, unless an order shall have been made directing a recount of the ballots contained therein, or a petition filed contesting any nomination or election necessitating the use of the ballots contained in such boxes, within the time limited by law.
When any election is required to be held for any purpose within such three months, the judge of the Superior Court assigned to the county, upon application of the governing body of any municipality, may direct that the contents of such ballot boxes be removed and preserved for two years and that these ballot boxes be used at such election.
N.J.S. § 19:18-4