N.J. Stat. § 30:8-33
In each county having a workhouse every person sentenced to imprisonment at hard labor for not more than six months shall be delivered by the sheriff or other proper officer of the county in which the conviction was had to the master of the workhouse, together with a copy of the sentence of the court, certified under the hand and seal of the clerk of the court or if there be no clerk, then under the hand and seal of the magistrate or judge imposing the sentence, and shall be there received and safely kept to hard labor, agreeably to such sentence, by the master of the workhouse for the term of his sentence and for such further time as the costs of prosecution and fine, if any, shall remain unpaid, unless the prisoner be sooner discharged in due course of law.
This section shall not apply to an offender whose sentence shall be imprisonment or the payment of a fine, or imprisonment and the payment of a fine, without the addition of hard labor in either case.
N.J.S. § 30:8-33