N.J. Stat. Ann. § 2B:23-3

The court may direct the impaneling of a jury with additional members having the same qualifications and impaneled and sworn in the same manner as a jury of 12 or 6. All the jurors shall hear the case, but the court for good cause may excuse any of them from service provided the number of jurors is not reduced to less than 12 or 6 in an appropriate civil case. If more than the prescribed number are left on the jury at the conclusion of the court's charge, the clerk of the court in its presence shall, by drawing names, randomly select that number of jurors' names as will reduce the jury to the required number.