N.C. Gen. Stat. § 81A-77
It shall be unlawful for any person to sell, or offer for sale, or put into use, a secondhand or rebuilt or reconditioned scale or weighing device unless said scale shall have been tested and approved by the Commissioner or his authorized agent, or shall be accompanied by a service certificate as provided for in this Article. Said service certificate shall be retained by the purchaser or user of said scale until an inspector of weights and measures has tested and approved such secondhand scale. The said certificate shall serve as proof of the accuracy of scale at the time scale was purchased or put into service. A secondhand or rebuilt or reconditioned scale or weighing device as referred to in this section shall be considered as being a scale or weighing device in the channels of trade which does not belong to the previous user.
N.C. Gen. Stat. § 81A-77