N.C. Gen. Stat. § 163-166.45
If a county uses a voting system with retrievable ballots, that county's board of elections may by resolution elect to conduct early voting according to the provisions of this Part. In a county in which the board has opted to do so, a voter during early voting shall cast the ballot and then shall deposit the ballot in the ballot box or voting system in the same manner as if such box or system was in use in a precinct on election day. At the end of each business day, or at any time when there will be no employee or officer of the board of elections on the premises, the ballot box or system shall be secured in accordance with a plan approved by the State Board, which shall include that no additional ballots have been placed in the box or system. Any county board desiring to conduct early voting according to this section shall submit a plan for doing so to the State Board. The State Board shall adopt standards for conducting early voting under this section and shall approve any county plan that adheres to its standards. The county board shall adhere to its State Board-approved plan. The plan shall provide that each ballot cast during early voting shall have a ballot number or an equivalent identifier to allow for retrievability. The ballot number or equivalent identifier shall not be a public record.
N.C. Gen. Stat. § 163-166.45