S.C. Code § 7-13-840
There shall be provided for each voting place a sufficient number of boxes to meet the anticipated requirements. In general and special elections they shall be provided by the board of voter registration and elections; in primaries by the county committee. There shall always be provided at least one box for each kind of ballot used. An opening shall be made in the lid of each box not larger than sufficient for a single ballot to be inserted therein at one time, through which the ballot shall be inserted by the person voting and by no other. Each box shall be provided with a sufficient lock and shall be publicly opened and inspected, to show that it is empty and secure, and locked just before the opening of the poll. The keys shall be returned to the managers and the box shall not be opened during the election. Each box shall be labeled in plain and distinct roman letters with the office or officers voted for and shall be painted in a color corresponding to the proper ballot to be placed therein, or have sample ballots conspicuously affixed to the box in which like ballots are to be deposited, and the managers, on the demand of the voter, shall be required to read to him the names of the boxes. The ballot boxes shall be so located as to be in view of the persons outside of the rail at the polling place during the time of the voting.
S.C. Code § 7-13-840