S.C. Code § 7-13-860
Each candidate who is not unopposed in a primary and each nonpartisan candidate, including announced write-in candidates in a general or special election, may appoint a watcher for any voting place where his name appears on the ballot. However, in any general or special election, all candidates who are certified by a political party must be jointly represented at each polling place by not more than two watchers from the party for each one thousand registered voters or fraction thereof registered at the polling place. Each watcher appointed hereunder must be a qualified voter in the county where he is to watch, and must be certified, in writing, to the managers of the voting precinct to which assigned. This certification must be signed by the primary or nonpartisan candidate or, in the case of watchers jointly representing all candidates of a political party, by an appropriate party official. Watchers must, at all times, wear visible identification specifying the candidate or party, as appropriate, which they represent. The identification badge of a poll watcher may not exceed four and one-fourth inches by four and one-fourth inches with individual letters on the badge not exceeding one-quarter inch in height or width. Badges may not be a color that has a fluorescent quality. After qualification, watchers must be placed in an area designated by the poll managers where the watchers can observe the entire election process at that polling place. No watcher may conduct himself in a manner that will interfere in the orderly conduct of the election or influence any voter in the casting of his ballot.
S.C. Code § 7-13-860