S.C. Code Ann. § 7-17-280: Mandatory recounts.

Whenever the difference between the number of votes received by a candidate who has been declared nominated for an office in a primary election or who has been declared elected to an office in a general election and the number of votes received by any other candidate or candidate not declared so nominated or elected or whenever the difference between the number of votes received by a candidate who received the least number of votes to qualify for a runoff election and a candidate or candidates who did not so qualify shall be not more than one percent of the total votes which were cast for such office therein, the committee or board charged by law with canvassing such votes shall order a recount of such votes to be made forthwith unless such other candidate or candidates shall waive a recount in writing.

Whenever the difference between the number of votes cast in favor of and opposed to any constitutional amendment, question or other issue is not more than one percent of the total cast thereon, the Board of State Canvassers shall order a recount of such votes to be made forthwith.