S.C. Code Ann. § 49-19-950

The commissioners at such meeting, or within ten days thereafter, shall each take and subscribe an oath that they will impartially discharge their duties as such commissioners and make a true report of the work done by them. The commissioners shall also at such meeting elect one of their own number as chairman. The secretary of the board of supervisors or his deputy shall be ex officio secretary of the board of commissioners during their continuance in office.