S.C. Code Ann. § 33-31-722: Quorum requirements.

(a) Unless this chapter, the articles, or bylaws provide for a higher or lower quorum, ten percent of the votes entitled to be cast on a matter must be represented at a meeting of members to constitute a quorum on that matter.

(b) A bylaw amendment to change the quorum for a member action may be approved by the members and, if required, be approved as provided in Section 33-31-1030.

(c) An amendment to the articles of incorporation or bylaws that adds, changes, or deletes a greater quorum must be adopted under the quorum then in effect or proposed to be adopted, whichever is greater.