S.C. Code Ann. § 40-11-340

An entity licensed under the classifications or subclassifications in Sections 40-11-410(1), (2), or (3) may act as a sole prime contractor on a project if forty percent or more of the work as measured by the total cost of construction falls under one or more of the licensee's license classifications or subclassifications. An entity licensed under the classifications or subclassifications in Section 40-11-410(4) and (5) may act as sole prime contractor if fifty-one percent or more of the work falls under one or more of the licensee's license classifications or subclassifications.