S.C. Code Ann. § 56-5-90: Driving limitations for intrastate motor carrier driver.

(A) For motor carriers subject to this title, an intrastate motor carrier driver may not drive:

(1) more than twelve hours following eight consecutive hours off duty;

(2) for any period after having been on duty sixteen hours following eight consecutive hours off duty;

(3) after having been on duty seventy hours in seven consecutive days;

(4) more than eighty hours in eight consecutive days.

(B) An intrastate driver is determined by his previous seven days of operation.