S.C. Code § 42-9-20
Except as otherwise provided in Section 42-9-30, when the incapacity for work resulting from the injury is partial, the employer shall pay, or cause to be paid, as provided in this chapter, to the injured employee during such disability a weekly compensation equal to sixty-six and two-thirds percent of the difference between his average weekly wages before the injury and the average weekly wages which he is able to earn thereafter, but not more than the average weekly wage in this State for the preceding fiscal year. In no case shall the period covered by such compensation be greater than three hundred forty weeks from the date of injury. In case the partial disability begins after a period of total disability, the latter period shall not be deducted from a maximum period allowed in this section for partial disability.
S.C. Code § 42-9-20