S.C. Code Ann. § 7-15-460
In the event of an emergency, as defined in this section, the State Election Commission must, in cooperation with United States government agencies, take all steps and action as may be necessary, including, but not limited to, electronic transmissions of Standard Form 76 issued by the federal government as an application for voter registration and an application for absentee ballots and electronic transmissions of absentee ballots to or from any elector in the United States armed services, to ensure that all South Carolina residents located in the immediate area of the emergency, who are serving on active duty in the armed services of the United States, in the Reserve or Guard components of the United States armed services having been called to active military duty, or as civilian personnel with the armed forces of the United States, have the opportunity to receive and cast any ballot they would have been eligible to cast if they resided in and had remained in South Carolina.
"Emergency" means any war, conflict, military action, or military mobilization outside the continental United States in which United States forces are involved which would make it impractical for South Carolina citizens serving in the United States armed services to register to vote or vote in person in the normal manner.
The State Election Commission shall promulgate regulations necessary for the implementation of this section.