Anyone operating a food service at a public festival, carnival, circus, fair or similar event lasting up to 14 days must get a Temporary Food Service permit (pdf) from DHEC.
Contact DHEC staff in the county where the event will take place ahead of time to get festival- specific information.
If your event will last from 1-3 days, you may possibly qualify for DHEC's Special Events Food Service permit, which is also free.
For more information, read DHEC's Food Service at Special Events (pdf).
If your special event will last more than 14 days, you will have to meet the same food safety and quality control standards as all other retail food services in South Carolina. Review the state's food service law, Regulation 61-25 Retail Food Establishments and DHEC's Food Equipment and Installation Manual (pdf).