S.C. Code Ann. § 56-5-4530

Either a tail lamp or a separate lamp shall be so constructed and placed as to illuminate with a white light the rear registration plate and render it clearly legible from a distance of fifty feet to the rear. Any tail lamp or tail lamps, together with any separate lamp for illuminating the rear registration plate, shall be so wired as to be lighted whenever the head lamps or auxiliary driving lamps are lighted.