SC HIGH SCHOOLS UTILIZE THE "30-30" RULE FOR LIGHTNING PROCEDURES
Begin counting when you see the “flash” of lightning and stop when you hear the associated “bang” of thunder. Divide the number by 5. This will tell you how many miles away the lightning is. When the “flash-to-bang” approaches 30 seconds, this means the lightning is within 6 miles and the next strike could conceivably be at your location. Wait 30 minutes after the last sound of thunder or flash of lightning before returning to the field. This will ensure that the lightning is far enough away so that a strike is unlikely. The count must start over at each subsequent lightning flash or thunder bang.
If the school utilizes lightning detector technology this may be used to assist officials however the above rules are still in force.