To bikerchef's point, this is rule 6 from the 2014 KCBS guide:
6) Fires shall be of wood, wood pellets or charcoal. Gas and electric heat sources shall not be permitted for cooking or holding. Propane or electric is permitted as fire starters, provided that the competition meat is not in/on the cooking device. Electrical accessories such as spits, augers, or forced draft are permitted. No open pits or holes are permitted, except at the election of the contest organizer. Fires shall not be built on the ground.