Covers clock-operated switches that close and open circuits to a load at predetermined intervals. The switching contacts are actuated by a clock-work, a gear-train, hand, electrically-wound spring motors, electric-clock type motors, or equivalent arrangements. These switches are to be rated 600 volts or less and employed in accordance with the National Electrical Code, ANSI/NFPA 70-1984. Does not cover switches incorporating electronic timing circuits or switching circuits without separable contacts.