An electrical distribution system for selectively connecting an electrical power source to a load device uses astronomical calculations. The system comprises a switching device electrically connected between an electrical power source and a load device for selectively delivering electrical power to the load device. A control system controls operation of the switching device. The control system comprises a programmed controller for commanding operation of the switching device in accordance with a scheduling routine stored in a memory. The scheduling routine enables control of the switching device based on sunrise and sunset time. The memory further comprises a database of a plurality of geographic locations and coordinate information for the plurality of geographic locations. The control system further comprises a setup routine comprising a user interface enabling a user to select one of the plurality of geographic locations and a manager routine automatically determining sunrise and sunset times using the coordinate information for the selected geographic location and providing the sunrise and sunset times to the scheduling routine.