Abstract: A time switch comprising: a clock (20) and a time counter (15) controlled by the clock and means (14,19) for starting the counter (15); input (12) and memory (13) means for entering and storing a base running time; a plurality of further input means (17) each associated with logic (18) and memory (13) means for entering a multiplier and calculating and storing the particular multiple of said base running time; the logic means (18) also being controlled by the clock (20) and being arranged successively to stop the counter (15) at the expiration of each multiple of the base running time stored in said memory (13), and to stop said clock at the end of the base running time; display means (11) for displaying the entered base running time, and, during a run, the elapsed running time; and switch means controlled to function only when said counter is running.