Abstract: An electronic switching circuit for controlling the supply of alternating current to a load, comprising a bi-directional rectifier combination having first and second trigger electrodes; first and second direct current trigger voltage supplies of equal voltage but electrically isolated from each other; a first switchable semiconductor device connected in series between the first direct current trigger voltage supply and the first trigger electrode of the bi-directional rectifier combination; a second switchable semiconductor device connected in series between the second direct current trigger voltage supply and the second trigger electrode of the bi-directional rectifier combination; and control means for rendering the switchable semiconductor devices conductive from the next zero-voltage instant of the alternating current supply after the onset of a control signal.