Abstract: In a lighting installation comprising light sources each connected to an A.C. supply system, a control device including: power variation circuits connected to the different sources and each comprising means for varying the electrical power supplied to the respective source, in response to magnitude variations of an electrical quantity, and control circuits associated to the different sources and each comprising a clock circuit, an illuminating programme circuit in which is recorded a programme representing desired timed variations of the illuminating power for a given period, a selection circuit receiving clock pulses from the clock circuit and connected to the programme circuit for selecting an illuminating power dependent on the elapsed time from the beginning of said period, and an output circuit for converting said selected power to a particular magnitude of said electrical quantity.