A device is disclosed for controlling the power of electric consumers connected to an alternating voltage supply grid, and comprising a circuit element (12, TRIAC) connected in series to the consumer and provided with a control input. The device also comprises a firing system for driving the circuit element and carrying out a phase control operation, and a firing capacitor (22) coupled to the firing system for supplying the energy required for activating the circuit element. The device is characterised in that the firing system comprises a switching element (32) which, when it is activated, establishes a connection between the firing capacitor and the control input of the circuit element, a release element (36) which compares the voltage applied to the firing capacitor with a reference value and generates a release signal, and a timing element (38) which is connected to the release element and activates the switching element (32) in response to the release signal and after a predetermined time period has elapsed, in such a way that the energy stored in the firing capacitor (22) is practically entirely used for firing the circuit element (12, TRIAC).