Dimmable lamp, having - a lamp base that can be electrically connected to an AC voltage of an AC network (N, L), for insertion, in particular for screwing, into a lamp holder, - at least one dimmable illuminant that can be operated with DC current, - a DC voltage module, which is designed for conversion of the AC voltage into a DC voltage, and for the output of the latter to a DC voltage branch, - a control circuit, supplied by the DC voltage branch, for the supply to and control of the at least one illuminant, - a detector circuit, - a dimming signal generation circuit, connected to the detector circuit, for the generation of a dimming signal (sD) for dimming of the at least one illuminant, wherein the control circuit controls the at least one illuminant as a function of the dimming signal (sD), together with - an energy store that can be charged by means of the DC voltage module, wherein the energy store is electrically connected to the DC voltage branch to support the DC voltage branch, wherein the dimming signal generation circuit is designed: - to identify the absence of a voltage or a current at the lamp base, and to record an associated time period of the absence, - to initiate a dimming procedure in the event that a definable first time period (δ) is exceeded, and - to continue the dimming procedure for the further time period in which the absence of a voltage or current at the lamp base is determined, and - to determine a subsequent presence of a voltage or a current at the lamp base, and to terminate the dimming procedure, while maintaining the dimming value last reached in the dimming procedure, wherein the energy store is designed for the intermittent supply of energy to the illuminant, the detector circuit, the dimming signal generation circuit, and the drive circuit, during the time period of the absence of a voltage and/or a current at the lamp base, characterised in that, the lamp also has a measuring device for the measurement of the impedance, in particular a network impedance, externally applied to the base, wherein the lamp is designed for the comparison of the measured externally applied impedance, in particular the network impedance, with a settable limit value, in the event of the absence of a voltage and/or a current at the lamp base, wherein the dimming procedure is only initiated if - the measured impedance exceeds the settable limit value and - the time period of the absence of a voltage and/or a current at the lamp base exceeds the definable first time period (δ), wherein the definable first time period (δ) is preferably 50 ms. - a lamp base that can be electrically connected to an AC voltage of an AC network (N, L), for insertion, in particular for screwing, into a lamp holder, - at least one dimmable illuminant that can be operated with DC current, - a DC voltage module, which is designed for conversion of the AC voltage into a DC voltage, and for the output of the latter to a DC voltage branch, - a control circuit, supplied by the DC voltage branch, for the supply to and control of the at least one illuminant, - a detector circuit, - a dimming signal generation circuit, connected to the detector circuit, for the generation of a dimming signal (sD) for dimming of the at least one illuminant, wherein the control circuit controls the at least one illuminant as a function of the dimming signal (sD), together with - an energy store that can be charged by means of the DC voltage module, wherein - to identify the absence of a voltage or a current at the lamp base, and to record an associated time period of the absence, - to initiate a dimming procedure in the event that a definable first time period (δ) is exceeded, and - to continue the dimming procedure for the further time period in which the absence of a voltage or current at the lamp base is determined, and - to determine a subsequent presence of a voltage or a current at the lamp base, and to terminate the dimming procedure, while maintaining the dimming value last reached in the dimming procedure, wherein the energy store is designed for the intermittent supply of energy to the illuminant, the detector circuit, the dimming signal generation circuit, and the drive circuit, during the time period of the absence of a voltage and/or a current at the lamp base, characterised in that, the lamp also has a measuring device for the measurement of the impedance, in particular a network impedance, externally applied to the base, wherein the lamp is designed for the comparison of the measured externally applied impedance, in particular the network impedance, with a settable limit value, in the event of the absence of a voltage and/or a current at the lamp base, wherein the dimming procedure is only initiated if - the measured impedance exceeds the settable limit value and - the time period of the absence of a voltage and/or a current at the lamp base exceeds the definable first time period (δ), wherein