An LED lamp arrangement adapted for fitting in a luminaire, the luminaire adapted for a fluorescent lamp and having a ballast, the LED lamp arrangement comprising: a plurality of LEDs (25, 26, 27); more than two electrodes for releasably connecting to the luminaire and for receiving a current from the ballast; one or more rectifier circuits for rectifying the current and for supplying a rectified current to the LEDs; a sensor circuit adapted to measure one or more parameters representing total current drawn from the ballast by the LED lamp arrangement; and a protection circuit connected in series with the plurality of LEDs (25, 26, 27) to receive the rectified current and adapted to control an amount of current drawn from the ballast by the LED lamp arrangement, wherein the LED lamp arrangement is arranged to operate in a plurality of operation modes including a first operation mode and a second operation mode, wherein the LED lamp arrangement has a different load impedance in the first operation mode than in the second operation mode, and wherein the protection circuit is arranged to automatically switch the LED lamp arrangement from the first operation mode to the second operation mode in reaction to the sensor circuit on the basis of the measured one or more parameters, such that the impedance of the protection circuit is increased, wherein the protection circuit comprises an impedance and a switch, wherein the impedance comprises an inductive element (16a, 16b) having an inductance, and the switch is connected across the impedance, and wherein, in the first operation mode, the switch is in a closed state, so that the impedance is shorted by the switch. a plurality of LEDs (25, 26, 27); more than two electrodes for releasably connecting to the luminaire and for receiving a current from the ballast; one or more rectifier circuits for rectifying the current and for supplying a rectified current to the LEDs; a sensor circuit adapted to measure one or more parameters representing total current drawn from the ballast by the LED lamp arrangement; and a protection circuit connected in series with the plurality of LEDs (25, 26, 27) to receive the rectified current and adapted to control an amount of current drawn from the ballast by the LED lamp arrangement, wherein the LED lamp arrangement is arranged to operate in a plurality of operation modes including a first operation mode and a second operation mode, wherein the LED lamp arrangement has a different load impedance in the first operation mode than in the second operation mode, and wherein the protection circuit is arranged to automatically switch the LED lamp arrangement from the first operation mode to the second operation mode in reaction to the sensor circuit on the basis of the measured one or more parameters, such that the impedance of the protection circuit is increased, wherein the protection circuit comprises an impedance and a switch, wherein the impedance comprises an inductive element (16a, 16b) having an inductance, and the switch is connected across the impedance, and wherein, in the first operation mode, the switch is in a closed state, so that the impedance is shorted by the switch.