a system for controlling a lamp comprises a central controller having a waveform converter capable of modulating a control signal at more than one frequency over a two wire power cable . the control signal is capable of modifying a property of the lamp . the central controller also has a load current sensor capable of identifying the configuration of the lamp . the system further comprises a lighting control unit coupled to the lamp . the lighting control unit is powered via the two wire power cable and is capable of demodulating the control signal .