A method is provided for detecting and correcting improper operation of a lighting system including a solid state lighting load. The method includes detecting first and second values of a phase angle of a dimmer connected to a power converter driving the solid state lighting load, the first and second values corresponding to consecutive half cycles of an input mains voltage signal, and determining a difference between the first and second values. When the difference is greater than a difference threshold, indicating asymmetric waveforms of the input mains voltage signal, a selected corrective action is implemented.