System for determining periodic values of phase angle Φ of waveform power input including voltage detector for detecting periodic values of average voltage of waveform power input and detecting corresponding periodic values of peak voltage of waveform power input. System also includes phase angle Φ detector in signal communication for receiving periodic values of average voltage and peak voltage from voltage detector. Phase angle Φ detector also detects periodic values each being ratio of one of periodic values of average voltage divided by corresponding periodic value of peak voltage, or being ratio of peak voltage divided by average voltage; and determines periodic values of phase angle Φ of waveform power input corresponding to periodic values of ratio. Lighting systems.