The thirteenth harmonic is an alternating current waveform component that oscillates at exactly thirteen times the frequency of the primary fundamental wave. In standard electrical power distribution systems operating on a 60 Hertz fundamental frequency, the thirteenth harmonic vibrates at a frequency of 780 Hertz. As a high-order odd harmonic, it frequently originates from the operation of heavy industrial multi-pulse rectifiers, variable frequency drives, and large-scale power electronics. While its amplitude is typically lower than fundamental or low-order harmonics, it still contributes to overall Total Harmonic Distortion and requires proper filtering to prevent high-frequency skin effect losses and interference.