The localization of the dominant harmonic distortion source in the electrical network is one of the practical tasks in the consideration of the power quality in electric power systems. The conventional methods of the estimating of the impacts of the utility and the customer to the harmonic distortion at the network node are the harmonic power flow analysis as well as the correlation analysis of the harmonic voltage and current phasors. The practical use of both methods is discussed below by means of the example of the identification of the dominant harmonic source in the LV supply feeder of an industrial consumer. Based on the analysis carried out it is shown that the direction of harmonic active power flows is a more common and reliable criterion in comparison with the correlation analysis for the identification of dominant harmonic sources in electric power systems.