The ideal electric power system normally provides power to consumers with a pure sinusoidal wave. Electrical power consumers are often located in areas with a network connected to the loads that produce harmonic distortion. Areas with non-linear loads may distort voltage and current such that the waveforms are distorted due to the presence of high frequency components. It is necessary to measure and analyze the level of harmonic distortion for a number of areas in order to obtain a relationship between the type and number of non-linear loads in that area to the level of harmonic distortion. The measurements were done using Power Quality Analyzer device in 10 areas with different distortion characteristics. The measurement results show the harmonic content of the voltage, current and individual harmonics (%) for every harmonic order. Based on the data obtained, data visualisation and analysis were carried out using Matlab R2012a to show the distorted waveforms. The results of measurement show that area of the normal house with area of the house near industry has different harmonic distortions, the highest THDv from PLN sources is 5,7% and the lowest 0,04%, while THDi at PLN sources in all areas shows 0%. At daytime loading the highest THDv and THDi are 0,105% and 12,6%, the lowest for THDv and THDi 0,005% and 2,3%. At the night loading the highest THDv and THDi are 0,109% and 7,5%, while THDv and THDi lowest is 0,007% and 1,3%
