IEEEIn this research work, a new harmonic responsibility measure is proposed to extract the amount of harmonic responsibility of each plant supplied from the point of common coupling (PCC). The proposed method uses a function of the correlation coefficients between the voltage and current signals measured synchronously at the PCC. After the verification of the method on synthetic data generated in simulation environment, field data measurements of voltage and current are used to test the practicability of the proposed method. Harmonic contributions of the iron and steel (I&S) plants obtained using the proposed method are compared with the results of one existing method in the literature and it has been shown that harmonic responsibilities of the plants can be obtained for each harmonic order. The harmonic currents absorbed by the shunt harmonic filters of the I&S plants from the rest of the system are also identified effectively with the proposed method to determine the actual source of the harmonics. The proposed method can serve the needs of the active power filters and other compensation systems to improve the effectiveness of those systems in reducing individual distorting effects of the I&S plants supplied from a PCC of the electricity transmission system.