Summary Because of the widespread application of new energy and power electronic–based residential loads in distribution networks, the impact of collective harmonics cannot be ignored. The harmonic impedance should be evaluated when determining the harmonic responsibilities at the point of common coupling. This paper presents a new noninvasive method to quantify the harmonic current responsibilities of the utility side and customer side on the basis of impedance-gathering trend. The method is compared with another noninvasive resistance-sign–based method. In addition, the emission level of the residential loads is calculated. The presented results of a field test conducted in a typical residential apartment in Shanghai, China, prove that the method works well in practical conditions.