This paper presents a new time domain load modelling technique based on the method of Instantaneous Symmetrical Components (ISC) for three-phase unbalanced and distorted power system loads. ISC is used here to obtain instantaneous symmetrical voltage and current components and these components are used in the calculation of the symmetrical component model parameters, resistance (R-(0,R-1,R-2)), inductance (L-(0,L-1,L-2)), capacitance (C-(0,C-1,C-2)) and a harmonic instantaneous current source (j(h)((0,1,2))(t)), which are all connected in parallel. The results cover four cases of the system operation and the load parameters are found for each case, even in the presence of harmonic distortion. Consequently, it is shown that the developed method is a very powerful modelling technique to model time varying, unbalanced and distorted three-phase loads, such as general loads: i.e. residential and commercial buildings. Copyright (C) 2004 John Wiley Sons, Ltd.