In this paper, a new method is presented for determining the contribution of different effective factors such as lateral loads, lines between buses, and voltage supply source to voltage unbalance in an n-bus radial distribution system. For this purpose, the factors affecting voltage unbalance at the place of load were analyzed based on the effects of source, line, and load. Furthermore, novel techniques are suggested to model and analyze passive, active (induction motor), and combined loads. The proposed method is then tested on a real distribution feeder with 9 jumper loads (20 kV/0.4 kV distribution transformer) in Iran. The results show the high accuracy of the proposed method.