This paper proposes an innovative method for calculating energy losses in distribution networks. The method utilizes a self-developed dedicated device designed ungrounded neutral systems (6-10 kV). The device is installed on all branches of overhead lines to measure conductor currents and temperatures in real time, enabling per-unit value-based conductor loss calculations. A multi-factor correction model is developed to optimize loss estimation by comprehensively considering harmonic distortion, temperature effects, and material properties. Experimental results demonstrate that energy losses increase by 1.28 times when the total harmonic current distortion (THD) rises from 0% to 50%, compared to sinusoidal conditions. Additionally, temperature variations between －40 °C and +70 °C cause loss fluctuations ranging from －24% to +17%.