This paper proposes a fast and accurate method to simulate the temperature rise due to a short-circuit condition in power conductors of aluminum based on one-dimensional reduction and the application of the finite difference method (FDM). The method suggested discretizes the analyzed conductor into several small one-dimensional nodes or elements. To improve accuracy and speed, the transient method proposed here applies a one-dimensional approach but analyzing in each node, the three-dimensional geometry of the conductor. By this way, and at each time-step, the convective coefficient and the incremental resistance of each node are determined and a further energy balance is calculated, thus obtaining realistic and accurate results. Results attained by means of the proposed method are validated against finite element method (FEM) simulations and experimental results conducted in a power laboratory, which corroborate the usefulness and accurate results of the proposed method.