<p>Optimal network reconfiguration helps with the reduction of total real power losses and the improvement of bus voltages. Several optimal network reconfiguration approaches are available in literature. However, as shown by a very recent study on the IEEE 33-bus radial distribution system, these approaches fail to attain the least total real power losses. Despite that, the recent study did not consider multiple test systems and load variations. Consequently, this article addresses those unexplored areas by introducing an optimal network reconfiguration approach that minimizes the total real power losses in the standard IEEE 33- and 69-bus radial distribution systems under nominal (100%) and heavy (160%) load conditions. The developed approach, which is based on Sparrow Search Algorithm, intelligently searches for the optimum tie and sectionalizing branches that have to be switched on and off, respectively, in order to minimize the systems' total real power losses. The search for the optimum tie and sectionalizing branches is performed in the permutations of loops created by the radial distribution systems' tie and sectionalizing branches. For the considered two test systems, the developed approach gave the least total real power losses and the best bus voltage than the referenced approaches.</p>