The prevalence of renewable energy sources (RESs) and electric vehicles (EVs) is significant in modern electrical distribution systems (EDS). Although these technologies undoubtedly contribute to environmental improvement, they also pose considerable challenges for power system operators owing to their intermittent and unpredictable nature. To address these concerns, EDSs prioritise efficiency and reliability, which can be achieved through optimal network reconfiguration (ONR). The ONR problem addresses the challenge of incorporating varying levels of RESs and EVs into the system by considering the distribution losses and line loadability index (LLI). To overcome convergence issues in load flow and identify the optimal branches and tie lines for switching on/off, thus significantly improving network performance, a novel optimisation methodology that combines the northern goshawk optimisation algorithm (NGO) and LLI is proposed in this study. To enhance the search capabilities of the original NGO algorithm, a Levy Flight distribution and a new adaptive parameter were introduced, resulting in an improved version called Improved NGO (INGO). Simulations were conducted on a modified east delta network (EDN) of the unified Egyptian network (UEN), covering various scenarios. By having photovoltaic (PV) penetration, the network loss reduced to 698.46 kW from 723.85 kW, but by having EV penetration, the losses are raised to 848.15 kW, however, by having both PV and EV load penetration, the losses are reduced to 764.53 kW. However, by implementing ONR, the network loss was reduced to 739 kW. Furthermore, the computational efficiency of INGO is compared to that of the basic NGO, as well as other algorithms such as the stochastic fractal search (SFS), harmony search algorithm (HAS), and artificial rabbits algorithm (ARO). The results obtained from INGO surpassed those of all other algorithms in terms of the target function and computation time. Furthermore, the reduction in losses and enhanced loadability demonstrated the adaptability of the proposed methodology for realtime applications.