Disparate power transmission performance reinforces Italian social inequities.

High-voltage electric power transmission systems facilitate the delivery of large shares of electricity to customers and, as such, are key to enabling equitable power service. Here, we investigate the historical performance of the Italian high-voltage power transmission grid delivering power to utility consumers. Using open socio-economic and power system data, we find that socially vulnerable regions experience higher frequency and energy loss than less vulnerable regions. We find that performance disparities stem from infrastructure and terrain characteristics. Components operating at 132 kV and 150 kV levels are more failure-prone than those at other voltage levels, possibly due to high congestion near large cities. Worst-performing substations demonstrate higher rates of failure among non-transmission system operator (TSO)-owned components and due to weather-induced line failures, emphasizing the need for standardized operations and maintenance procedures. Altogether, our work offers practical recommendations for improving energy equity and highlights the critical role of high-voltage transmission in achieving that aim.