This study analyzes service continuity metrics provided by E-REDES over ten years (2014–2023), focusing on medium-voltage connections in mainland Portugal. Key indicators—TIEPI, SAIDI, and SAIFI—were used to assess continuity across three Quality Service Regulation (QSR) zones (Zones A, B, and C), classified by population density and municipal code. Zone A, comprising densely populated areas, showed the highest performance with fewer and shorter interruptions. Zone B showed moderate performance, whereas Zone C exhibited the most prolonged and frequent interruptions, exhibiting a need for infrastructure improvements. The study employed a two-step cluster analysis and a linear model analysis to examine disparities across municipalities, with the Silhouette Coefficient validating cluster quality. The analysis revealed statistically significant variations in energy service performance across different municipal codes, with temporal trends showing improvement in continuity metrics alongside increased investment in network infrastructure.

The first author was supported by Fundação para a Ciência e a Tecnologia, I.P. (FCT) [ISTAR Projects: UIDB/04466/2020 and UIDP/04466/2020]. The second was supported by Portuguese funds through the Center of Naval Research (CINAV), Naval Academy, Portugal

electricity continuity service,Interruption Frequency Index,Interruption Duration Index,ime of Interruption Equivalent Power Installed,Cluster Analysis