This study introduces a methodology for categorizing Finnish electricity distribution system operators (DSOs) using geographic spatial data to be used for improved network business regulation. By employing open geographic spatial data and k-means clustering, the study provides a rapid, transparent and unbiased method for categorization. The clustering is implemented to find similar DSOs. The k-means clustering method grouped DSOs into seven categories, revealing more nuanced classifications beyond the traditional three classes. The results were validated by comparing differences in results of another clustering based on the key-figures. The differences were explained by further analysing the results with information of population density. The results are coherent with earlier studies and suggest that geographic spatial data can effectively enable further studies and regulatory applications by bridging datasets from different publishers based on spatial data. Essential for further studies are internal variations within operating environments of DSOs for targeted network business regulation.