IntroductionA shapefile containing the postcode areas supplied by secondary substations. Methodological approach The dataset is generalised using our GIS customer connectivity model. Each Secondary Substation's connected LV Network is traced out to its electrical extents, including all connected customers. Using the geographic position of customer connections and key network points of both the Substation being traced and surrounding Substation's network, a Voronoi diagram is created. Each Voronoi polygon that intersects with the traced network is joined together to produce a single polygon, depicting the Supply Zone. Quality Control Statement The data is provided "as is". Assurance Statement The Open Data team has checked the data against source to ensure data accuracy and consistency. The data domain owners have checked their respective data aspects. This dataset is redacted in that any secondary sites with less than five customers will not be included to protect privacy. Other Download dataset information: Metadata (JSON) Definitions of key terms related to this dataset can be found in the Open Data Portal Glossary: https://ukpowernetworks.opendatasoft.com/pages/glossary/