Introduction This dataset is a geospatial view of the areas fed by primary substations. The aim is to create an indicative map showing the extent to which individual primary substations feed areas based on MPAN data. Methodological Approach Data Extraction: MPAN data is downloaded from the geographical system. The system searches with a geographical window and assigns it to the nearest supply point. Connectivity.  Data is taken from the connectivity model and mapped to the relevant MPAN. Data Filtering: Any coordinates that are more than 500m from the nearest secondary site are removed. Primary Assignment: Postcodes of the MPANs are assigned to a primary substation based on the number of MPANs fed. Polygon Creation: Primary Feed Polygons are created and cleaned up to remove holes and inclusions. Hierarchy Construction: Grid Supply Point polygons are produced from schematics and merged based on hierarchical relationships. FLOC Matching: Functional Location Codes (FLOC) are matched to the respective sites. Quality Control Statement Quality control measures include: Verification steps to match features only with confirmed FLOCs. Manual review and correction of data inconsistencies. Use of additional verification steps to ensure accuracy in the methodology. Regular updates and reviews documented in the version history. Assurance Statement The Open Data team, worked with the Geospatial Data Engineering team ensure data accuracy and consistency. 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/