UK Power Networks - UKPN own and maintain 'distribution' electricity cables and lines across London, the South East and East of England making sure your lights stay on. In general that includes cable to properties, under and above roads and fields and links to local transformers and substations. We maintain and upgrade power equipment. We move and connect new electricity cables - excluding very high voltage (e.g. 400KV, 133KV) transmission lines (usually on tall pylons).  The Transmission network is the responsibility of National Grid.