The power plant has two electrical substations. So far, four new transformer substations in Guangxi are in various stages of completion. A transmission grid is a network of power stations, transmission lines, and substations. Their network of turbines, roads, transmission lines and substations can result in "energy sprawl". Early efforts to remote control substations used dedicated communication wires, often run alongside power circuits. Subtransmission lines carry higher voltage power from regional substations to local substations. Cascading outages affected areas powered by substations in Villa Betina and Quebrada Negrito. Electrified railways also use substations, often distribution substations. Distribution lines carry power from local substations to customers. The heat distribution piping network is long and comprises 14,000 substations and 10,000 heated buildings. There are six grid substations in North Bihar. Its transmission system consists of 23 substations and of transmission lines. There are around thirteen police stations and eight police substations (Pondok Polis) serving the city. The 275 kV substations in Scotland and their interconnections are given in the following table. A particular concern in design of electrical substations is earth potential rise.