High-voltage power transmission consists of three phase wires. Above 35KV, there is one or two lightning protection wires on the top of the iron tower (electric pole). Therefore, the three-wire setup is high-voltage transmission, while the four-wire setup is high-voltage transmission with lightning protection wires (on the top, thinner than the phase wires, without insulators) or low-voltage 380/220V transmission (four wires are the same thickness, on the same cross-arm, using the same insulators). The five-wire setup is high-voltage transmission with two lightning protection wires (on the top, thinner than the phase wires, without insulators), the six-wire setup is two circuits of high-voltage transmission, the seven-wire setup is high-voltage transmission (three wires on the top) + low-voltage transmission (four wires on the bottom), and the two-wire setup is low-voltage 220V transmission (single phase).