(2) Good corrosion resistance. Because of the outer insulating layer, the overhead insulated wire is less corroded by oxidation than the bare wire, and the corrosion resistance is stronger, which can extend the service life of the line. (2) (3) Prevent external damage. Reduce the impact of external factors such as trees, flying metal film and dust, and reduce interphase short circuit and grounding accidents. (3) The strength meets the requirements. Although the insulated wire has less steel core, it is tough, so that the mechanical strength of the entire wire can meet the requirements of stress design.