There is no uniform "15 years or 5 years" standard for wire lifespan, and the actual lifespan depends on the material, insulation type, installation environment, and load conditions. Common ranges are as follows: Copper core + PVC insulation, exposed installation in dry environment: about 10–15 years Copper core + XLPE insulation, concealed installation in conduit: up to 20–30 years Aluminum core wire, high temperature, high humidity, or overload operation: often needs to be replaced after 5–10 years Therefore, "15 years" is the average design lifespan of common high-quality wires, while "5 years" often refers to the accelerated aging point of inferior wires or in harsh environments. Both scenarios may occur, and the key lies in specific conditions.