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A power line is a wire that carries current. The current transmission is usually point-to-point. Power cord can be divided into AC AC power line and DC DC power line according to the purpose. Usually, AC power line is wire rod with high voltage. Due to high voltage, this kind of wire can be formally produced after obtaining safety certification according to unified standard. The DC line is basically through the low voltage DC, so the safety requirements are not as strict as AC line, but for the sake of safety, countries still require unified safety certification.