1. Check the certification mark. Products that have obtained compulsory certification shall be affixed with a certification mark, namely the "CCC" mark, in a prominent position of the product, otherwise, it is an unlicensed product.

Second, look at the inspection report. As products that affect personal and property safety, wires and cables have always been listed as the focus of government supervision and inspection, and regular manufacturers are inspected by supervision departments on a periodic basis. Therefore, the seller should be able to provide the inspection report of the quality inspection department, otherwise, there will be no basis for the quality of the product.

3. Test insulation and sheath. The thickness of insulation and sheath should be uniform without deflection, and there should be obvious tension and elongation by hand. At the same time, the surface of the insulation and sheath should have the manufacturer's name and product model continuously printed with logos.

4. Observe the finish and color of the line body. The copper conductor of the wire and cable is metal-plated or non-metal-plated annealed copper wire, the aluminum conductor is aluminum or aluminum alloy wire, the surface is smooth, the copper conductor is light purple, and the aluminum conductor is silver-white, otherwise, the conductor is likely to be mixed with other impurities, thus cause a decrease in electrical conductivity.

5. Measure the DC resistance. In order to ensure the quality of the purchased wires and cables, you can first cut them from the products you want to buy.