How do you identify the quality of the wire and cable when you buy it?

The state has explicitly ordered the use of copper conductors in new residential buildings. But it is also a copper wire, also a poor copper wire, copper core of its core selection of copper, containing a lot of impurities, and some poor quality copper wire conductive performance is even less than iron wire, it is very easy to trigger electrical accidents. At present, there are many kinds of wires in the market, many specifications, and chaotic prices. It is very difficult for consumers to choose. As for the price of 2.5 square millimeter and 4 square millimeter copper core line used in the family decoration, the same size line is 20%~30% for the price of the same specification. It is difficult for consumers to judge whether the quality is up to standard or not. According to industry sources, the reason why the price difference of wires is huge is due to the different raw materials used in the production process. The main raw materials for producing electric wires are electrolytic copper, insulating materials and sheathing materials. At present, the electrolytic copper per ton in the raw material market is about 50 thousand yuan, and the recycled copper is only about 40 thousand yuan per ton; the high quality products of insulation materials and sheaths are 8000 yuan ~10000 yuan per ton, while the price of the defective products is only 4000 yuan ~5000 yuan per ton, and the difference price is very wide. In addition, insufficient length and inadequate glue content are also important reasons for price differences. The length of each wire is 100 meters for the top grade and 90 meters for the defective products, 35% - 40% for the top grade insulators and 15% for the residual products. By comparing consumers, it is easy to see that the difference between the sale price of finished products and wires is due to the fact that the material is tricky.