1. Uneven insulation layer, too thick or thin wire insulation layer is not good, the national standard stipulates that the insulation layer should be uniform, not eccentric, and it will not break easily if you pull it hard, otherwise pay attention.
2. You can't buy wires with black and dark copper core. The excellent pure copper core is purple-gold, with smooth and bright appearance and no burrs. At present, copper core wires are mostly pure copper. If it is doped with conductivity, the quality will be much worse, and the cost will of course be lower. The price is much cheaper. You cannot choose wires that are too far from the market price.
3. The appearance is not marked, the national standard wire body will be printed with the manufacturer, 3C certification, manufacturing standard, square number, voltage and other parameters. If not, it is best not to buy or use.
4. Looking at the length, the allowable error range of the length of a coil of wire is ±0.5 meters. If it exceeds this value, then pay attention.
Fold the wire by hand when selecting. If the flexibility of the wire is good, then the quality of the wire is also good. If it is easily broken, then the quality of this wire is not very good. So don't choose this kind of wire when buying.
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