Whether there is the Great Wall logo and production license number of China Electrical Product Certification Committee on the coil of wire packaging card; Whether there is a quality system certificate; Whether the certificate is standardized; Whether there is a factory name, address, inspection seal and production date; Whether the wires are printed with trademarks, specifications, voltages, etc.

Looking at the cross section of the copper core of the wire, the superior copper is bright and soft, and the copper core is red and yellow, indicating that the copper used is of good quality, while the whitening and yellow is a reflection of inferior copper materials.

Take the end of a wire and bend it repeatedly by hand 1. Soft feel, good fatigue strength, elastic-plastic or rubber feel, and conductor insulators without cracks are first-class products.

Cut a section of insulation to see if the wire core is in the center of insulation.

What is not centered is the eccentric core phenomenon caused by low technology. If you have less power, you can live in peace. Once the power consumption is large, the thinner side is likely to be broken down by current.

Look at the length of the wire and the thickness of the core.

According to relevant standards, the error of wire length cannot exceed 5.

%, the cross-section line diameter can't exceed 0.02%, does not conform to the poor quality.