Look at the qualified certification: no matter how bad the national standard line is, it is much better than the non-standard line. Look at whether there is a "CCC" and production license number of the national compulsory product certification, see whether there is a quality system certification, see whether the certificate is standardized, and see whether there are trademarks, specifications, voltages, etc. printed on the wire.

Look at the color of the copper core: peel off the insulation layer of a section of the wire, look at the color of the copper core conductor inside, the high-quality copper core wire is purple-red, called copper or red copper, the poor copper wire is golden yellow, called brass, and the worst copper wire is black, called iron copper.

Bending detection: take a section of wire, bend repeatedly in a certain place, high-quality wire can feel very soft in the bending process; if the insulation layer is white after bending, it proves that the insulation layer is too hard, too brittle, and it is easy to leak electricity after long-term use.

Combustion detection: burn the insulation layer with a lighter until the insulation layer catches fire, then take the lighter away, and calculate the extinguishing time of the insulation layer. Automatic extinguishing within 5 seconds, proving that the flame retardant performance of the insulation layer is up to standard; if the automatic extinguishing time is long, or even more and more vigorous, the flame retardancy is too poor, it is recommended not to buy.