1, with eyes
See if there is no quality system certification; two look at the certificate is standardized; three to see whether the name of the factory, site, inspection chapter, production date; four to see whether the printed trademark, specifications, voltage and other product details.
2, hand test
It is desirable to take a wire head repeatedly bent by hand, all feel soft, good anti-fatigue strength, plastic or rubber feel high elasticity and no insulator on the wire insulator is excellent.
3, identified copper
Usually qualified wire copper core should be purple, shiny, feel soft. And shoddy wire copper core was purple black, yellow or partial white, impurities and more, poor mechanical strength, poor toughness, a little force that will break, even in the wire often broken phenomenon. Check, as long as the wire stripped 2cm, and then with a white paper in the copper core on a little rub about, if the white paper with black material, indicating more impurities in the copper core.
4, weighing
Good quality wires are generally within the specified weight range. Here to provide several sets of data for your reference.