(1) Check the label and insulation on the printed words, if there are wrong words or printed with different depth, words fuzzy, please pay attention.
(2) Rub the insulation skin with your fingers, some inferior insulation wire skin easy to fade, especially the red line will appear this problem, after rubbing the fingers left on the color of the wire skin or printed on the line of the word is erased is generally poorly electrical wire.
(3) USe fingernail delimit, nibble insulation skin, can delimit, nibble down a piece of general is poorly electrical wire.
(4) Repeatedly bend the electrical wire, poor quality wire insulation layer is generally poor material, bending 3 to 4 times after the insulation layer will break.
(5) Ignition insulation layer, leaving the open fire can be spontaneous combustion of poorly electrical wire.
(6) Check the core color, quality color gray and no metallic luster.
(7) The length of the package is generally 100 meters per bundle or loop, and the allowable error is ±0.5% according to the national regulations. The length of the inferior wire is only 95 meters, or even less. Some of the packaging, to "code" as a unit to mislead.
(8)Through the above seven method can also measure the insulated wire diameter and wire core diameter, the measured value is large, is basically a inferior insulated wire (note: at present, there are many bad manufacturer enough conductor cross-section, increasing the thickness of the insulation or sheath to deceive users) in order to achieve the whole wire diameter.