1. Length identification

It can be said that basically all wires on the market are under 100 meters, and it is already a serious manufacturer that can meet the requirements of wires above 98 meters.

2. Wire diameter identification

The 2.5 square BV line, commonly known as copper sheet, refers to the BV line of one line, that is, the cross-sectional area of ​​the BV line of the bv2.5 line is 2.5 square millimeters. Then, according to the area formula of the circle, the diameter of the BV line should be about 1.78 mm, which is the value in the national standard.

It should be specially reminded that when measuring, if you measure from both ends of the reel, even if the wire diameter is sufficient, it does not necessarily mean that the entire wire is sufficient. Because many counterfeit and shoddy products have no problem within the first three meters, but start to thin after three meters, and then return to normal diameter. This is because the manufacturer pulls the BV wire during the production process.

3. Copper identification

The major cost of wire is in the metal conductor. The national standard plastic BV wire uses oxygen-free copper as the conductor, that is, oxygen-free copper (a kind of red copper). Non-standard wires will use metals with low copper content as conductors, such as brass, galvanized copper, copper clad (brass coated with a layer of copper), and even copper clad aluminum and copper clad steel. The resistance of wires made of this material is much higher than that of copper. A lot of heat is generated during use, resulting in an accident.

How to judge? In general, the yellower the color, the less copper there is. Brass is pure yellow, and copper is a little red. Cut it out with pliers and see if the color of the part is consistent. At least it's easy to tell if it's copper clad aluminum. Some netizens said that someone bought a wire similar to cement, and the middle is not conductive at all. I am refreshed again:

4. Insulator identification

Check the thickness of the wire casing (insulator) first. National standard oxygen-free BV wire 1.5-6 square wire, skin thickness (insulation thickness) is 0.7mm. If it is too thick, there is a suspicion of cutting corners, because the inner core diameter is not enough; then judge the quality of the insulator. If you pull the counterfeit product by hand, the wire sheath is easy to crack.

5. Weight identification

Wires are normally within specified weight limits. For example, the weight of ordinary bv1.5 wire is 1.8-1.9kg per 100m; the weight of bv2.5 wire is 3-3.1kg per 100m; the weight of bv4.0 wire is 4.4-4.6kg per 100m, etc., poor quality wire Insufficient weight, or insufficient length, or too much impurities in the copper core of the wire.

In addition, there are other identification methods, such as core deviation rate, flame retardancy, resistivity, pressure resistance, high temperature impact resistance, low temperature winding performance, acid and alkali resistance, etc. These identification methods are more complicated. Generally speaking, an instrument is required, so we won't talk about it here. Our ordinary consumers can only make simple judgments based on the above five points.