The price is not the only difference for the seemingly same national standard cable

It depends. Check whether there is quality system certification; Check whether the certificate of conformity is standardized; Check whether there is factory name, address, inspection seal and production date; Check whether the trademark, specification, voltage, etc. are printed on the wire. It also depends on the cross section of the copper core of the wire. The superior red copper has bright color and soft color, otherwise it is a defective product.

Try. A wire head can be bent repeatedly by hand. Those with soft hand feeling, good fatigue resistance, large elasticity of plastic or rubber hand feeling and no cracks on the wire insulator are excellent products.

weighing. Good quality wires are generally within the specified weight range. For example, the commonly used plastic insulated single strand copper core wire with a cross-sectional area of 1.5mm2 has a weight of 1.8 ~ 1.9kg per 100m; 2.5mm2 plastic insulated single strand copper core wire, with a weight of 3 ~ 3.1kg per 100m; The wire with poor quality has insufficient weight, or insufficient length, or too many impurities in the copper core of the wire.

Look at copper. The copper core of qualified copper core wire shall be purplish red, shiny and soft. The fake and shoddy copper core wire is purple black, yellow or white, with many impurities, poor mechanical strength and poor toughness. It will break with a little force, and there are often wire breaks in the wire. During the inspection, you only need to peel off 2cm of one end of the wire, and then rub it on the copper core with a piece of white paper. If there is black material on the white paper, it indicates that there are many impurities in the copper core. In addition, the insulation layer of fake and shoddy wires seems to be very thick. In fact, most of them are made of recycled plastic. Over time, the insulation layer will age and leak electricity.

Look at the price. Due to the low production cost of fake and shoddy wires, vendors often sell at low prices under the guise of low price and good quality.

"Non standard / enterprise standard / market national standard" and "national standard of protective resistance"?

When many sales companies are asked whether it is a national standard cable, they often hear words such as "market national standard" and "resistance protection national standard". Many people know a little. What do these vague words mean?

National standard for resistance protection: the cable is used to energize, and the resistance value of the conductor directly affects the conductivity. If the conductor resistance is too large, the conductivity is poor. When a large current passes through, a large amount of heat will be generated and a fire will be caused. At the same time, due to the large resistance, it will also produce heat and inaction consumption of electric energy.

Resistance preserving cable is to ensure that the resistance value of the cable meets the national standard, but it does not guarantee that the constituent materials of the cable are produced in full accordance with the national standard, such as conductor square, insulation, sheath, etc. To put it bluntly, it means that the manufacturer can make the cable meet the safe use conditions on the premise of reducing the material cost through various technological innovations (or means).