How to identify low-quality cables

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I. The hazards of substandard wires Wires are special products that are crucial for the safety of lives and property in thousands of households, as well as for the proper operation of almost all industries; they are used on a very wide scale, especially in temporary wiring and for indoor use in home renovations. If counterfeit or substandard wires and cables are used, it can lead to short circuits or electric shocks in mild cases, while in severe cases it may cause fires and result in casualties. The sampling tests conducted by the Yunnan Provincial Administration for Industry and Commerce at the end of 2009 showed that nearly 60% of the wires and cables in circulation within the province were substandard, and in nearly 50% of these wires and cables, the copper core – the essential component – was of inferior quality due to cutbacks in manufacturing standards. Rough statistics from the fire department show that in recent years, over 40% of fires were caused by electrical faults, with copper-core wires and cables that have shrunk in size being one of the main causes. II. Characteristics of substandard wires 1. Insufficient cable length: A common tactic used by unscrupulous manufacturers is to manipulate the length of wires and cables, with the actual length being less than the stated length, while pricing is still based on the stated length. The most typical example is cloth-wrapped wires packaged in rolls. **The standards specify that each roll should contain 100 meters of wire, with a measurement error of no more than 0.5%, meaning the actual length of each roll is 100 ± 0.5 meters. However, many manufacturers blatantly indicate on the certification cards that the length is 100 ± 20 meters; in reality, the length is only around 80 meters. If the price is calculated per meter, it isn’t cheap at all. Such scams are relatively easy to identify; one way is by checking the legitimate card ； The second is the sampling length, as cloth wires are relatively soft and easy to measure. 2. The resistance value does not meet the **standard; wires with excessive resistance values may reach too high temperatures under the same current, which accelerates the aging of the outer insulation layer and can lead to short circuits and fires ； Moreover, due to the excessive resistance, it also **increases energy consumption during power transmission, raising electricity costs. 3. Poor quality of raw materials: The first solution is to focus on copper conductors, which account for 80% of the cost of wires; unreputable manufacturers reduce the quality of the copper used. The use of impure copper, recycled copper, or even copper produced by informal methods at much lower costs results in extremely unstable copper content, which leads to a significant increase in the resistivity of copper conductors. Second is to reduce the use of copper. By reducing the actual cross-sectional area of the copper core, these two approaches directly result in the wire overheating during use, which damages the insulating plastic and leads to short circuits that can cause fires. The second trick involves manipulating the plastic used in the insulation layer by reducing its quality, just as is done with copper materials. The price of recycled insulation material differs from that of high-quality PVC plastic powder by nearly 2,000 yuan per ton. However, recycled insulation material contains higher levels of impurities, has lower mechanical strength, and suffers reduced aging resistance and electrical insulation properties; this approach will directly lead to leaks in wires. III. Identification of fake and inferior wires 1. Check the label. The contents of the certificate of conformity for wires produced by legitimate manufacturers should include: the 3C certification mark, certification number, model specifications, applicable standards, rated voltage, wire length, production date, manufacturer, inspector, factory name, factory address, landline phone number, and anti-counterfeiting marks. The labels of counterfeit products are often poorly printed or incomplete. 2. Look at the surface. The plastic coating of proper wires is soft and smooth, with a uniform color. On its surface, it should also bear several items listed on the product certification, such as the 3C certification mark, certification number, model, rated voltage, applicable standards, and manufacturer name. At the same time, the handwriting must be clear and not easy to erase. 3. Try bending. One can take a wire end and bend it repeatedly by hand; a high-quality product is one that feels soft to the touch, has good fatigue resistance, exhibits significant elasticity due to its plastic or rubber material, and shows no cracks in its insulation. The insulation layer of inferior wires appears to be quite thick, but in reality it is mostly made from recycled plastic; with a slight amount of pressure applied, the area under pressure turns white, and the wire breaks after being bent 4 to 6 times ； 4. Tear off the insulation. High-quality insulating materials possess a certain degree of mechanical strength and flexibility, and cannot be easily torn apart. And inferior wires can have a piece torn off or snapped off by hand ； 5. Observe the combustion. By regulation, the insulation layer of wires must have certain flame-retardant properties. If stripping a section of the insulation layer and lighting it with a lighter results in the wire continuing to burn on its own after being moved away from the flame, then it is a low-quality wire. 6. Check thickness. Cut a section of the insulating layer to check whether there are any visible pores in its cross-section, and whether the core is located right in the center of the insulating layer. The lack of centering is caused by eccentricity resulting from poor manufacturing quality, while the presence of pores indicates that the insulating material used is of inferior quality. Severe eccentricity most easily leads to leakage on the thinner side, and the presence of pores also affects the voltage resistance. 7. Check the copper wire. High-quality copper wire is bright red in color, while low-quality copper wires are purplish-black, appearing darker, yellower, or whiter. They are harder, contain more impurities, have poor mechanical strength and low toughness; they break easily with even slight force, and breaks often occur within such wires. For multi-strand flexible wires, gently touch the tip of the copper wire with the palm of your hand; it should feel smooth, without any stinging sensation, and quite soft to the touch. Otherwise, it is low-quality wire. 8. Check the price. Due to the low production cost of fake and inferior wires, sellers often sell them at low prices under the pretext of offering good quality at a low price, thereby deceiving people. Based on these few simple verification methods, it is generally possible to determine whether it is a high-quality or low-quality wire. If you need data to back up your claims, use the appropriate instruments to measure the length, diameter, thickness, resistance, voltage tolerance, and strength of the wires.