In the current wire and cable, most of the conductors are made of metal copper according to the wire and cable production process, and among the conductor materials of wire and cable, it is the most widely used conductor material.

 

一、 Why use copper for wires?
According to the wire conductor material, copper is the most widely used conductor material, and the output is large and relatively cheap. The advantage is that the resistivity is small and easy to process, and the full frequency conduction is balanced. The disadvantage is that ordinary copper impurities are more stable.
二、Why is copper a good conductor?
1. Good conductivity: Copper is the most widely used conductor material for connecting wires and cables. The most important feature is good conductivity. The purer the copper, the better the conductivity in wires and cables.
2. Ductility: Copper itself has good ductility, coupled with mature technology and advanced processing equipment, copper naturally becomes the main choice of raw materials in the wire and cable industry. For example: wires used in home decoration and electrical wiring, and conductor materials used in polyvinyl chloride insulated wires and cables.
3. Corrosion resistance: Copper conductors have good corrosion resistance, have strong corrosion resistance in dry air, and are not prone to oxidation reactions.
Therefore, copper is a good conductor choice, but improper operation of copper in the production of wire and cable, as well as the influence of the use environment will cause blackening and other phenomena.

                                      
三、The reason why the copper conductor of the wire and cable will appear black
Generally, the oxidation and discoloration (blackening) of the copper conductor of the cable is due to the wet environment or the immersion of rainwater into the cable conductor during the production, transportation, storage, laying, and use of the product, which causes the copper conductor to chemically react with oxygen and water to change color (blackening). The parts and conditions of the blackened copper conductors of wires and cables are also different: the ends of the cable conductors are blackened or both ends are intact and the middle is blackened.
1. Improper sealing of cable joints
The cable joint seal is not packed properly, causing air to intrude into the copper conductor and cause blackening. When packing the cable head, most of the masters will directly seal it with insulating tape. In fact, the insulating tape is not waterproof and there is a layer of glue on it, which will make the cable black after a long time.
2. Insulation damp
This kind of situation is very common and usually occurs at the cable joints in direct burial or pipelines. If the cable joints are made unqualified and the joints are made under humid weather conditions, water or water vapor will enter the joints, and the cables will turn black over time. The humidity in the air in summer is relatively high, and the higher temperature will accelerate the oxidation reaction of copper conductors, so this phenomenon generally occurs in summer.
3. Irregular use
During the customer's laying and installation process, if the cut cable is not sealed at the cable head or the irregular construction operation causes water to generate oxygen, it will also easily cause the cable to blacken.
4. Transportation environment
The finished product is bumped during transportation, and the cable insulation layer is damaged by extrusion, bumping, scratching, etc. When the partially damaged part of the cable copper conductor is in contact with oxygen and moisture in the air for a long time, it may be oxidized and discolored (blackened).
5. Copper rod drawing process
Copper rods are made into copper wires of various specifications through a wire drawing process. For the process of large drawing machine, medium drawing machine, and fine wire machine, wire drawing emulsion (lubricant) needs to be added. If the emulsion (lubricant) remains on the surface of the copper wire and is not treated well, it will contact the surface of the copper wire with air for a long time. It will be oxidized and discolored (blackened).
6. Construction and installation
Some users do not standardize the construction when laying and installing cables, which is likely to cause mechanical damage; civil construction on direct-buried cables is also very easy to damage the cables in operation. If the copper conductor of the cable is locally damaged, it will be oxidized and discolored (blackened) if it is damp underground or exposed on the surface for a long time.