It is stipulated in the operation of the electrician that the copper wire and the aluminum wire cann

Question: Why can't aluminum wire be connected to copper wire?

1.The potential of copper and aluminum is different, and the part in contact with copper and aluminum will accelerate the oxidation of the aluminum wire due to the reaction of the galvanic battery, and the copper-aluminum joint will be in poor contact after a long time. In order to be connected together, it is necessary to use copper and aluminum over-wire clamps or over-wire pipes.

2.This is a chemical problem, the chemical characteristics of metals are relatively active and inactive, such as **, never rust, which shows that **chemical is not active, iron is easy to rust, iron is more lively than **, if the two metals are put together will accelerate the oxidation of active metals, aluminum and copper compared to aluminum, aluminum is more lively, two cable connections, will accelerate aluminum oxidation (that is, rust), affect the use.

3.When the copper and aluminum conductors are directly connected, the contact surface of these two metals is easy to form an electrolyte under the action of moisture, carbon dioxide and other impurities in the air, thus forming a galvanic battery with aluminum as the negative electrode and copper as the positive electrode, which causes the aluminum to produce galvanic corrosion and increase the contact resistance at the connection of copper and aluminum. In addition, due to the large difference between the elastic modulus and thermal expansion coefficient of copper and aluminum, after multiple cold and hot cycles (energizing and power-off) during operation, a large gap will be generated at the contact point and the contact will be affected, and the contact resistance will also be increased.

The increase in contact resistance causes the temperature to rise during operation. At high temperatures, corrosion and oxidation will intensify, creating a vicious circle, which will further deteriorate the quality of the connection, and finally lead to excessive temperature at the contact point and even accidents such as smoke and burning.

Because if aluminum and copper are screwed together, as long as they come into contact with water vapor, they will form galvanic batteries, which will accelerate the corrosion rate of aluminum, which is very dangerous.

Because when the air is humid, it is an electrolyte, when the copper wire and the aluminum wire are screwed together to connect the line, the two metals have a chemical reaction, which will corrode one of the less active metals.

Electrical conductivity, copper is stronger than aluminum. Your question is theoretically best not to be directly connected.

In actual operation, electricians often screw the two wires together directly, and wrap them firmly with electrical tape, of course, it is still necessary to check them for a long time.

The best way: when choosing a terminal board fixed to the wall, choose one with two wiring screw holes on the insulating board "the same metal binding post". A hole is connected to the copper wire, which is firmly connected with screws and tablets; The other hole is connected to the aluminum wire, which is firmly pressed with screws and tablets.

Copper and aluminum wires cannot be connected together.

Due to the difference in potential between the two, the contact part will be oxidized by the aluminum wire due to the reaction of the battery, resulting in poor contact. In addition, copper and aluminum differ in their modulus of elasticity and coefficient of thermal expansion. After multiple power-ons and power-offs, the resistance will increase indefinitely, resulting in high contact point temperatures, resulting in accidents such as smoke and even burns.

How to connect copper and aluminum:

1.Copper-aluminum nose (or copper-aluminum clip).

The aluminum nose is used for connection and is a quick and convenient way to connect copper and aluminum. The aluminum wire is first equipped with a copper aluminum nose, and then tightly welded with the copper wire, so that there is no gap between the two, which can eliminate galvanic corrosion.

2.Weld. If you don't have a copper aluminum nose, you can weld it yourself. When welding, copper and aluminum should be tightly joined together, without gaps and exposed to air.

3. Shabu tin. It is also possible to use the method of shabu-shabu. First, the place where copper and aluminum come into contact is coated with tin, which can prevent the joint from coming into contact with air and avoid galvanic corrosion.

1. Copper and aluminum belong to different elements, and the metal inertness of copper is greater than that of aluminum, that is, the chemical activity of copper is much lower than that of aluminum, so that electrochemical reactions will occur after the two metals are connected, resulting in the gradual oxidation of aluminum wires and reducing the mechanical strength and conductivity of aluminum wires.

2. Copper wire and aluminum wire will heat up when passing current, and their resistivity is different. When passing through the same current, the heat generation of the aluminum wire is large, and the heat generation of the copper wire is small, so it is easy to have a fault point at the joint.

3. The hardness of copper wire and aluminum wire is different, if it is directly connected, its binding force will not be too good, if the wire is stressed greatly, it is easy to disconnect from the connection of copper wire and aluminum wire.

4. At the same time, due to the problem of galvanic corrosion, copper and aluminum are connected together, and aluminum is easy to be corroded. Such joints should not be found where corrosion is present.

There is some truth to it, but it is exaggerated.

Resistivity of aluminum.

Larger than copper, that's for sure, and therefore the same wire diameter on the premise, regardless of conductivity.

and tensile performance, copper wire is better than aluminum wire, but the cost of copper wire is higher. Therefore, in recent years, copper wire has gradually replaced aluminum wire.

At the same high current, the aluminum wire heats up.

more, so the possibility of causing a fire is greater, but as long as the wiring management is strictly in accordance with the electrical specifications, including copper and aluminum connections, as long as the connection is guaranteed to have a large enough contact area and is tightened as required, the risk is controllable.

Because copper and aluminum are two different metals, simply joining them together causes an electrochemical reaction (corrosion). For a long time, the contact resistance at the connection will increase and heat up, causing the circuit to turn on and off, the voltage to rise and fall, and even cause disasters.