Why Can’t Copper and Aluminum Wires be Directly Connected

2021-10-21 by No Comments

When we are renovating a new house, concealed engineering has always been a topic that everyone pays more attention to. Whether it is the choice of materials or the layout of the circuit, it will attract everyone’s attention, especially for those who do not understand the decoration. It is easy to be cheated. Therefore, we must pay special attention to some issues. Today we will discuss together why copper and aluminum wires cannot be directly connected together. What should we do if they have to be connected together?


First, why can’t copper and aluminum wires be directly connected?


1. For copper and aluminum wires, the potential is actually different. When we use copper and aluminum wires to connect, the place where the copper and aluminum are connected will accelerate the oxidation of the aluminum wire due to the voltage reaction. In this case, it takes a long time As a result, contact between the copper wire and the aluminum wire will be incorrect.


2. In fact, for this problem, we also introduce a chemical problem. For metals, from the chemical point of view, there will be active and inactive distinction. For example, our common gold will not rust no matter how long it is. This means that gold is inactive, but it will not take long for iron to meet the water and rust will appear. This proves that the nature of iron is lively. If we connect two wires of different materials when wiring, If they are together, they will accelerate the oxidation of live lines. Compared with copper wires, aluminum wires will be more active. If they are directly connected, they will accelerate the oxidation of aluminum wires. Various problems will occur, affecting our normality use.


3. When we connect the copper wire and the aluminum wire directly, the contact surfaces of the two materials will easily generate electrolyte under the action of moisture and carbon dioxide in the air and other substances. The primary battery with the negative electrode and copper wire as the positive electrode will cause galvanic corrosion of the aluminum wire, which will eventually increase the contact resistance at the position where the copper wire and the aluminum wire are connected. 4. For comparison between copper wire and aluminum wire, since the difference in thermal expansion coefficient is relatively large, after a number of cold and heat cycles in normal operation, a large gap will be created between the contact points of the copper wire and the aluminum wire. , Which affects the contact of the line, which will increase the contact resistance. If the resistance value becomes larger, the temperature of the line will be increased during operation, and if the temperature of the line is increased, the corrosion of the line will also be increased, resulting in a vicious cycle. If the situation is serious, it will also cause smoke and fire on the line, which is prone to danger.



Second, what do I need to do if I have to connect them together?


1. When we are wiring, we will also connect the two kinds of wires because of special circumstances. Therefore, in such cases, we are best to use copper-aluminum transition clamps or transition tubes to handle this. If so, we can guarantee the safety of the normal use of the line.


2. If the copper wire and aluminum wire are directly connected together, the joint is relatively easy to oxidize, which will also increase the resistance value. It is very easy to be dangerous for a long time, so for our ordinary family, copper and aluminum When crossing wires, it is best to connect the two wires after tinning the copper wires.


3. When we connect, we can also use the method of wire transition. Pad the tin at the connection position. If we have the conditions, we can also apply a layer of conductive paste. For our ordinary home wiring connection, we can After tinning the position of the copper wire, it can be connected to the aluminum wire, which can also ensure that the circuit is corroded.


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