What happens when connecting copper and aluminum wires?

When carrying out home decoration, it is inevitable to lay and install wires. Nowadays, copper wire or aluminum wire can be selected. Can copper wire and aluminum wire be connected? What will be the consequences? Here is a brief introduction.

Can copper wire and aluminum wire be connected? What are the consequences?

Copper wire and aluminum wire cannot be connected. Copper wire and aluminum wire will oxidize when connected. The greater the current, the faster the oxidation. It is recommended not to connect. The specific reasons are as follows:

1. Copper wire and aluminum wire belong to two different elements, so their chemical properties are different. If the two are forcibly connected, an electrochemical reaction will occur after the power is turned on. Over time, aluminum will be oxidized, reducing the conductivity of aluminum wires.

2. The resistivity of the two is different. When the copper wire and aluminum wire are energized, they will generate heat. When passing the same current, the heat of aluminum wire is large, while that of copper wire is small. If the power supply is applied for a long time, the fault point is easy to occur at the connection between the two.

3. The hardness of copper wire is different from that of aluminum wire. One is soft and the other is hard. Of course, their combination is not good, and the connection between them is easy to break if they are slightly careless. It will be very troublesome to repair the problem when it occurs.

Why try to use copper wire instead of cheaper aluminum wire?

1. Low current carrying capacity

The standard for selecting a wire is the current carrying capacity of the wire. Through the current carrying capacity, we can calculate how thick the wire is needed to load so much current. The current carrying capacity of aluminum wire is 1/3-2/3 of the current carrying capacity of copper wire (the thicker the wire, the greater the gap). For example, if the wire is made of copper, the current carrying capacity is about 32A; If it is made of aluminum, the current carrying capacity is only about 20A.

Therefore, when we say that a circuit needs 4 square (copper) wires, we mean that it needs to load 32A current – it is obviously not enough to put a 4 square aluminum wire here (the current carrying capacity is only 20A).

2. Copper aluminum connection is easy to damage

If aluminum wires are used, there must be copper aluminum connection places – even without copper wires, the terminals of switches, sockets and lamps are also copper.

When copper and aluminum are directly connected, the chemical reaction of the primary battery will occur after the power is turned on: aluminum with higher activity will accelerate oxidation, resulting in low current carrying capacity at the joint until overload occurs.