1. The gray-white substance generated in the connection place of copper wire and aluminum wire is Al2O3 for a little longer, and the contact resistance at the connection will increase and generate heat. When the circuit is formed, it is easy to cause building fire when it is on and off. So use a special copper-aluminum transition clip. Avoid unnecessary troubles!

2. If the copper wire and the aluminum wire are directly hinged together, the joint is easily oxidized, resulting in an increase in resistance, which makes it easier to burn out. The real reason for this damage is that the aluminum element is more active than the copper element, and there will be many micro-potentials (that is, micro-battery) on the copper-aluminum junction surface, resulting in micro-electrocorrosion, and the contact resistance will increase over time. For ordinary homework, it is more reliable to tin the copper first and then connect.

3. In the power system, copper and aluminum are directly connected, and galvanic corrosion will occur when current flows. Therefore, copper-aluminum transition should be used, or a tin sheet should be placed in the middle of the contact surface, and a layer of conductive paste should be applied if possible. When connecting ordinary households, the copper wire can be tinned and then connected to the aluminum wire to avoid galvanic corrosion.