Why Can not Copper Wire & Aluminum Wire be Twisted Together?

1. Copper and aluminum have different potentials. The contact part of copper and aluminum will accelerate the oxidation of the aluminum wire due to the reaction of the galvanic reaction. And the copper and aluminum joints will have poor contact over time. Otherwise, you must use a copper-aluminum transition clamp or transition tube to connect the copper wire and the aluminum wire.

2. Copper and aluminum have different chemical properties. Compared with copper, aluminum is chemically more active. The connection between the two cables will accelerate the oxidation of aluminum and affect the use.

3. When the copper and aluminum conductors are directly connected, the contact surfaces of the two metals can easily form electrolyte under the action of moisture, carbon dioxide and other impurities in the air, thus forming a galvanic cell with aluminum as the negative electrode and copper as the positive electrode. Aluminum produces galvanic corrosion resulting in the copper and aluminum contact resistance increased.

4. Due to the large difference between the elastic modulus and thermal expansion coefficient of copper and aluminum, after multiple cooling and heating cycles (power on and off) during operation, a large gap will be generated at the contact point, which will affect the contact and increase the contact resistance.

The increase of contact resistance will cause the temperature to rise during operation. Corrosion and oxidation will intensify at high temperatures, resulting in a vicious cycle, and eventually lead to an excessive temperature at the contact point and even accidents such as smoking and burning.

By: Cathy Qin