Why does the connection of aluminum and copper wires require attention?
Modern electric consumers( washing machines, air conditioners, kettles, irons, etc.) of high power often require replacement of the entire internal network in an apartment or house. For this, copper wires are used, but the connection of the apartment network must be made to the power cable - an input made of aluminum.
Then it becomes urgent to connect aluminum and copper wire. The same picture is observed when connecting a built house. And here the power transmission lines are made of aluminum, at the same time, the internal wiring is made of a copper wire of the appropriate cross-section.
With such a wiring provided by the project, it is necessary to make numerous outlets for lighting devices, sockets, etc. The copper wires can be connected by twisting, soldering, welding or using commutation boxes or clamps.
The twisting of copper wires, not being the recommended method of connection, can be performed for single- or multicore wires, provided they are thoroughly cleaned at joints of at least 5 cm in length. If they are thin enough, they can be welded using the flame of an ordinary match.
Copper wires of very thin cross-section can be twisted without cleaning. The scroll should be dipped in acetone and placed in a melt of tin after rubbing. For this purpose, an ordinary electric soldering iron is quite suitable. When twisting stranded wires, it is necessary to ensure the splitting of the cores, both for straight twisting and for tapping.
Ways of connecting copper wires
The most reliable way to connect copper wires is to combine twisting with soldering lead-tin solders or welding the joint. For welding, small-sized welding machines( inverters) are often used, very convenient due to their low weight and ability to provide the required current( up to 35 A).
The operation is carried out using a copper-plated graphite electrode, in the absence of a graphite brush from the electric motor. Welding can also be carried out using gas burners. These methods are also applicable to aluminum.
Sufficiently simple and reliable methods will be pressing and banding joints. It is necessary to carefully isolate the places of twisting or welding. To do this, insulating materials are used in the form of adhesive fabric or plastic tapes, shrink tubes, etc.
Reliable methods for combined wiring
Asking the question how to connect copper wires, one can not help remembering the screw terminals. This method, being quite universal and reliable, has its drawbacks. In particular, using this type of connection, it is necessary to remember the need to tighten the screws of the joints, due to the fluidity of the materials. This is especially true for aluminum.
In addition, using a stranded wire, at its ends it is better to seal special crimp terminals. The soldering of the joint increases its reliability. Terminal and bolt methods allow to connect the aluminum and copper wires correctly. It has long been known about the inadmissibility of direct contact between copper and aluminum.
Due to the varying degree of oxidation and electrical conductivity of materials, the contact potential difference, with increasing load, arcing, heating, and fire hazard of such connections are possible. If the joint is exposed to external atmospheric influences, these processes are intensified, electrolysis can be observed leading to shells and contact breakage.
Therefore, the connection of copper-aluminum wires is carried out only by means of the specified methods .Reliable and convenient in operation are the popular WAGO contact systems, which do not require special adaptations and equipment. Completely suitable and bolted connection, subject to the exclusion of direct contact.
To do this between the wires it is enough to place a simple steel washer and to tighten with a conventional nut. And in this case the connection site must be reliably isolated. The most appropriate is the placement in the junction and branching areas of special boxes that provide free access for preventive inspections and maintenance.