Repairing wiring in old houses, you can face a situation where you have to change large parts of the wiring. However, in most cases, the old wiring is made of aluminum, and for replacement you only have copper wire. In general, it is strictly forbidden to connect conductors from such different materials, but it happens that there is simply no other way out. Consider how to still connect the aluminum and copper wire so that there is no short circuit or fire.
- 1 Why can not connect copper and aluminum
2 Recommended Ways
- 2.1 Twist
- 2.2 Threaded connection
- 2.3 Connection via terminal block
- 2.4 Flat-spring clamp and terminal block
- 2.5 Rivet
- 2.6 Soldering
- 3 Conclusion
Why can not connect copper and aluminum
To do this, it is worthwhile to strain your memory and recall a school course in chemistry and physics.
For starters, remember what galvanic cell. Simply put, a galvanic cell is a simple battery that generates an electrical current. The principle of its appearance is based on the interaction of two metals in the electrolyte. So, twisting between the copper and aluminum wire and will be the same battery.
Galvanic currents quickly destroy the material. True, in the dry air, their appearance is excluded. And if you make a twist to the outlet, then it will not fall apart in a few hours. However, later troubles such a wiring provided.
Over time, the materials from which the wires are made are destroyed, along with this constantly resistance increases. If a powerful current consumer is connected to the outlet, the twist will begin to heat up. With regular use of such an outlet, the risk of fire increases.
Therefore, to connect the aluminum conductor with copper is strictly prohibited. However, emergency situations arise when it is simply necessary to make such a connection.
Let's consider several ways how to connect aluminum and copper wire. These methods will help to successfully cope with a difficult task.
Is an the easiest way mount the wires. It does not require special knowledge and qualifications. However, it is not the most reliable way to connect. Due to temperature fluctuations, the metal expands. As a result, a gap is formed between the conductors, which increases the resistance. After some time, the contact oxidizes and breaks down.
Of course, this will not happen within a year, but if the connection has to function for a long time, then you should think about other ways of bonding.
The very principle of fastening by the twisting method is that both conductors wrapped around each other. For better connections, copper cable is tinned with solder. Stranded copper wire will have to be tinned on a mandatory basis.
To connect copper and aluminum in this way you need a pair of simple pucks, one spring washer, screw and nut. This method is very reliable - contact between the conductors will be provided for many years. For this fastening, neither the wire cross section nor its type is stranded or single-core.
Insulation is removed from the end of the wire. The spring washer is put on the screw, then the usual washer is put on, then the ring of aluminum wire. It is supported by a simple washer. Then the copper conductor is put on, and then the nut is screwed on the screw. It tightly compresses the entire connection.
Stranded cable before connecting, be sure to run it with solder.
Connection via terminal block
This is a modern method of mounting wires. Although it loses a little in reliability of the threaded connection methodThe method has its advantages:
- connection can be made very quickly;
- When connecting you can do a small margin of wire.
The last explain, it happens that a small piece of cable sticks out of a wall or ceiling. Twisting is impossible - the wires are very small. Yes, and made on the ceiling twist will not last long, after some time the wires just break off. And the terminal block will hold both conductors with screws for a long time. Then the pad completely eliminates the contact of the two stripped conductors.
Installation is performed as follows: the end of the wire stripped of insulation (about 5 mm.) Is inserted into the terminal opening of the block, after which lock screw is tightened.
The terminal strip must not be hidden in plaster or in a wall without a junction box.
Flat-spring clamp and terminal block
This method appeared not so long ago. There are two types of such compounds: disposable and reusable. For the last connection in the terminal block there is a special lever. Thanks to him, the wire can be inserted and removed several times. Terminal blocks of this type can successfully connect copper and aluminum stranded wires of various kinds.
Widely used to install chandeliers and junction boxes in junction boxes. It takes some force to insert the wire into the hole in the terminal block. To pull the conductor will take even more effort. For practical use it is better to use reusable models. In case of an error, the connection can be quickly redone.
To perform such installation is very simple. First with cable isolation is removed (about 10 mm.). Then on the reusable terminal block you need to raise the lever, insert the wire, and then return the lever to its original position. It's simple!
Reliability is not inferior to the threaded connection and has its own Advantages and disadvantages:
- such a connection is established very quickly;
- it is very durable, reliable and affordable;
- however, unlike threaded fasteners, this connection is disposable.
Installation is performed using a special tool - zaklepochnik. Aluminum wire is put on the rivet, then a spring nut, followed by a copper wire and a flat washer. Then the riveter goes and the connection is ready.
It is worth mentioning that the connection area must be isolated.
Is it possible to solder conductors made of various materials? It is possible if meet certain conditions.
There will be no problem with copper soldering, unlike aluminum. Amalgam is formed on the surface of this metal, which exhibits surprising chemical resistance. That is, the solder can not stick to it. This phenomenon is often surprising for novice electricians.
To solder two different conductors, stock up with copper sulfate solution, a “Krona” battery and a piece of copper wire. On the aluminum wire, the future soldering site is neatly cleaned. Then drip onto this place copper sulphate solution.
The copper wire is connected to the positive pole of the Krona battery and lowered into the copper sulfate. An aluminum conductor is connected to the negative pole of the battery. After a time, a layer of copper will settle on the aluminum, on which you can solder the necessary wire without any problems.
Once again, it should be noted that any connection of wires must be insulated.
Can accommodate connections in special distribution boxes.
If you plan to make the connection with your own hands, then you should not resort to the soldering method. It requires certain experience and qualifications. It is better to use another of the above methods of connecting aluminum and copper conductor.
The most accessible and common methods were discussed in the article. However, in the absence of experience in such work, it is better to turn to professionals.