Connection of aluminum and copper through an automatic machine. How to properly connect copper and aluminum wires? Methods for connecting wires made of different metals

Although, by modern standards, wiring in residential apartments is made primarily of copper wires, you can often find electrical wiring made of aluminum. If it is impossible to replace the old wiring with a new one, then you need to learn how to connect aluminum wires with your own hands. So, for example, how to connect a chandelier, socket and other electrical appliances correctly? Is it possible to connect aluminum wires with others? How to make the connection reliable? How to firmly connect aluminum wires to each other? You can get answers to these questions in this article.

Feature of aluminum wire

Due to its special characteristics, aluminum is difficult to work with. Also, during the oxidation of this metal, an oxide film is formed on the surface. This, in turn, prevents the good flow of current. This film melts at a temperature of two thousand degrees, and this figure is higher than the melting point of aluminum itself. If you peel off the film mechanically, then literally in a short period of time it appears again. As a result, the oxide film prevents high-quality contact of the connection.

Other features of aluminum include an increased degree of brittleness and fluidity. Based on this, the contact should not be subject to any mechanical stress. For example, if the connection is made using a bolt, then it must be constantly tightened from time to time. This is due to the fact that the aluminum will leak out from under the contact over time.

Electrochemical corrosion

Is it possible to connect aluminum wire with others? Yes! But here it is important to take into account some important points. If there is no moisture, then such a connection will be eternal. However, moisture is present everywhere, which in turn contributes to the destruction of contacts. It is also important to take into account the fact that each electrical conductor has its own electrochemical potential. In this regard, accumulators and batteries were created, however, when water enters the junction of metals, a short-circuited galvanic cell is formed. As a result, one of the metals is destroyed. To find out which metals can be connected and which cannot, it is important to know the value of the electrochemical potential of a particular current conductor.

For example, it is permissible to connect different wires if the level of electrochemical potential between them does not exceed 0.6 mV. Based on this, it turns out that the connection of copper with stainless steel will be of high quality with a potential difference of 0.1 mV, in contrast to the connection with silver (0.25 mV) or gold (0.4 mV).

Note! If the copper wire is coated with tin-lead solder, then any mechanical connection to the aluminum wire is allowed.

Methods for joining aluminum and copper

Based on the above, it may seem that connecting aluminum wires is not an easy task. However, it is not! In the process of connecting aluminum wire to copper wire, you just need to follow the technology. Let's consider several well-known methods for connecting aluminum wire to copper:

Twist

This is one of the easy methods for connecting wires. In this case, absolutely no qualifications or special knowledge are required. But the result is a far from reliable connection. Why? Everything is due to the fact that during the period of temperature fluctuations, a linear expansion of the wires occurs and, as a result, a gap forms between them, which in turn increases the resistance. Afterwards, the contact oxidizes and after some time is destroyed.

Note! This will not happen in the first year. But if you want to create a reliable and high-quality connection, then you should think about a more reliable alternative.

How is such a connection made? It is important here that one wire does not wrap around the other, but that they both wrap around each other. To ensure a high-quality connection, the copper wire can be tinned with solder. There is no restriction on the diameter of the connected wires. If the copper wire is stranded, then it must be tinned with solder. If the wire is thick, then three turns will be enough, and on a thin wire up to Ø1 mm, five turns must be made.

Threaded connection

One of the most reliable options for connecting aluminum and copper wires using nuts and screws. Such connections will ensure high-quality contact for many years. This method can be used to connect wires of different sections, stranded and single-core.

So, first you need to remove the insulation from the end of the wire. Then a spring washer, a regular washer, a ring of one conductor, a simple washer, a ring of another conductor, a washer and finally a nut are put on the screw, which tightens the entire structure.

Note! If the conductor has a Ø2 mm core, then the screw should be M4.

If the wire is stranded, then it should first be tinned with solder.

Terminal block

Terminal block is another modern method of connecting aluminum and copper wires. Although it is very popular, the screw and bolt connection method is much more reliable. However, the terminal block allows you to quickly and efficiently connect wires. In this case, there is no need to form rings at the end of the wire, or additional insulation. This design completely eliminates the possibility of contact between two exposed wires.

This connection is made as follows: The end of the wire is stripped of insulation to a length of up to 5 mm. Afterwards, a wire is inserted into the hole in the terminal block and tightened with a screw.

Note! The screw should be tightened with sensitivity, especially with aluminum wire.

This connection is very helpful in cases where a short piece of aluminum wire sticks out from the ceiling. If in this case you use the twisting method, then sooner or later the wire will simply break off. The same cannot be said for using a terminal block. Also, if aluminum wires were accidentally broken in the wall, then this technology simplifies their connection. But there is one thing! The terminal block cannot be hidden in plaster or in the wall without a special distribution box.

Terminal block and spring clamp

This method of connecting wires appeared relatively recently. There are two types: disposable and reusable. In the latter case, there is a special lever that allows you to remove and insert the wire several times. Such terminal blocks allow you to connect stranded wires of different types of aluminum with copper wires.

They are widely used for mounting chandeliers, as well as for connecting wires in junction boxes. The wire is inserted into the hole of the block with force and is securely fixed there. It will take a lot of effort to remove the wire. In practice, it is better to use reusable terminal blocks, which allow you to redo the connection in case of a miscalculation.

10 mm of insulation is removed from the wire. The lever on the reusable terminal block rises up and the wire is inserted. Then the lever returns to the reverse position. The connection is ready!

This type of connection has almost all the advantages of a threaded connection. You can highlight the speed of installation, durability, affordable price and ease of connection. The principle of its operation is simple. To connect the wire with a rivet, rings with a diameter of 4 mm are prepared. First put on the aluminum wire, then the spring washer, copper wire and flat washer. A steel rod is inserted into the rivet gun and compressed until the handle clicks. As a result, the excess conductor is cut off and the connection is completely ready.

The reliability of such a connection is very high. It is used for splicing wires. The most important requirement when using it is insulation of the connection area.

Twisting aluminum wires together

We talked about the advantages and features of twisting above, but now we will consider this issue from a different angle, namely, connecting an aluminum wire with a similar one. In this case, the success of using the twisting method will directly depend on the cross-section, diameter of the wires and other important factors. Ideally, aluminum wires are best soldered by first twisting them with a groove.

However, it is important to be careful here, since an oxide film forms on the surface of aluminum wires. Even if you clean it, it will reappear very quickly, as noted above, so the ends of the wire can be cleaned with a file until shiny or with sandpaper. It is recommended to compress the lowest turn with pliers. Such a connection will be durable and strong.

Each wire connection must be properly insulated.

It is recommended to place them in junction boxes. If such a connection is simply plastered in the wall, then access to it is limited and, accordingly, it will be impossible to tighten the contacts. Although if you use spring clamp technology, this will not be necessary.

If you want to make such a connection with your own hands at home, it is not recommended to use soldering or welding wires if you have no experience in performing such work. The best option would be a contact clamp or one of the methods described above for connecting aluminum wire to copper or to each other.

So, we have reviewed with you the most common methods of connecting aluminum wire. Of course, if you have no experience or are simply afraid to take on such work, then it is better not to risk it and turn to a specialist. Otherwise, if you have experience with such work, proceed by following all the recommendations in this article.

Video

Watch a master class on joining copper and aluminum:

There are still quite a few apartments in which the electrical wiring is made with aluminum wires. And since manufacturers of lighting devices and electrical equipment have switched to copper power cables, the question of how to connect copper and aluminum wires is still relevant today. Due to the fact that copper and aluminum have different electrical potentials, voltage will certainly form between them. If this bundle of two metals were located in a vacuum, the connection would last forever. The same cannot be said about the air atmosphere where humidity is present. It is a catalyst for chemical processes within the contact between copper and aluminum.

Experts have long come to the conclusion that a potential difference greater than 0.6 mV is already dangerous for wire connections. Such contact cannot be called long-term. As for copper and aluminum, the electrical potential between them is 0.65 mV, which is higher than normal. The result is a galvanic couple, like in a battery. Therefore, connecting them in electrical wiring is not allowed. But what should those who have an aluminum wiring diagram in their apartment or house do? There are several ways out.

Twisting two wires

The oldest method of connecting electrical wires is twisting. It is also the simplest. Let's return to the electrical potentials of metals. For aluminum with lead-tin solder, the potential difference is 0.4 mV, for copper with solder it is only 0.25 mV. It turns out that if one of the connected wires is treated with this solder, then they can be connected safely. Solder is usually applied to the copper wire.

You can tin both single-core and multi-core wires. In the second case, the cores must be twisted, and their number is taken into account. For large cross-section cables, three cores can be tinned; for small cross-sections (no more than 1 mm²), five wires can be tinned.

But even this connection option does not provide a 100% guarantee that the contact will work for a long time. There is such a thing as linear expansion of metals, that is, they expand under the influence of temperatures. When twisting, it is not always possible to tightly press the wires to each other. When expanding, gaps form between them, which reduce the joint density. And this leads to a decrease in the conductive value. This is why twisting is rarely used today.

Threaded contact

It is believed that threaded connections of copper with aluminum are the most reliable contacts that will last without problems for the entire life of the wires themselves. The ease of connection and the ability to connect several cables in one node make this type in demand today. True, it is usually used for joining large cross-section wires. The number of connected electrical lines will be limited only by the length of the bolt (screw).

We return to the electrical potential of metals and determine that between aluminum and steel (all elements of a bolted connection are made from it) the potential difference is 0.2 mV, between copper and steel - 0.45 mV, which is again less than the standard. That is, all metals present in the bond are not at risk of oxidation. The strength of the connection between aluminum and copper wires in this case is ensured by a well-clamped nut. Steel washers are installed between the two cores as a limiter or contact breaker.

Attention! During operation of the threaded connection, care must be taken to ensure that the nut does not unscrew spontaneously due to vibrations of the building. This will cause the contact to weaken. Therefore, a Grover washer must be placed under the flat washer.

How to make correct contact with a threaded connection

To properly connect aluminum and copper wires to each other, you must:

• Remove the insulating layer to a length equal to four bolt diameters. If an M6 bolt is used, the length of the open section should be 24 mm.
• If the veins already have oxidation on the surface, then they need to be cleaned.
• The ends are rolled into rings with a diameter slightly larger than the diameter of the bolt.
• Now they are put on the bolt in sequence: a simple flat washer, any one wire, a flat washer, a second wire, another flat washer, a Grover washer and a nut that is screwed in until it stops.

Please note that to clamp wires with a cross-section of no more than 2 mm² in this way, you can use an M4 bolt. If the copper wire is treated with solder, then it is not necessary to place a washer between the two wires. The end of a multi-core copper cable must be treated with solder.

Permanent connection

This type of contact is similar to the previous one, only it is permanent. And if there is a need to add another wire to it, then you will have to break the connection and make it in a new way. Essentially, this contact is based on a rivet clamp. The process itself is carried out using a special tool called a riveter.

• The ends are cleared of insulation, as in the previous version.
• Rings are made slightly larger than the diameter of the rivet (maximum size 4 mm).
• The aluminum end is put on first.
• Then a flat washer.
• Copper end.
• Another puck.
• Insert the end of the rivet into the rivet gun and squeeze the tool handles until you hear a click, which indicates that the steel rod has been trimmed.

Contact in terminal block

This type of connection of copper and aluminum wire is most often used in lighting fixtures. The blocks come complete with the lamps. In terms of connection reliability, they are inferior to threaded contacts, but this is one of the simplest options. There is no need to twist rings, or tin the ends, or insulate. It is necessary to strip the wires to a length of 5-10 mm and insert them into the terminal slots of the device. The clamp is made with a screw. You will have to make an effort, especially for aluminum wire.

If copper and aluminum are connected to each other using a terminal block, then the device cannot be laid under plaster. It can only be used in closed boxes: in a distribution box or in a lamp hood.

Terminal block

Wago

There is no way to bypass the Wago adapter. This is a German-made device with which you can connect aluminum and copper together without effort and without tools. The only thing you need to do is clean the ends of the conductors.

The Wago terminal block is a spring device into which cable cores are inserted, and it automatically clamps them. Today the manufacturer offers two versions of the pad: disposable (series 773) and reusable (series 222). In the first case, the wires are inserted into the terminal block and can only be pulled out by breaking the device. The second option is a device that includes levers. By raising or lowering them, you can pinch the end of the core or release it. Each connector socket has its own lever.

You can install wires with a cross-section of no more than 2.5 mm² in a disposable terminal block (it can withstand current up to 10 A), in a reusable terminal block no more than 4 mm² (current up to 34 A).

Nuts

Another design with which you can join aluminum and copper. The device consists of a plate-type metal connecting element and a plastic body, somewhat similar to a nut. Hence the name.

The principle of fastening is the same as that of the threaded version. Just by design, these are two plates that are pressed against each other with four screws. In one of the plates, a thread is cut into the holes, onto which screws are screwed, compressing the plates together. Aluminum is connected to copper using a nut like this:

• Protects the ends of conductors.
• One is inserted on one side into a specially formed groove between the plates.
• On the other hand, a second one is inserted. It is important here that the two wires (aluminum and copper) do not touch inside the connecting device. Therefore, the nut includes an additional steel plate, which is located between the clamping elements. So one wire must be placed on top of this plate, the second under it. This will ensure that there is no contact between the copper and aluminum wires.
• The screws are tightened all the way, which ensures reliable contact.
• The structure is closed by a spring-loaded housing.

Today, manufacturers offer a wide variety of nuts, both in power and size. There are options in which the case itself does not open, and all the filling is hidden in it and is inaccessible. The connection is made by inserting the end of the wire into the socket, where it is clamped with a screw. There are nuts with a toothed connection; you just need to insert the conductor into the groove, where compression will occur with the help of teeth, which will ensure reliable contact.

Returning to the questions of whether it is possible to connect and how to correctly connect copper and aluminum wires, we need to make a generalization that there are many options. Each has its own pros and cons, but depending on the necessary requirements, you can choose the right one, which will create conditions for long-term operation of the electrical wiring diagram.

If you find an error, please highlight a piece of text and click Ctrl+Enter.

How to connect two aluminum wires to each other? It would seem like a rather banal question, but even here the first answer that comes to mind is not always correct. After all, twisting of wires is prohibited according to the PUE standards, and any wires can be connected only by crimping, soldering, welding and using screw clamps. And we’ll talk about how to do it correctly in our article.

But we propose to start our conversation with a quick analysis of the properties of aluminum wire. This will allow you to identify problem areas and understand possible problems during its installation.

• Let's start with the advantages of aluminum wire. The main one is the price, which is an order of magnitude lower than that of its main competitor - copper.
• Another advantage of this material is its lightness. This has led to its widespread use in power lines, where weight is very important.
• Well, the last advantage is its resistance to corrosion. Aluminum is almost instantly coated with a persistent oxide film, which prevents further oxidation. At the same time, this film also has negative aspects - it is a very poor conductor of electric current.

• Then there were only continuous shortcomings. And the first of them is the low electrical conductivity of aluminum. For this material it is 38×106 S/m. For comparison, for copper this parameter is 59.5 × 106 S/m. This results in the fact that, for example, a copper wire with a cross-section of 1 mm2 is capable of passing a current almost 2 times greater than a similar aluminum wire.

• The next significant disadvantage is that aluminum wires have very low flexibility. In this regard, they cannot be used in places where the wiring is subject to repeated bending or other mechanical stress during operation.
• Well, and finally, the instructions say that aluminum has such a bad property as fluidity. As a result of thermal and mechanical influences, it can lose its shape, which has an extremely negative effect on contact connections.

Note! According to the PUE standards, since 2001 it has been prohibited to use aluminum wire for installing electrical wiring in residential premises. This ban significantly reduced the use of aluminum electrical wiring in everyday life.

Methods for connecting aluminum wires

As we said above, aluminum wires can be connected in four main ways - screw or bolt clamps, pressing, welding and soldering. Let's look at the features of each of these types of connections.

Connecting aluminum wires using the compression method

Let's start with the most common connection method - compression. It can be of several types - bolted, screw or using a pressure spring, which is used in Wago terminals.

Connecting aluminum wires using the pressing method

Recently, connecting aluminum wires with a sleeve has become increasingly popular. This is partly due to the widespread use of crimpers or, as they are also called, crimping pliers. This tool allows you to crimp wires of different sections, ensuring fairly reliable contact.

• The connection of wires by crimping is carried out using special sleeves. These sleeves are available in different diameters and materials. To connect aluminum wires, either aluminum or brass sleeves should be used. Copper should not be used under any circumstances, since the connection of these two materials can lead to the formation of galvanic isolation and ultimately the complete destruction of the aluminum conductor.

When installing electrical wiring, sometimes the question arises about connecting copper and aluminum wires. This issue is especially relevant during electrical work in old housing stock, where the main part of the electrical networks is made of aluminum wire. How to connect aluminum and copper wires to avoid problems with electrical wiring will be discussed later in this review.

What is the difficulty of connecting copper and aluminum wiring directly

As is known, the cause of problems in the direct connection of copper and aluminum is electrocorrosion processes. In a dry environment, nothing will happen even with direct contact, but with increased humidity, a short-circuited galvanic cell is formed at the junction, in which the metals begin to play the role of a battery with a “plus” and a “minus”. The metal itself practically melts, resulting in a network rupture with a possible short circuit and insulation fire. Which in turn can lead to a fire.

In order to avoid this, various types of contact devices are used to indirectly connect copper and aluminum wiring.

All connection methods can be divided into 2 groups based on the presence of wire contact:

1. There is direct contact between the wires: twisting, crimping, connection with rivets, strips.
2. There is no direct contact between the wires: threaded fixation, connection with various types of terminal blocks.

Important! To connect aluminum and copper wires, it is recommended to use methods from the second group. It is allowed to use connections from group 1 provided that the copper wire is processed. For example, it can be tinned with solder.

Twist

The main method of connecting wires at home, it is quite convenient in that it does not require special tools and equipment. But in the case of connecting aluminum and copper wires, this method must be used extremely carefully, observing the following conditions:

• A twisted connection is made by mutually twisting both ends of the wire with each other; wrapping the end of one wire around the other is not allowed;
• It is recommended to tin the copper cable with tin or solder before twisting; this point is especially important for stranded copper wire;
• A protective moisture-resistant coating must be applied to the connection between aluminum and copper wires.

There are three main types of twist: simple, bandage and groove twist. It should be noted that bandage twisting will give the best results. When performing twisting, it is worth considering that the number of turns directly depends on the diameter of the wiring, so for a wire up to 1 mm in diameter it is necessary to make at least 5 turns, for large sections at least three turns. In addition to moisture insulation, one should not forget about the electrical insulation of the twist; for this you can use special tips.

High-quality twisting will last quite a long time, but only the use of an indirect connection can provide a true guarantee.

How to make a twist correctly

First you need to prepare the ends of the wires. To do this, remove the insulation at a distance of 3–5 cm from the edge of the cable. It should be noted that the heat-shrink tube is placed on one of the wires, before twisting, upon completion of all operations, the tube is moved to an open place and fixed there. After cleaning the ends, you need to twist the wires according to the proposed diagram. In this case, it is necessary to ensure that the cores are wrapped around each other, and that one cable core does not overlap another.

To make it easier to twist a multi-core copper cable, its cores can and should be tinned. It should also be noted that tinning copper in any case increases the reliability of the twisted connection. After twisting, the connection point must be coated with moisture-resistant varnish. Electrical insulation can be done using heat shrink tubing or cap caps with a soft clamp or cone spring.

Insulation of wire ends with caps with a cone spring

Important! Unless absolutely necessary, it is not recommended to use twisting to connect copper and aluminum cables. Currently, there are many safer and more reliable ways to combine copper and aluminum into one network.

In this case, a metal or plastic sleeve or tip is placed on the twisted connection, which is fixed to the connection with press pliers, a special crimping tool. Fixation in this case is carried out by crimping the connection with the sleeve material. The sleeves are a metal tube with insulation made of PVC materials. The nozzles are usually plastic caps into which the compound is inserted, after which the cap is crimped with press jaws.

Separately, it is necessary to note the connection using cap attachments with a clamping ring or cone spring. In this case, after twisting the wires, a cap is put on the twist, after which it is screwed onto the connection with rotational movements, after which it is simply crimped with pliers. In this case, a ring of soft metal inside the cap tightly compresses the junction. This crimping option is quite accessible for household use.

Threaded fixation

A reliable, although somewhat cumbersome, way of connecting copper and aluminum wiring is a threaded connection; in this case, the cores are clamped with a nut on a threaded base. In order to avoid direct contact, a washer is placed between the exposed ends of the cores.

The advantages of this connection method are simplicity and versatility. In this way, you can connect several electrical wires of different cross-sections. But at the same time, this type of connection is quite cumbersome, and it is also very inconvenient to isolate. But, at the same time, this type of connection requires only a bolt and nut.

First of all, the ends of the wire are prepared. The insulation is removed at a distance of 1–1.5 cm from the cut, after which rings with a diameter slightly larger than the diameter of the bolt or rivet are made from the exposed wires. These rings are used to attach the wire to the rivet or threaded part of the bolt. A spring washer is placed between the aluminum and copper cable; this is necessary to ensure that there is no direct contact between these metals. After which the connection is fixed by tightening the nut or a riveter.

It is worth noting that this option is suitable for splicing wires of sufficient length; when saving length, which is often found when connecting lighting electrical equipment to the short ends of an aluminum wire, as is often the case in old apartments, it is better to use terminal boxes.

Connecting copper and aluminum wires with rivets

The clamping of the wires in this case is carried out by a wedged rivet, consisting of a tube and a core, fixed with a rivet gun. To connect, prepared conductors with wound rings are placed on a rivet tube with a gasket - a steel washer. After which the rivet is crimped with a rivet tool, the core wedges the rivet tube, thereby compressing the metal cores among themselves, thereby fixing the cable cores.

The contact in this case is permanent, but at the same time strong and reliable. For this type of connection, you need a special tool - a riveter, and skills to work with it. This method is used mainly for working with wire breaks and splicing wire ends in hard-to-reach places.

Connection with two steel strips

You can connect copper and aluminum wires in this tricky way, which also requires pre-treatment of the copper wire with tinning: clamp the wires with two steel strips with bolts at the edges. Advantages of the method: the ability to connect several branches of wiring at once, without increasing the length of the bolt. In this case, the bare ends of the cores are placed between the slats. The method is applicable for wires of the same cross-section.

Important! The connection with two steel strips requires mandatory external insulation, as well as preparation of the copper wire by tinning.

Terminal blocks and terminal boxes

Convenient and reliable connection method. The terminal block is a strip of insulating material in which sockets for wires are located. The wires are fixed in the sockets using clamping bolts. An important feature in our case is the absence of contact between the wires. To connect copper and aluminum wires, you only need a screwdriver.

The terminal box is a system of several separately located terminal blocks, combined into one structure and having several terminals.

The advantages of this connection method are:

• Easy to install, all you need is an electrician's knife to strip the ends of the wire and a screwdriver to tighten the screws;
• Reliability of insulation, very often when using a terminal block or terminal box, additional insulation is not required;
• Undemanding to the length of the wire; 1–2 cm of wire is enough to fix the wire in the terminal box.

At the same time, to install hidden wiring in the wall, the terminal block requires the installation of a distribution box. Without a distribution box, installation of hidden wiring is unacceptable. But in this case, you can use a terminal box for flush mounting.

When working with the terminal box, it is important to carefully fix the ends of the wire in the socket, especially for aluminum wires. This is especially important when installing the box outdoors or indoors where temperature fluctuations are possible.

Connection with spring and self-clamping terminal blocks

Currently, both reusable and single-use terminal blocks and terminal blocks are produced.

• spring terminal blocks and reusable terminal blocks have a retaining spring that can be loosened by lifting a lever located on the device body. This allows you to remove or insert the wire without any effort. Lowering the lever securely fixes the cable cores;
• Single-use terminal blocks automatically clamp the wire when inserting it into the socket; removing the wire will require physical force, which can damage the clamping spring, so their single use is recommended.

Both reusable and single-use terminal blocks are produced in a wide range, including with a different number of connected wiring branches, designed to fix wires with a cross-section from 0.08 mm² to 6 mm². Including in the form of ready-to-install terminal boxes. This method of connecting aluminum and copper wires is currently the most optimal in terms of reliability and ease of use.

Section of the spring terminal block and placement of the connection in the junction box

Terminal boxes with spring clamps were first produced by the German company Wago, from which they got their name, but currently there are a large number of analogues, including counterfeit ones. For this reason, it is necessary to purchase spring terminal boxes only from electrical stores. When purchasing terminal boxes on the market, there is a high probability of purchasing low-quality products that do not meet the stated requirements.

To fix the wires in the terminal box, it is necessary to prepare the wires; to do this, remove the insulation from their ends; the size of the exposed part must be at least 0.5 cm. After that, the open part of the cable core is inserted into the desired socket of the terminal box and fixed in it using a spring clamp or screw. It should be noted that mounting in a terminal box usually does not require additional insulation, but at the same time, when they are located in a wall, a distribution box is required. Thus, spring terminal blocks have a number of advantages over other types of connections due to ease of connection.

conclusions

In this way, it is quite possible to connect copper and aluminum wire, but it is necessary to take into account the location of the cable and the environment. Copper and aluminum can only be connected by twisting in a dry room. If the humidity in the room increases, this connection may become unusable and, moreover, cause a fire. The most optimal method today is to connect electrical wiring using spring terminal blocks.

The main advantage of this method is stable fixation in any environmental conditions. Despite all the advantages of a screw terminal block, threaded or rivet connection, when operating under conditions of sudden temperature changes, the contact under the screw may weaken. Due to the difference in temperature expansion of the metals of the wires. These changes may result in loss of contact or short circuit. Thus, with all the variety of methods for connecting copper and aluminum wiring, the safest method at the moment is the use of self-clamping terminal blocks.

Video on the topic

Any cable consists of aluminum or copper current-carrying conductors. According to the electrical installation rules, the usual twisting of such wires is strictly prohibited. But there are situations during installation when there are no options other than connecting aluminum and copper wire. There are many such opportunities. All that remains is to choose an accessible and safe one.

Electrochemical destruction of metals

The opinion that it is impossible to combine aluminum and copper is often mentioned. This is true from the analysis of the chemical compatibility of metals. In the world of modern technology, you can find dozens of matings of metal pairs.

There is a concept of electrochemical potential difference, the indicators of which are summarized in a special reference table. Take from it as necessary indicators and are determined with compatibility:

• Copper - lead-tin solder 25 mV.
• Aluminum - lead-tin solder 40 mV.
• Copper - steel 40 mV.
• Aluminum - steel 20 mV.
• Copper - zinc 85 mV.

To imagine what is happening, it is necessary to understand the reactions that electrodes made of different metals undergo upon contact.

In the absence of moisture, the reliability of contact is undeniable. But there is no ideal situation. Atmospheric humidity always negatively affects the quality of connections. Any conductor has a certain electrochemical potential. This property is used in practice in the operation of rechargeable batteries.

Getting onto the contacting surfaces from various compounds, water creates a short-circuited galvanized environment. One electrical conductor begins to deform. The material from which it is made is also subject to destruction.

Methods for connecting wires made of different metals

Technological rules allow direct connection of different metal conductors with an electrochemical potential coefficient of over 0.6 millivolts. According to the tabular data, for a combination of aluminum and copper it is equal to 0.65 mV, which makes such a combination unacceptable. However, there are ways to correctly interconnect different wires.

Cable connection by twisting method

Most famous, but an unreliable technique is called twisting. This method does not require special skills and is easy to make. For these reasons, it is used quite often. Before connecting the aluminum wire with copper, you need to imagine what is happening in a similar combination with temperature changes and precipitation:

• There is a gap in the connection.
• Increased resistance at the ligament point.
• Heat.
• Oxidation of cables, destruction of contact.

This method is not suitable for ensuring secure communication. Although, if you perform certain operations, in some cases you can use twisting to connect aluminum and copper wires:

Threaded connection of wires

A similar method is performed by clamping the ends of the cable into a bolted fastening. This is the most reliable connection between aluminum and copper wires together. It guarantees tight contact for the entire period of use of the twist. Replacing bolts of different lengths makes it possible to combine an unlimited number of cables:

• Different sections.
• Stranded and monolithic.
• With washers to prevent direct contact with copper and aluminum conductors.

Procedure:

1. Cut the insulating coating to the length required for fastening.
2. Sand and degrease the cleaned areas. Tin the multi-wire cable. Connect the cores using threads through steel washers.
3. Tighten the nut tightly.
4. Shock absorbers are placed in front of the outer washers to prevent pinching and breaking of the wire. When crimped, it will straighten and the connection will be fixed.

Connecting different cables with a terminal block

Splicing cables through terminal connections has become widespread in recent times. Although the quality of contact it is inferior to the bolted one, there are also undeniable advantages:

• The wires are connected in random order.
• There is no need to make connecting rings and put on ferrules.
• The design features of the terminal blocks do not allow short circuits of the wires.
• Isolation of the contact point is not required.
• The work on connecting the terminal contacts is simple.

The ends of the wires are exposed by approximately five millimeters, inserted into the clamp and pulled through. This method is indispensable when connecting aluminum cables, the cores of which break due to repeated bends.

Repairing damaged cables using terminal blocks also turns out to be the only acceptable option due to the short length of the wires. After splicing, a junction box is installed.

From the numerous connecting devices, not least occupied by the German Vago spring terminal blocks of the same company. They are either disposable or with a clamp for repeated splicing of the wire. Such terminal blocks are used when working with single-wire wires with a cross-section from one and a half to two and a half squares made of any metal in insulating boxes. According to the passport, they are designed for twenty-four amperes in load. The contacts are treated with a special compound to prevent oxidation.

These are the simplest devices to use. The wire is stripped and forcefully inserted into the block. The fixation is reliable. It is possible to get the wire out with good effort. In this case, the spring block is destroyed and reuse is impossible, which is the biggest drawback of this product.

Wago reusable terminal blocks with an orange lever are designed for the use of wires of any type with a cross-sectional area of ​​up to four square millimeters and currents of up to thirty-four amperes. Apply repeatedly until completely worn out.

The method of application is available to anyone. The insulation is stripped to a distance of approximately ten millimeters, the lever is raised, the wire is placed in the channel and the lever slams shut. The connection is fixed.

Vago terminal blocks are effective devices for installation of electrical networks. They do not require the use of special tools, but are quite expensive.

Monolithic connection method

The technique for making such a connection is similar to a threaded one. A rivet and a special device - a riveter - are used as a fastening element. The rivet is a hollow aluminum rod, thickened on one side. A wire pin with a cap is placed in it. When passing through the cavity, it creates a thickening on one side. Then the pin breaks off, forming a rivet.

If you do not take into account the price of the riveter, this method of contact becomes the most affordable besides twisting. The disadvantage of such contact is its disposability and the impossibility of disconnection if the work is performed incorrectly.

The use of special copper sleeves will be another way to permanently connect conductors. They are produced in various sizes, each with its own cable section. The bare ends of the wires are threaded through them and crimped with special pliers. This method is the most compact along with twisting.

Connecting wires by soldering

If desired, dissimilar wires can be soldered. This method must take into account certain technological features. Before connecting the wires correctly, aluminum and copper must be prepared for soldering. Copper doesn’t require any special tricks. Aluminum wire is another matter. On its surface, under the influence of ambient air, an oxide film - amalgam - is formed. It resists chemical attack and solder does not stick to it.

To neutralize it, you will have to make a simple device. The tip of the aluminum wire is stripped and treated with a solution of copper sulfate. Take a battery and attach this conductor to its minus. The copper wire is fixed to the positive with one end, and the other is dipped in the same solution. After a certain period of time, the aluminum will be covered with a copper coating and will become available for soldering.

Specifics of connections for outdoor installation

Electrical connections in outdoor installations are exposed to various weather conditions. Insulation requirements are more stringent. To prevent short circuits, a Walnut clamping kit is used.

Its plastic shell contains metal clamps in which the wires are connected by tightening the screws. The housing halves are tightly compressed with screws or spring rings. Such a cocoon guarantees protection from external weather fluctuations. This is a rather large connection, but in outdoor conditions it is not critical.