Aluminum wiring is now rarely used for laying electrical networks in houses and apartments. It needs to be replaced during repair work. However, it also happens that the work is partially completed. In this case, the problem arises: how to connect the copper and aluminum wires.

What problems may arise when joining aluminum and copper?

When answering the question whether it is possible to connect copper with aluminum, it must be recalled that when twisting copper and aluminum wires, the following problems arise:

1. Reduced electrical conductivity. Aluminum is an active metal; under normal conditions it is covered with an oxide film that has low conductive qualities. Copper does not have this property.
2. Loosening contacts. Due to the formation of plaque, contacts become worse. No such film is formed on copper conductors, therefore the metals are considered electrochemically incompatible.
3. Fire hazard. When wondering how to connect an aluminum wire to a copper wire, they remember that electrical contact occurs between the oxide deposits formed on the wires. Over time, the metals begin to heat up, which leads to fire.
4. Electrolysis. If the system is operated in conditions of high humidity, the connection begins to deteriorate, becoming a source of fire. Corrosion primarily affects the aluminum parts of the wiring. With regular heating and cooling, cracks appear in the insulating braid, and the connection is covered with an oxide or salt layer, which accelerates destruction.
5. Formation of conductive soot. In this case, contact is broken and a fire starts in the house. When operating electrical wiring in a dry room, this process lasts for years. With high humidity, fire occurs within a few months.

Methods for connecting different wires

How to connect copper and aluminum wires:

• using another metal;
• preventing the appearance of harmful oxide plaque.

In the second case, special compounds are used that can protect the metal from the effects of moisture and oxidation. Pastes prevent the connection from breaking down. Another method of fire protection is tinning. Tinned stranded cable can be twisted with single-core aluminum cable. Special devices are also used for connection:

1. Clamps. Used to connect to an aluminum riser in the driveway. Branch clamps have punctures or lack them. The device is equipped with an intermediate plate that prevents contact between two metals. Some clamps are treated with paste. Sometimes the use of special compounds is not required.
2. Spring and self-clamping terminal blocks. Wires made of different metals can be joined and spliced ​​using terminals that have sockets and partition plates that separate the aluminum conductors from the copper ones.
3. Bolts. When making a bolted connection, a stainless or galvanized steel washer is placed between the wires.

Terminal blocks

Terminal blocks are:

1. Disposable. Used when connecting wires in junction boxes and installing chandeliers. To insert the cores into the hole of the device, you need to make an effort. Even more difficult is removing the cable from the block.
2. Reusable. There is a lever for fixation, thanks to which the cable can be inserted and removed several times. Terminals of this type are used when connecting stranded wires made of different metals. If the work is done incorrectly, the connection can be redone.

Installation is carried out as follows:

• the cable is cleared of its insulating coating;
• the veins are cleaned to a metallic shine;
• a lever rises on the reusable terminal block;
• the cleaned part of the wire is inserted into the hole in the block until it stops;
• the lever returns to its original position.

Crimping

In this case, tubular sleeves are used to reliably and safely fasten the wiring elements. To connect the cables you will need a press, mechanical, hydraulic or electric pliers. Installation includes:

• sleeve selection and tool adjustment;
• cleaning wires from braid;
• stripping the cores (sandpaper is used for this);
• application of quartz-vaseline composition;
• insertion of cable ends into the rivet;
• crimping (when using a simple tool, several crimps are performed over a short distance; when using a good tool, crimping is performed once);
• insulation of connection points.

The wires are inserted into the sleeve from opposite sides so that the joint is located in the middle of the connector. The cores can be inserted from one side. Connecting cables with a sleeve is sometimes replaced by using nut clamps, but the latter are less reliable. Over time, the rivet weakens, increasing the risk of fire.

Bolted connection

If the installation rules are followed, the method ensures durable fastening. To complete the work you will need 2 simple washers, 1 spring washer, a nut and a bolt. The wires are cleared of insulating material. The spring washer is placed on the bolt, which is inserted into a simple washer. The end of the aluminum cable is folded into a ring, which is thrown onto the bolt. After this, put on a simple washer and screw on the nut. Before starting work, the stranded wire is covered with solder.

Soldering

This is a reliable and technologically advanced method that ensures a high-quality connection. Before soldering, the conductors are cleaned of braid and oxide film. If necessary, the cables are tinned, loosely twisted, treated with flux and soldered. It is impossible to connect aluminum and copper wires using acid flux. The composition destroys metals, reducing the strength of the fastening. The junction is isolated in the usual way.

Features of connecting wires on the street

When performing work outdoors, take into account that the wires will be affected by precipitation, high and low temperatures, and wind. Therefore, when performing installation work, sealed structures are used that are insensitive to ultraviolet radiation and high humidity. When connecting wires on roofs, facades and poles, piercing clamps are used.

There are still quite a few electrical networks with aluminum wires in the secondary housing stock. And solving the problem of how to connect copper and aluminum wire remains vital when connecting electrical products. The safety of splicing with simple twisting, it is not for nothing that it is not recommended by the PUE, is quite precarious. In conditions without excessive humidity, the contact is benign. As soon as moisture appears, the connections begin to heat up and break down.

What happens when dissimilar metals join

Each conductor has its own electrochemical potential. This feature is successfully used in the manufacture of batteries and accumulators. But when two metals come into contact under conditions of humidity and stress, they begin to actively deteriorate. The results of this process are: fire of insulation, breakage of the electrical circuit.

Eliminating such a defect in hidden wiring will require time to detect, open and restore the surface of the walls. This happens when the splicing was performed by simply twisting two dissimilar cores. If connected correctly, the electrical contact will be reliable and will last a long time.

Methods for properly connecting aluminum and copper electrical conductors

When creating temporary electrical circuits, twisting copper and aluminum wires occurs quite often. This is the most quick way splicing power lines in the absence auxiliary materials. For short-term use, although not recommended, this option is possible. When laying a major power line, the following types of connections are used:

twisting with tinning of a copper core;

• threaded
• block
• one-piece
• spring clamps (Wago)

Tinned copper wire

The pre-cleaned copper core is coated with tin solder (tinning) using a soldering iron. After this procedure, you can connect both wires by twisting. The length of the ends cleared of insulation should be 4-5cm.

Simple twisting is done by twisting the wires onto each other. After this, the connection is insulated with tape, cambric or heat shrink tubing. The latter option significantly enhances the reliability of contact.

Threaded connection

It is possible to reliably connect copper and aluminum electrical conductors using nuts, washers, and screws. The assembled contact is easily disassembled and of high quality. Provides good connection for the entire period of operation of the electrical network. The number of wires you can connect limits the size of the screw.

The conductors are exposed to a length four times the diameter of the screw. They clean off oxides and form rings into which the screw will be inserted. In a certain sequence they wear:

• spring washer
• an ordinary washer
• copper wire ring
• puck
• aluminum core ring
• a simple washer
• nut

By tightening the screw, the entire package is tightened until the spring washer straightens. In stranded copper wires, a ring is first tinned to form a solid segment.

Terminal block connection

The most common option for splicing aluminum and copper conductors. In terms of reliability, it is inferior to the threaded one, but allows you to quickly complete the process in any combination. There is no need to prepare connecting areas or carry out insulation.

Structurally, the pads eliminate the presence of exposed wires and accidental contact with them. To connect, the ends of the cores are stripped to 0.5 cm. They are inserted into the holes in the block and clamped with screws. This option is the fastest and quite reliable. It is necessary to take into account that when wiring is hidden, the terminal blocks must be placed in the junction box.

Pads with clamps

New items on the electrical market, “Wago” clamps, have recently appeared in the arsenal of electricians. They are produced by a German manufacturer in two versions: disposable and reusable. Single-use designs allow the product to be used only once. Once the wire is inserted into the device, it is no longer possible to remove it back.

Reusable designs have a lever that allows the removal and insertion of conductors. The device is reliable and convenient, but has the most high cost when used. An unpleasant feature: the presence of many fakes on the market. As a result, connections may be unreliable, since the quality of non-originals leaves much to be desired.

Permanent connections

They have all the advantages of the threaded method. Disadvantage: there is no possibility of disassembling the structure. The connection is made by exposure special tool to the rivet. The preparation procedure is similar to the threaded connection diagram.

The prepared structure is placed in the tool, then it is compressed until it clicks. After this, the connection is ready for use. The method is convenient for splicing damaged sections of hidden aluminum wiring with copper wire inserts and in other cases. Required condition– careful isolation of exposed areas.

Methods for connecting copper and aluminum wires (video)

When making repairs (even cosmetic ones), we are often faced with the need to put the electrical wiring in order. In old houses, it happens that the wires are almost the same age as the owners of the apartment, and therefore it is simply necessary to replace entire sections of the wiring.

But this is where the main problem lies: very often old wires are made of aluminum, and you only have a piece to replace. Let’s immediately say that according to all the rules, joining them is strictly prohibited, but there are all sorts of situations.

So in this article we will discuss aluminum and copper ones, so as not to become the culprit of a short circuit and fire?

Why can't you do this?

In order for you to fully understand the danger of such actions, you should talk about why you should not twist copper and aluminum wires. We have to remember physics and chemistry.

Do you remember what Roughly speaking, this can be called a battery in which the current arises as a result of the interaction between two metals in the electrolyte. Accordingly, the twist between aluminum and copper is such a battery.

Of course, in dry air the formation of galvanic currents, which quickly destroy the material, is practically impossible. Yes, even the twist to the socket, which is constantly used to connect a kettle or other powerful appliance, will not fall apart after a couple of hours, but troubles await you for sure.

Judge for yourself: over time, the wire materials gradually deteriorate, and the resistance constantly increases. Accordingly, the twisting area begins to heat up very much when a powerful current consumer is connected to the outlet. If this happens regularly, the likelihood of a fire becomes extremely high.

That is why it is not recommended to join aluminum and copper wires for a long time. How to connect them if an emergency arises? Agree, in the countryside it is not always possible to visit an electrical goods store!

Let us repeat once again that it is not always possible to do everything “according to science,” but we still strongly recommend using terminal blocks to connect wires. This is the simplest, fastest and safe way, with the help of which even the most inexperienced electrician can connect the wires. Let's look at the most common structural types.

"Nuts"

The oldest and most proven method is called nuts. As you can understand, they received the nickname because of their specific shape. Structurally, they consist of three plates, between which the wires are fixed.

A special advantage of this method is the fact that it is not at all necessary to cut the central line to insert the second wire. To do this, you just need to peel off the insulation in the right place, and then clamp this area between two “nut” plates. A branch wire is inserted between them, after which the plates are securely twisted together.

WAGO

No less common are the methods of connecting wires, which are united under one abbreviation WAGO. These are very simple and reliable devices with which you can dock everything in a couple of seconds. This is done as simply as possible: the ends of the wires are stripped of insulation, after which they are inserted into the connectors.

The trick here is that the internal space of this connection is filled with a special lubricant, which prevents oxidation and galvanic reaction between different types of metals. But! We could recommend the use of this kind of devices only in those networks to which powerful devices will not be connected.

The fact is that under heavy load, connections of this type will become very hot, as a result of which the terminal materials will begin to deteriorate. It is not surprising that WAGO is most often used when working with lighting fixtures.

Terminal blocks

They are also quite common and popular. They look most like a small strip with terminals. As in the case described above, to use them you need to strip one end of the wire, then insert it into the adapter hole and tighten the bolts. On the other hand, everything is done exactly the same.

Here again lies the rub. How will aluminum and copper wires behave in this case? How to connect them if you need to connect really powerful devices to the network?

Fortunately, pads are quite suitable for this purpose. If the thickness of the insulating plate is normal, then it will withstand even very high loads without problems. But remember that it is highly not recommended to install it in a room with high humidity. There is no insulating lubricant in them, so the formation of a galvanic couple cannot be ruled out.

What other ways to connect wires are there? Let's figure it out.

Bolt-on mounting

This installation method is also great when you need to join copper and aluminum. The wires are clamped with a bolt, and between the two metals it is necessary to place a washer made of high-quality anodized steel. Remember that this type of connection must be checked for strength at least twice a year. If such a joint is used in a network that experiences high loads, then this needs to be done even more often!

Soldering iron

Is it possible to solder wires that are made of different metals? Yes, this is quite possible, but some important conditions will need to be met.

We won’t talk about copper for a long time, since there shouldn’t be any difficulties in this matter. But there will be problems with aluminum. Their cause is amalgam, which instantly forms on the surface of this metal when it enters an oxygen environment. It is surprisingly chemically resistant, and therefore solder does not stick to it at all. This is constantly faced by those novice electricians for whom any soldering of aluminum wires is a curiosity.

How to remove this annoying film? First you will have to prepare a saturated solution of copper sulfate, a Krona battery and a piece of normal copper wire (not Chinese). On the aluminum wire, you need to carefully clean the future soldering area, and then drop a couple of drops of copper sulfate solution onto it.

Attach aluminum to the negative terminal of the battery, and a piece of copper wire to the positive terminal. Lower its end into After some time, a fairly decent layer of copper will settle on the aluminum, onto which you can easily solder the wire you need.

As you can see, soldering wires, even in this case, can provide a reliable and high-quality connection.

Important!

In almost all the cases that we have discussed above, rigid fixation of wires stripped of insulation is used. Somewhere terminals are used for this, somewhere bolts... But few people take into account one important point when twisting aluminum and copper wires. We already know how to connect them, but it’s also worth talking about the safety precautions of this process.

The fact is that aluminum under load becomes quite plastic and begins to “flow”. All (!) connections of this kind must be checked regularly and the bolts must be tightened. Otherwise, the day will come when a terminal that is kept on its word of honor will simply burst into flames, unable to withstand the strong heat.

• Stranded copper wires should never be clamped. The fact is that when clamping, a whole range of conditions are formed that this wire really does not like. So, part of the veins may well come out of the connection. The remaining part of the wire will be subject to a very high load, which may result in a fire.
• It is very important to select the terminal exactly for the cross-section of the wire you are using. From a channel that is too narrow or wide, the wire will simply fall out, and this is fraught with unpleasant consequences.
• Don't overdo it! In most cases, brass is used in terminals and sleeves, and this material is characterized by increased fragility.
• Look carefully at the markings, which indicate the maximum permissible current. As a rule, it is exaggerated: it is better to divide the indicated value by two.

We strongly advise against buying the so-called NoName from China. You won't go broke by spending a couple of rubles more, but buy a really high-quality terminal from a normal manufacturer! Manufacturers Tridonik, ABB, and Verit have proven themselves to be excellent.

What about the multi-core option?

If you have carefully read the article, then you already know very well that stranded wires should not be clamped. But what to do in the case when you need to connect them to a thick aluminum outlet, but you don’t have a soldering iron, copper sulfate and batteries, and you don’t want to bother with them?

It's time to tell you that there are special types of wire connections that are specifically designed to solve this kind of problem.

Sleeve connections

IN specialized stores For electricians, you can easily find sleeves specially designed for normal connections. They look like miniature tournament spears of knights: behind a protective plastic cap there is a hollow metal tip.

How to work with them? It's simple: carefully remove the insulation from the end of the wire, twist the strands into one “pigtail”, and then insert it into the hollow tip. Afterwards it is crimped (you can use the most ordinary pliers). The resulting tip is inserted into the terminal.

This way you can easily connect the wires without soldering. Of course, no one forbids the above-mentioned “pigtail”, provided that you have a soldering iron, to tin it with solder and weld it with aluminum in the way that we described above.

Twist

Of course, making twists among professional electricians is considered bad manners and almost a violation professional ethics, but in life anything happens, and therefore no one is immune from the need to make such a connection.

What advice can be given in this case? Let's start with the fact that twisting aluminum and copper wires is allowed only after thoroughly cleaning the aluminum section. If the copper wire is presented in a multi-core version, it must not only be twisted into one “pigtail”, but also covered with solder for better contact.

Twisting should be done as carefully as possible, avoiding breaking off the wires. It is recommended to close its ends with a special insulating cap, which can be purchased at almost every hardware store.

Finally, we have already written more than once that twisting should under no circumstances be placed in a room with high humidity air. Under such conditions, the connection is destroyed almost instantly.

In short, although it is not recommended by professional electricians to connect copper and aluminum wires, if you use the simplest means you can easily do it without exposing your home to the risk of fire.

We have long and widely switched to copper wires in home electrical wiring. But the likelihood of joining with aluminum conductors from the past is still high. This usually occurs when replacing or repairing existing electrical wiring that was previously installed. However, aluminum is also contained in the new SIP wire (self-supporting insulated wire), which is now commonly used to make connections from the pole to the house. Everything would be fine, but aluminum and copper are not “friends” at the molecular level, and we have to solve this problem ourselves. Let's see which method works best for you.

Twisting is not the best method

In the past, ordinary twisting was used to connect home electrical wires. This was a familiar procedure, and no additional devices were required at all. Quite often this method is used even now, because simple and quick solutions are difficult to refuse. If you do have to twist, then try to minimize the risks: the wires must be tightly wrapped around each other. A method where one core is straight and the other wraps around it is completely unacceptable - such a connection will be initially defective.

In the connection, we select the number of turns in accordance with the diameters of the cores. If the diameter is less than 1 mm, we make 5-6 turns. When twisting larger diameter wires, three turns are sufficient. After tightly twisting, you need to seal the connection with a protective varnish with waterproof properties.

Simple way with screws

Wires of different materials can be successfully connected using screws and nuts. It is convenient that such a connection can be quickly disassembled and remade if necessary. If executed correctly, the threaded connection will be of high quality and durable. The attractiveness of this option is the possibility of simultaneously connecting several wires, the number of which can only be limited by the length of the screw itself.

The screw method is well suited for connecting wires with different numbers of cores and different diameters. The main thing is that there is no conflicting approach between wires made of different materials. Washers are used for separation. The procedure is simple: we remove the sheath from the cable to the required length, and then we make wire rings according to the diameter of the screw. We successively place a spring washer, a wire ring, a washer, a ring of the next conductor, etc. on the screw rod. At the end of assembly, tighten the nut until the spring washers are completely straightened.

When you have a riveter at hand

This method of joining resembles a bolted one, but instead of a nut and bolt, a blind rivet is used, forming a permanent connection. But after fixation, it will no longer be possible to correct the connection without “surgical” removal of the assembly. From the stripped ends of the wires we make rings with the same diameter as the rivet. We use galvanized washers in the connection. Having threaded the assembly, we pull out the rivet and get a very high-quality connection. But it can only be used inside the installation box.

We connect with a terminal block

A fairly popular method of connecting conductors with special terminal blocks, of course, is inferior to the screw method in terms of reliability, but makes it possible to connect wires as quickly and simply as possible. To do this, it is enough to remove the insulation from the connected ends of the wires by about 5 mm, insert them into the terminal block and tighten them with a screw. The aluminum soft wire should be tightened with little force.

Terminal blocks are convenient to use when connecting a chandelier to aluminum wires. Periodic twisting often leads to breakage of such wires, which is why almost nothing remains of their original length over time. In such cases, the block comes to the rescue, since only a short end of the wire is enough to connect with it. Docking with terminals is well suited for broken wires laid in the wall, when laying new wiring is difficult, and the remaining length of the wires is clearly not enough for connections by other means. But such pads can be plastered only when they are installed in a junction box.

We use spring clamps

Relatively recently, modified terminals with spring clamps have appeared. There are disposable express terminals, in which the wires are fixed without the possibility of their further removal, and reusable ones - with a lever that allows you to remove and insert the wires many times. The most popular are the so-called terminal blocks of the German company Wago with paste, specially designed for connecting copper with aluminum. Disposable ones allow you to connect single-core wires with a cross-section from 1.5 to 2.5 mm 2, and manufacturers allow their load up to 24 A. But professional electricians still do not recommend applying a current higher than 10 A to such terminals. Strictly speaking, it is better to use Wago terminal blocks only in lighting fixtures. Under increased load, their contact spring overheats, and the contacts between the conductors are critically disrupted.

Reusable express terminals are equipped with a pressure lever (usually orange color) and can connect wires with any number of cores and cross-section up to 4 mm 2. The maximum current for them is allowed up to 34 A. If terminals without levers simply snap into place, then for reusable ones you need to lift the lever up to the stop, insert the wire and smoothly lower the lever. As a result, the cores will be securely fixed. The cost of such a connection will be much higher than dubious twisting, but the work is done quickly and without the use of any additional tools.

Let's pay attention to the "nuts"

This practical type of connecting (branch) clamps is successfully used on the facades of private houses, when it is necessary to switch from aluminum overhead wiring to noble copper inside the house, since aluminum is prohibited from entering the house by the rules. This is where simple and reliable clamps in a rounded black polycarbonate case, popularly nicknamed nuts for their resemblance, come in handy.

Inside the case there are two steel dies and an intermediate plate, which we compress with screws after installing the wires. Dissimilar wires here do not conflict electrochemically - they are located on different “floors” of the clamp, without touching at all and honestly performing their current-carrying function. To get to the internal parts of the compressor, it is necessary to disassemble its body by removing the two retaining rings on the sides. In the dies we will see prudently stamped grooves for conductors of a certain cross-section. All that remains is to choose the right size depending on the cross-section of the cores so that the connection is strong and reliable.

You can also use branch clamps in cases where you do not want to damage the integrity of the cable. After all, it is known that the more connected breaks in the power circuit, the lower its reliability. And if it is a grounding cable, then it should not be severed at all. This is where reliable “nuts” will come to your aid. But special care must be taken when connecting copper and aluminum wires so that our stay in the house is safe and comfortable.

Electrical wiring may consist of wires of different materials: aluminum or copper, and in certain situations it may be necessary to combine them. The connection principle is no different from connecting identical wires, as well as the method of connecting copper and aluminum wires, which can be done in any way. However, a direct connection can hardly be called a reliable and durable connection.

This is because aluminum combined with copper oxidizes, and corrosion occurs, which spoils the quality of the connection. Different wires will heat up more and melt under the influence of temperature, so long-term use direct method is considered unsafe for humans due to the risk of fire.

Features of connecting different wires

Most people who have at least some connection with the electrical installation work, there is a known fact regarding the junction of copper and aluminum wires: it is not recommended to connect them. However, many people know about this, but they do it anyway: maybe they’ll hold out somehow.

As a result, it turns out that copper-aluminum twisting lasts a very, very short time. In the case where the connection is placed on outdoors or in a room with high humidity, the service life of such a pair is significantly reduced.

But situations in which it is necessary to connect copper and aluminum wires are far from uncommon. In particular, similar phenomenon It has practically become the rule when carrying out repair work in rooms with aluminum wiring.

In such cases, the solution to the problem will be specially made terminal blocks or bolt-type connections, through which contact between the copper and aluminum wires will be made. By using a clamped or bolted connection, direct contact between the two metals is eliminated. Let's consider the most popular options for such connectors, without delving into the design details.

Perhaps one of the earliest and most tested methods is to use a nut-type terminal connection. As you might guess, the reason for the name was the external similarity of the shape of the adapter to a nut.

The design of such a connection consists of three plates that clamp the wires together. The advantage of this type of connection is that there is no need to break the main line to install the outgoing wire. You just need to unscrew a couple of bolts, insert the desired wire between the plates, and then return the bolts to their place. The outgoing wire is allocated a place between the middle and third plate. Once it's in place, the connection is effectively complete.

In second place in popularity are spring-type express connection terminals. As the name suggests, their use provides maximum connection speed. Indeed, to make the connection you only need to strip the ends of the copper and aluminum wires, and then insert them into the holes and secure them.

Inside such a terminal block there is a special lubricant that prevents the oxidation of the wires. It should be noted that such adapters are most suitable for lighting circuits or other areas with low load. For example, using it in a power circuit can cause the contact to overheat and break.

Terminal blocks have also found quite wide application. It looks like a strip on which the terminal blocks are located. To connect a wire to it, you need to strip the conductor and then fix it in the hole using a mounting screw. Accordingly, another wire is inserted into another hole.

Let’s assume an option in which wires made of copper and aluminum will be connected with a bolted connection. To do this, it is necessary to place a special anodized washer on the bolt between conductors of different metals, which prevents direct contact of the materials.

It should be borne in mind that installation work should be carried out by specialists of the appropriate profile. In the future, you should regularly check screw and bolt connections: for aluminum wires this is twice a year, for copper sections - once every 2 years.

Why you can't connect copper and aluminum directly

To do this, you should strain your memory and remember the school course in chemistry and physics. To begin with, let's remember what a galvanic cell is. Simply put, a galvanic cell is a simple battery that generates electric current. The principle of its appearance is based on the interaction of two metals in an electrolyte. So, the twist between the copper and aluminum wire will be the same battery.

Galvanic currents quickly destroy the material. True, in dry air their appearance is excluded. And if you twist it to the socket, it will not fall apart in a few hours. However, later troubles with such wiring are guaranteed.

Over time, the materials from which the wires are made deteriorate, and along with this, the resistance constantly increases. If a powerful current consumer is connected to the outlet, the twist will begin to heat up.

Regular use of such an outlet increases the risk of fire. Therefore, connecting an aluminum conductor to a copper conductor is strictly prohibited. However, there are emergency situations, when making such a connection is simply necessary.

How to connect copper and aluminum wires

It's no secret that it is not recommended to connect copper and aluminum wires. But many, even knowing this, still neglect it, hoping for the Russian “maybe it will pass.” As a result, such twisting of a copper-aluminum pair will not last long. And if the connection is located outdoors or in a room with high humidity, then the lifespan of such a pair is several times shorter.

But quite often situations arise when we need to connect copper and aluminum wiring. Often this situation arises when repairing electrical wiring in houses where aluminum wiring is installed.

Special terminal blocks and bolted connections, through which we will connect copper and aluminum wires. By using clamp and bolt connections, we do not allow direct contact between the copper-aluminum pair.

Without going into too much design features terminal clamps, consider the most used of them. One of the old and proven methods of connecting wires is nut-type terminal connections. They got their name because of their external resemblance to nuts.

Connections of this type consist of three plates, between which the wires are actually clamped. One of the advantages of this type of connection is that to connect the outgoing wire, there is no need to break the main line. Simply unscrew the 2 bolts, insert a wire between the two plates, and screw the bolts into place. The outgoing wire is inserted between the middle and remaining plates. That's it, the connection is ready.

The next most popular are connections of the WAGO type. These connecting terminals allow you to connect wires made of aluminum and copper. It is enough to simply strip the wires by 10-15 mm, insert them into the hole in the terminal block, and that’s it, the next connection is ready for use.

The inside of the terminal block is filled with a special lubricant that prevents the wires from oxidizing. We recommend using this type of connection in lighting circuits. We do not recommend using these connections in power circuits, since a large load can lead to heating of the springy contacts, and as a result, poor contact.

Another popular connection is terminal blocks. Externally, they look like a strip with terminal strips. It is enough to strip the end of the wire, insert it into one hole and tighten it with a screw. The stripped end of the second wire is inserted into the other hole. These terminal blocks also allow you to connect wires of different metals.

Bolted wire connections. This type of connection can also be used if you need to connect copper and aluminum wires. When installing the connection, it is necessary to install a metal anodized washer between the copper and aluminum wire.

All installation work must be carried out by a specialist. All screw and bolt connections must be checked: for aluminum wires - once every six months, for copper - once every two years is sufficient.

How to solder aluminum to copper? This is theoretically possible, but practically it makes no sense. Such soldering requires special fluxes, more high temperature(there is a high risk of overheating the wires) and over time, electrochemical corrosion will develop at the junction.

Twist connection

Twisting used to be the most common option for connecting wires during installation. This is due to the simplicity of the action, which does not require high qualifications from the performer. However, when connecting wires made of dissimilar metals, this option is completely unacceptable!

When temperature fluctuations occur environment, a gap appears in the twist between the wires, due to which the contact resistance increases, the connection heats up, and the wires oxidize. As a result, the contact between the conductors is completely broken.

Naturally, such an event does not occur immediately, but if long-term reliable operation of the electrical network is required, then a twisted connection cannot be used; it should be replaced with another, more reliable one. A fairly reliable contact will be obtained if the copper conductor is first tinned with solder.

In this way you can twist wires with different diameters, even when one had many veins, and the other only one. If there are several cores, you must first coat them with solder, after which you will get one core.

The twist performed must contain at least three turns for thick wires, and at least five if the conductor diameter is up to 1 mm. Twisting must be done in such a way that the wires wrap around each other, and not one wire wraps around another.

If you connect a copper and aluminum conductor with a screw and nuts, you will get the most reliable contact, capable of ensuring conductivity for the entire life of the electrical wiring. This connection is easy to disassemble and also allows for the installation of many conductors. Their number is limited only by the length of the screw.

Any combination of metals can be successfully secured with a threaded connection. The basic rule is to avoid direct contact between aluminum and copper, and to install spring washers under the nuts. To properly organize a threaded connection, it is necessary to expose the conductors to a length that is four times the diameter of the screw.

If there is oxide on the wires, they are cleaned to a shine and rings are formed into which a screw can be inserted.

Then put it on the screw:
1. spring washer;
2. a simple washer;
3. conductor ring;
4. a simple washer;
5. ring of the second conductor;
6. a simple washer;
7. nut.

By tightening the screw, tighten the entire package until the spring washer straightens. To connect thin conductors, it is enough to use an M4 screw. With stranded copper wire, it is better to coat the ring with solder first.

Wago clamp connection

One of the new products on the electrical market are terminal blocks (article “Terminal blocks for junction boxes”), equipped with a Wago clamp from a German manufacturer.

They come in two versions:
• Disposable designs - the wire is inserted and after it cannot be removed.
• Reusable – there is a lever that allows insertion and removal of the conductor.

Spring blocks are convenient for connecting wires inside distribution boxes and connecting chandeliers. It is enough to insert the wire with force into the hole on the box so that it is fixed securely. The Wago block is a modern device for reliable and fast connection wires, but its use is more expensive than other options.

There is one unpleasant thing to consider about Wago pads. There are often fakes on sale that look very similar to the original, but are of much worse quality. Such clamps will not provide good contact, and sometimes it will not be possible to insert the wire into them. Therefore, you need to be very careful when purchasing.

Permanent connection

The permanent connection has all the advantages of the threaded method. Its only drawback is the impossibility of subsequent disassembly without destroying the riveted assembly, as well as the need to have a special tool. To connect conductors with rivets, they are prepared in the same way as for a threaded connection. The rings are made so that the rivet passes through them freely.

First, an aluminum conductor is put on the rivet, then a spring washer, then a copper wire, and finally a flat washer. The steel rod of the rivet is placed into the tool and squeezed until its handle clicks. The connection is ready. The reliability of the one-piece connection option is quite high.

In a similar way, aluminum wires damaged in the wall during repair are successfully spliced ​​by organizing an additional copper insert. It is imperative to reliably insulate the exposed parts of the resulting connection.

Electrochemical corrosion

Any electrician will confirm that copper and aluminum cannot be connected together, and this statement will be correct. What happens when two such different conductors touch? As long as there is no moisture, the connection will be reliable. However, there is always water vapor in the air, which becomes the culprit when the contact is destroyed.

Each conductor has its own electrochemical potential. This property of materials is widely used; accumulators and batteries are created on its basis. However, when moisture penetrates between the metals, a galvanic cell is formed that is short-circuited.

The current flowing through it destroys one of the metals in the connection. The easiest way out is to coat the copper wire with solder made from a mixture of tin and lead, then you can safely allow it to come into contact with aluminum, using any connection option! Connecting copper wires to old aluminum wiring is not at all difficult. The main thing in this process is to strictly follow the technological requirements.

How to properly connect copper and aluminum wire

You can connect copper and aluminum conductors using a screw, a nut and three washers, one of which is a spring one. Strip the connecting wires. Place a lock washer on the bolt, then a simple washer. Bend the aluminum core into a ring and put it on next. Throw on a simple washer. Place the copper wire bent into a ring. Now tighten the connection with the nut until the spring washer is completely straightened.

More convenient way connections of cores made of different materials - terminal blocks. This product has a plastic body, busbar and terminals. It is enough to strip the wire to a length of 5 mm, tuck it into the terminal and tighten the screw. Contact between two conductors is prevented by the design of the terminal block itself. The connection must be placed in a junction box.

The fastest and easiest way to connect wires is with Wago spring terminals. There are disposable and reusable products. As the name implies, the first ones can be used only once: insert the end stripped of insulation and you’re done. To change the network diagram, you will have to cut off the terminal strip and connect the wires with a different product. Reusable Vagos allow you to insert and remove wires multiple times.

Terminals for connecting aluminum and copper wires

If anyone still believes that there is nothing better for connecting wires than stripping their ends with a knife, twisting them, and wrapping them with electrical tape, then he is behind the times. Today there are already a lot of alternative devices that greatly facilitate the process of connecting wires, and at the same time are quite reliable. The times of twisting will soon disappear into oblivion, because they are being replaced by a variety of terminals.

What are the benefits of terminals? How, for example, can an aluminum wire be connected to a copper wire so that the connection is reliable and durable? It is absolutely forbidden to twist copper and aluminum, because then a galvanic couple is formed, and corrosion will simply destroy the connection, and no matter how much current passes through the twist, it will collapse sooner or later, and if the current is higher, the devices will be turned on and off more often, then The twisting resistance will increase faster, and over time the heating of the twisted area will become more and more.

In the end, this is fraught with fire, or, at best, with the smell of melted insulation. The terminals would have been saved in this situation, and things would not have come to the point of destroying the contact point.

The simplest solution is to install a polyethylene terminal block. Polyethylene terminal blocks are sold today in every electrical goods store and are not expensive. Inside the polyethylene frame there are several tubes (sleeves) made of brass located in a row, in which the ends of the connected wires are clamped with two screws. If desired, you can cut off as many tubes in polyethylene as you need and connect as many pairs of wires as you want.

However, not everything is so rosy, aluminum flows under screw pressure at room temperature, so periodically, once a year, the connection will need to be tightened. Otherwise, when it comes to connecting copper conductors, everything will be fine.

If you do not promptly tighten the aluminum wire that is loose in the terminal block, then the end of the wire that has lost its former contact will spark and heat up, and this can lead to a fire. You cannot clamp stranded wires into such a terminal block without auxiliary pin lugs, which we will discuss later.

If you simply clamp a stranded wire into such a terminal block, then the pressure of the screw on the thin wires, combined with rotation and an uneven surface, will lead to the fact that some of the wires will become unusable, and this threatens overheating. If the stranded wire fits tightly along the diameter of the sleeve, this is the most acceptable connection option, because there is less risk of breaking the connection.

As a result, we can conclude that polyethylene terminal blocks are good for single-core, and only for copper wires. If you need to clamp a stranded one, you will have to wear an auxiliary tip, which will be discussed later.

The next option for convenient connection terminals is terminals on plastic blocks. Such terminal blocks are also equipped with transparent covers that can be removed if desired. Fastening is very simple: the stripped end of the wire is inserted between the pressure and contact plates, and pressed with a screw.

What are the advantages of such terminal blocks? Firstly, unlike polyethylene terminal blocks, plastic terminal blocks have an even steel clamp; there is no direct pressure screws on the cores. The clamping part has a recess for the wire. As a result, these terminal blocks are suitable for connecting groups of both single-core and stranded wires. Why groups? Because this terminal strip cannot be cut like a polyethylene one.

Next are self-clamping terminals (so-called wire connectors), an example of which is the 773 series from WAGO. These are express terminals for quick, one-time wiring installation. The wire is pushed all the way inside the hole, and there it is automatically fixed there by a pressure plate, pressing the wires against a special tinned busbar. The clamping force is maintained at all times due to the material of the clamping plate.

These express terminals are disposable, but in principle you can pull out the wire by gently rotating it as you pull it out. But if you pull out the wire, then it is better to make the next connection in a new clamp, fortunately, they are not expensive, 10-20 times cheaper than terminal blocks.

The internal copper plate is tinning, and allows you to fix either aluminum or copper wires. The pressing force is maintained continuously, and the wire does not have to be pressed once a year, as happens with terminal blocks.

There is also a base lubricant inside quartz sand with technical petroleum jelly, for an abrasive action that removes the oxide film on the surface of the wire, preventing, thanks to petroleum jelly, its reappearance. These express terminals are available in transparent and opaque types. In any case, plastic does not support combustion.

WAGO branded express clamps are suitable for connections with an expected current of up to 25 A. Terminals from other manufacturers may suffer from heat, for example, the clamping force of spring contacts will weaken, so use only branded, well-proven terminals.

The 222 series from WAGO is suitable as reusable terminals. These are terminal blocks with lever clamps. Various types of wires can also be clamped here. The fastening process is simple: lift the lever, insert the end of the clamped wire, press the lever - fixation occurs.

This clip is reusable. When you lift the lever, the fixation is removed, you can pull out one wire and insert another. This terminal type is ideal for reconfiguring groups of conductors over and over again. Withstands currents up to 32 amperes without overheating. The design of the clamp is a bit similar to a disposable express clamp, the difference, again, is the ability to repeatedly switch the connected conductors.

Next, we will consider Scotch-lock type couplings. These are disposable couplings for wires designed for low currents. Using tape locks you can connect low-power telephone wires LED lamps etc. The essence of this fastener is a mortise contact.

Several wires, directly in insulation, are inserted into the coupling, then crimped using pliers. Structured cabling installers love duct tape. Scotch locks allow you to connect wires without having to strip them. The plate with cutting contacts simply cuts into the insulation and comes into contact with the conductor, with the core.

Scotch locks come in two and three cores. The peculiarity of such terminals is that they are cheap, waterproof, universal, and do not require stripping the ends, but are crimped with simple pliers. There is a hydrophobic gel inside the coupling to protect the contacts from moisture and corrosion. If it is necessary to replace the connection, the adhesive tape is simply cut out along with the pieces of wires, and a new one is installed.

When you need to connect several wires into one powerful unit, for example, simply to combine them, or to lay them on a terminal block, sleeves are used. The sleeves are most often used as universal ones; these are usually tinned copper sleeves in the form of tubes, or in the form of flat tips with a mounting hole.

The wires are inserted into the sleeve and crimped with a special tool - a crimper. A crimper is a crimping pliers. The great advantage of the sleeves is that such crimping does not create increased resistance at the connection point. Sleeves in the form of a flat tip with a hole are convenient when you need to secure a wire or bundle of wires to the housing with a screw. Simply select a sleeve of the appropriate diameter, crimp it, and attach the tip where you need it.

For connecting stranded wires, for combining single-core wires with stranded wires, or simply to fix them in terminal blocks, pin sleeve lugs are used. The stranded wire is conveniently inserted into the lug, the lug together with the wire is crimped, after which the stranded wire can be fixed in any terminal block, even a polyethylene one, without fear that the connection will be broken.

The decisive thing here is the correct choice of the diameter of the tip; it must correspond to the total diameter of the cores being crimped, combined into a bundle, so that the wires do not jump out later.
To crimp the pin terminals, you can use pliers or use a screwdriver and a hammer.

Why is it strictly forbidden to connect copper and aluminum wires directly? Aluminum is a highly oxidizable metal. This is the process of formation of an oxide film on its surface, which has a very high resistance, which naturally cannot but affect the conductivity of such a connection. Copper wires are less susceptible to oxidation, or rather, the oxide film on them has much less resistance than the oxide film on aluminum wires, so this affects the current conductivity very little.

Therefore, when connecting copper and aluminum wires, electrical contact actually occurs through oxide films of copper and aluminum, which have different electrochemical properties, which can significantly impede current conduction at this junction. On the street, under the influence of precipitation and the passage of electric current through the connection, the process of electrolysis occurs. The result is the formation of shells at the junction, heating and sparking of the contacts - an increased fire hazard of the joint.

There are the following options for connecting copper and aluminum wires:
1. Connections of copper and aluminum wires outdoors or indoors are allowed only with the use of special adapters - terminal blocks. A good solution for outdoor connections would be to use branch clamps for SIPs (“punctures”) with a paste that protects the surface of the wires from oxidation.
2. A good option is branch clamps (“nuts”) - the wires in them are connected through an intermediate plate inside, i.e. direct contact of copper with aluminum is excluded.
3. Indoors, it is advisable to use self-clamping ones with a paste that prevents the oxidation of aluminum wires. This is a quick way to connect copper and aluminum wires and does not require additional insulation. Due to their small size, self-clamping, screw or spring terminal blocks are very convenient for connecting wires in junction boxes.
4. Finally, if you don’t have a terminal block or “nut” at hand, there are different situations, it is much safer, instead of the usual twisting of copper and aluminum wires, to tighten them with a bolt and nut, placing a washer between them, which will prevent direct contact of copper and aluminum. In terms of contact reliability, such a connection will be inferior to manufactured terminal blocks or “nuts”, except that it is bulkier - it is more difficult to place it in a junction box. When using this method, it is also worth noting the need for good insulation of the connection.

When connecting conductors, many considerations must be taken into account. important factors: material of the current-carrying cores of the switched wires, their electrochemical compatibility or incompatibility (in particular, copper and aluminum), wire cross-section, twist length, network load, etc.

However, the regulatory documents regulating the rules for performing electrical installation work, in particular the PUE (Electrical Installation Rules), clearly state the prohibition on connecting wires using the twisting method: PUE: clause 2.1.21. Connection, branching and terminating of wires and cables must be carried out using crimping, welding, soldering or clamping (screw, bolt, etc.) in accordance with current instructions.

As you can see, the PUE allows only 4 types of wire connections, and twisting is not among them (except for cases when the twisting is preliminary, for example, before soldering or welding). Therefore, endless debates and discussions about the advantages or disadvantages of twists lose all meaning, because not a single fire inspector will approve an electrical installation if its wires are switched using twists.

Soldering or welding significantly increases installation time; this procedure is much longer than using terminal blocks - you need to remove the insulation from the wires, tin the wires, if it is soldering, connect the welder, then insulate all the wires. If it is necessary to reconnect the wires (for example, add a wire), there are also difficulties - removing the insulation, soldering (cooking) again. With terminal blocks everything is much simpler, but better contact is achieved using welding or soldering.

There are different types terminal blocks suitable for connecting electrical wires in an apartment or house.

Here are the main and most common among them:
• Self-clamping terminal blocks can have from 2 to 8 places for wires with a minimum cross-section of 0.75 mm 2 and a maximum of 2.5 mm 2. Capable of withstanding loads up to 4-5 kW (24 A). Such terminal blocks are very convenient to install, greatly reducing installation time - there is no need to twist and then insulate the wires. But they occupy more space in soldered boxes, in contrast to twisting, which can be given any shape, laid, bent in any way.
• Connecting screw terminal blocks are designed to connect wires to each other. Typically used for switching wires in junction boxes. Material: polyethylene, polyamide, polycarbonate, polypropylene. It is better not to use such terminal blocks for aluminum wires - in screw terminal blocks they are severely deformed and can be broken.

Insulating connection clamps (PPE) are used to connect single-wire conductors of wires with a total maximum cross-section of up to 20 mm 2 and a minimum cross-section of 2.5 mm 2. They have an insulated casing made of polyamide, nylon or fire-resistant PVC, so that the wires do not require further insulation, into which an anodized conical spring is pressed.

When connecting the wires, the insulation is removed from them (10-15 mm), collected into one bundle and the PPE is screwed onto them (clockwise) until it stops. PPE caps are very convenient and easy to install, but they are much inferior to terminal blocks in the quality of twisting, so it is still better to give preference.

Calculation of wire and cable cross-section

The material of manufacture and the cross-section of the wires (it would be more correct) are, perhaps, the main criteria that should be followed when choosing wires and cables. Why is the correct choice of wire cross-section so important? First of all, because the wires and cables used are the main elements of the electrical wiring of your home or apartment. And it must meet all standards and requirements for reliability and electrical safety.

The main regulatory document regulating the cross-sectional area of ​​wires and cables is the Rules for the Construction of Electrical Installations (PUE). Wires that are incorrectly selected in cross-section and do not correspond to the consumption load can heat up or even burn out simply because they cannot withstand the current load, which cannot but affect the electrical and fire safety of your home. The case is very frequent when, for the sake of economy or for some other reasons, a wire of a smaller cross-section than necessary is used.

So, speaking about the electrical wiring of a house or apartment, the optimal application will be: for “outlet” - power groups of copper cable or wire with a core cross-section of 2.5 mm 2 and for lighting groups - with a core cross-section of 1.5 mm 2. If the house has high-power appliances, for example, electric stoves, ovens, electric hobs, then cables and wires with a cross-section of 4-6 mm 2 should be used to power them.

The proposed option for choosing cross-sections for wires and cables is probably the most common and popular for apartments and houses. Which, in general, is understandable: copper wires with a cross-section of 1.5 mm 2 are capable of “holding” a load of 4.1 kW (current - 19 A), 2.5 mm 2 - 5.9 kW (27 A), 4 and 6 mm 2 - over 8 and 10 kW. This is quite enough to power outlets, lighting devices or electric stoves. Moreover, such a choice of cross-sections for wires will provide some “reserve” in the event of an increase in load power, for example, when adding new “electrical points”.

Calculation of the cross-sectional area of ​​aluminum conductors of wires and cables. When using aluminum wires, it should be borne in mind that the values ​​of the long-term permissible current loads on them are much less than when using copper wires and cables of a similar cross-section. So, for conductors of aluminum wires with a cross-section of 2 mm2, the maximum load is slightly more than 4 kW (current is 22 A), for conductors with a cross-section of 4 mm2 - no more than 6 kW.

Not the last factor in calculating the cross-section of wires and cables is the operating voltage. Thus, with the same power consumption of electrical appliances, the current load on the cores of power cables or wires of electrical appliances designed for single phase voltage 220 V will be higher than for devices operating on a voltage of 380 V.

In general, for a more accurate calculation of the required cross-sections of cable cores and wires, it is necessary to be guided not only by the load power and the material used to make the cores; You should also take into account the method of laying them, length, type of insulation, number of cores in the cable, etc.