Is it possible to combine copper and aluminum? Connection of aluminum and copper wires

When you need to connect 2 different sections of wire with each other, it is necessary, in addition to high-quality contact, to obtain sufficient strength of the section where these wires are connected to each other.

If we take into account the regulatory documents that are in force in our country, then it is permissible to connect aluminum wires to each other using various methods:

1. Welding.
2. Crimping.
3. Soldering.
4. Connection using .

Despite the fact that all these connection methods specified in regulatory documents, are presented as universal ones, not every one of them will be suitable when working with aluminum wires.

First of all, this is due to the characteristics of a material such as aluminum, in particular, its technical characteristics. As is known from school course chemistry, there is always an oxide film on the surface of aluminum, formed due to direct contact with atmospheric oxygen.

She is not able to carry through herself electricity. In addition, the oxide film has quite heat melting - around 2000 degrees. This figure is significantly higher than the melting point of aluminum itself.

If you shoot this film mechanically, then it will arise again very quickly. It is worth noting that the presence of this film when soldering aluminum greatly interferes with the process of connecting the aluminum core to the solder. Also, it can cause difficulties when welding wires, because due to its presence various inclusions arise, due to which the quality of contact is greatly reduced.

Additional characteristics of a material such as aluminum include increased fragility and fluidity. In this regard, when connecting aluminum wires, care should be taken in advance to ensure that they are located so that the possibility of mechanical impact on the wires is completely excluded. this area.

It is worth noting that when connecting wires using a standard bolt clamp, it will have to be tightened periodically, since the metal will gradually flow out from under the bolt. As a result, the connection will become weaker.

Twist

Aluminum wires are often connected to each other using twisting. This is the simplest, but also the most dangerous method of connecting wires to each other.

The sequence of actions when using this technology will be as follows:

1. At first, remove the insulation from the wires approximately 4-5 cm on each side. It is most convenient to use a special tool designed specifically for this purpose.
2. Now the contacts should be degreased. To do this, you will have to wipe them with a cloth pre-moistened in acetone.
3. Sandpaper remove the oxide film from the surface of the metal, that is, clean it until a metallic shine is obtained.
4. Wires are crossed with each other, after which one of the cores is wound as tightly as possible onto the other using pliers.
5. Second wire screw onto the first one in the same way.
6. The twist should now be insulated with help insulation tape. Professional electricians also recommend using a special heat shrink tube or cambric. With its help, you can qualitatively protect the exposed area from negative impact external environment.

In principle, the technology is quite simple. You just need to remember that the wires need to be exposed at least 4-5 cm, and the twisting should not be done manually, but only with the help of pliers, so that the wires fit as closely as possible to each other.

If this is not done, the result will be loose contact, which can cause the area to become very hot. In turn, this effect causes a short circuit, and in some cases even a fire.

Threaded connection

This type of connection can be very reliable if done correctly. It is worth noting that aluminum has the greatest linear expansion, and therefore a gap appears between the connected wires over time, worsening their contact with each other. To prevent short circuits, you need to tighten these screws from time to time.

To get rid of this need, special washers with cuts or groovers are installed. They select the resulting gaps and increase the reliability of the connection several times.

The wires will need to be wound around the screw so that the area of ​​its contact with the contact pad is much larger. Professional electricians often do this: they flatten this ring on an anvil to increase the contact area.

Technology for performing high-quality threaded connection wires begins with removing their insulation to a distance equal to 4 screw diameters. The cleaned areas are degreased.

Then you need to bend their tips so that rings are formed.

The elements are put on the screw in the following sequence:

1. Spring washer.
2. Standard washer.
3. Ring of the first wire.
4. Another standard washer.
5. Ring of the second wire.
6. Screw.

This entire system is tightened until the spring washer is in a straightened state. In principle, if both wires are made of aluminum, then there is no need to place a standard washer between them.

We use terminal blocks

If aluminum wires If the current load is insignificant, they can be connected to each other using terminal blocks. Although appearance Although such products may differ greatly, the principle of their operation is the same.

The body of the pads is made of plastic or carbolite. It contains tubes with thick walls made of brass. There are threaded holes on the sides. The wires to be connected are inserted into opposite ends and secured with screws. It should be noted that you can insert as many wires into one brass tube as will fit there.

It's not too much reliable connection Compared to soldering, however, installation work requires several times less time. In addition to connecting conductors made of the same material, it is permissible to use different wires in terminal blocks.

Permanent connection

If you do not plan to disassemble the wire connection in the future, you can use the so-called one-piece methods. These methods are among the most reliable. It is advisable to use them, first of all, in hard-to-reach places.

One of the easiest methods of permanent connections is crimping. For this purpose it is taken aluminum tube suitable diameter, the wires are twisted together, inserted into this tube and clamped with press pliers. It is best here that the conductors fit as tightly as possible.

Only in this case will the connection be the most durable. It is worth noting: if the wires fit into the tube quite tightly, then you don’t even have to twist them together. On last stage the connection is isolated.

Today on sale you can find special tips for making this connection, which already have an insulating cap. It shrinks together with the tip and wraps around the wires, blocking any access to them.

To obtain a high-quality permanent connection, you need to have special pliers that will not bite, but only squeeze. If they are not available, then standard pliers will do just fine.

Soldering and welding

Soldering wires allows you to get a fairly high-quality and permanent connection. However, when connecting aluminum wires, you should be aware of the presence of an oxide film on them, due to which the solder will not adhere very well.

To prevent such a defect from occurring, you need to follow a certain sequence of actions:

1. Connected sections of wires treated with a special flux, which removes the oxide film from the surface.
2. Solder is processed as carefully as possible so that he has largest area contact with wires.
3. When the connection area has cooled down, it is advisable to process it sandpaper to remove sharp edges that could damage the insulation layer.
4. Wires must be insulated.

Soldering requires certain skills.

It should be said that this method has several negative aspects:

1. He has to be isolated.
2. The method itself is quite complicated, especially if you have to solder wires under the ceiling while standing on a stepladder.
3. If an error was made during the work, then fixing it will be quite problematic.
4. Leaves for work a large number of time.

Welding is somewhat reminiscent of soldering wires, but it is much faster. In order to obtain a high-quality connection, the electrode is brought to the connection area for only 1-2 seconds. Both ends of the wire are pre-treated with flux to remove the oxide film.

If you have no experience in this area, then you should initially practice on twists prepared in advance, but not connected to the system.

After completing the welding process, the twists are treated with a special solvent and varnished. The result is a high-quality connection that can last for a long period of time, since this method helps prevent overheating. Accordingly, such an area will need to be isolated.

Alternative options

flat spring clamp

The wires can be connected to each other using a rivet. In principle, this technology is similar to screw technology, only here a rivet is used instead of a screw. The end result is a permanent connection.

This connection is made quite simply: Both conductors are put on the rivet through a spring washer, then it is inserted into the rivet gun and the handles are pulled together until a click is heard.

There is also a special flat spring clamp. Such products are disposable and reusable, when the wire can be either inserted or removed. However, it should be remembered that such clamps are made of plastic, so it is not advisable to use them for currents exceeding 10 A.

Working with them is very simple: The wires are stripped and inserted into the clamp until they click. It is impossible to pull them out from there without using a special lever. It is also advisable to insulate this section of the wire.

Connection Features

Aluminum wires are best placed in special ones, to which they should fit in corrugated sleeves. This is especially important when the installation is carried out outdoors or in the case of wiring in a damp room such as a bathroom.

In general, when connecting aluminum wires that will function outdoors, care must be taken to ensure that moisture does not approach the connection areas.

Otherwise, short circuit will not be avoided. In this case, it is very convenient to use the technology of welding wires, since the subsequent use of a special varnish eliminates the impact of water on the joint, and the insulating layer will additionally protect against electric shock.

1. Professional electricians It is not recommended to connect aluminum and copper wires together. This is due to many reasons, the most important of which is the different resistance of metals. In addition, when interacting with each other, copper and aluminum oxidize very quickly, which causes heating of the wires and significantly worsens the contact. In addition, their rigidity is different, which significantly complicates the work.
2. You can, if necessary, combine certain methods of connecting wires. In particular, twisting goes well with soldering or welding. The result is a very reliable and permanent contact that will last for a long time.

Very often in old houses it is necessary to repair electrical wiring connect aluminum wires of old wiring with copper- re-laid.

Those who are unfamiliar with this topic and make repairs with their own hands simply stupidly twist them together and close them in a junction box, not understanding which headache they will acquire for themselves in the future...

This issue - copper and aluminum - is faced not only when installing internal electrical wiring, but also when replacing the input into the house

The point is that the wires overhead line(VL) are aluminum and if you are making a copper input cable, then you can’t just screw the cable core onto an aluminum wire!

But they do! How many times have I seen it myself... And then they are surprised - “Why is the light in my house blinking?!”

Yes, indeed, but why? Here's why.

A little chemistry. Aluminum is a very active metal, try soldering it simple method like a copper wire, nothing will work.

Aluminum reacts actively to air, or rather not even to the air itself, but to moisture in the air, quickly forming a thin film of oxide on its surface.

This film has high resistance to electric current - the so-called “transition resistance” appears at the junction of the wires.

But copper wire also oxidizes, but not as strongly and intensively as aluminum and the oxide film on the surface of copper has much less resistance to the flow of current.

It turns out that when copper and aluminum wires are connected, they come into contact with their oxide films.

Also, these two metals have different linear expansion, therefore, when the temperature in the room changes or the amount of current flowing through the copper-aluminum twist, the contact between them over time weakens.

The transition resistance in the twist already “slowed down” the electric current, and even weakening the contact further increased the value of the transition resistance.

This causes the twist to begin bask The further you go, the more the wire insulation heats up. It is destroyed by heat and can even burn.

You know how many houses have burned down due to faulty electrical wiring, and often it is the transition resistance or poor contact that is to blame.

Speaking of transition resistance.

This active resistance , that is, all the power on it is 100% converted into heat, just like in an iron, for example)))

To understand what it is, imagine that two wires are connected to each other nichrome wire and an electric current flows through them, which heats the nichrome red hot.

Inside the twisted copper and aluminum wire there is such a red-hot nichrome thread. Do you need it?!

Remember - transition resistance is an analogue of a red-hot nichrome thread.

So, enough chemistry. Now how to get out of the situation if necessary connect copper wire to aluminum.

The point here is this: the main thing is that these two metals didn't touch between themselves. Between them there must be a material neutral in relation to them, naturally conductive.

It can be lead solder, duralumin, steel, stainless steel, chrome coating.

By the way, it’s interesting - you can’t: zinc, carbon (graphite) and silver with gold and platinum.

Although I can’t imagine who can afford such a pleasure - connecting copper with aluminum through platinum)))

In this case, if there is a lot of money, it is better to make the wires entirely from platinum, the voltage losses will disappear completely)))

So, we combine copper with aluminum:

-Using terminal clamps;

-Bolt connection via washers

- Layer of neutral material

Terminal clamps are branch clamps (so-called “nuts”), wago, insulated terminal blocks, etc.

Well, a bolted connection is understandable - a loop is made on the wire, a bolt is inserted, and steel washers are placed between the copper and aluminum.

This connection is much more reliable than all terminal blocks and clamps, the only negative is the large dimensions, which take up a lot of space in the junction box.

I did this myself, for example, at the entrance to a house, when it was necessary to connect a copper cable with an aluminum input from an overhead line. Moreover, the cable was four-wire, and the network was 220.

Then I made two cable cores per phase and zero, connected them through a bolted connection with a piece of aluminum wire, and this piece was already connected by power engineers to the input.

The second year has already passed and there are no comments))) This is despite the presence of an electric stove in the house and everything else - electric titanium, kettle, iron, microwave, etc.

Now about the layer of neutral material. I mean lead-tin solder.

I’ll show you how to do this in the photo:

This good way out from a situation when there are no clamps at hand or you don’t want to use them, and the bolted connection does not fit into the box.

Then you need to cover the copper wire with solder and twist it with aluminum - the connection will be reliable! Although according to the PUE it is incorrect...

It requires either soldering-welding or terminal blocks-bolts, pure twisting according to the PUE is illegal...

Although I personally once opened the lighting distribution box in an old house - there was a copper wire going from the switch, and an aluminum wire to the light bulb. The twist was purely copper and aluminum without any terminal blocks, solder, etc.

So the state is as if it had just happened!

Everything is clean, no oxidation or scorching. I think this is because the apartment was always dry and besides, the junction box was tightly sealed in the wall, that is, air did not penetrate into it.

And therefore, the aluminum did not oxidize, and besides, the load on twisting was minimal - only one light bulb was hooked up.

Therefore, if a large current will pass through the copper-aluminum connection, then it is better to make a bolted connection as the simplest; soldering is more difficult.

But in this case, I would not recommend using a Vagov clamp; it is better to use other terminal blocks where the wires are at least clamped with a screw.

So now you knowhow to connect copper wire to aluminum and if you have to do this, I’m sure you will make the right choice!

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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 -- active metal, V normal conditions it is covered with an oxide film with 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 high humidity, the connection begins to collapse, 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 panel. 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 distribution boxes and installation of 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. Pads of this type are used when connecting stranded wires from 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;
• inserting the ends of the cables into the rivet;
• crimp (when using simple tool several compressions are performed over a short distance, when applying good tool compression 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 exposed to precipitation, high and low temperatures, 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.

Greetings! Today I will tell you how to connect copper and aluminum wires to each other so that they do not oxidize and the connection is as reliable as possible.

In general, in theory it has always been explained to us that connecting conductors with different resistivity, in this case, copper and aluminum are strictly prohibited, but no one said that this ban could be circumvented without breaking any rules.

Although theory tells us that such crafts are categorically excluded, even in everyday practice we increasingly have to build up (extend) aluminum with copper wire. For example, when, when replacing an outlet, a wire breaks off at the root. This happens everywhere, since the shelf life of aluminum electrical wiring has long expired, and aluminum wires are becoming increasingly difficult to find on the electrical goods market.

Now let’s look at several options for combining copper with aluminum:

The first option there will be a connection using bolt terminal blocks, this is one of the simplest and safe ways connections. And it is simple because you just need to insert the wires, stripped of insulation, into the terminal block sleeve and tighten them tightly with bolts. For two conductors with a cross section of 2 * 2.5 mm, 16 Ampere terminal blocks are suitable.

After the work done, everything looks quite neat and reliable.

This connection method has been practiced for quite some time and has not caused any particular complaints. But nevertheless, there are disadvantages here:

• When the bolts are tightened tightly, notches appear on the cores, which can later lead to the wires breaking off when bent. The serifs are very visible in the photo.

• and the second problem is that if the wire that needs to be extended is too short, then the ability to use a terminal block immediately disappears, since you simply cannot crawl into the problem area.

Second option we are associated with a certain innovation called Wago. These are self-clamping terminal blocks designed for connecting wires in distribution boxes, and also for extending wires, including aluminum and copper. There are a large variety of such terminal blocks.

But for extending aluminum wire with copper, this type of Wago is most suitable

All we need is to simply pull the clamps up, at a right angle, and insert the wires we need into the opened contacts, then snap the clamps back. We are guaranteed a tight connection. Today this is the most popular connection due to its speed and reliability. But unfortunately, if the break is in an inconvenient place, you again will not be able to use this terminal block.

If the situation is a little more serious, than a broken wire in a socket... For example, if there is a fire in your switchboard, and you need to efficiently build up the input (supply wires) wires, then we will need special connecting clamps

Compressions will ensure a tight connection and make it possible to withstand heavy loads. But if it is not possible to buy clamps, then for such loads, the correct bolted connection is quite suitable.

To increase the contact area, both wires must be bent into rings. The cores must be covered with washers on all sides so that when the wires are pulled together they are not pushed out. Be sure to tighten it at the end so that the screw does not unscrew over time.

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.

Elimination of 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 of 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. For major installation of power lines, they are used the following types connections:

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 easy to disassemble and is 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 highest cost of use. 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)