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

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

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

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

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

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

Methods for connecting aluminum wires

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

Connecting aluminum wires using the compression method

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

	Connecting aluminum wires to each other using of this type connection carries with it one drawback. If you use conventional screw terminals, then using a screw you can completely or partially press down the soft aluminum core. This will either reduce or completely destroy contact.
	To exclude this option, the connection should be made through special contact nozzles made of brass. Brass has less elasticity and is more difficult to bend. Therefore, such attachments provide reliable contact and eliminate the possibility of damage to the wire.
	For bolted connections of aluminum wire, special lugs should also be used. They are attached to a wire or cable using the crimping method and then these lugs are connected using a bolted method.
	As for Wago terminals, everything is much simpler here. This type of connection cannot damage the wire, so such terminal blocks can be used without additional attachments. This somewhat compensates for their higher price.

Connecting aluminum wires using the pressing method

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

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

When 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 you know from a school chemistry course, there is always an oxide film on the surface of aluminum, formed as a result of direct contact with atmospheric oxygen.

It is not capable of conducting electric current through itself. In addition, the oxide film has quite high temperature 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.

TO additional characteristics A material such as aluminum is characterized by increased fragility and fluidity. In this regard, when connecting aluminum wires, care should be taken in advance that they are located so that the possibility of mechanical impact on this area is completely excluded.

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 here 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 using insulating tape. Professional electricians also recommend using a special heat-shrinkable 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.

The technology for making high-quality threaded connections of wires begins with removing the insulation from them 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 have a low current load, they can be connected to each other using terminal blocks. Even though 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.

This is not a very reliable connection compared to soldering, however installation work spends 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. To do this, take an aluminum tube of suitable diameter, twist the wires together, insert them into this tube and clamp them 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 quality permanent connection, must have special pliers, which 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 it has the largest area of ​​contact with the wires.
3. When the connection area has cooled down, it is advisable to treat it with sandpaper to remove sharp edges that could damage the insulating 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 large number 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 damp room type of 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.

When repairing electrical wiring in old houses, you may encounter a situation where you have to change large sections of wiring. However, in most cases, the old wiring is made of aluminum, and for replacement you only have copper wire. In general, connecting conductors from such different materials is strictly prohibited, but it happens that there is simply no other way out. Let's look at how to connect aluminum and copper wires so that there is no short circuit or fire.

Why you can't combine copper and aluminum

To do this, you should strain your memory and remember school course chemistry and physics.

To begin with, let's remember what it is galvanic cell. 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 the 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 are destroyed, and at the same time constantly resistance 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, emergency situations arise when making such a connection is simply necessary.

Let's look at several ways to connect aluminum and copper wire. These methods will help you successfully cope with a difficult task.

Twist

Is the most in a simple way install the wires. It does not require special knowledge or qualifications. However, it is not the most reliable connection method. Due to temperature fluctuations, the metal expands. As a result, a gap is formed between the conductors, increasing the resistance. After some time, the contact oxidizes and breaks down.

Of course, this will not happen within a year, but if the connection is to function long time, then you should think about other fastening methods.

The very principle of fastening using the twisting method is that both conductors wrapped around each other. For a better connection, the copper cable is tinned with solder. Stranded copper wire will have to be tinned.

Threaded connection

To connect copper and aluminum in this way you will need a pair of simple washers, one spring washer, screw and nut. This method is very reliable - contact between conductors will be ensured for many years. For this fastening, neither the cross-section of the wire nor its type - stranded or single-core - matters.

The insulation is removed from the end of the wire. The spring washer is put on the screw, then a regular washer is put on, then a ring of aluminum wire. It is supported by a simple washer. After which it is put on copper conductor, and then a nut is screwed onto the screw. She squeezes the entire joint tightly.

A multi-core cable must be tinned with solder before connecting.

Connection using terminal block

This is a modern method of wiring. Although it is slightly inferior in reliability to the threaded connection method , the method has its advantages:

• connection can be made very quickly;
• When connecting, you can get by with a small supply of wire.

Let us explain the last thing, it happens that a small piece of cable sticks out from the wall or ceiling. It is impossible to twist - there is very little wire. And the twist made on the ceiling will not last long; after some time the wires will simply break off. And the terminal block will hold both conductors with screws for a long time. Then the block completely eliminates contact between the two stripped conductors.

Installation is carried out as follows: the end of the wire stripped of insulation (about 5 mm) is inserted into the terminal hole of the block, after which the locking screw is tightened.

The terminal block must not be hidden in plaster or in a wall without a junction box.

Flat spring clamp and terminal block

This method appeared not so long ago. There are two types of such connection: disposable and reusable. There is a special lever for the last connection in the terminal block. Thanks to it, the wire can be inserted and removed several times. Terminal blocks of this type can successfully connect copper and aluminum stranded wires of various types.

Widely used for installing chandeliers and connecting wires in junction boxes. It takes some force to insert the wire into the hole in the terminal block. To pull out the conductor you will need to put in even more effort. For practical application It is better to use reusable models. In the event of an error, the connection can be quickly redone.

This installation is very simple. First with cable insulation is removed(approximately 10 mm.). Then on the reusable terminal block you need to lift the lever, insert the wire, and then return the lever to its original position. It's simple!

Rivet

The reliability is not inferior to a threaded connection and has its own advantages and disadvantages:

• such a connection is established very quickly;
• it is very durable, reliable and affordable;
• however, unlike threaded fasteners, this connection is disposable.

Installation is carried out using a special tool - a riveter. An aluminum wire is placed on the rivet, then a spring nut, followed by a copper wire and a flat washer. Then the riveter is used and the connection is ready.

It is worth mentioning that the connection area must be insulated.

Soldering

Is it possible to solder conductors made of different materials? It is quite possible if comply with certain conditions.

There will be no problems with soldering copper, unlike aluminum. An amalgam is formed on the surface of this metal, which exhibits amazing resistance in chemical terms. That is, the solder cannot stick to it. This phenomenon often surprises novice electricians.

To solder two different conductors, you should stock up on a solution of copper sulfate, a Krona battery and a piece of copper wire. The future soldering area is carefully cleaned on the aluminum wire. Then they drip on this place copper sulfate solution.

The copper wire is connected to the positive pole of the Krona battery and lowered into copper sulfate. An aluminum conductor is connected to the negative terminal of the battery. After a while, a layer of copper will settle on the aluminum, onto which you can solder the desired wire without any problems.

Conclusion

Once again, it is worth noting that any connection of wires must be insulated.

Connections can be placed in special distribution boxes.

If the connection is planned to be made with my own hands, then you should not resort to the soldering method. It requires certain experience and qualifications. It is better to use another of the above methods for connecting aluminum and copper conductors.

The most accessible and common methods were discussed in the article. However, if you have no experience in carrying out such work, it is better to turn to professionals.

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

What is the difficulty of connecting copper and aluminum wiring directly

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

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

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

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

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

Twist

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

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

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

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

How to make a twist correctly

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

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

Insulation of wire ends with caps with a cone spring

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

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

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

Threaded fixation

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

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

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

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

Connecting copper and aluminum wires with rivets

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

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

Connection with two steel strips

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

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

Terminal blocks and terminal boxes

Convenient and reliable connection method. The terminal block is a strip of insulating material in which sockets for wires are located. The wires are fixed in the sockets using clamping bolts. Important feature in our case, there is no contact between the wires. To connect copper and aluminum wires, you only need a screwdriver.

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

The advantages of this connection method are:

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

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

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

Connection with spring and self-clamping terminal blocks

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

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

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

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

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

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

Conclusions

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

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

Video on the topic

IN residential buildings, which were built in Soviet times, electrical wiring was carried out with aluminum wires. Professional electricians prefer to make a modern household network with copper wires. Therefore, whether we like it or not, we often have to face the problem of how to connect copper and aluminum wire. Don’t listen to those who tell you that you absolutely can’t do this. Of course, not all methods are suitable for this case, however, connecting electrical aluminum and copper wires is a completely solvable task. The main thing is to do everything correctly.

These two metals have different chemical properties, which affects the quality of their connection. But there were smart heads who figured out how to connect two conductors, while eliminating direct contact between them.

We will look at all existing options for how you can connect copper and aluminum wires, but first, let's figure out why this cannot be done with ordinary twisting and what is the reason for this incompatibility?

Reasons for incompatibility

The main reasons for the undesirable connection between these two metals lies in the aluminum wire.

the result of twisting copper and aluminum is overheating of the connection, melting of the insulation, the possibility of fire

There are three reasons, but they all lead to the same result - over time, the contact connection of the wires weakens, begins to overheat, the insulation melts and a short circuit occurs.

1. Aluminum wire has the ability to oxidize when exposed to moisture in the air. This happens much faster when in contact with copper. The oxide layer has a resistivity value greater than that of the aluminum metal itself, which leads to excessive heating of the conductor.
2. Compared to copper conductor, aluminum is softer and has lower electrical conductivity, due to which it heats up more. During operation, the conductors heat up and cool down many times, resulting in several cycles of expansion and contraction. But for aluminum and copper big difference in the magnitude of linear expansion, therefore, a change in temperature leads to a weakening of the contact connection, and weak contact is always the cause of strong heating.
3. The third reason is that copper and aluminum are galvanically incompatible. If you twist them, then when an electric current passes through such a unit, even with minimal humidity, a chemical electrolysis reaction will occur. This, in turn, causes corrosion, as a result of which the contact connection is again broken, and as a result, heating, melting of the insulation, short circuit, and fire.

Bolted connection

Bolted connection of aluminum wires to copper is considered the most affordable, simple, fast and reliable. To get started you will need a bolt, a nut, some steel washers and a wrench.

Of course, you are unlikely to be able to use this method to connect wires in an apartment junction box, because now they are produced in miniature sizes, and the resulting electrical unit will be very bulky. But if you still have boxes from Soviet times in your house or when you need to make a connection in a distribution panel, then this bolted method is best suited. In general, he is considered ideal option when it is necessary to connect absolutely incompatible conductors - with different sections, made of various materials, multi-core with single-core.

It is important to know that using the bolt method you can connect more than two conductors (their number depends on how long the bolt is long enough).

You will need to do the following:

1. Strip each connected wire or cable from the insulating layer by 2-2.5 cm.
2. From the stripped ends, form rings according to the diameter of the bolt so that they can easily be put on it.
3. Now take the bolt, put a washer on it, then a ring of copper conductor, again a washer, a ring of aluminum conductor, a washer and tighten everything securely with a nut.
4. Insulate the connection using insulating tape.

The most important thing is not to forget between aluminum and copper wires position the intermediate washer. If you will connect several different conductors, then you do not need to place an intermediate washer between the cores of the same metal.

Another advantage of this connection is that it is detachable. At any time you can unwind it and, if necessary, connect additional wires.

How to do it correctly bolted connection wires are shown in detail in this video:

Walnut clip

Another good way to connect copper and aluminum wires is to use nut clamps. It is more correct to call this device a branch compressor. It was already the electricians who nicknamed it “the nut” because of its external resemblance.

It is a dielectric polycarbonate housing, inside of which there is a metal core (or core). The core is two dies, each of which has a groove for a certain cross-section of the conductor, and an intermediate plate, all of which are connected to each other with bolts.

Such clamps are sold in any electrical goods store; they have different types, which depend on the cross-section of the wires being connected. The disadvantage of such a device is that it is not sealed, that is, there is the possibility of moisture, dust and even small debris getting in. For reliability and quality of connection, it is better to wrap the “nut” with insulating tape on top.

The process of connecting wires using this compression is as follows:

1. Disassemble the compression housing; to do this, pry up and remove the retaining rings using a thin screwdriver.
2. On the wires to be connected, strip the insulating layer to the length of the dies.
3. Unscrew the fixing bolts and insert the exposed conductors into the die grooves.
4. Tighten the bolts, position the die in the compression housing.
5. Close the housing and install the retaining rings.

A practical example of using a nut clamp is shown in this video:

Terminal block

Cheap and simple solution The question of how to connect aluminum wires to copper wires is the use of terminal blocks. Buying them now is not a problem at all; moreover, you can buy not a whole section, but ask the seller to cut it off required quantity cells. Terminal blocks are sold different sizes, depending on the cross-section of the conductors connected to them.

What is such a block? This is a transparent polyethylene frame designed for several cells at once. Inside each cell there is a brass tubular sleeve. From opposite sides, the ends of the wires to be connected must be inserted into this sleeve and clamped with two screws.

The use of terminal blocks is very convenient because you can always cut off exactly as many cells from it as there are pairs of wires that need to be connected, for example, in one junction box.

Using the terminal blocks is very simple:

1. Unscrew one clamping screw, thereby freeing one side of the sleeve for the conductor to pass into it.
2. On the cores of the aluminum wire, strip the insulation to a length of 5 mm. Insert it into the terminal, tighten the screw, thereby pressing the conductor to the sleeve. The screw should be tightened firmly, but do not force it too hard, so as not to break the core.
3. Do the same operations with the copper wire, inserting it into the sleeve from the opposite side.

Why do you have to do everything one by one? You can immediately unscrew two screws, insert the wires and tighten them. This is done to ensure that the copper and aluminum wires do not touch each other inside the brass sleeve.

As you can see, the advantages of terminal blocks are their ease and speed of use. This connection method is a detachable one; if necessary, you can remove one conductor and replace it with another.

Terminal blocks are not entirely suitable for connecting stranded conductors. In order to do this, you must first use ferrules that will crimp the bundle of cores.

There is one more feature in the use of terminal blocks. Under screw pressure at room temperature aluminum can leak. Therefore, periodic inspection of the terminal and tightening of the contact connection where the aluminum wire is fixed will be required. If this is neglected, the aluminum conductor in the terminal block will become loose, the contact will weaken, begin to heat up and spark, which may result in a fire.

How to connect wires using a terminal block is shown in this video:

Self-clamping terminals

It is even faster and easier to connect aluminum and copper conductors using self-clamping terminals.

The stripped conductors must be inserted into the terminal holes until they stop. There they will be automatically fixed with the help of pressure plates (it will firmly press the conductor to the tinned busbar). Thanks to the transparent housing of the terminal block, you can check whether the core has fully entered the terminal. The disadvantage of such devices is that they are disposable.

If you want a reusable clamp, use lever terminals. The lever rises and releases the entrance to the hole into which the stripped core must be inserted. After which the lever is lowered back, thereby fixing the conductor in the terminal. This connection is detachable; if necessary, the lever is raised and the wire is removed from the terminal.

Self-clamping terminals “WAGO” have proven themselves best in the electrical goods market. The manufacturer produces a special series of terminals that contain “Alu-plus” contact paste. This substance protects the contact junction between aluminum and copper from the manifestation of electrolytic corrosion processes. You can distinguish these terminals by the special marking on the packaging “Al Cu”.

Using such terminals is also extremely simple. The clamp itself indicates how long the insulating layer of the conductor needs to be stripped.

The advantages and disadvantages of using WAGO terminal blocks are described in this video:

Twist connection

Twisting of copper and aluminum wires is not recommended. If you cannot do without this, then first you should tin the copper conductor, that is, cover it with lead-tin solder. This way you will eliminate the possibility of direct interaction between aluminum and copper.

Do not forget that aluminum is very soft and brittle and can break even under minor loads, so twist it very carefully. Do not forget to properly insulate the connection, it is best to in this case use heat-shrinkable tubing.

We tried to tell you in detail whether it is possible to connect wires made of aluminum and copper, as well as how to do this efficiently and reliably. Choose the most suitable method for yourself, depending on where this connection will be switched and operated.