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How to connect aluminum and copper wires, methods and differences. Aluminum and copper wires - how to connect? Terminal blocks for connecting wires How best to connect an aluminum wire to a copper wire

There are many rumors about the connection of copper and aluminum wire. Some say that there is nothing wrong with this and give examples where such connections last for decades, while others say that they know from practice how quickly they break down. We will discuss who to believe and how to correctly connect such wires in our article.

First of all, let's figure out why you can't connect these wires together, and what you need to ensure that such a connection lasts for many years. To do this, we will have to dive a little into the theory and understand the structure of these metals.

Why you can’t connect copper and aluminum wire

To understand how to connect copper and aluminum wire, let's figure out what's wrong with such a connection. After all, there are several theories about the inadmissibility of such a connection, and almost all of them have a rational grain.

Like any other metal, copper and aluminum oxidize when exposed to oxygen. As a result, an oxide film forms on their surface. The copper oxide film practically does not interfere with the passage electric current, but the aluminum oxide film has a fairly high resistance.

If we connect copper and aluminum wires, no matter how much we want, the metals will interact. Aluminum is a more active metal, therefore, when moisture appears between the connection, which is in any case present in the air, the process of electrolysis begins, that is, aluminum ions are transferred to copper.

As a result, the aluminum conductor loses its mass. Voids and cavities form in it. They, in turn, also oxidize and further accelerate the electrolysis process. And the more moisture in the compound, the faster this process occurs.

As a result, we have an almost destroyed aluminum conductor. Its cross section is reduced, which means the current density increases. The current density increases, the metal begins to heat up more, and as a result, this will either lead to burnout of the aluminum at the junction, or, in the worst case, to a fire.

How to connect copper and aluminum conductor

But you can connect a copper wire to an aluminum one. To do this, it is enough to place a third material between these two conductors or completely eliminate the possibility of moisture penetrating to the point of contact of the metals.

• Let's look at both of these options. Let's start with the simplest one - placing a third metal between the conductors. Usually, an inactive metal is also chosen for this, so that we again do not have the electrolysis process. And usually the instructions recommend using brass for this.

• This is due to the fact that this material has fairly good electrical properties. It is chemically stable and interferes with the electrolysis process.
• Some suggest using regular steel or stainless steel for this. But you shouldn't do this. The fact is that these materials do not have very good conductivity. Therefore, when large currents pass through them, they will become very hot. As a result, we may get a fire again.

Aluminum wiring is often used in construction when laying power lines, including residential buildings. In order for such cables to be reliable and serve for a long time, you need to know the features of their operation.

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What is the difference between copper and aluminum wiring?

The main differences in electrical wiring modern apartments are as follows:

• duration of cable operation;
• the amount of power and maximum load on the wires;
• the value of electrical potentials.

Service life and operation of wiring

For aluminum cables The average service life in accordance with the standards specified in SNiP is about 10-15 years. Copper conductors last an order of magnitude longer - around 20-30 years. The overall service life of cables is affected by their operating conditions. If wiring is carried out regularly high load, as well as aggressive external conditions, then the service life will be significantly shorter.

This means the following impacts:

• Sun rays;
• low negative temperatures;
• rain and moisture (during fog, for example);
• high temperatures.

If all SNiP requirements are met and the power supply to the network is not critical, then the service life of the wiring will be up to one hundred years. Moreover, much in this matter depends on correct use electrical equipment and machines.

The channel “Sami with a Mustache” spoke in detail about the need for replacement electrical cables and about their service life.

A cable with a core cross-section of 2.5 mm can withstand a current of up to 25 amperes. If a 16 A circuit breaker is installed in the apartment, it will break out before the wire heats up to a critical temperature at high power. Automatic equipment rated at 40 amps will work, but the cable will melt if a current of 32-35 amps passes through it.

Table of electrochemical potentials (mV) arising between connected conductors

Basic standards values technical parameters when connecting cables are given below.

Material: copper.

			Voltage parameter 380 V
	Current parameter	Power value	Current value	Power level
1,5	19	4,1	16	10,5
2,5	27	5,9	25	16,5
4	38	8,3	30	19,8
6	46	10,1	40	26,4
10	70	15,6	50	33
16	85	18,7	75	49,5
25	115	25,3	90	59,4
35	135	29,7	115	75,9
50	175	38,5	145	95,7
70	215	47,3	180	118,8
95	260	57,2	220	145,2
120	300	66	260	171,6

Material: aluminum.

Wiring connection cross-section size	Voltage value is 220 volts		Voltage parameter 380 V
	Current parameter	Power value	Current value	Power level
2,5	20	4,4	19	12,5
4	28	6,1	23	15,1
6	36	7,9	30	19,8
10	50	11	39	25,7
16	60	13,2	55	36,3
25	85	18,7	70	46,2
35	100	22	85	56,1
50	135	29,7	110	72,6
70	165	36,3	140	92,4
95	200	44	170	112,2
120	230	50,6	200	132

Pros of aluminum

This material for laying wiring has certain advantages:

1. Ease. Compared to other materials, aluminum wiring has significantly less weight.
2. Resistant to corrosion. Aluminum material is less susceptible to destructive effects. When this type of conductor interacts with air, oxidation occurs. But due to the formation of a film on the cable structure, the material is reliably protected from further destruction.
3. Price. Aluminum itself inexpensive metal. So he found wide application in the manufacture of power conductors. Thanks to its low weight and affordable price aluminum is considered the best option for laying the air inlet.
4. Large selection of conductors various types. If, when renovating a room, it is necessary to install and connect power cables, then you can use SIP type products. For implementation internal wiring Options APBPP, APPV, APV are used.

The Chipdip channel spoke about the features of using such cables, as well as their advantages.

Disadvantages of aluminum

This material has both pros and cons, they are considered in accordance with the reviews:

1. Low level of electrical conductivity of aluminum wiring. For this material this figure is 38*106 S/m. If compared with copper conductors, then this value will be 59.5 * 106 S/m. As a result, the latest cables with a diameter of 1 mm2 will be able to carry almost twice as much current as aluminum products.
2. Low flexibility of conductors. Because of this, the use of aluminum cables is not allowed in places where the wires will be subject to repeated bending. To maximize the integrity of the product, the laying route must be straight. It is important that during use the conductor is minimally exposed to various mechanical influences.
3. Aluminum cables are characterized by reduced fluidity properties. Due to constant mechanical and thermal influences, such a conductor will lose its shape over time. As a result, this will negatively affect the twisting area and contact connections.

User Vladislav Rezanov spoke about residential electrical wiring made of copper and aluminum, as well as the disadvantages of both materials.

Need to replace wiring

It may be necessary to change cables in an apartment or house in the following cases:

1. The period of use of the wires came to an end, which led to the destruction of the insulating layer. As a result, the old cable overheats and melts, especially when it comes to aluminum conductors.
2. When carrying out electrical installation work. If the quality of the electrical network is satisfactory or worse, it is recommended to change it.
3. As a result of cable breakage. This process will cause the appearance of areas where current leaks will occur.
4. There is a possibility short circuit. This is usually due to broken conductors and destruction of the insulating layer.
5. A section of cable caught fire. This will be indicated by sparking, as well as a burning smell.
6. The automatic switch or protective shutdown device often trips.
7. The electricity in a house or apartment is constantly cut off, for no apparent reason.
8. More powerful electrical equipment is being installed in the room. If the old wiring is not designed for it, it is recommended to install a new one.

Is it possible to connect copper and aluminum wiring?

When these two materials come into contact, a chemical reaction occurs, which ultimately leads to deterioration in quality electrical contact. As a result, the junction of the conductors will become very hot due to the passage of current. As a result, this can lead to cable ignition and even fire. If there is high humidity in the room, this process goes much faster. This is due to the fact that a thin film appears between the conductors, which is characterized by increased resistance, and therefore leads to heating and breakage.

If you correctly approach the process of connecting a copper conductor to an aluminum conductor, then all these problems can be avoided.

In any case, you should completely replace the old cables with new ones. The wiring must have the necessary load capacity, which will correspond to the current consumption of electrical equipment. If it is not possible to immediately replace all cables, then you can resort to a partial replacement process. Then you will need to correctly connect two different types of conductors.

Methods for connecting different wires

To connect cables from various materials, you can resort to one of several methods:

• by using terminal blocks;
• by twisting with tinning of a copper conductor;
• by carrying out a crimping procedure;
• bolt connection method;
• threaded connection.

Threaded connection of two different cables using a bolt Using a terminal clamp to secure conductors Crimping method using special sleeves

Terminal blocks

This connection option is considered quite popular, but cannot boast of maximum reliability. However, it has many advantages. By connecting using terminal blocks, you can quickly and reliably connect aluminum and copper conductors to each other in any combination. To complete the task, you do not have to form rings at the ends of the cables, or isolate the connection point. This is due to the fact that the terminal clamp device prevents the bare parts of the cables from touching each other.

The use of such blocks is advisable when connecting lamps to short aluminum cables that come out of the wall or ceiling. As a result of repeated twisting, such conductors lose flexibility and break, which leads to a decrease in their length. If the cable extends 1 cm from the surface of the wall or ceiling, using a terminal clamp will ensure a high-quality and reliable connection.

The connection procedure is performed as follows:

1. The end of the conductor is stripped of the insulating layer by approximately 5 mm. To do this, you can use a stationery knife or a special device.
2. The end of the cable is then installed into the hole in the terminal clamp.
3. The conductor is fixed by tightening the bolt on the block. When performing this task, it is important that the effort be significant.

Hide terminal blocks under plaster without installation in the distribution panel is not allowed.

The Radio Amateur TV channel spoke in detail about the use of such fixation elements.

Tinned copper wire

This method is simple to implement. Its implementation does not require the user to use additional devices other than a soldering iron. But practice shows that the twisting method is unreliable, especially if the wires are made of different materials. This is due to the fact that various metals can change their sizes as a result of temperature changes. This leads to the fact that over time a gap forms at the connection point, which increases the value of the contact resistance.

As a result, heat will be generated, the conductors will oxidize, and their connections will be damaged. When performing this task with twisting, one must take into account important rule— the cables must wrap around each other. If one conductor is straight, and the second wraps around it, then the connection point will become unreliable - this option is not suitable. The implementation of this method is allowed when connecting cables with different diameters. It is possible to connect conductors with one or several cores, but the latter must be tinned in advance using solder, this will make it single-core.

When implementing a task, the number of turns must be chosen taking into account the diameter of the cable. If this value is 1 mm, then at least five coverages must be made. When the conductor is thicker, it is necessary to provide at least three turns.

User Valera shevchenko spoke about the nuances of tinning and clearly showed the procedure for soldering cables.

Crimping method

This connection method involves the use of sleeves. Its implementation is the most expensive due to the need to use special devices. In practice, installing a sleeve allows you to ensure reliable and high-quality contact that will last for many years. In industrial plants, this method is often implemented with wires connected to high-voltage, high-power equipment.

To complete the task, you will need aluminum-copper sleeves, as well as special tools.

Features of the choice of sleeves:

1. If you are connecting conductors of different cross-sections, then you need to select the right connecting element. The sleeves may have different diameters and the size of the inlets.
2. The connecting elements must have a certain length. The sleeves do not have a reserve, so they cannot be cut into several parts to save money. When connecting two conductors, crimping must be done twice with opposite elements. If you cut the sleeve, this will not work, resulting in poor quality contact.
3. The use of connecting elements is allowed when connecting single-core and multi-core cables. The main nuance is to choose a sleeve with the necessary input parameters. Since conductors usually have different cross-sections.

The Electrician's Advice channel talked about the choice of sleeves and the implementation of the method of crimping conductors in practice.

Bolted connection

This option will allow you to ensure high-quality contact using available materials, without the use of special devices and tools. To complete the task, you will need a regular bolt with two or three washers and a nut. The main nuance is to separate the two various metal. This type of connection is recommended to be implemented in a distribution panel.

The procedure is performed like this:

1. A layer of insulation is removed from the conductor to a length corresponding to four bolt sizes.
2. The condition of the veins is diagnosed. If they are acidified, then it is necessary to clean the metal component until it shines. Rings are made at the ends of the veins.
3. Then a regular spring washer is installed on the bolt one by one. A core ring of one conductor is mounted on top.
4. A regular washer is put on. Then a core ring of the second cable, another washer element and a nut are installed. The latter is used to tighten the bolt. Tightening is carried out until the spring washer is completely straightened.

In the case when the size of the conductor core is no more than two millimeters, M4 class bolts are used. If two cables made of the same metal or aluminum and copper are connected, and its end is tinned, the use of a washer between the rings is not necessary. In the case when a copper conductor with several cores is used, it must be tinned in advance using solder.

Aluminum Wiring Connection

To complete this task, you can use all the methods described above. It is also possible to use special spring connections. To do this, stripped conductor cores are installed in the holes of the terminal blocks. Due to the presence of a spring in the device, the consumer does not need to re-tighten the contact. On sale you can find different types terminal blocks, which are divided into disposable and reusable.

The former are used to connect cables without the possibility of their subsequent disconnection. The end of the core is installed in the hole on the terminal, where it is secured. To disconnect, the wire will have to be cut. If we talk about reusable devices, they can be used several times. To fix the conductor, you need to lift a special lever, install the stripped end of the cable into it and lower the fixing element back.

To connect aluminum cables, you can resort to the soldering method:

1. The process of completing the task is not easy. Its difficulty lies in removing the oxide from the surface of the conductor. Abrasive materials are used. But when removing the oxide, you cannot overdo it, as this will lead to the appearance of a new film, but you need to reduce its thickness.
2. Then the two ends of the conductors are fastened using flux and solder. As a last resort, experts recommend using COP or other similar options.
3. To work with aluminum, you will need flux F-59A, F-61 or F-54. In their absence, similar compositions are used. This flux allows you to effectively remove the oxide film.
4. The solder must be scraped across the surface of the conductor. This will make the oxide removal process easier. If flux is not used when performing a task, then the solder must be used more intensively.

Is it possible to twist aluminum wires?

Connecting these types of cables to each other is not prohibited. Their connection to each other is more secure than copper and aluminum conductors.

Features of connecting wires on the street

When laying cables outdoors, you need to consider negative impact external factors on cable line. Icing and exposure to rain will reduce the service life of wires. That's why installation work laying and connections must be carried out in sealed and closed structures. The wiring will be as resistant to impact as possible low temperatures and the rays of the sun. If connections are made on poles or on roofs, it is recommended to use special piercing clamps.

The Electrician's Tips channel spoke in detail about the implementation of a hermetic connection of two conductors.

Is it worth replacing old aluminum wiring or not?

If the wiring is outdated, then it must be replaced. Cables that were installed 20 or more years ago will not be able to withstand a load of modern houses and apartments.

This is due to the use of more high power as a result of installing the following household appliances:

• boilers;
• microwaves;
• computers;
• air conditioners.

Briefly, the wiring replacement algorithm looks like this:

1. At the first stage, you need to prepare for electrical installation work. It is necessary to completely study the room where the wiring will be installed. The condition of the components should be assessed and the load on the electrical network should be calculated.
2. Then the compilation is made technical documentation, project. It is recommended to entrust this task to qualified specialists. When implementing it, the parameters of household equipment and appliances that are installed in the future are taken into account. Places for installation of electrical points and lighting devices are marked.
3. A full estimate is drawn up, as well as the purchase of materials that will be required to complete the task. Experts advise purchasing wires with a rigid and solid core. Cables for sockets are selected with a cross-section of 2.5 mm2. To connect lighting equipment, conductors rated at 1.5 mm2 are laid. To provide quality work powerful devices, you will need cables with a cross-section of 4 mm2.
4. We must not forget about additional equipment. We are talking about automatic devices, mounting boxes, RCD and other components.
5. The next stage is laying the cables. If carried out closed installation, then it is necessary to perform gating of the walls. When implementing open wiring, the cables are laid in special channels. At this stage, the installation of electrical equipment is carried out. We're talking about switches distribution boxes, sockets.
6. A new power line is being connected; the ends of the conductors need to be connected. Before closing the electrical channel after connection, you need to check the operation of all devices. If testing shows problems, it is easier to get rid of them immediately.

User Electroconductor 116 clearly demonstrated the procedure for replacing wiring in three-room apartment.

Security measures

Tips for safely connecting two types of cables to each other:

1. If the connection is made by soldering, then you need to remember one thing. Tinning copper is a simple process. In the case of aluminum, you will have to use special solder.
2. When performing the task, strong squeezing of the cable connections is not allowed. Some consumers do not understand why this cannot be done. This leads to deformation and damage to the conductors, resulting in possible loss of current.
3. When making connections, you must follow the markings and select the correct terminal clamps. The cross-section of the core is taken into account, as well as the installation method - in the house or on the street.
4. It is not allowed to use the conventional twisting method when connecting conductors made of different materials. This option is unsafe and will lead to heating and fire.

Video “A Practical Guide to Connecting Wires”

The Electrician's Tips channel talked about ways to connect cables made of different materials and clearly showed the process of performing this task.

We have long ago and everywhere 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 customary 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 second 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 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. At correct execution threaded connection It 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 works well for connecting wires with different numbers lived and various 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: remove the sheath from the cable 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 it is used blind rivet, 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 V 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 internal parts compression, it is necessary to disassemble its body by removing the two locking 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.

I know what the topic is among themselves is as old as the hills, but I would like to touch on this topic and consider ways to connect wires from different materials.

When renovations begin in an apartment, the question arises of repairing or replacing (full or partial) electrical wiring. Someone wants to move sockets or switches, or add new ones. In this case, you cannot do without connecting the wires. This is where the fun begins.

As you know, in old houses built in the Soviet Union, all electrical wiring was made with aluminum wire. Why? Aluminum cheap material, has good conductivity, chemical resistance, lightweight, so there were no difficulties with installation. True, the load in the apartments was small. With the development of technology, various powerful devices appeared, and the use of aluminum wires became impractical. Therefore, copper wires began to be used in apartments.

When repairing or replacing electrical wiring, it is necessary to use copper wire. It's good if it happens complete replacement wires But what if we only partially change the wires? After all, then we need to connect the aluminum wire with the copper wire to each other.

Previously, aluminum wires were connected using conventional twisting. Then they began to connect copper wires as well. But you can’t connect copper and aluminum wires by twisting them,

Although many electricians used to do this (and still do it now). Moreover, at present, twisting is generally prohibited by the rules (PUE). Someone will say that this paragraph of the rules does not directly prohibit twisting, but twisting is not specified. as one of the ways to connect wires, therefore it is considered that twisting is PROHIBITED!!!

Why can't you connect wires by twisting?

Each material has such a property as linear expansion - a change in linear dimensions with temperature changes. Copper and aluminum have different coefficients of linear expansion, therefore, when current flows through the twist, over time the contact between the wires weakens, the gap between the wires increases, the resistance at the contact point increases, the contact point heats up, which in the future can lead to destruction of the contact and burning of the insulation wires In the photo on the left you can see how the electrical tape on the aluminum-copper twist has been burnt. And on the right is the same twist after removing the burnt electrical tape.

And now it’s not far from disaster – a fire. Therefore, if an electrician offers you connect aluminum and copper wires using a twist and wrapping it with electrical tape, then drive him out of your apartment by the neck.

How to properly connect aluminum and copper wires to each other?

There are several ways to connect wires made of different materials:

Each of these methods has pros and cons. Let's consider each of them separately.

Bolted connection

For such a connection you will need a bolt and nut, several steel washers that will need to be placed between the wires, and electrical tape to insulate the connection. To do bolted connection, you need to make rings at the ends of the wires of such a size that they will accommodate the bolt with which the connection will be made. Then we assemble our structure, placing washers between the wires, and using wrenches we tighten the nut and get an excellent connection, which is also very reliable. One drawback: the connection is bulky and very difficult to push into the junction box.

Screw connection

This type of connection is made using screw terminals (terminal blocks),

which are isolated from each other. Screw connections of wires are usually found in lamps and chandeliers. Screw terminals are brass tubes with a plastic housing. The tubes have two screws for fastening the wire. In this way, you can connect wires not only from different materials, but also homogeneous ones.

Disadvantages of this connection:

— the plastic housing of the terminal block may burst, and the insulation will accordingly be damaged;

- may burst on its own brass tube. This happens. When you tighten the screws too hard;

— the screw can crush the wire when tightening, and it will subsequently break off. Moreover, this applies not only to aluminum, but also copper wires;

- You can break the screw when tightening. Then there is no need to talk about good contact;

- if you apply insufficient force, you may not tighten the screw and get poor contact.

Screw terminal blocks are convenient to use as a temporary connection or for connecting lamps. They also help out if you need to repair a broken wire whose tip is sticking out of the wall.

Connection using WAGO terminal blocks

WAGO terminal blocks appeared in Russia not so long ago, although the first screwless terminal blocks were developed in Germany in 1951. There are many self-clamping WAGO terminal blocks, but we are only interested in those that are suitable for connections of aluminum and copper wires.

These are special terminals of gray or black color, inside of which there is conductive paste. This paste prevents oxidation of aluminum wires. These terminal blocks are disposable, although they can be reused if desired. However, the quality of the connection deteriorates.

WAGO self-clamping terminal blocks have many advantages:

• fast and accurate installation;
• the connection does not need to be isolated;
• You can connect wires from different materials and different sections;
• the connection can easily be redone if necessary;
• connection with WAGO terminal blocks is less than twisting.Therefore, it is easier to fit in the distribution box (see photo);

• can be used to connect multiple wires (2 to 8)

The only drawback of these terminals is their cost. Therefore, many electricians use screw terminal blocks and even twist them. But I believe that this disadvantage is compensated by the advantages, and there are significantly more of them.

My colleagues and I, who carry out electrical installation work in Syzran, use exactly WAGO terminal blocks for connecting aluminum and copper wires.

If you need someone who will do everything correctly and accurately, then you can contact me using the information on. You can also ask questions in the comments to this article. I will be happy to answer them.

Modern electrical wiring in an apartment or house it is carried out only with copper wires, as the PUE says. But in old houses, wiring was most often done with aluminum wire, and a situation arises in which it is necessary to connect 2 wires from different materials. And in this article you will learn how to connect copper and aluminum wire different ways.

Is it possible to twist copper wire with aluminum

Let's start with the fact that is it possible to connect aluminum wires with copper wires, and will such a connection not lead to a fire? The answer is yes, you can. But let's first get acquainted with these materials.

If you ask yourself which wiring is better, copper or aluminum, then the choice is, of course, copper. This comes out technical specifications copper, the cross-section of aluminum wire under the same conditions has to be taken larger. There are also disadvantages: copper is more expensive. It is easier to distinguish copper wire from aluminum by color; copper has a reddish tint, aluminum is gray and white.

Having looked at the electrical performance of metals, the question of which conducts current better disappears. Here's some information:

• Resistivity: copper – 0.017 Ohm mm²/m, aluminum – 0.028 Ohm mm²/m.
• Heat capacity: copper - 0.385 J/gK, aluminum - 0.9 J/gK.
• Elasticity of the material: copper – 0.8%, aluminum – 0.6%.

So why can’t you twist copper and aluminum wires, because twisting, especially with a small cross-section, is the cheapest option in terms of both money and time? The thing is that when these materials are connected they create a galvanic couple.

Galvanic pair - 2 metals various kinds, the connection of which will lead to increased corrosion. Copper and aluminum are just such a galvanic pair. The electrochemical potentials of the two metals are too different, so rapid corrosion will increase the resistance at the junction and subsequent heating. More details about the compatibility of metals are indicated in GOST 9.005-72. Below is a table with some data on metals:

Galvanic compatibility of meltals

You can achieve high-quality contact between two conductors in different ways (soldering, using a simple terminal block, more expensive WAGO terminals, or an ordinary bolt and nut).

Wire connection

Connecting aluminum and copper wires to each other requires technological solutions, simple twisting is not enough here.

Methods for connecting conductors with different electrochemical potentials:

• By soldering. But not simple soldering.
• Using simple terminal blocks or expensive WAGO. There is no point in saving money here, and if the question is how to properly connect copper and aluminum wires, then it is better to take WAGO. The advantages of this manufacturer will be described below.
• Using a bolted connection, which has many advantages: low cost, simplicity and the ability to work with wires large section.
• Crimping with sleeves. Requires specialized tools.

WAGO

WAGO clamps for joining aluminum and copper are very popular, as they are very convenient to use:

1. Click the pressure plates to the side.
2. Insert the wires into the holes.
3. Place the plates in their places and clamp them.

WAGO terminals for connecting copper wire to aluminum are an excellent solution

But now WAGO is casting doubt on its reputation. According to numerous reviews, the spring contact weakens, which leads to burning of the terminal block and its rapid replacement.

Twisting wires

Twisting aluminum and copper wires was previously mentioned as a very unreliable connection method, but sometimes this is the only way to quickly restore power supply.

A couple of tips before twisting:

• Before twisting, the copper wire should be well tinned.
• The amount of twist must be at least 5 turns.
• After work, the joint must be protected with several layers of insulating tape or heat shrink tubing.

Soldering copper to the terminal block

You can solder copper and aluminum together. If everything is clear with copper, then for soldering aluminum you need a special flux. Some electricians simply solder copper wire to the terminal block.

Flux for aluminum

Terminal blocks

List of tools and Supplies Electrical includes terminal blocks. Terminal blocks are copper or brass coated with a layer of nickel, designed for wires of a certain cross-section and covered with a layer of insulating plastic. The wires are secured with 2 small screws.

When connecting copper and aluminum terminal blocks, the locking screws must be properly tightened. If you overtighten them, you can damage the aluminum conductors, which will not have a very good effect on further exploitation electrical wiring. Therefore it is necessary to find golden mean: do not tighten too tightly, but achieve good contact.

Bolted connection

If you don’t have a terminal block, soldering iron or WAGO at hand, and the cross-section of the wires is large enough, then you can achieve high quality with an ordinary bolt.

To connect two wires you will need: a bolt, a nut, 3 washers. Sequencing:

1. Make rings at the ends of the wires, the same diameter as the bolt. For convenience, it is better to use round nose pliers.
2. Place the rings on the bolt in such an order that they are between the three washers.
3. Tighten the nut and check the quality of the connection.
4. Apply several layers of insulating tape.

Bolted connection of aluminum and copper

Nut connection

"Nut" is another type of terminal block, most often used for branching large-gauge wires. It consists of 2 copper plates placed in a plastic case.

Copper and aluminum wire, as well as a branch wire, are placed between the plates. But you can simply use the “nut” as a connecting element. After laying the conductors, the plates are tightened with bolts. As insulation, a plastic case is placed over the entire structure, consisting of two halves, for fastening which standard screws are used.

Walnut connection is suitable for all types of street connections and branches

Crimping

For this method you will need special crimping pliers and sleeves. The principle of connecting wires with a sleeve is very simple: an aluminum wire is inserted into the sleeve on one side, a copper wire on the other, and the sleeve is crimped on both sides with pliers. There are sleeves for wires with a large cross-section - from 16 mm 2 to 300 mm 2, but in this case you will need a special Hydraulic Press. The only drawback of crimping is the high cost of the tool.

Special sleeve for connecting aluminum and copper

Lubrication

To improve the quality of contact, you can use a special lubricant or paste. Usually this is quartz vaseline paste. It is usually used to improve the connection of aluminum wires.

But this paste can be used for all types of connections (threaded, using terminal blocks, crimping), especially if the connection takes place outdoors. Then the contact is affected by additional factors that significantly reduce the durability of the connection. Although the use of lubricant without insulation raises doubts.

Bottom line

Based on all of the above, select the method that is suitable for you, depending on the location of the connection (street, house) and material capabilities.