Terminal blocks for connecting copper and aluminum. Can copper wire be connected to aluminum wire? Video - Connecting aluminum and copper wires

Almost everyone already knows that aluminum wiring is a legacy of the last century, and it must be changed when repairing an apartment. Few people carry out major repairs and forget about it.

However, there are situations when the repair is carried out partially, and there is an urgent need to connect the aluminum wire to the copper wire or simply build them up by adding a few extra centimeters of the core.

Electrochemical corrosion

However, aluminum and copper are not galvanically compatible. If you connect them directly, it will be something like a mini battery.

When current passes through such a connection, even with minimal humidity, an electrolytic chemical reaction occurs. Problems are sure to manifest themselves sooner or later.

Oxidation, contact weakening, its further heating with insulation melting. Transition to a short circuit, or burnout of the core.

What such contact can eventually lead to, look at the photo.

How to make such a connection competently and reliably in order to avoid problems in the future.

Here are some common methods that electricians use. True, not all of them are convenient for working in mounting boxes.

Let's take a closer look at each of them and choose the most reliable one that does not require subsequent maintenance and revisions.

Connection through bolt and steel washers

Here, a steel washer and a bolt are used for connection. This is one of the most proven and simple methods. Indeed, it is a very large structure.

For installation, twist the ends of the wires with rings. Next, pick up the pucks.

They must be of such a diameter that the entire eye of the wire is hidden behind them and cannot come into contact with another conductor.

The most important thing is how to position the ring. It must be worn so that during the tightening of the nut, the eyelet does not turn around, but, on the contrary, is pulled inward.

Steel washers between conductors of different materials prevent oxidation processes. In this case, do not forget about the installation of the engraver or spring washer.

Without it, contact will weaken over time.

The fact is that metals can be safely connected to each other, in which the electrochemical potential of the connection does not exceed 0.6 mV.

Here is a table of such potentials.

As you can see, copper and zinc have as much as 0.85 mV here! Such a connection is even worse than direct contact between aluminum and copper conductors (0.65mV). This means that the connection will not be reliable.

However, despite the simplicity of the threaded assembly, the result is a large, awkward structure, similar in shape to a beehive.

And to shove the whole thing into a shallow socket is not always possible. Moreover, even in such a simple design, many manage to screw up.

The consequences will not keep you waiting in a very short time.

Squeeze - walnut

Another way is to use a walnut-type connecting clamp.

It is often used to branch off a supply cable that is much larger than a tap.

And here it is not even required to cut the main wire. It is enough to remove the top layer of insulation from it. Some have found a use for it to connect the input cable to the SIP.

However, this should not be done. Why, read the article below.

But again, nuts are not suitable for junction boxes. Moreover, even such clips sometimes burn out. Here is a real review from a user on one of the forums:

Wago clamps

There is a series of special clamps that can be used to join copper to aluminum.

Inside these terminals is an antioxidant paste.

However, disputes about the 100% reliability of such clamps, especially for socket rather than lighting groups, have not subsided so far. With a certain installation in a limited space, the contact may weaken, which will inevitably lead to burnout.

Moreover, this can happen even at a load below the minimum for which Vago is designed. Why and when does this happen?

The fact is that when the connected conductors are compressed, a small gap appears between the pressure plate and the contact point. Hence all the problems with heating.

Here is a very visual video, without further ado explaining this problem.

Terminal block

This method has one significant disadvantage. Most pads sold are of very poor quality.

Some contrive and, in order to avoid direct contact between copper and aluminum, the copper core is soldered to the side of such a clamp, and not inserted inside.

True, the terminal will have to be disassembled for this. In addition, reliable aluminum contact under the screw without revision does not last very long.

Screws every six months or a year will need to be tightened. The frequency of revision work will directly depend on the load and its fluctuations during periods of maximum and minimum.

Forget to pull up and expect trouble. And if all this connection is hidden deep in the socket, then climbing there every time is not a very convenient task.

Therefore, the most reliable of the available methods remains - crimping. Here we will not consider the use of specialized copper-aluminum sleeves GAM, since they start from sections of 16mm2.

For home wiring, as a rule, you need to build up wires of 1.5-2.5 mm2 no more.

Connection of copper with aluminum by crimping

Consider the most common case that occurs in panel houses. Let's say you need to power one or more additional outlets from an existing aluminum outlet in a through niche.

For building, take a FLEXIBLE copper wire with a cross section of 2.5 mm2. This will reduce the mechanical impact on the aluminum conductor when you lay the wires in the socket.

For soldering, it is convenient to use a homemade crucible, which is a slightly modified soldering iron in the shape of an axe.

In this case, before soldering with flux, remove the oxide layer from the core.

The tinning process itself consists in dipping the wire into a special hole in the soldering iron filled with tin.

After the core has cooled, the flux residues are removed with a solvent.

Next, move on to the aluminum wires sticking out of the wall. Carefully clean their ends and also remove the oxide layer.

To do this, you can use an oxide conductive paste. The same paste is used when mounting modular ground pin systems.

It is designed to work in any conditions and eliminates the further appearance of oxide on the surface of the wire. Keep in mind that the oxide film may subsequently have a resistance several times greater than the aluminum itself.

And without removing it, all your further work will go down the drain. Moreover, the melting temperature of such a film reaches 2000 degrees (against about 600C for Al).

After all the preparatory work, insert the wires into the GML sleeve from both sides. All that remains is to pressurize this connection.

Some will have a logical question, but will the layer of solder on the core not be pressed during crimping? Then it turns out that all manipulations on tinning will be in vain.

The main thing here is to choose the right sleeve and tool dies for crimping according to the cross section.

In this case, soft solder seals the contact spot of the copper-aluminum joint, as it were. And without the lack of oxygen access to this point, contact erosion will not be observed.

Be careful when working with aluminum conductors, you need to be extremely careful, as this is a very brittle material. One careless movement and you are guaranteed a bummer.

After crimping, it is necessary to insulate this connection with adhesive heat shrinkage.

It is the adhesive type that will provide 100% tightness and prevent the flow of oxygen to the contact points. In order not to risk and not burn through the insulation, it is better to heat the heat shrink with a building hair dryer, and not with a lighter or a portable burner.

The resulting bundle of wires must be laid in the socket box with great care, since aluminum does not like sharp bends.

Since the extended copper wires were flexible, you put on insulated NShVI tips on the ends of these conductors.

Only after that they can be safely inserted into the terminal blocks of the sockets and the screws tightened.

Of course, this is not the only way to build aluminum wires, but it is one of the simplest (unlike welding or soldering) and reliable (unlike twisting).

If you have the slightest opportunity to change the entire aluminum wiring, do it without fail, do not save on your safety.

There are still quite a few apartments in which the electrical wiring is made with aluminum wires. And since manufacturers of lighting fixtures and electrical equipment have switched to copper power cables, the question of how to connect copper and aluminum wire is still relevant today. Due to the fact that copper and aluminum have different electrical potentials, a voltage will necessarily form between them. If this bond of two metals were located in a vacuum, then the connection would last forever. What can not be said about the air atmosphere, where there is moisture. It is a catalyst for chemical processes inside the contact of copper and aluminum.

Experts have long come to the conclusion that a potential difference of more than 0.6 mV is already dangerous for wire connections. Such a contact cannot be called long-term. As for copper and aluminum, the electric potential between them is 0.65 mV, which is above the norm. It turns out a galvanic pair, like in a battery. Therefore, it is not allowed to connect them in electrical wiring. But what about those who have an aluminum wiring diagram in their apartment or house? There are several exits.

Twisting two wires

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

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

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

Threaded contact

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

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

Attention! During the operation of the threaded connection, care must be taken that, under the influence of vibrations of the building, spontaneous unscrewing of the nut does not occur. This will weaken the contact. Therefore, a Grover washer must be placed under a flat washer.

How to properly make contact with a threaded connection

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

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

Please note that for clamping wires with a cross section of not more than 2 mm² in this way, you can use an M4 bolt. If the copper wire is treated with solder, then it is not necessary to lay a washer between the two cores. The end of the stranded copper cable must be treated with solder.

Permanent connection

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

• The ends are cleared of insulation, as in the previous version.
• Rings are made slightly larger than the diameter of the rivet (its maximum value is 4 mm).
• The aluminum end is put on first.
• Then a flat washer.
• Copper end.
• Another puck.
• Insert the end of the rivet into the riveter and squeeze the handles of the tool until it clicks, which indicates that the cutting of the steel rod has occurred.

Contact in terminal block

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

If copper is connected to aluminum using a terminal block, then it is impossible to lay the device under plaster. It can only be used in closed boxes: in a junction box or in a luminaire dome.

Terminal block

Wago

It is impossible to bypass the Wago adapter. This is a German-made device with which you can connect aluminum and copper to each other effortlessly and without tools. The only thing to do is to clean the ends of the conductors.

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

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

nuts

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

The principle of fastening, as in the threaded version. Only by design, these are two plates that are pressed against each other with four screws. In one of the plates, a thread is cut in the holes, onto which the screws are screwed, compressing the plates together. Connect aluminum with copper with a nut like this:

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

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

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

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Depending on the type of connection chosen, you will need different materials and tools.

For mechanical connections:

• pliers;
• knife or device for removing insulation;
• PPE caps;
• self-clamping terminals;
• sleeves;
• screw terminals;

Pressing will require presses (hydraulic, mechanical, manual of various types, pressing tongs, etc.).

Welding will require the following:

• argon-arc welding machine;
• oscillator;
• rubber boots;
• welding mask;
• burner;

For soldering;

• a knife or a device for removing insulation;
• (for small sections of aluminum wires - 60-100W; for sections over 2 mm - 100-200W);
• solder (solders POS40, POS60 are ideal for home conditions);
• steel brush;
• sandpaper;

The choice of fluxes deserves special attention, since the better the flux, the easier it will be to braze aluminum. Today, despite the large selection of fluxes, FIM, F-64, FTBf are the most preferred for soldering aluminum at home.

Connection methods

The need to connect aluminum products with copper, aluminum, or aluminum-copper, especially often arises in Soviet-built apartments - this happens due to the failure of individual sections of aluminum wiring, or in connection with its complete replacement.

Few people know that the joints must be as strong as possible to prevent heating. If the work done is done poorly, the resistance will increase, as a result of which they will heat up, which will result in a short circuit.

There are the following ways:

1. Soldering.
2. Welding.
3. Mechanical connections:
   • twist;
   • use of terminal blocks;
   • use of contact clamps (self-clamping terminals);
   • connection with bolts;
   • crimp method (crimping);
   • spring devices;

Each of these methods has its own characteristics.

Twisting

Considered the most durable method, especially when connecting with cables made of other metals. However, there are rules for twists, the observance of which will significantly strengthen the quality of work, increase service life and safety.

types of twists

Types of twists:

1. Bandage twist. Bandage twist is used to connect cables of large diameters. To strengthen the bandage twist, soldering is used - only after tinning the copper wire.
2. Groove twist. The most durable twist.
3. Simple twist. Simple twisting is used exclusively in domestic conditions; in this way, conductive cores are most often connected to.

Especially responsibly it is necessary to treat the connection of stranded wires (cables):

1. Places of twisting be sure to clean.
2. To strengthen the received contacts PPE caps are recommended.

Welding

Welding aluminum wires at home- the process is time-consuming, requiring experience and special knowledge. The main feature is that the seams obtained during welding must form an exclusively integral whole with the original product - only if this condition is met, the current can flow unhindered.

Obtaining a positive result is complicated by the fact that when welding in air, the aluminum surface is covered with a refractory oxide film, so argon-arc welding or fluxes are used.

Welding has a number of specific features:

1. Additive be sure to apply with short reciprocating movements.
2. Additive wire together with a special electrode during welding must be at an angle of 90 °.
3. Must comply one selected arc length (most often - 1.5-2.5 mm.).
4. Electrode should be at a distance of 1-1.5 mm from the burner tip.
5. Weld necessary only from right to left.

Spike

The safest way is soldering - with certain skills, soldering can be done at home:

1. Before soldering the ends of the wires must be tinned: the part that will be connected is densely covered with rosin and lies on the grinding surface (circle or sandpaper).
2. Next soldering iron the wire is pressed to the surface, constantly adding rosin - until the required wire thickness is obtained.
3. Then soldering is carried out in the usual way.
4. The most important thing in the soldering process is to prevent contact of the aluminum surface with oxygen - otherwise, a heat-resistant oxide film will form. To do this, the stripped cable is abundantly lubricated, or filled with flux, in some cases, heated.
5. In the case of soldering wires with a cross section of up to 4mm.kv., they can be cleaned directly in the solution.
6. If the cross section of the aluminum wire is 4-10 mm2, it is necessary to remove the insulation, clean it to a shine and twist it.
7. When to Use Soft Solders, AF-44 flux is optimal.
8. The resulting connection should be cleaned of the flux residue, wiped with gasoline, covered with moisture-resistant varnish, then with electrical tape, then again with varnish.

Crimping (crimping method using sleeves)

For cases when it is necessary to connect a multi-core cable, or more than 2 single-core wires into one connector, it is best to use crimp (crimp) sleeves:

1. In such a sleeve start the stripped ends of the wires.
2. Then the sleeve is crimped using a press or special tongs, reliable, one-piece contact.

This method is most widely used when connecting powerful consumers.

Instead of sleeves, NCI tips are widely used, at one end of which there is a small crimp sleeve - cable cores are inserted into it. At the other end is a contact ring, thanks to which you can get a high-quality connection with screw terminals.

Use of terminals

The easiest way to combine aluminum cables into a single current-carrying core is the use of contact clamps.

Their types:

• polyethylene clamps;
• self-clamping terminals (terminals);
• screw;
• spring (PPE caps);

Advantages of terminal clamps:

1. No need for additional insulation, to connect aluminum cables, it is enough to strip them, assemble them into a bundle, and then screw the clamp onto the bundle until it stops (insert it into the terminal, or clamp it with a screw, etc.);
2. Received contacts have much greater mechanical strength than when twisting;
3. Received contacts do not heat up, which minimizes the possibility of short circuits and fires.

screw connection

Screw (bolted) connection- the most common contact connection of aluminum wires and cables to electrical appliances, instruments, machines. However, the properties of this metal to spread under excessive pressure, along with the difference in coefficients. thermal expansion of aluminum and the metal of the screw (bolt) can lead to mixing of the screw contact of the wire.

As a result, the ring gradually creeps out from under the flat washers, most often used for screw (bolt) contacts.

To prevent the described violation (which can lead to short circuits), cable clamps must have the following devices:

1. limiting unwinding the cable ring (limiting star washers).
2. Not allowing weakening of the contact pressure followed by yielding (standard spring washers).

Spring connection (PPE caps)

These are caps made of non-flammable plastic, metal springs are located inside. After winding the PPE onto the wires (twisting), the springs move apart, compressing the cable cores and providing tight and reliable contact, and also removes the oxide layer from the wires.

At the same time, plastic serves for the entire connection as electrical insulating, fire and mechanical protection. For high-quality contact, the size of the PPE caps must be selected correctly - they must be screwed onto the cables with force.

Safety

1. Connecting wires, you must be careful and strictly follow the operating instructions, which prohibit simple twisting (twisting a spiral) of aluminum wire and any other metal (copper, aluminum copper, aluminum). The reason is that, when oxidized, aluminum releases galvanic vapor, which sooner or later breaks the contact, and sparks that occur when high power currents pass through such contacts often cause a fire.
2. The most traumatic is aluminum welding– to avoid trouble, be sure to use rubber boots and a welding mask.
3. In room where welding is carried out, there should be no wooden objects - in order to prevent fire.
4. Even wooden floors it is recommended to cover with iron sheets.

1. When using a bolted connection, it is necessary to remember the fluidity of aluminum - the clamping bolt must be periodically tightened so that the aluminum does not leak out over time. At the same time, the mechanical pressure on the cable without tension should not exceed 150 kg/cm2. When the tip is copper-clad, the pressure should not exceed 100kg/cm2. When heating wires under voltage, the maximum pressure is not more than 200kg/cm2. If these values ​​are exceeded, the live aluminum cable will “leak”.
2. If you have no other choice, in addition to using a simple twist, you must remember that the contact will be more reliable when using certified PPE caps. Remember that any cable pins covered only with insulating tape are not recommended.
3. For fast and quality soldering aluminum cables, it is necessary to replace the rosin with high-quality mineral oil (for sewing machines), or gun oil.

In residential buildings that 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 face such a problem as connecting copper and aluminum wire. Do not listen to those who will tell you that this cannot be done categorically. 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 right.

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 excluding direct contact between them.

We will consider all the existing options for how copper and aluminum wire can be connected, 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 - 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, starts to overheat, the insulation melts and a short circuit occurs.

1. Aluminum wire has the ability to oxidize under the influence of moisture in the air. When in contact with copper, this happens much faster. In the oxide layer, the resistivity value is 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 less 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 aluminum and copper have a big difference in the magnitude of linear expansion, so 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 node, even with minimal humidity, a chemical electrolysis reaction will occur. It, 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, fire.

Bolted connection

Bolted connection of aluminum wires with copper is considered the most affordable, simple, fast and reliable. To work, you will need a bolt, 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 assembly will be very cumbersome. But if there are still Soviet-era boxes in your house or when you need to make a connection in a switchboard, then such a bolted method is best suited. In general, it is considered an ideal option when it is necessary to switch absolutely incompatible cores - with different cross-sections, made of different materials, stranded 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 tips, form rings according to the diameter of the bolt so that they can be easily put on it.
3. Now take a bolt, put a washer on it, then a copper conductor ring, another washer, an aluminum conductor ring, a washer and securely tighten everything with a nut.
4. Insulate the connection with electrical tape.

Most importantly, do not forget to place an intermediate washer between the aluminum and copper wires. If you connect several different conductors, then you can not put 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 properly bolt the wires is shown in detail in this video:

Clamp "Nut"

Another good way to connect copper and aluminum wires is to use walnut clamps. It is more correct to call this device a branch clamp. It was already electricians who called him "nut" because of the resemblance.

It is a dielectric polycarbonate case, inside of which there is a metal core (or core). The core is two dies, each of which has a groove for a certain section of the conductor, and an intermediate plate, all this is interconnected by bolts.

Such clamps are sold at 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 its non-tightness, that is, there is the possibility of moisture, dust and even small litter. For the reliability and quality of the connection, it is better to wrap the “nut” with insulating tape on top.

The process of connecting wires using such a compression is as follows:

1. Disassemble the clamp housing, to do this, pry and remove the retaining rings with 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 bare conductors into the die slots.
4. Tighten the bolts, position the plate in the compression housing.
5. Close the housing and put on the retaining rings.

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

Terminal block

A cheap and easy solution to the question of how to connect aluminum wires to copper is to use 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 off the required number of cells. Terminal blocks are sold in 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 tubular brass sleeve. From opposite sides, it is necessary to insert the ends of the wires to be connected into this sleeve and clamp it with two screws.

The use of terminal blocks is very convenient because it is always possible to cut exactly as many cells from it as how many pairs of wires 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 passage of the conductor into it.
2. On the strands of 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 be too zealous, 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 in order? After all, you can immediately unscrew the two screws, insert the wires and tighten. This is 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 the simplicity and speed of their application. This connection method refers to detachable, if necessary, you can pull out one conductor and replace it with another.

Terminal blocks are not quite suitable for connecting stranded conductors in them. In order to do this, you must first use the end sleeves that will compress the bundle of cores.

There is another feature in the use of terminal blocks. Under the pressure of the screw at room temperature, aluminum can flow. Therefore, a periodic revision 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 loosen, the contact will weaken, it will start to heat up and spark, which may result in a fire.

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

Self-clamping terminals

Even faster and easier to connect aluminum and copper conductors in self-clamping terminals.

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

If you want a reusable clamp, use lever-type terminals. The lever rises and releases the entrance to the hole into which it is necessary to insert the stripped core. After that, the lever is lowered back, thereby fixing the conductor in the terminal. This connection is detachable, if necessary, the lever rises, and the wire is taken out of the terminal.

WAGO self-clamping terminals have proven themselves in the best way on the electrical goods market. The manufacturer produces a special series of terminals in which there is an Alu-plus contact paste. This substance protects the contact junction of aluminum and copper from the manifestation of electrolytic corrosion processes. These terminals can be distinguished by a special marking on the package "Al Cu".

Using these clamps is also extremely simple. The clamp itself indicates how long it is necessary to strip the insulating layer of the conductor.

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

Twisted connection

Twisting copper and aluminum wires is not recommended. If you can’t do without this, then first you should tin the copper conductor, that is, cover it with lead-tin solder. So you exclude the possibility of direct interaction of aluminum and copper.

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

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

Until now, there is a considerable number of premises where electrical wiring is made of aluminum. At the same time, modern systems are based on the use of copper as a conductor. That is why the problem of joining wires from these dissimilar materials is relevant. How to join copper and aluminum wires will be discussed below.

Electrochemical corrosion

It is often possible to meet statements that it is undesirable to combine copper and aluminum into one. From the point of view of material compatibility, these are fair statements. What about combining copper and zinc or steel and silver? There are many options for metal pairs, and remembering which ones are compatible with each other and which are not is difficult. To simplify the task, there are special tables, one of which is presented below.

Table of electrochemical potentials (mV) that occur between connected conductors.

To understand the issue, you need to know what processes occur when different conductors of electricity touch each other. If there is no humidity, the contacts will be reliable anyway. However, in practice, this situation is impossible, since moisture is always present in the atmosphere, which breaks the connections.

Each conductor of electricity has a certain electrochemical potential. This circumstance is used by a person for practical purposes, for example, batteries and batteries work on the basis of different potentials.

When moisture gets on the contacting metal surfaces, a short-circuited galvanic medium occurs, and one of the electrodes is deformed. In the same way, one of the two metals is destroyed. Thus, in order to determine the compatibility of metals, it is necessary to have information about the electrochemical potential of all materials involved in the reaction.

What happens if copper is connected directly to aluminum

According to technical regulations, mechanical joining of metals is allowed if the electrochemical voltage between the two materials is not higher than 0.6 mV. For example, from the table above, it can be established that in the case of a combination of aluminum and copper, the electrochemical potential is 0.65 mV, which is much higher than when the same copper is joined with duralumin (0.20 mV).

And, nevertheless, if it is very necessary, then it is possible to combine such not quite compatible materials, which include copper and aluminum. How to connect copper and aluminum wires will be discussed below.

Overview of connection methods

There are several ways to connect aluminum and copper wires. Moreover, in each of the described cases, special devices will be needed. Let's consider each type of docking separately.

This type of connection is the most common, since it is simple and cheap. When done correctly, a wired connection with nuts and bolts will provide reliable contact for the life of the wiring and electrical appliances. In addition, you can always disassemble the connection, attach additional conductors, etc. Thanks to the threaded connection, the relevance of the electrochemical incompatibility of metals is lost, it becomes possible to join aluminum and copper, thick and thin wires, stranded and single-core. It is important to avoid direct contact between dissimilar materials by making gaskets from spring washers.

To do the job, you will need a bolt and nut, as well as a washer (it must be made of anodized steel).

The connection is made as follows:

1. We remove the insulating layer from the wires for a short length (about four bolt diameters). We also perform stripping of the conductor, especially if its cores have undergone oxidation. We form rings from the veins.
2. First, an aluminum conductor is screwed to the bolt in one girth.
3. We put on the puck.
4. Now it's the turn of the copper conductor. We also screw it in one turn.
5. Next, screw the nut in such a way as to achieve a secure connection.

Note! If docking is carried out for operation in a room where, according to technical conditions, there is vibration, an additional nut will be required for a qualitative result.

Terminals

There are several options for terminal connections. One option is the so-called "nuts". Such an unusual name for terminal blocks comes from their external resemblance to nuts. There are several varieties of "nut" terminals available.

The model, which is the most primitive in its structure, has three delimiting plates inside. Conductors are located between the plates. Thus, it is possible to avoid direct contacts between dissimilar materials. At the same time, "nuts" allow you to save the supply circuit of the electrical circuit.

To achieve the integrity of the circuit, it is necessary to strip the supply conductor from the insulating layer, unscrew a couple of bolts, install a bare wire between the plates and tighten the bolts again. Remove the insulator from the outlet ends, and then direct the wires into holes located perpendicular to the inlet channel. Further, the conductors are fixed between other delimiting plates.

There is also a more complex model on the market, the design of which is designed in such a way that there is no need for cutting conductors. The fact is that the plates of the device contain teeth, which, when squeezed by bolts, simply break the insulating layer. The described docking option is considered very reliable.

There is another option for terminal blocks - ordinary pads. The device is a bar with terminals. To connect two dissimilar materials, you need to strip their ends and send the wires to the terminals. The ends are fixed with bolts that are located over the terminal holes.

Wago terminal blocks

The connection of copper and aluminum wires can be done using Wago terminal blocks. This device belongs to the aforementioned terminals, however, Wago pads should be described in a little more detail due to their popularity among buyers.

Wago is made in two versions: disposable with a non-removable wire and reusable - with a lever that allows you to repeatedly install and remove the conductor.

Wago is used for all types of solid wires, the cross section of which is between 1.5 and 2.5 square millimeters. The block can be used in distribution boxes with a current of up to 24 amperes. However, in practice, it is believed that 10 amperes is more than enough and large figures will lead to overheating.

To connect the conductors, it is necessary to force one of them into the shoe hole, as a result of which it will be securely fixed there. To remove the conductor from the hole, you will also need to apply force. Please note that removing the wire from the disposable terminal block may deform the contact, so a reliable contact is not guaranteed next time.

It is much more convenient to use the Wago reusable device. A characteristic feature of such a terminal block is the presence of an orange lever. With the help of such a device, it is possible to dock or disconnect all types of wires with a cross section from 0.08 to 4 square millimeters. Permissible current level - 34 amperes.

To create a connection, you need to remove the insulation from the wire by 8-12 millimeters, raise the lever up, direct the wire into the hole in the terminal block. Next, return the lever to the opposite position, thereby fixing the wire in the terminal.

The only significant drawback of Wago is the higher cost compared to traditional terminals.

Rivets

This method of joining dissimilar conductors resembles a bolted one. However, instead of a nut and a bolt, a rivet is used, which forms a permanent connection. In other words, after fixing, it is no longer possible to remove the rivet without damaging it.

To perform the docking, we clean both conductors from the insulating material, and also bend the wires into rings. Next, we string one of the rings onto the rivet, after that we put on a steel washer, then we string the ring again, but already the second conductor.

The rivet has a cap on one side. Now you need to flatten the second side, thus forming a second hat, which will act as a fastener. The deformation of the rivet is carried out either with a hammer or with a special tool similar to pliers. The method of joining with rivets allows you to get a very high-quality connection.

soldering iron

If desired, you can solder two dissimilar metals. However, this will require compliance with some technological nuances.

As for copper, there will be no problems with soldering, but with aluminum the situation is more complicated. The fact is that as a result of soldering and under the influence of oxygen, an amalgam appears on the metal surface. This alloy-film is incredibly chemically resistant, which means it does not adhere to solder. To eliminate the film, you will need a solution of copper sulfate, a Krona battery and a piece of copper wire.

On the aluminum wire, we clean the soldering area, and after that we apply a little vitriol there. We fix the aluminum wire on the negative pole of the battery, and we fix the copper wire with one end on the positive pole, and put the other end in copper sulfate. After some time, aluminum will be covered with a copper layer, on which you can solder a copper conductor.

Connection quality

In most of the cases considered earlier, rigid fastening of the conductors cleared of the insulating layer will be used. However, when joining copper and aluminum, one important technological nuance must be taken into account: aluminum under the influence of the load acquires plasticity, as experts say, it begins to "flow". As a result of this process, the connection is weakened, and therefore the bolts must be tightened regularly. If the bolts are not tightened in time, the terminal may simply catch fire due to severe overheating.

There are a number of rules, adhering to which, you can achieve a high-quality connection:

1. Conductors with multiple strands must not be clamped too tightly. In such wires, the cores are too thin, they are easily torn under the influence of compression. The result of the gaps is an overload on the remaining cores, which may cause a fire.
2. It is important to choose the right terminal, taking into account the cross section of the conductor. If the channel is too narrow, the conductor will not fit, and if it is too wide, it will fall out.
3. Brass sleeves and terminals are very fragile, so do not overtighten them.
4. You should carefully consider the marking, where the maximum possible current strength is suggested. Moreover, it is better not to achieve this indicator, limiting yourself to no more than 50% load.

Note! It is not recommended to buy nameless products made in China. Connectors are too important a detail to skimp on. It is best to give preference to products of well-known companies (for example, the Swiss company ABB).

stranded wires

As mentioned earlier, conductors with many strands should not be strongly pinched. To connect stranded wires, sleeves or ordinary twists are most often used. We will discuss these methods in more detail below.

Sleeves

The sleeve is a protective cap made of plastic, under which there is a hollow metal tip. First of all, it is necessary to remove the insulating layer from the conductor. Further, the veins are twisted into one whole, and the resulting "pigtail" is sent to the sleeve. Next, the sleeve is crimped (pliers are suitable for this operation). The tip of the sleeve is inserted into the terminal. To increase the reliability of the connection, the sleeve can be treated with solder.

Twisting

Among professional electricians, twisting is not revered. However, there are situations when twisting is the most convenient way out (for example, to create a temporary connection or in the absence of the necessary materials).

So, twisting from copper and aluminum is allowed only after a thorough cleaning of the aluminum surface. If the copper conductor has many strands, all available strands must be assembled into one "pigtail". Also, copper must be coated with solder - this will improve contact.

When twisting, it is important to prevent the wires from breaking. The endings are best covered with insulating protective caps, which can be purchased at any hardware store.

Note! Twisting is unacceptable in rooms with humid air.

So, there is nothing complicated in connecting copper and aluminum conductors. You just need to remember the price of a mistake: incorrectly connected wires can cause not only the failure of electrical appliances, but also a fire.