Connecting aluminum and copper wires to each other. How to combine copper with aluminum - the better and more reliable

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

Whoever is unfamiliar with this topic and makes repairs with their own hands, they just stupidly twist them together and close them in the switch box, not understanding what kind of headache they will get in the future ...

This topic - copper with aluminum - is encountered not only when installing internal wiring, but also when replacing the input to the house

The fact is that the wires of the overhead line (VL) are aluminum, and if you are making a copper lead-in cable, then you cannot just wind the cable core on the aluminum wire!

But they do it! How many times did I see it myself ... And then they are surprised, “Why is my light blinking in my house ?!”

Yes, indeed, but why? But because of what.

Some chemistry. Aluminum is a very active metal, try to solder it with a simple method like a copper wire, nothing will work.

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

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

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

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

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

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

This leads to the fact that the twisting begins bask, the further, the more, the insulation of the wire heats up. breaks down from heat can even burn.

You yourself know how many houses burned down due to faults in the electrical wiring and it is often the transition resistance or poor contact that is to blame for this.

By the way, about the transition resistance.

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

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

Here, inside a twist of copper and aluminum wire, there is such a red-hot nichrome thread. Do you need it ?!

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

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

The point is this: the main thing is that these two metals did not touch between themselves. Between them there must be a material neutral to them, naturally conductive.

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

By the way, it’s interesting - it’s impossible: zinc, carbon (graphite) and silver with gold and platinum.

Although I can't imagine who can afford such pleasure - to combine copper with aluminum through platinum)))

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

So, we combine copper with aluminum:

-With terminal clamps;

-Bolt connection through washers

-Layer of neutral material

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

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

Such a connection is much more reliable than all terminal blocks and clamps, the only minus is the large dimensions, they take up a lot of meters in the distribution box.

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

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

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

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

I will show you how this is done in the photo:

This is a good way out of a situation when there are no clamps at hand or do not want to use them, and the bolted connection does not fit into the box.

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

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

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

So the state is as if just now!

Everything is clean, no oxide and burn. I think this is because it was always dry in the apartment and, moreover, the switch box was tightly sealed in the wall, that is, the air did not penetrate into it.

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

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

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

So now you know how to connect copper wire to aluminum and if you have to do it, I'm sure you will make the right choice!

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

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

Electrochemical corrosion

At the same time, 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 electrolysis chemical reaction occurs. Problems will certainly manifest themselves sooner or later.

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

What such contact can ultimately 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 of the common methods that electricians use. True, not all of them are convenient for working in junction boxes.

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

Bolt and steel washer connection

Here, a steel washer and a bolt are used for the connection. This is one of the most proven and simple methods. True, it turns out to be a very dimensional design.

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

They must be of such a diameter that the entire wire eyelet 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, while tightening the nut, the eyelet does not unfold, but, on the contrary, contracts inward.

Steel washers between conductors of different materials prevent oxidation processes. Do not forget to install the engraver or spring washer.

Without it, contact will weaken over time.

The fact is that it is safe to connect together metals, 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 0.85mV here! Such a connection is even worse than direct contact of 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, uncomfortable structure, similar in shape to a hive.

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

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

Squeeze - nut

Another way is to use a nut-type joint clamp.

It is often used to branch off a supply cable with a much larger cross-section than the 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 found a use for it for connecting the input cable to the self-supporting insulated wire.

However, this is not worth doing. Why, read the article below.

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

Clamps Wago

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

There is an antioxidant paste inside these terminals.

However, the debate about the 100% reliability of such clamps, especially for socket, and not lighting groups, does not subside until now. With a certain installation in a confined space, the contact can weaken, which will inevitably lead to burnout.

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

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

Here is a very visual video that explains this problem without further ado.

Terminal block

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

Some are tricky and to avoid direct contact between copper and aluminum, a copper vein is soldered on 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.

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

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

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

Crimping copper to aluminum

Let's 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 lead-through outlet.

To build up, take a FLEXIBLE copper wire with a cross section of 2.5mm2. This will reduce the mechanical stress 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 a hatchet.

At the same time, remove the oxide layer from the core before soldering with flux.

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 remaining flux is removed with a solvent.

Next, move on to the aluminum wires sticking out of the wall. Gently peel off the ends and also remove the oxide layer.

To do this, you can use an oxide conductive paste. The same paste is used when installing modular grounding stud 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 can subsequently have a resistance several times greater than the aluminum itself.

And without removing it, all your further work will go to waste. Moreover, the melting point of such a film reaches 2000 degrees (versus about 600C for Al).

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

Some people will have a logical question: will the solder layer on the conductor be squeezed out during crimping? Then it turns out that all the tinning manipulations will be in vain.

The main thing here is to choose the correct cross-section of the sleeve and the tool matrix for crimping.

In this case, the soft solder seals the contact spot of the copper-aluminum joint. 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 it is a very brittle material. One careless movement and a break in the vein is guaranteed to you.

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

It is the glue type that will ensure 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 shrinkage with a building hairdryer, and not with a lighter or portable burner.

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

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

Only then can they be safely inserted into the terminal blocks of the sockets and tighten the screws.

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

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

The connection of wires made of dissimilar metals (a particular and most common case is copper with aluminum) is most often necessary in cases where the home wiring is made with a copper conductor, and the entrance to the house is made of aluminum.

It happens the other way around. The main thing here is the contact of dissimilar metals. Direct combining of copper and aluminum cannot be performed.

The reasons lie in the electrochemical properties of metals. Most metals, when combined with each other in the presence of an electrolyte (water is a universal electrolyte), form a kind of ordinary battery. For different metals, the potential difference during their contact is different.

For copper and aluminum, this difference is 0.65 mV. It is established by the standard that the maximum allowable difference should be no more than 0.6 mV.

In the presence of a greater potential, the material of the conductors begins to collapse, covered with oxide films. The contact will soon lose reliability.

For example, the electrochemical potential difference of some other metal pairs is:

• copper - lead-tin solder 25 mV;
• aluminum - lead-tin solder 40 mV;
• copper - steel 40 mV;
• aluminum - steel 20 mV;
• copper - zinc 85 mV;

Twisting wires

The easiest but least reliable way to connect conductors. As mentioned above, you cannot directly twist copper and aluminum wires. The only possible contact option for such materials is tin-plating of one of the conductors.

It is very difficult to irradiate aluminum at home, but there will be no problems with copper. Powerful enough, a piece of solder and a little rosin, or other flux for brazing copper and copper alloys. Served copper and pure aluminum conductors are tightly twisted together using pliers or pliers so that the conductors are tightly and evenly wrapped around each other.

It is unacceptable that one conductor be straight and the other twisted around it. The number of turns must be at least 3-5. The thicker the conductors, the fewer the number of turns can be made. For reliability, the place of twisting can be wrapped with a bandage made of thinner tinned copper wire and additionally soldered. The place of twisting must be carefully insulated.

Threaded connection

The most reliable connection of wires is threaded (bolted). The conductors are pressed against each other by means of a bolt and a nut. To make such a connection at the ends of the wires to be connected, it is necessary to make rings with an inner diameter equal to the diameter of the bolt.

As well as for twisting, the copper core must be irradiated. A stranded wire must be tinned (even if wires are connected from the same metal).

The resulting connection looks like a sandwich:

• bolt head;
• washer (with an outer diameter not less than the diameter of the ring on the wire);
• one of the wires to be connected;
• second wire;
• a washer similar to the first;
• nut;

The copper core does not need to be tinned, but in this case, it is imperative to lay a steel washer between the conductors.

A significant drawback of this method is its large size and, as a result, difficulties with insulation.

Terminal blocks

The most technologically advanced way to connect wires is to use special terminal blocks.

And finally, a few tips that you should take into account in order to protect yourself in the future and not redo the work:

1. For stripping conductors do not use side cutters, pliers or any other tool with a similar operating principle. Cutting the insulation without touching the body of the wire requires considerable experience and still, in most cases, the integrity of the wire will be compromised. Aluminum is a soft metal, but it does not tolerate kinks very well, especially if the integrity of the surface is broken. The possibility is not excluded when the wire breaks already during the installation process. And much worse if it happens a little later. It is necessary to remove the insulation with a sharp knife, moving it along the conductor, like stripping a pencil. Even if the edge of the knife removes some layer of metal, a scratch along the wire is not terrible.
2. For tinning copper conductors in no case should you take acid-containing fluxes (zinc chloride, etched hydrochloric acid, and so on). Even a thorough cleaning of the connection will not save it from destruction for some time.
3. Stranded conductors before installation, it is necessary to irradiate it to obtain a monolithic conductor. The only exceptions are spring clamps and terminal blocks with pressure plates.
4. Washers, nuts and bolts for detachable or permanent connections should not be made of galvanized metal. The potential difference of copper - zinc is 0.85 mV, which is much larger than the difference in the direct connection of copper and aluminum.
5. For the same reason, do not purchase excessively cheap terminal blocks. unknown manufacturer. Practice shows that metal elements in such pads are often zinc coated.
6. Can't take advice protect the direct connection of copper and aluminum conductors with various water-repellent coatings (grease, paraffin). Machine oil is difficult to remove from the skin alone. The sun, air, freezing temperatures will destroy the protective coating much faster than we would like. In addition, some lubricants (especially fatty grease) initially contain up to 3% water.

There are still quite a few apartments in which the electrical wiring is made with aluminum wires. And since manufacturers of lighting devices and electrical engineering have switched to copper power cables, the question of how to connect copper and aluminum wires is still relevant today. Due to the fact that copper and aluminum have different electrical potentials, then a voltage will necessarily form between them. If this bond of two metals were located in a vacuum, then the bond would last forever. The same cannot be said about an airy atmosphere where humidity is present. She 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 contact cannot be called long-term. As for copper and aluminum, the electric potential between them is 0.65 mV, which is higher than normal. 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 an apartment or house? There are several ways out.

Twisting two wires

The oldest option for connecting electrical wires is twisting. It is also the simplest one. 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 wires to be connected is treated with this solder, then they can be safely connected. Usually the solder is applied to the copper wire.

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

But even this connection option does not give a 100% guarantee that the contact will work for a long time. There is such a concept 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 density of the abutment. And this leads to a decrease in the conductive value. This is why twisting is rarely used today.

Threaded contact

It is believed that threaded connections of copper with aluminum are the most reliable contacts that will serve without problems the entire service life of the wires themselves. 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 electrical lines to be connected 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 the elements of the bolted connection are made of it), the potential difference is 0.2 mV, between copper and steel - 0.45 mV, which is again 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 wires in this case is ensured by a well-conducted nut clamp. Steel washers are installed between the two cores as a contact limiter or breaker.

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

How to make the correct 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, the length of the open section must be 24 mm.
• If the veins already have oxidation on the surface, then they must be cleaned.
• The ends are rolled into rings with a diameter slightly larger than the diameter of the bolt.
• Now, in sequence, they are put on the bolt: a simple flat washer, any one wire, a flat washer, the second wire, another flat washer, a Grover washer and a nut that is tightened all the way.

Please note that for clamping in this way wires with a cross section of no more than 2 mm², you can use an M4 bolt. If the copper wire is treated with solder, it is not necessary to place a washer between the two conductors. The end of a stranded copper cable must be soldered.

One-piece connection

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

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

Contact in the terminal block

This type of connection between copper and aluminum wires is most often used in lighting fixtures. The pads are supplied with the fixtures. 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 rings, or to tin the ends, to carry out 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 the aluminum wire.

If copper and aluminum are connected using a terminal block, then the device cannot be laid under plaster. It can only be used in closed boxes: in a junction box or in a luminaire cover.

Terminal block

Wago

There is no way to bypass the Wago adapter. This is a German-made device with which you can connect aluminum and copper together without effort and without tools. The only thing to do is clean the ends of the wires.

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 types of pads: disposable (773 series) and reusable (222 series). In the first case, the wires are inserted into the terminal block and you can only pull them out of there by breaking the device. The second option is a device that includes levers. By raising or lowering them, you can pinch or release the end of the core. 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 a current up to 10 A), in a reusable terminal block no more than 4 mm² (current up to 34 A).

Nuts

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

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

• Protect the ends of the conductors.
• One is inserted from 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 contains an additional steel plate, which is located between the clamping elements. So one wire must be placed on top of this plate, the second one under it. This will ensure that there is no contact between copper and aluminum wires.
• The screws are tightened to the stop, which ensures reliable contact.
• The construction is closed by a spring-loaded body.

Manufacturers today offer a wide variety of nuts, both in power and size. There are options in which the case itself does not open, and the entire filling is hidden in it and is 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 compression with the teeth will occur, 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, it is necessary to generalize that there are many options. Each has its own pros and cons, but for the necessary requirements, you can choose one correct one, which will create the conditions for long-term operation of the electrical wiring diagram.

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When installing electrical wiring, the question sometimes arises of connecting copper and aluminum wires. This issue is especially relevant for electrical work in the old housing stock, where the bulk of the power grids is made of aluminum wire. How to connect aluminum and copper wires to avoid wiring problems will be discussed later in this review.

What is the difficulty of connecting copper and aluminum wiring directly

As you know, the cause of problems of direct connection of copper and aluminum is electrocorrosive processes. In a dry environment, nothing will happen with direct contact, but with increased humidity at the junction, a short-circuited galvanic cell is formed, in which metals begin to play the role of a battery with "plus" and "minus". The metal itself practically melts, as a result of which a network break occurs with a possible short circuit and insulation fire. Which in turn can lead to fire.

In order to avoid this, various types of contact devices are used for the indirect connection of copper and aluminum wiring.

All connection methods can be divided into 2 groups according to the presence of a wire contact:

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

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

Twisting

The main method of connecting wires in a domestic environment, it is quite convenient in that it does not require special tools and equipment. But in the case of connecting aluminum and copper wires, this method must be used with extreme caution, observing the following conditions:

• The twist connection is made by mutual twisting of both ends of the wire with each other, it is not allowed to wrap the end of one core on the other;
• It is recommended to tin or solder the copper cable before twisting, this point is especially important for stranded copper wire;
• The connection of aluminum and copper wires must be covered with a protective moisture-resistant coating.

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

High-quality twisting will last long enough, but only the use of an indirect connection can give a sure guarantee.

How to twist correctly

First you need to prepare the ends of the veins. To do this, remove the insulation at a distance of 3-5 cm from the edge of the cable. It should be noted that the heat shrinkable tube is put on one of the wires, before twisting, upon completion of all operations, the tube is shifted to an open place and fixed on it. After cleaning the ends, you need to twist the wires according to the proposed scheme. In this case, it is necessary to ensure that the cores are twisted mutually, and that one cable core does not overlap with another.

For the convenience of twisting a multicore copper cable, its conductors can and should be irradiated. It should also be noted that copper tinning in any case increases the reliability of the twist connection. After twisting, the connection point must be covered with a moisture-resistant varnish. Electrical insulation can be done with heat shrink tubing or soft-grip caps or cone spring caps.

Insulation of wire ends with cone spring caps

Important! Unless absolutely necessary, it is not recommended to use a twist to connect copper and aluminum cables. Nowadays there are many safer and more reliable ways to combine copper and aluminum into one network.

In this case, a metal or plastic sleeve or tip is put on the twist connection, which is fixed on the connection with press tongs, a special crimping tool. Fixation in this case is carried out by crimping the connection with the sleeve material. The sleeves are a metal tube with PVC insulation. The nozzles are usually plastic caps, into which the connection is inserted, after which the cap is crimped with pressing tongs.

Separately, it is necessary to note the connection using nozzles-caps with a clamping ring or a cone spring. In this case, after twisting the cores, a cap is put on the twist, after which it is screwed onto the connection with rotational movements, after which it is simply squeezed with pliers. In this case, a soft metal ring inside the cap tightly compresses the joint. This crimping option is quite affordable for domestic use.

Threaded fixation

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

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

First of all, the wire ends are prepared. The insulation is removed at a distance of 1–1.5 cm from the cut, after which rings with a diameter slightly larger than the diameter of the bolt or rivets are made from the bare cores. With these rings, the wire is put on the rivet or the threaded part of the bolt. A spring washer is laid between the aluminum and copper cables, this is necessary so that there is no direct contact between these metals. Then the connection is fixed by tightening the nut or rivet.

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

Connecting copper and aluminum wire with rivets

In this case, the wires are clamped by a riveted rivet, consisting of a tube and a core, fixed with a rivet. For connection, the prepared cores with wound rings are put on a rivet tube with a gasket - a steel washer. After that, the rivet is crimped with a rivet, the core wedges the rivet tube, thereby squeezing the metal of the veins together, thereby fixing the cable veins.

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

Connection by two steel strips

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

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

Terminal strips and terminal boxes

Convenient and reliable connection method. The terminal block is a strip of insulating material that houses the wire slots. Fixation of the wire in the sockets is carried out with clamping bolts. An important feature in our case is the absence of wire contacts between themselves. A screwdriver is enough to connect copper and aluminum wires.

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

The advantages of this connection method are:

• Ease of installation, an electrician's knife is enough to strip the ends of the wire and a screwdriver to tighten the screws;
• Insulation reliability, very often when using a terminal block or terminal box, additional insulation is not required;
• Undemanding to the length of the wire, 1-2 cm of wire is enough to fix the wire in the terminal box.

At the same time, for the installation of hidden wiring in the wall, the terminal block requires the installation of a junction box. Flush wiring is not permitted without a junction box. In this case, however, the flush-mounted terminal box can be used.

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

Connection with spring and self-clamping terminal blocks

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

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

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

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

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

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

conclusions

Thus, it is quite possible to connect copper and aluminum wires, but it is necessary to take into account the location of the cable, the environment. Twisting, copper and aluminum can only be bonded in a dry room. If the humidity in the room rises, this connection may become unusable and, moreover, cause a fire. The most optimal today is the method of connecting electrical wiring by means of spring terminal blocks.

The main advantage of this method is stable fixation in any environment. With all the advantages of the screw terminal block, threaded or riveted connection, when operating under conditions of sharp temperature changes, the contact under the screw may weaken. Due to the difference in thermal expansion of the metals of the wires. Loss of contact or short circuit is possible as a result of these changes. Thus, with all the variety of methods for connecting copper and aluminum wiring, the safest method at the moment is to use self-clamping terminal blocks.

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