Connection of aluminum and copper wires to each other. How to connect copper to 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 laid.

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

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

The problem is that the wires overhead line(VL) - aluminum and if you make a copper lead-in cable, then just wind it on aluminum wire cable core - no!

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

Yes indeed, why? But because of what.

A little 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 on its surface thin film oxides.

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

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

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

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

Transitional resistance in the twist so "slowed down" electricity, and even the weakening of the contact further increased the value of the transient resistance.

This causes the twist to start bask, the further, the more, the insulation of the wire is heated. is destroyed by heat and can even tan.

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

Speaking of transient resistance.

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

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

Here, inside the 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 hot nichrome filament.

Yes, 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 that is neutral with respect to them, naturally conductive.

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

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

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

In this case, if there is a sea of ​​\u200b\u200bmoney, it’s better to make wires completely out of platinum, voltage losses will disappear completely)))

So, we connect copper with aluminum:

- With terminal clamps;

- Bolted connection through washers

- Layer of neutral material

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

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

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

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

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

How this is done I will show in the photo:

This good exit from a position 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 make a twist with aluminum - the connection will be reliable! Although the PUE is wrong ...

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

Although I personally once opened the lighting distribution box in an old house, there was a copper wire from the switch, and an aluminum wire to the 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 oxidization and burning. I think this is because it was always dry in the apartment and besides, the switch box was tightly sealed in the wall - that is, air did not penetrate into it.

And therefore, aluminum did not oxidize, and besides, the load on the twist 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 difficult - soldering.

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

So now you knowhow to connect copper wire to aluminum and if you have to do it - I'm sure you'll 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 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, electrolysis occurs. chemical reaction. Problems are sure to manifest themselves sooner or later.

Oxidation, contact weakening, its further heating with insulation melting. Go to 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. It is one of the most tested 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 made of different materials interfere with the oxidation process. 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. Enough to take it off upper layer isolation. 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 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, it remains the most reliable of available ways- pressing. 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 oxide film may subsequently have a resistance several times greater than aluminum itself.

And without deleting it, all yours 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 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 as if sealing the contact spot of the copper-aluminum connection. 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 the insulation, it is better to heat the heat shrink building hair dryer and not with a lighter or 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.

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

It happens the other way around. The main thing here is the contact of dissimilar metals. Direct combination 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 conventional battery.For various metals the potential difference when they are in 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 higher potential, the material of the conductors begins to break down, covered with oxide films. 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;

Wire twisting

The simplest, but least reliable way to connect conductors. As mentioned above, copper and aluminum wire cannot be twisted directly. The only one possible variant contact of such materials - tinning one of the conductors with lead-tin solder.

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 soldering copper and copper alloys. Tinned copper and pure aluminum conductors are tightly twisted together with pliers or pliers so that the cores wrap tightly and evenly around each other.

It is unacceptable for one conductor to be straight and the other to wrap around it. The number of turns should be at least 3-5. The thicker the conductors, the smaller the number of turns can be made. For reliability, the place of twisting can be wrapped around with a bandage 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 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 tinned. Must be serviceable stranded wire(even if wires of the same metal are connected).

The resulting connection looks like a sandwich:

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

The copper core may not be tinned, but in this case a steel washer must be laid between the conductors.

A significant drawback of this method is its large dimensions 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 other tools with a similar principle of operation. In order to cut the insulation without affecting the body of the wire, considerable experience is required and in most cases the integrity of the wire will still be compromised. Aluminum is a soft metal, but it does not tolerate kinks very well, especially if the integrity of the surface is compromised. It is possible that 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 acidic 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 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 copper - zinc is 0.85 mV, which is much greater than the difference in the direct connection of copper and aluminum.
5. For the same reason, you should not purchase overly cheap terminal blocks. unknown manufacturer. Practice shows that metal elements these 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). It is difficult to remove machine oil only from the skin. sun, air, negative temperatures destroy protective covering much faster than we would like. In addition, some lubricants (especially fatty grease) initially contain up to 3% water in their composition.

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't be said about air atmosphere where moisture is present. She is the catalyst. 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, combine them into electrical wiring not allowed. But what about those who have an aluminum wiring diagram in their apartment or house? There are several exits.

Twisting two wires

Most old version connections electrical wires- twist. 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).

Back to electrical potential metals and we 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 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 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 open area should 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 most simple 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 long-term operation. electrical circuit wiring.

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

What is the difficulty of connecting copper and aluminum wiring directly

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

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

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

1. There is a 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 irradiated with solder.

Twisting

The main method of connecting wires in living conditions, it is quite convenient in that it does not require special tools and equipment. But in the case of connecting aluminum and copper wires, this method must be used 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 irradiate the copper cable with tin or solder before twisting, this point is especially important for stranded copper wire;
• A protective moisture-resistant coating must be applied to the connection of aluminum and copper wires.

There are three main types of twist: simple, bandage and groove twist. It should be noted that bandage twist 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, at least 5 turns must be made, 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 a long time, but only the use of an indirect connection can give a true guarantee.

How to make a twist

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 shrink tube is put on one of the wires, before twisting, upon completion of all operations, the tube is moved 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 mutually twisted, and there is no overlay of one cable core on another.

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

Insulating the ends of the wire with caps with a cone spring

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

In this case, a metal or plastic sleeve or ferrule is put on the connection by twisting, which is fixed on the connection with press tongs, a special tool for crimping. Fixation in this case is carried out by crimping the connection with the material of the sleeve. The sleeves are a metal tube insulated with PVC materials. Nozzles, as a rule, are plastic caps into which the compound is introduced, after which the cap is crimped with press tongs.

Separately, it should be noted the connection using nozzle 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 wound onto the connection with rotational movements, after which it is simply crimped with pliers. At the same time, a soft metal ring inside the cap tightly compresses the junction. This crimping option is quite affordable for domestic use.

Threaded fixation

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

The advantages of this connection method are simplicity and versatility. In this way, several electrical wires of various sections can be connected. 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 nut.

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

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 aluminum wire, as is often the case in old apartments, it is better to use terminal boxes.

Joining copper and aluminum wires with rivets

The clamping of the wires in this case is carried out by a wedged rivet, consisting of a tube and a core, fixed with a riveter. For connection, 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 riveter, the core wedges the rivet tube, thereby compressing the metal of the cores among themselves, thereby fixing the cable cores.

The contact in this case is one-piece, but at the same time strong and reliable. This type of connection requires special tool- riveter, and skills to work with him. This method is mainly used to work with wire breaks, splicing wire ends in hard-to-reach places.

Connection with two steel strips

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

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

Terminal blocks and terminal boxes

Convenient and reliable way connections. The terminal block is a strip of insulating material in which the sockets for the wire are placed. Fixing the wire in the sockets is carried out by clamping bolts. An important feature in our case is the absence of wire contacts between each other. To connect copper and aluminum wires, only a screwdriver is enough.

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

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;
• Reliability of insulation, 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 mounting concealed wiring in the wall, the terminal block requires the installation of a junction box. Without a junction box, installation of hidden wiring is not allowed. In this case, however, a flush-mounted terminal box can be used.

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

Connection with spring-loaded and self-clamping terminal blocks

At present, 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 body of the device. This allows you to get or insert the wire without any effort. Lowering the lever securely fixes the cable cores;
• single-use terminal blocks automatically clamp the wire when inserted into the socket, removing the wire will require physical force, which can damage the clamp spring, therefore it is recommended that they be used once.

Both reusable and single-use terminal blocks are available in a wide range, including with different amount connected wiring branches designed to fix wires with a cross section from 0.08 mm² to 6 mm². Including, and in the form of ready-to-install, terminal boxes. This method of connecting aluminum and copper wire 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 currently exist a large number of analogues, including counterfeit ones. For this reason, spring-loaded terminal boxes should only be purchased from electrical supply stores. When purchasing terminal boxes on the market, there is a high probability of purchasing low-quality products that do not meet the stated requirements.

To fix the wire in the terminal box, it is necessary to prepare the wires, to do this, remove the insulation from their ends, the size of the bare 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 screw. It should be noted that mounting in the terminal box usually does not require additional insulation, but at the same time, when they are located in the wall, it is necessary junction box. Thus, spring terminal blocks have a number of advantages over other types of connections due to ease of connection.

findings

Thus, it is quite possible to connect copper and aluminum wire, but it is necessary to take into account the location of the cable, environment. By twisting, copper and aluminum can only be connected in a dry room. If the humidity in the room increases, 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 environmental conditions. With all the advantages of a screw terminal, threaded or riveted connection, when operating under conditions of a sharp change in temperature, the contact under the screw may loosen. Due to the difference in thermal expansion of wire metals. As a result of these changes, a loss of contact or a short circuit is possible. Thus, with all the variety of methods for connecting copper and aluminum wiring, the most safe method at the moment, is the use of self-clamping terminal blocks.

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