Many people have probably encountered such a problem when twisting wires begins to spark and knock out the machines. Naturally, this is unpleasant and poses a major security risk. Using wires from the home electrical network various materials you should clearly know how to connect copper and aluminum wire and do it correctly. After all, with direct contact, copper and aluminum oxidize, compromising the quality and integrity of the twist.

Any conductor (copper, aluminum, steel and others) has a certain electrochemical potential. When moisture in the air and oxygen interact, electrochemical corrosion occurs in the resulting short-circuited galvanic cell. This reaction leads to a deterioration in the electrical conductivity of the wire. In this case, it is necessary to take additional measures to protect the connections.

The table below defines the potentials of various conductors. Knowing them, you can choose the right materials that are well connected to each other.

Metal	Copper and its alloys	Lead-tin solder	Aluminum	Duralumin	Steel	Stainless steel steel	Zinc coating	Chrome coating	Silver	Carbon (graphite)	Gold Platinum
Copper and its alloys	0,00	0,25	0,65	0,35	0,45	0,10	0,85	0,20	0,25	0,35	0,40
Lead-ol. solder	0,25	0,00	0,40	0,10	0,20	0,15	0,60	0,05	0,50	0,60	0,65
Aluminum	0,65	0,40	0,00	0,30	0,20	0,55	0,20	0,45	0,90	1,00	1,05
Duralumin	0,35	0,10	0,30	0,00	0,10	0,25	0,50	0,15	0,60	0,70	0,75
Soft steel	0,45	0,20	0,20	0,10	0,00	0,35	0,40	0,25	0,70	0,80	0,85
Stainless steel steel	0,10	0,15	0,55	0,25	0,35	0,00	0,75	0,10	0,35	0,45	0,50
Zinc coating	0,85	0,60	0,20	0,50	0,40	0,75	0,00	0,65	1,10	1,20	1,25
Chrome coating	0,20	0,05	0,45	0,15	0,25	0,10	0,65	0,00	0,45	0,55	0,60
Silver	0,25	0,50	0,90	0,60	0,70	0,35	1,10	0,45	0,00	0,10	0,15
Carbon (graphite)	0,35	0,60	1,00	0,70	0,80	0,45	1,20	0,55	0,10	0,00	0,05
Gold Platinum	0,40	0,65	1,05	0,75	0,85	0,50	1,25	0,60	0,15	0,05	0,00

According to the requirements of the standards, mechanical connection between materials is allowed, the electrochemical potential (voltage) between them does not exceed 0.6 mV. Therefore, direct connection of copper and aluminum is unacceptable - the electromechanical potential in this case is 0.65 mV, which is 0.05 mV more than the maximum norm. Therefore, it is necessary to select some kind of spacer between these materials, which optimizes the tension in the bond.

Looking at copper wire the best option The connections for it will be copper and steel itself (potential 0.1 mV). Same with aluminum. Accordingly, in order to connect the copper and aluminum wires correctly, you need to add a steel gasket (washer) between the conductors. Also, according to the table, you can select other combinations of connections.

Having dealt with electrochemical corrosion of connected metals, let's move on to considering the main methods of connecting electrical wires.

Twisted connection

Twisting is the most common but less reliable method of connecting wires.

Many people resort to this method due to its simplicity and lack of appropriate qualifications. But you need to know that with temperature fluctuations environment, due to the linear expansion of metals, the following occurs:

• A gap is formed between the twisted wires.
• The contact resistance of the conductors increases.
• Heat begins to be released.
• The wires oxidize and the contact is completely broken over time.

In order to obtain a more reliable contact, it is better to avoid using twisting. But if you still stop at this method connection, the following rules should be followed:

• The different conductors should wrap around each other well
• Measures are required to additionally seal the twist. To do this, you can use any waterproof protective varnish.
• The optimal connection of copper and aluminum conductors will be obtained if the ends are pre-tinned with solder.

The number of turns in the twist must be at least three (for a thick core) and at least five for a thin one (with a diameter of less than 1 mm).

Threaded connection of wires

The next acceptable type of connection is threaded using screws and nuts. It is the most reliable and is able to provide good contact throughout the entire service life of the wiring.

Limiting yourself to a long thread, you can easily connect and disassemble any number of conductors:

• From different metals (for example, copper and aluminum).
• Various thicknesses (core diameter).
• Stranded and single-core.

Use intermediate (spring) steel washers to avoid direct contact between copper and aluminum wires.

Let's consider the stages of creating a threaded connection:

1. It is necessary to remove from the wire an insulating layer long enough to crimp the thread of the bolt.
2. Oxidized areas must be cleaned and degreased. And when using a stranded conductor, it must first be tinned.
3. Then a washer - a copper core (as an example) - a washer - an aluminum core - a washer are installed on the screw one by one. The washers must be steel.
4. Finally, the entire structure is secured with a nut.

To prevent excessive crimping of the wires, a spring washer must be installed in front of the first washer. When the nut straightens while screwing in, the connection will be optimally secured.

Terminal block connection

Connecting wires using a terminal block is inferior in reliability to connecting using a screw and nut and has, perhaps, the only advantage:

• Simplifies the process of connecting wires (aluminum, copper and others in any combination).

To create a bundle of conductors using this method, the ends of the conductors are cleared of insulation to a length of 4 - 8 mm (depending on the diameter), inserted into the hole and clamped with the supplied screws.

1. Under no circumstances should terminal blocks be used in critical and powerful areas. Putting it into the plaster under the finishing layer is also not the best option.
2. Suitable for use in visible areas (in junction boxes) and in conjunction with low-power devices (lamps, chandeliers).
3. When fixing the cores, the screw must be firmly clamped. This will prevent the contacts from loosening.
4. When using conductors made of different metals, keep in mind that an excessively exposed core may have contact with a core threaded on the other side. In this case, partial oxidation and weakening of the bond will occur.

As additional measure As a precaution, it is recommended to additionally wrap the connection made with the terminal block with insulating tape. This is because loose contact can lead to accidental release of a live wire.

Connection using terminal blocks

Connection using WAGO terminal blocks

The most common type of this connection is terminal blocks with spring clamps from the German manufacturer Wago. They are designed for connecting any types of single-core wires (tinned stranded) with a cross-section from 1.5 to 2.5 mm².

There are main types of terminal blocks:

• Disposable. In this case, the wire is fixed in a permanent connection.
• Reusable. The lever on the body of the product allows you to repeatedly fix the cores.

The use of these connectors is justified:

• When connecting electrical appliances (chandeliers, spotlights).
• When connecting wiring in junction boxes. It is worth taking into account the load on the lines of the home electrical network and selecting terminal blocks of the appropriate rating.

As with the methods discussed above, the use of Vago spring terminal blocks is justified when connecting copper and aluminum wires. To do this, it is enough to remove 8 - 10 mm of insulation from the conductor. and insert it into the terminal.

Having studied the question of how to connect copper and aluminum wires, you can apply the acquired knowledge in practice without doubting the reliability of the connection. You just need to choose one of the considered methods.

poweredhouse.ru

Method of connecting copper and aluminum wire

Hello dear readers of the site sesaga.ru. I wrote this short post with the assistance of my neighbor Vladimir Sh, for which special thanks to him.

The other day Vladimir approached me with a request to look at his outlet. A year after the repair, the outlet began to smell, and over time it began to get warm. Well, when the socket sparkled, he began to sound the alarm.

Everything turned out to be simple. The wiring in the apartment was made with aluminum wire, and the newly introduced and additional wiring was carried out with copper wire, and the copper was connected to aluminum using ordinary twisting without any adapters or devices.

Never join aluminum and copper together. Fire is possible.

It was necessary to separate the copper from the aluminum, but still leave the connection. There was nothing suitable at hand, and the first thing that came to mind was to make a bolted connection: cheap and cheerful.

First of all, we break the connection, and if possible, we bite off the damaged parts of copper and aluminum. But, in our case, the wires turned out to be short, and we cut off only the most damaged parts, and cleaned the rest.

To restore the connection, and at the same time separate the copper from the aluminum, we need:

1 . Two bolts with a diameter of 4 or 5 mm;
2 . Four nuts with a diameter of 4 or 5 mm;
3 . Eight washers of suitable internal diameter;
4 . Insulating tape;
5 . Copper two-core wire with a cross-section of 2.5 square and a length of about 40 cm.

We remove the insulation from the aluminum wire and make a half-ring of such a diameter that the bolt will fit.

We put a washer on the bolt, and together with the washer we insert the aluminum wire into the half ring.

Close the half ring on top with a washer and Fine tighten with a nut.
Now the aluminum wire must be extended with a piece of copper so that further connections can be made copper to copper.

Take a segment copper wire 15 - 20 cm long, make a half ring, put it on the same bolt, and between two washers Fine tighten with a nut.

You will get a “sandwich” like this.

Now we isolate this “sandwich” and hide it in the depths of the box.

In the same way we make the second bolted connection.
And now you can freely screw any copper to the resulting two ends.

Let's restore the circuit back.

The twists made can be tinned, or not tinned.
Next, we insulate the twists, put them inside the box and separate them so that they do not interfere with the outlet.

Well, all that remains is to connect and secure the socket to the wall.

So simple, but at the same time in an efficient way We combined copper with aluminum, and at the same time, eliminated a malfunction that could lead to unknown consequences.
Good luck!

sesaga.ru

There are still a considerable number of premises where electrical wiring is made of aluminum. Moreover, modern systems are based on the use of copper as a conductor. That is why the problem of joining wires made of these dissimilar materials is relevant. How to connect copper and aluminum wires will be discussed below.

Electrochemical corrosion

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

Table of electrochemical potentials (mV) arising 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 in any case. However, in practice, such a situation is impossible, since there is always moisture in the atmosphere, which disrupts the connections.

Every conductor of electricity has some electrochemical potential. This circumstance is used by humans for practical purposes, for example, accumulators and batteries operate on the basis of different potentials.

When moisture gets on the contacting metal surfaces, a short-circuited galvanic environment occurs and one of the electrodes is deformed. One of the two metals is destroyed in the same way. Thus, 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 combined directly with aluminum?

According to technical regulations, mechanical joining of metals is permitted 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 joining aluminum and copper, the electrochemical potential is 0.65 mV, which is significantly higher than when joining the same copper with duralumin (0.20 mV).

And, nevertheless, if you really need it, you can also combine materials that are not entirely compatible, such as copper and aluminum. How to connect copper and aluminum wires will be discussed below.

Overview of connection methods

Several methods are used 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.

Bolted connection

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

To complete 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 to a short length (about four bolt diameters). We also strip the conductor, especially if its cores have been oxidized. 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 reliable connection.

Pay attention! If the 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 high-quality result.

Terminals

There are several options for terminal connections. One option is the so-called “nuts”. Such an unusual name for terminal blocks is due to their external resemblance to nuts. Several types of “nut” terminals are available.

The most primitive model in its design has three demarcation plates inside. The conductors are located between the plates. In this way, direct contact between dissimilar materials is avoided. At the same time, the “nuts” allow you to maintain 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 the bare wire between the plates and tighten the bolts again. The insulator must be removed from the outlet ends, and then the wires must be directed into holes located perpendicular to the inlet channel. Next, 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 tear the insulating layer. The described docking option is considered very reliable.

There is another option for terminal blocks - ordinary blocks. The device is a strip with terminals. To connect two dissimilar materials, you need to strip their ends and route the wires into the terminals. The ends are secured with bolts that are located on top of the terminal holes.

Wago terminal blocks

Connecting copper and aluminum wires can be done using Wago terminal blocks. This device belongs to the above-mentioned terminals, however, we should talk about the Wago pads in a little more detail due to their popularity among buyers.

Wago comes in two versions: disposable with a non-removable wire and reusable - with a lever that allows repeated installation and removal of the conductor.

Wago is used for all types of single-core wires whose cross-section is between 1.5 and 2.5 square millimeters. The block can be used in distribution boxes with a current strength of up to 24 amperes. However, in practice it is believed that 10 amperes is more than enough and higher values ​​will lead to overheating.

To connect the conductors, you need to force one of them into the block 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. It should be borne in mind that as a result of removing the wire from the disposable terminal block, the contact may be deformed, so the next time reliable contact is not guaranteed.

It is much more convenient to use a reusable Wago device. A characteristic feature of this terminal block is the presence of an orange lever. Using such a device, you can connect or disconnect all types of wires with a cross-section from 0.08 to 4 square millimeters. Acceptable level current - 34 amperes.

To create a connection, you need to remove 8-12 millimeters of insulation from the wire, lift the lever upward, and direct the wire into the hole in the terminal block. Next, return the lever to the reverse position, thereby fixing the wire in the terminal.

The only one significant drawback Wago - higher cost compared to traditional terminals.

Rivets

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

To make the connection, we strip both conductors from 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 with the second conductor.

The rivet has a head on one side. Now you need to flatten the second side, thereby forming a second cap, 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 obtain 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 is why it does not form adhesion to solder. To remove 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 area for soldering, and after that we apply a little vitriol there. We fix the aluminum wire on the negative pole of the battery, and fix the copper wire with one end on the positive pole, and put the other end in copper sulfate. After some time, the aluminum will be covered with a copper layer, onto which you can solder copper conductor.

Connection quality

In most of the previously discussed cases, rigid fastening of conductors stripped of the insulating layer is used. However, when joining copper and aluminum, one important thing must be taken into account technological nuance: aluminum under the influence of load acquires plasticity, as experts say, it begins to “flow”. As a result of this process, the connection weakens, and therefore the bolts need to be tightened regularly. If you do not tighten the bolts in time, the terminal may simply catch fire due to severe overheating.

There are a number of rules that you can follow to achieve a quality connection:

1. Conductors with multiple cores should not be clamped too tightly. The wires in such wires are too thin, they easily break under pressure. The consequence of ruptures is an overload on the remaining wires, which can lead to 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 wide, it will fall out.
3. Brass sleeves and terminals are very fragile, so do not clamp them too hard.
4. You should pay close attention to the markings, which indicate the maximum possible current strength. Moreover, it is better not to achieve this indicator, limiting yourself to no more than 50% load.

Pay attention! It is not recommended to buy unnamed products made in China. Connectors are too important a part to skimp on. It is best to give preference to products from well-known companies (for example, the Swiss company ABB).

Stranded wires

As mentioned earlier, conductors with many cores should not be overly pinched. To connect stranded wires, sleeves or ordinary twists are most often used. We'll talk about these methods in a little 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. Next, the strands are twisted into one whole, and the resulting “pigtail” is directed into 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.

Twist

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

So, twisting of copper and aluminum is permitted only after thorough cleaning of the aluminum surface. If the copper conductor has many cores, all existing wires must be collected into one “pigtail”. The copper also needs to be coated with solder - this will improve contact.

When twisting, it is important to prevent the wires from breaking. It is best to cover the ends with insulating protective caps, which can be purchased at any hardware store.

Pay attention! Twisting is not allowed in rooms with humid air.

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

How to connect copper and aluminum wire - an overview of popular methods

220.guru

How to properly connect copper and aluminum wire?

At partial replacement electrical wiring, extending the conductor or replacing a burnt section, a wire is used. It happens that in terms of their material they do not coincide. Then it becomes necessary to connect aluminum wires with copper. There are five ways to make this connection, and each has its own advantages and disadvantages. Some of them require preliminary preparation conductor.

Danger of poor wire connections

The industry produces two types of wires for household purposes, copper and aluminum. The former have less resistance, which makes it possible to use a smaller cross-section for the same load. They are more resistant to mechanical loads, this makes it possible to twist them repeatedly without fear of breaking at the cut site. The latter have one advantage - comparative cheapness. But sometimes it plays a key role. What can happen if the connection is poor quality?

Copper and aluminum have different characteristics, For example, different coefficient expansion when heated. When a large current passes through an aluminum conductor, it begins to “flow.” If the conductors move relative to each other when heating or cooling, this will lead to the appearance of a gap between them. The gap, in turn, will lead to a discharge (spark). Sparks may cause a fire. Along with this, copper and aluminum begin to oxidize. The resistance between them increases, and because of this, the voltage drops or may completely disappear. Voltage fluctuations can have a negative impact on connected devices.

Methods for joining copper and aluminum

There are several connection methods. They all have their pros and cons. Some demand special equipment and skills, others are easy to use. Here are a few of them:

• twist;
• threaded;
• terminal;
• one-piece.

Twisting wires

It is strictly forbidden to use twisting in fire hazardous areas. This is the fastest and easy way. Two or more wires are taken and wrapped around each other. One or more than one core must not be left straight. There is a rule - thick wires must have at least three turns, thin ones (from 1 mm or less) - five. To reduce oxidation of the conductor, the copper core is soldered to the length of the twist. The same rule applies to multi-core copper cables.

After the twist has been made, it must be protected from the environment by covering it with any waterproof varnish. This is necessary to reduce further excessive oxidation. Then it is insulated with electrical tape or special caps, which are sold in the store, and hidden in an insulating casing. But even all this does not guarantee that the twisting will work flawlessly.

Threaded method

A more labor-intensive connection compared to twisting. Requires a tool and some skill. Has more mechanical strength. Electrically, it is better than twisting. Allows you to connect a large number of wires at once, and different sections. Both single-core and multi-core can be connected.

For connection, a bolt is used, onto which the conductors are put in turn. They are pre-cleaned and wrapped in rings. Each core, if they are made of different materials, is laid with a washer. A washer and a spring washer are placed on the last conductor. The entire package is tightened with a nut until the spring washer is straightened. Further compression may lead to conductor breakage.

To prevent the washer from cutting the wires, they must be put on in a checkerboard pattern (so that they do not lie on top of each other). If the copper wire is tinned, washers are not needed. Stranded copper wire also needs to be soldered, then it will not fall apart when compressed.

After assembly, it is necessary to take measures to prevent short circuits with adjacent packages. Over time, it is necessary to check the condition of the spring washer; if it is loose, tighten the nut. This connection prevents sparking and allows wires to be routed out different directions. If necessary, it can be easily disassembled and assembled without damaging the conductor.

Terminal method

The terminal connection is manufactured in factories. Has a wide range. Two groups can be distinguished:

• pads;
• terminal blocks.

Pads have different shapes and designs. The idea is to attach several wires to one conductor (plate, tetrahedron, etc.), which are inserted into special connectors and pressed with a screw. As a rule, the pads themselves are attached to the base, creating rigidity of the structure.

The advantage of the pads is that no preliminary steps are required, with the exception of stripping the cores. The connection occurs quickly, without requiring any skills. They are indispensable if the conductor is short (connecting a chandelier, restoring a broken wire). If they are located in distribution panels or metering panels, they do not require insulation. Since each wire is connected separately, both copper and aluminum wires can be used.

The disadvantages include the following:

• less resistant to mechanical loads than a threaded connection;
• each block is designed for a conductor of a certain cross-section;
• you cannot connect large and small diameter wires at the same time;
• occupy more space compared to previous options.

Terminal blocks have recently found widespread use. According to their purpose, they are of two types:

• reusable;
• for one-time use.

Reusable The terminal block is a fully insulated block. Instead of screws, a spring plate is used, which is pressed out using a plastic lever. After which the wire is inserted into the opening. In some versions, the plate has teeth, which allows the use of unstripped wires. To pull out the wire, you need to lift the lever again.

One-time have the same principle, but do not have a lever. Intended for one-time use. If the wire is pulled out and reinserted, the quality of the connection will be poor.

Advantages:

• allows you to very quickly connect aluminum and copper wires to each other;
• minimal preparation required;
• ease of use;
• the necessary insulation is ready.

Flaws:

• the method is the most sensitive to mechanical loads;
• compared to other connections it is the most expensive;
• sensitive to high current and, according to user comments, cannot withstand the regulated load.

One-piece method

Perhaps the most labor-intensive method. Requires special knowledge and skills. Special tools and devices are required. This method includes:

• riveted;
• soldering.

Riveting very similar to a threaded connection, the only difference being that a rivet is used instead of a bolt. The ends of the wires are cleared of insulation and sanded with sandpaper. When combining aluminum and copper wires, the latter is tinned. This also applies to copper stranded wire. After that, rings are made with a slightly larger diameter than the rivet. Finally, when the entire structure is assembled (without intermediate washers), a washer is put on top. All this is compressed by the terminal block. It is insulated in the same way as a threaded one.

Soldering used where high connection reliability and low resistance are required. Similar to twisting, but the wires are soldered together. In the usual way This cannot be achieved for aluminum, so the wires must be prepared.

To do this you will need a solution of copper sulfate, a small non-metallic container, a source DC voltage at 9−24 V. Pour a solution of copper sulfate into the container and lower the pre-cleaned conductors to the length of the twist. We connect the copper wire to “+” so that electrons come from it, and the aluminum wire to “-“. Turn on the power source.

The voltage, of course, can be increased, the main thing is that the solution does not boil or there is no overload in the electrical circuit. You can also reduce the voltage, then the process will proceed more slowly. All this works until the aluminum wire is covered with a copper film.

After which both wires are coated with a layer of tin. A twist of 3 turns is made for a thick wire and 5 turns for a thin one (less than 1 mm). All this is carefully soldered. All that remains is to cover them with waterproof varnish, insulate them - and the connection is ready.

Advantages:

• has an aesthetic appearance;
• good mechanical strength;
• reliable connection.

Flaws:

• there is no way to disassemble;
• you can only work with removable wires;
• purchase of additional equipment;
• requires some skills.

Now that you know all the ways to connect copper and aluminum wires without soldering, you can eliminate this problem when it occurs.

elektro.guru

How to connect aluminum wires - methods for connecting aluminum and copper wires

Almost every electrician will say and agree that electrics is the science of contacts. In practice this becomes obvious. A large number of problems in the power supply arise due to heavy wiring overload, as well as weak contacts in the junction box. In this article, we will focus on the last problem, namely how to connect aluminum wires.

What is their feature?

Aluminum has special metal properties that can make joining difficult. Due to oxidation, an oxide film forms on aluminum, which prevents the passage of electric current. This film will melt only at a temperature of at least 2000°C, and this indicator is higher than the melting point of aluminum itself. Moreover, if you clean off the oxide film mechanically, then after a while it appears again.

If you want to solder aluminum, this film will prevent the solder from adhering to the core. Also, during welding, the film forms inclusions that negatively affect the quality of contact. Among other things, aluminum belongs to the category of metals that are characterized by high fluidity and brittleness. As a result, the contact should be completely protected from possible mechanical influences. For example, if you connect aluminum with a bolt clamp, then you need to regularly tighten the contact, since the aluminum, figuratively speaking, “leaks out” from under the contact, which, in turn, weakens.

Are there then ways to reliably connect aluminum wire? Let's look at a few common methods and decide how best to get the job done.

Screw

This connection method is very simple. It is necessary to strip the wire of 20 mm of insulation. Afterwards it is recommended to clean the vein with fine-grained sandpaper. Next, twist the bare core into a ring and insert it into the clamping screw, which should be tightened tightly.

Complete set for screw connection

The disadvantage of this connection method is that due to the fluidity of aluminum, the contact must be tightened from time to time. Therefore, the connection point must be in an accessible location.

Spring

In this case, special terminal blocks are used. Due to the presence of a special spring, there is no need to regularly tighten the contact. The inserted stripped aluminum wire is held securely. There are terminal blocks, both disposable and reusable. Disposable ones are used to connect wires without further disconnection. The wire is inserted into the hole in the clamp; it cannot be pulled back out. As for the reusable connection, the wire is easily pulled out if you press the special lever that holds the wire.

Twist

In rare cases, aluminum wire can be connected by twisting. It is immediately worth noting that this method is very unreliable, even despite the fact that in Soviet times it was used relatively often. This is partly explained by the fact that in the past the number of household appliances and, accordingly, the load on the wiring was less. Now the picture looks different.

Moreover, the life of such a connection depends on various factors, such as current load, humidity and temperature. If the temperature rises, the metal expands, causing the gap between the wires to widen. This can lead to transient resistance, the contact area will heat up and then oxidation will form and, in the end, the contact will be completely broken. However, this process continues for a long time, so the twisting method is acceptable for temporary connections.

When joining aluminum using this method, it is important to adhere to the following rules:

• The wires should wrap around each other evenly.
• If the wire is thick, then there should be no more than three turns, and for a thin wire, no less than five.
• If copper and aluminum wires are connected, then the copper wire must be tinned.
• It is recommended to use heat-shrinkable tubing as contact insulation.

Permanent connection

• Crimping.
• Soldering.
• Welding.

Each of these methods has its place. Several factors influence the choice:

• Availability of suitable tools and equipment.
• Wire diameter.
• Availability of consumables.
• Availability of relevant skills.

Let's look at each method permanent connection separately.

Welding

Fast and reliable connection method. This technology is especially relevant if a large number of connections need to be made. However, for this you need to have a welding transformer and skills.

Wire welding

The welding process is as follows:

• The wires are twisted together.
• Apply a special flux to the end.
• Afterwards, welding occurs with a carbon electrode for up to 2 seconds.
• As a result, a drop should form at the end of the twist.

Flux

• The drop should be treated with a solvent and then varnished.
• When the varnish has dried, the connection is isolated.

Soldering

The method of soldering the connection is simple. This will require components such as rosin, a soldering iron, solders and additional elements. So, the wire is twisted, and then apply solder to them with a soldering iron.

Crimping

For such a connection, you will need special press pliers and sleeves, which are hollow rods. To crimp, strip the ends of the wires, insert them into the sleeve and perform crimping in three places. You can also additionally twist the wires.

Crimping kit

If the wire is aluminum, then use an aluminum sleeve; for copper wires, use a copper sleeve. If you are connecting aluminum to copper, then copper-aluminum sleeves are available for sale.

Aluminum and copper wire

Connecting 2 copper and aluminum wires may cause some problems. The problem lies in the potential difference, the difference of which reaches up to 0.65 mV. When humidity increases due to this difference, the contact will be destroyed. Moreover, the contact will heat up, which can lead to disastrous consequences.

• one-piece;
• threaded;
• terminal;
• with spring contact.

Using these techniques, aluminum wires can be connected to copper wires.

In this article, we looked at several methods of how to connect wires to each other. If you know of other methods, please leave a comment at the end of this article.

Video

In the video provided, you can learn about other intricacies of connecting aluminum wire:

kakpravilnosdelat.ru

How to connect copper and aluminum wire

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

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

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

Reasons for incompatibility

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

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

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

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

Bolted connection

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

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

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

You will need to do the following:

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

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

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

How to properly bolt a wire connection is shown in detail in this video:

Walnut clip

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

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

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

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

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

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

Terminal block

Cheap and simple solution The question of how to connect aluminum wires to copper wires is the use of terminal blocks. Buying them now is not a problem at all; moreover, you can buy not a whole section, but ask the seller to cut it off required quantity cells. Terminal blocks are sold 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 brass tubular sleeve. From opposite sides, the ends of the wires to be connected must be inserted into this sleeve and clamped with two screws.

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

Using the terminal blocks is very simple:

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

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

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

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

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

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

Self-clamping terminals

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

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

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

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

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

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

Twist connection

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

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

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

yaelectrik.ru

How to connect aluminum and copper wire

When repairing or replacing electrical wiring, a situation often arises when it is necessary to splice aluminum and copper wires. The contact should be very tight, and over a fairly large area. This is due to the fact that quite a large current will flow here. This situation is especially relevant when it is necessary to splice wires through which electricity is introduced into residential premises. How to connect aluminum and copper wires to each other so that the connection is reliable and effective? You will find the answers in this material.

Figure 1. Simple methods for connecting wires

Why can't you just twist aluminum and copper wires together?

Is it possible to connect aluminum and copper wires? You need to work with aluminum carefully, this is due to the specifics of the metal. It has peculiar characteristics and oxidizes quickly. At the same time, a durable film of aluminum oxides is formed on its surface. Its strength is indicated by its melting point - it is higher than that of pure aluminum. The film prevents the normal passage of current. A method such as mechanical cleaning does not help - the film layer is still restored.

There are still obstacles to simple merging - a high level of fragility, strong fluidity. That is, the aluminum wire cannot be bent as you please. It will just break. This is much easier to do with copper, as it is more flexible. Chemical processes in the presence of moisture, such as electrochemical corrosion, destroy metals at the points of contact. The reason is that copper and aluminum have different electrochemical potentials. There is a big difference between them, equal to 0.65 mV, it exceeds the maximum permissible value.

This is why aluminum and copper wires should not be connected simple method twists. Many, not knowing this circumstance, still manage to twist it. They are attracted by the simplicity of the process and the absence of the need for additional materials other than insulating tape. At first, this connection of wires will work well. Then, due to the difference in linear expansion coefficients resulting from the daily temperature difference, the contact will begin to weaken. This will lead to an increase in resistance and the start of oxidative processes. Subsequently, corrosive destruction will begin.

It is necessary to understand that all of the above will not happen in one day and, perhaps, not in one month. But it will definitely happen. It's good if it ends like this. Because there are cases when fires arise from sparks that appear. How to connect copper and aluminum wires to create reliable, long-lasting contact?

For this you will need additional devices. For example, connecting aluminum and copper wires is possible by twisting, if you first tin the copper wire to be connected with tin-lead solder. The difference in electrochemical potentials between them is low - 0.25 mV. Solder with aluminum alloys has a potential difference of 0.4 mV. So the twisting method is suitable for this case.

Tinning is mandatory if you have to connect a multi-core cable made of copper to aluminum. You should know that both wires must wrap around one another, although they have different degrees of rigidity. You cannot twist one core around another. Below are suggested methods for twisting and simple connections for wires.

Figure 2. Twisted connection methods

Connection with threaded devices

This method is the easiest after twisting. True, it requires one bolt, a nut, two spring-loaded and three simple washers. Thus, strong connections are obtained that serve well for many years. The advantage in this case is the ability to connect conductors of different cross-sections, single-core, multi-core.

The connection of aluminum wires to copper wires is carried out in the following sequence:

• the insulation is removed from one of the wires;
• A spring-loaded washer is placed on the bolt head, and a simple washer is placed on top of it;
• the exposed wiring is wrapped around the bolt thread so that its diameter is slightly larger than the outer diameter of the thread, then it is located above a simple washer;
• another simple washer is placed on top;
• a ring of another wire with the insulation removed is laid on top of it;
• another simple and spring-loaded washer is placed on the wire;
• All structural elements are firmly connected with a nut.

Figure 3. Threaded connection

Depending on the diameter of the conductors, the size of the bolt thread is selected for the best connection. For example, for a core with a cross-section of 2 mm, the optimal thread diameter is M4. If the copper conductor is stranded, it would be better to solder it, connecting all the wires into one bundle.

Rivet splicing

Copper and aluminum wires can be connected in another way, where a rivet is used instead of a screw and nut. How to connect aluminum and copper wire with a rivet? To do this you will need a rivet, one spring and one simple washer. An aluminum conductor wrapped around it is placed on the rivet head. A spring-loaded washer is placed on top. Then they wrap a tinned copper core around the rivet, onto which a simple washer is put.

The riveting process takes place using a special device - a riveter, which you need to have with you. The contact is strong, but such a connection is one-time only. If necessary, you can make a branch from the threaded connection, increasing another reliable contact. With a rivet this upgrade option is not possible.

Blocks and clamps with terminals

These are some of the most convenient devices in order to connect copper and aluminum wire. Terminals can be used to connect not only aluminum and copper wiring, but also apply them to other combinations of metals and their alloys. This connection of copper and aluminum conductors has several advantages.

• It is possible to connect aluminum and copper wires of different diameters to the terminal block.
• It is possible to connect copper stranded wire without covering it with solder.
• In order to connect the wires, you only need to remove a layer of insulation from their ends.
• The pads are conveniently attached to the electrical wiring.

Figure 4. Blocks and clamps with terminals

The wires are clamped with the ends of screws or special clamping plates. Stranded conductors can be damaged if simply clamped with screws. Plates are much more practical in this regard.

An alternative to blocks can be spring-type terminal clamps. Terminal blocks from the German company Wago are especially popular. These devices can be disposable or reusable. Designed for splicing any conductors, including copper and aluminum. Connecting conductors to clamps is much faster and easier than twisting them.

There are no requirements for conductors - they can be made of different alloys, have various diameters. Any combination of sections is possible - from 0.08 mm to 4 mm 2. They just need to be cleaned to a depth of 10 mm. Reusable clamps can secure conductors, allowing current to pass through them up to 34 amperes. Fixation is done with a special lever, which should be lowered down. In order to pull the core back, the lever must be lifted.

Such devices are used to connect chandeliers and wall lighting fixtures. They are convenient to use for wiring inside junction and distribution boxes.

External connections

Everything listed above is used for splicing inside buildings. But how to connect copper and aluminum cables externally? For this purpose, a special clamping mechanism called “Nut” is offered. The clamp body, made of plastic, reliably protects the splice and branch points of conductors from external influences. For reliable contact Several plates made of metal neutral to copper and aluminum are used.

Figure 5. Wire connector “Walnut”

• To remove insulation, do not use tools such as wire cutters or pliers. Their use may result in damage to the wires. This is especially true for brittle aluminum. Before connecting the wire correctly, it is preferable to clean its wires with a stationery or any other sharp knife. Remember how you clean a pencil - the insulation is removed in the same way. In this case, damage to the current-carrying conductors is minimal.
• In order to tin a stranded copper conductor, only rosin should be used as a flux. Materials such as zinc chloride or hydrochloric acid cannot be used - over time they will destroy the conductor.
• For threaded connections, it is unacceptable to use washers, nuts and bolts made of galvanized materials. This is due to the fact that the difference in electrochemical potential between aluminum and zinc is 0.85 mV. This value is even greater than that of a copper-aluminum contact.
• For splicing, it is best to purchase terminal blocks and clamps from reputable manufacturers. They may cost more, but the materials used in manufacturing will ensure reliable contact.

Resume

As you can see, there are quite a few ways to connect cables made from different metals. For each of them, you need to follow simple rules to get a reliable connection. Of course, for modern electrical wiring it is better to use only copper cables. But even in this case, the input may require splicing of different metals.

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

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

Why you can’t connect copper and aluminum wire

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

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

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

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

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

How to connect copper and aluminum conductor

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

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

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

There are still quite a few electrical networks with aluminum wires in the secondary housing stock. And solving the problem of how to connect copper and aluminum wire remains vital when connecting electrical products. The safety of splicing with simple twisting, it is not for nothing that it is not recommended by the PUE, is quite precarious. In conditions without excessive humidity, the contact is benign. As soon as moisture appears, the connections begin to heat up and collapse.

What happens when dissimilar metals join?

Each conductor has its own electrochemical potential. This feature is successfully used in the manufacture of batteries and accumulators. But when two metals come into contact under conditions of humidity and stress, they begin to actively deteriorate. The results of this process are: fire of insulation, breakage of the electrical circuit.

Elimination of such a defect in hidden wiring will require time to detect, open and restore the surface of the walls. This happens when the splicing was performed by simply twisting two dissimilar cores. If connected correctly, the electrical contact will be reliable and will last a long time.

Methods for properly connecting aluminum and copper electrical conductors

When creating temporary electrical circuits, twisting of copper and aluminum wires occurs quite often. This is the most quick way splicing power lines in the absence auxiliary materials. For short-term use, although not recommended, this option is possible. When laying a major power line, the following types of connections are used:

twisting with tinning of a copper core;

• threaded
• block
• one-piece
• spring clamps (Wago)

Tinned copper wire

The pre-cleaned copper core is coated with tin solder (tinning) using a soldering iron. After this procedure, you can connect both wires by twisting. The length of the ends cleared of insulation should be 4-5 cm.

Simple twisting is done by twisting the wires onto each other. After this, the connection is insulated with tape, cambric or heat shrink tubing. The latter option significantly enhances the reliability of contact.

Threaded connection

It is possible to reliably connect copper and aluminum electrical conductors using nuts, washers, and screws. The assembled contact is easy to disassemble and is of high quality. Provides good connection for the entire period of operation of the electrical network. The number of wires you can connect limits the size of the screw.

The conductors are exposed to a length four times greater than the diameter of the screw. They clean off oxides and form rings into which the screw will be inserted. In a certain sequence they wear:

• spring washer
• an ordinary washer
• copper wire ring
• puck
• aluminum core ring
• a simple washer
• nut

By tightening the screw, the entire package is tightened until the spring washer straightens. In stranded copper wires, a ring is first tinned to form a solid segment.

Terminal block connection

The most common option for splicing aluminum and copper conductors. In terms of reliability, it is inferior to the threaded one, but allows you to quickly complete the process in any combination. There is no need to prepare connecting areas or carry out insulation.

Structurally, the pads eliminate the presence of exposed wires and accidental contact with them. To connect, the ends of the cores are stripped to 0.5 cm. They are inserted into the holes in the block and clamped with screws. This option is the fastest and quite reliable. It is necessary to take into account that when wiring is hidden, the terminal blocks must be placed in the junction box.

Pads with clamps

New items on the electrical market, “Wago” clamps, have recently appeared in the arsenal of electricians. They are produced by a German manufacturer in two versions: disposable and reusable. Single-use designs allow the product to be used only once. Once the wire is inserted into the device, it is no longer possible to remove it back.

Reusable designs have a lever that allows the removal and insertion of conductors. The device is reliable and convenient, but has the highest cost of use. An unpleasant feature: the presence of many fakes on the market. As a result, connections may be unreliable, since the quality of non-originals leaves much to be desired.

Permanent connections

They have all the advantages of the threaded method. Disadvantage: there is no possibility of disassembling the structure. The connection is made by applying a special tool to the rivet. The preparation procedure is similar to the threaded connection diagram.

The prepared structure is placed in the tool, then it is compressed until it clicks. After this, the connection is ready for use. The method is convenient for splicing damaged sections of hidden aluminum wiring with copper wire inserts and in other cases. Required condition– careful isolation of exposed areas.

Methods for connecting copper and aluminum wires (video)

Any cable consists of aluminum or copper current-carrying conductors. According to the electrical installation rules, the usual twisting of such wires is strictly prohibited. But there are situations during installation when there are no options other than connecting aluminum and copper wire. There are many such opportunities. All that remains is to choose an accessible and safe one.

Electrochemical destruction of metals

The opinion that it is impossible to combine aluminum and copper is often mentioned. This is true from the analysis of the chemical compatibility of metals. in the world modern technologies You can find dozens of matings of metal pairs.

There is a concept of electrochemical potential difference, the indicators of which are summarized in a special reference table. Take from it as necessary indicators and are determined with compatibility:

• Copper - lead-tin solder 25 mV.
• Aluminum - lead-tin solder 40 mV.
• Copper - steel 40 mV.
• Aluminum - steel 20 mV.
• Copper - zinc 85 mV.

To imagine what is happening, it is necessary to understand the reactions that electrodes made of different metals undergo upon contact.

In the absence of moisture, the reliability of contact is undeniable. But there is no ideal situation. Atmospheric humidity always negatively affects the quality of connections. Any conductor has a certain electrochemical potential. This property is used in practice in the operation of rechargeable batteries.

Getting onto the contacting surfaces from various compounds, water creates a short-circuited galvanized environment. One electrical conductor begins to deform. The material from which it is made is also subject to destruction.

Methods for connecting wires made of different metals

Technological rules allow direct connection of different metal conductors with an electrochemical potential coefficient of over 0.6 millivolts. According to the tabular data, for a combination of aluminum and copper it is equal to 0.65 mV, which makes such a combination unacceptable. However, there are ways to correctly interconnect different wires.

Cable connection by twisting method

Most famous, but an unreliable technique is called twisting. This method does not require special skills and is easy to make. For these reasons, it is used quite often. Before connecting the aluminum wire with copper, you need to imagine what is happening in a similar combination with temperature changes and precipitation:

• There is a gap in the connection.
• Increased resistance at the ligament point.
• Heat.
• Oxidation of cables, destruction of contact.

This method is not suitable for ensuring secure communication. Although, if you perform certain operations, in some cases you can use twisting to connect aluminum and copper wires:

Threaded connection of wires

A similar method is performed by clamping the ends of the cable into a bolted fastening. This is the most reliable connection between aluminum and copper wires together. It guarantees tight contact for the entire period of use of the twist. Replacing bolts of different lengths makes it possible to combine an unlimited number of cables:

• Different sections.
• Stranded and monolithic.
• With washers to prevent direct contact with copper and aluminum conductors.

Procedure:

1. Cut the insulating coating to the length required for fastening.
2. Sand and degrease the cleaned areas. Tin the multi-wire cable. Connect the cores using threads through steel washers.
3. Tighten the nut tightly.
4. Shock absorbers are placed in front of the outer washers to prevent pinching and breaking of the wire. When crimped, it will straighten and the connection will be fixed.

Connecting different cables with a terminal block

Splicing cables through terminal connections has become widespread in recent times. Although the quality of contact it is inferior to the bolted one, undeniable advantages also available:

• The wires are connected in random order.
• There is no need to make connecting rings and put on ferrules.
• The design features of the terminal blocks do not allow short circuits of the wires.
• Isolation of the contact point is not required.
• The work on connecting the terminal contacts is simple.

The ends of the wires are exposed by approximately five millimeters, inserted into the clamp and pulled through. This method is indispensable when connecting aluminum cables, the cores of which break due to repeated bends.

Repairing damaged cables using terminal blocks also turns out to be the only acceptable option due to the short length of the wires. After splicing, a junction box is installed.

From the numerous connecting devices, not least occupied by German Vago spring terminal blocks from the company of the same name. They are either disposable or with a clamp for repeated splicing of the wire. Such terminal blocks are used when working with single-wire wires with a cross-section from one and a half to two and a half squares made of any metal in insulating boxes. According to the passport, they are designed for twenty-four amperes in load. The contacts are treated with a special compound to prevent oxidation.

These are the simplest devices to use. The wire is stripped and forcefully inserted into the block. The fixation is reliable. It is possible to get the wire out with good effort. In this case, the spring block is destroyed and reuse is impossible, which is the most big drawback of this product.

Reusable terminal blocks Wago with an orange lever are designed for the use of wires of any type with a cross-sectional area of ​​up to four square millimeters and currents of up to thirty-four amperes. Apply repeatedly until completely worn out.

The method of application is available to anyone. The insulation is stripped to a distance of about ten millimeters, the lever is raised, the wire is placed in the channel and the lever slams shut. The connection is fixed.

Vago terminal blocks are effective devices for installation work electrical networks. They do not require the use of special tools, but are quite expensive.

Monolithic connection method

The technique for making such a connection is similar to a threaded one. As fastening element a rivet and a special device - a riveter - are used. The rivet is a hollow aluminum rod, thickened on one side. A wire pin with a cap is placed in it. When passing through the cavity, it creates a thickening on one side. Then the pin breaks off, forming a rivet.

If you do not take into account the price of the riveter, this method of contact becomes the most affordable besides twisting. The disadvantage of such contact is its disposability and the impossibility of disconnection if the work is performed incorrectly.

The use of special copper sleeves will be another way to permanently connect conductors. They are produced various sizes, for each cable section its own. The bare ends of the wires are threaded through them and crimped with special pliers. This method is the most compact along with twisting.

Connecting wires by soldering

If desired, dissimilar wires can be soldered. This method must take into account certain technological features. Before connecting the wires correctly, aluminum and copper must be prepared for soldering. Copper doesn’t require any special tricks. Aluminum wire is another matter. On its surface, under the influence of ambient air, an oxide film - amalgam - is formed. It resists chemical attack and solder does not stick to it.

To neutralize it, you will have to make a simple device. The tip of the aluminum wire is stripped and treated with a solution of copper sulfate. Take a battery and attach this conductor to its minus. The copper wire is fixed to the positive with one end, and the other is dipped in the same solution. After a certain period of time, the aluminum will be covered with a copper coating and will become available for soldering.

Specifics of connections for outdoor installation

Electrical connections under installation conditions outdoors exposed to various weather factors. Insulation requirements are more stringent. To prevent short circuits, a Walnut clamping kit is used.

Its plastic shell contains metal clamps in which the wires are connected by tightening the screws. The housing halves are tightly compressed with screws or spring rings. Such a cocoon guarantees protection from external weather fluctuations. This is a rather large connection, but in outdoor conditions it is not critical.

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

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

This issue - copper and aluminum - is encountered not only during installation internal wiring, but also when replacing the input to the house

The fact is that the overhead line (OHL) wires are aluminum and if you do input cable copper, you can’t just screw a cable core onto an aluminum wire!

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, but why? Here's why.

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

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

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

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

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

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

The transition resistance in the twist was already “slowing down” electric current, and even weakening the contact further increased the value of the transition resistance.

This causes the twist to begin bask The further you go, the more the wire insulation heats up. It is destroyed by heat and can even burn.

You know how many houses have burned down due to faulty electrical wiring, and often it is the transition resistance or poor contact that is to blame.

Speaking of transition resistance.

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

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

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

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

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

The point here is this: the main thing is that these two metals didn't touch among themselves. Between them there must be a material neutral in relation to them, naturally conductive.

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

By the way, it’s interesting - you can’t: zinc, carbon (graphite) and silver with gold and platinum.

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

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

So, we combine copper with aluminum:

-Using terminal clamps;

-Bolt connection via washers

- Layer of neutral material

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

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

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

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

Then I made two cable cores per phase and neutral, connected them 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 already passed and there are no comments))) This is despite 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.

I’ll show you how to do this in the photo:

This is a good way out when you don’t have clamps at hand or don’t want to use them, and the bolted connection doesn’t fit in 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 the PUE it is incorrect...

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 going from the switch, and an aluminum wire to the light bulb. The twist was purely copper and aluminum without any terminal blocks, solder, etc.

So the state is as if it had just happened!

Everything is clean, no oxidation or scorch. I think this is because the apartment was always dry and besides, the junction box was tightly sealed in the wall, that is, air did not penetrate into it.

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

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

But in this case, I would not recommend using a Vagov 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 this, I’m sure you will make the right choice!

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