How to properly connect copper wiring to aluminum. How to connect aluminum and copper wires, methods and differences

When installing electrical wiring, it is quite often necessary to connect different current conductors, namely, aluminum and copper wires. From the point of view of electrical and fire safety, this type of connection is more risky and must be carried out with strict adherence to a number of rules.

What is the essence of the problem of connecting aluminum and copper wires, and what are the options for solving it? Let's try to figure it out.

Difficulties connecting aluminum and copper wires

Over the past decades, there has been a rapid increase in energy consumption by the population. This has led to an increase in the load on the electrical networks and, accordingly, on the connection of wires in the wiring.

Therefore, today there are serious requirements for the installation of electrical wiring, aimed at improving electrical and fire safety.

Indicators of a reliable wire connection:

1. The density of the contracted contact.
2. Electrochemical compatibility of contact wires.

The first requirement of high-quality electrical wiring is quite simple to fulfill. The second requirement is often ignored in practice and incompatible current conductors are connected in a direct way (twisting). It is because of the electrochemical incompatibility of metals that difficulties arise when connecting copper and aluminum wires.

Aluminum is a metal with a high degree of oxidation. The oxide film formed on the surface of the aluminum wire in contact with moisture has a high resistance. This negatively affects the electrical conductivity of the connections.

Copper is a rather inert metal and the oxide film on copper wires has less resistance.

In a pair, copper and aluminum form a short-circuited galvanic connection - when moisture enters the contact, the aluminum wire begins to actively oxidize. A thin film with high resistance is formed between the current conductors, as a result, the current conduction becomes difficult, the electrolysis process occurs, shells, heating, and sparking of the contacts form at the contact point. This situation may cause a fire.

The electrochemical potential between copper and aluminum is 0.65 mV, while the allowable value of this indicator is 0.60 mV

The solution to this problem is the elimination of direct contact between aluminum and copper wires. There are several options for connecting different conductors, ensuring the reliability and safety of electrical wiring.

The main methods of connecting different current conductors

application of terminal blocks

The most common way is to connect wires through terminal blocks.

In essence, a terminal block is an insulating plate with contacts. Fastening wires in the terminal block is of two types:

• screw tightening (there is a risk of damage to the wire by the screw itself);
• pressing with plates (more reliable mounting option).

Among the advantages of the "terminal" method of connecting wires include:

• ease of connection;
• the connection does not need to be further isolated;
• affordable cost of adapters.

The sequence of connecting copper electrical wires with aluminum:

The terminal block is convenient to use when connecting a chandelier, when the conductor length is too short, or for connecting copper and aluminum wires that have been broken and broken in the wall.

The terminal block, before being hidden under the finish, must be placed in a junction box

spring terminals for connecting wires

One of the varieties of terminal blocks are Wago spring clamp blocks.

Spring terminal blocks are the most efficient and fastest way to connect wires. The main difference from conventional terminal blocks is the method of fixing the wire - a spring clip is used. It is enough to remove the insulating layer from the conductor and insert the wire into the terminal block.

In order to connect copper and aluminum wire, it is better to use special Wago terminal blocks. The contacts in such a terminal block are made of a bimetallic plate and coated with a special paste that prevents oxidation of the wires.

Spring terminal blocks are of two types:

The disadvantage of spring terminal blocks is their cost, they are an order of magnitude more expensive than conventional adapters.

connection through the "nut"

To connect wires with a large cross section (4 mm² or more), you can use a branch clamp, known in everyday life as a “nut”. It is an oval-shaped plastic case, inside which there is a block of metal plates. Aluminum and copper wires are clamped between the plates with screws.

This connection option is not entirely convenient due to the large dimensions of the adapter itself, which is difficult to hide under the decoration of the room: skirting boards and boxes.

permanent connection

A permanent connection is made using a special tool - a riveter.

The principle of operation of the riveter is simple - retraction and subsequent cutting of the rod, which passes through the tubular rivet with a cap.

The wire connection technology is as follows:

1. Remove the insulation from the conductors (the length of the cleaning is equal to 4 diameters of future rings). It is optimal if the diameter of the rings is slightly larger than the diameter of the rivet.
2. Twist rings from the cleaned ends of the wire.
3. Put all the elements on the rivet in the following order:
   • aluminum wire;
   • spring washer;
   • copper wire;
   • flat washer.
4. Insert the steel rod into the riveter and squeeze its handles until a characteristic click.
5. Bare areas of the connection must be isolated.

The reliability of the permanent connection is very high, the only drawback is that it is not possible to disconnect and re-fasten the wires.

Alternative ways to connect aluminum and copper wires

If there are no special adapters or a riveter at hand, you can use alternative methods for connecting different conductors.

Bolted connection considered quite durable and safe. Among its advantages, one can single out ease of installation and versatility (in this way, almost any type and brand of aluminum wires can be connected to copper wires).

Bolted connection technology:

For connecting conductors with a cross section of less than 2 mm², an M4 screw is suitable

A technologically more complex and time-consuming method is applying solder to a copper wire. You can use lead-tin solder.

When aluminum comes into contact with lead-tin solder, the electrochemical resistance index is 0.40 mV (the permissible rate is not more than 0.60 mV)

The wire connection sequence will be as follows:

This method can be used if there are no jumpers or the bolted connection does not fit into the box. However, for an electrical wire with significant loads, such a connection cannot be used.

Features of connecting wires indoors and outdoors

Outdoor wire connections are exposed to external factors and need additional protection.

The optimal solution for outdoor connections is the use of branch clamps for SIP. The material of the clamps is resistant to ultraviolet rays and low negative temperatures.

In addition, branch clamps nuts are also suitable for the street.

To connect the wires in the room, you can use different conductors. One of the most convenient is the Wago self-clamping terminal block.

Expert advice: how not to connect aluminum and copper wires

There are frequent cases of the use of dangerous, unacceptable methods for connecting aluminum and copper wires, which had very sad consequences. These methods include:

1. Stranding copper and aluminum wire. It should be noted that a number of experts do not recognize twisting, even if a layer of solder is applied to the copper wire.
2. Twisting of wires with subsequent protection of the junction from moisture. As a waterproofing, some "craftsmen" use paraffin, oil or varnish. This method is unacceptable and, to put it mildly, ineffective.

To date, the problem of connecting different current conductors is solved very simply and quickly - just purchase one of the special adapters. Therefore, it is completely inappropriate to waste time and test untested methods, endangering the safety of not only housing, but also the people living in it.

There are a lot of rumors about the connection of copper and aluminum wire. Some say that there is nothing wrong with this, and give examples when such compounds last for decades, while others say that they know from practice how quickly they break down. Whom to believe, and how to connect such wires correctly, we will talk in our article.

First of all, let's see why it is impossible to connect these wires together, and what is needed for such a connection to serve for many years. To do this, we have to dive a little into the theory, and deal with the structure of these metals.

Why you can not connect copper and aluminum wire

To understand how to connect a copper and aluminum wire, let's figure out what is so special about such a connection. After all, there are several theories at once 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 prevent the passage of electric current, but the aluminum oxide film has a fairly high resistance.

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

As a result, the aluminum conductor loses its mass. It forms voids and shells. They, in turn, are also oxidized and further accelerate the electrolysis process. And the more moisture in the compound, the faster this process occurs.

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

How to connect copper and aluminum conductor

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

• Let's look at both of these options. Let's start with the simplest - place a third metal between the conductors. Usually, an inactive metal is also chosen for this, so that we again do not have an electrolysis process. And usually the instruction recommends 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 ordinary steel or stainless steel for this. But you should not do this. The fact is that these materials do not have very good conductivity. Therefore, when passing through them large currents, they will get very hot. As a result, we can again get a fire.

Aluminum wiring is now rarely used for laying electrical networks in houses and apartments. It must be replaced during repair work. However, it also happens that the work is carried out partially. In this case, the problem arises: how to connect copper and aluminum wires.

What problems can arise when joining aluminum and copper

When answering the question whether it is possible to connect copper to aluminum, it must be recalled that the following problems arise when twisting copper and aluminum wires:

1. Decreased electrical conductivity. Aluminum is an active metal, under normal conditions it is covered with an oxide film with low conductive qualities. Copper does not have this property.
2. Weakening of contacts. Due to the formation of plaque, contacts become worse. Such a film does not form on copper conductors, therefore metals are considered electrochemically incompatible.
3. Fire hazard. When wondering how to connect an aluminum wire to a copper one, they remember that electrical contact occurs between the oxide deposits formed on the wires. Over time, metals begin to heat up, which leads to a fire.
4. Electrolysis. If the system is operated in conditions of high humidity, the connection begins to break down, becoming a source of fire. First of all, corrosion covers the aluminum parts of the wiring. With regular heating and cooling, cracks appear in the insulating braid, the connection is covered with an oxide or salt layer, which accelerates destruction.
5. The formation of conductive soot. Contact in this case is broken, a fire starts in the house. When operating electrical wiring in a dry room, this process lasts for years. With high humidity, ignition occurs after a few months.

Ways to connect different wires

How to connect copper and aluminum wires:

• using another metal;
• preventing the appearance of harmful oxide plaque.

In the second case, special compounds are used that can protect the metal from the effects of moisture and oxidation. Pastes prevent the destruction of the connection. Another way to protect against fire is tinning. Tinned stranded cable can be twisted with aluminum single core. For connection, special devices are also used:

1. Clamps. Used to connect to an aluminum riser in the driveway. Branch clamps have punctures or lack them. The device is equipped with an intermediate plate that prevents contact between two metals. Some clips are treated with paste. Sometimes the use of special formulations is not required.
2. Spring and self-clamping terminal blocks. It is possible to dock and splice wires from different metals using terminals that have sockets and partition plates that separate aluminum conductors from copper ones.
3. Bolts. When making a bolted connection between the wires, a washer made of stainless or galvanized steel is laid.

Terminal blocks

Terminal blocks are:

1. Disposable. They are used when connecting wires in junction boxes and installing chandeliers. To insert the cores into the hole of the device, efforts must be made. Even more difficult is the extraction of the cable from the block.
2. Reusable. For fixing there is a lever, thanks to which the cable can be inserted and removed several times. Blocks of this type are used when connecting stranded wires from different metals. If the work is not done correctly, the connection can be redone.

Installation is carried out as follows:

• the cable is cleared of the insulating coating;
• the veins are stripped to a metallic sheen;
• on the reusable terminal block, a lever rises;
• the cleaned part of the wire is inserted into the hole of the block until it stops;
• the lever returns to its original position.

Crimping

In this case, tubular sleeves are used, which reliably and safely fasten the wiring elements. To connect the cables, you will need a press, mechanical, hydraulic or electric pliers. Installation includes:

• sleeve selection and tool adjustment;
• cleaning the wires from the braid;
• stripping the cores (sandpaper is used for this);
• applying a quartz-vaseline composition;
• inserting the ends of the cables into the rivet;
• crimping (when using a simple tool, several crimps are performed at a short distance, when using a good tool, crimping is performed once);
• connection isolation.

The wires are inserted into the sleeve from opposite sides so that the joint is located in the middle of the connector. Cores can be inserted from one side. The connection of cables with a sleeve is sometimes replaced by the use of “nut” clamps, however, the latter are less reliable. The rivet will loosen over time, increasing the risk of fire.

Bolted connection

Subject to the installation rules, the method provides a durable fastening. To complete the work, you will need 2 simple washers, 1 spring washer, nut and bolt. The wires are cleaned of insulating material. A spring washer is put on a bolt, which is inserted into a simple washer. The end of the aluminum cable is folded into a ring, which is thrown onto the bolt. After that, put on a simple washer and screw on the nut. The stranded wire is coated with solder before starting work.

Soldering

This is a reliable and technologically advanced method that provides a high-quality connection. Before soldering, the cores are cleaned of braid and oxide film. If necessary, the cables are tinned, loosely twisted, treated with flux and soldered. It is impossible to connect aluminum and copper wire using acid flux. The composition destroys metals, reducing the fastening strength. The junction is isolated in the usual way.

Features of the connection lived on the street

When performing work on the street, take into account that the wires will be affected by precipitation, high and low temperatures, and wind. Therefore, when performing installation work, sealed structures are used that are insensitive to ultraviolet radiation and high humidity. When connecting wires on roofs, facades and poles, piercing clamps are used.

Many, probably, faced such a problem when the twisting of wires begins to spark and knock out machines. Naturally, this is unpleasant and poses a great security risk. Using wires from various materials in a home electrical network, you should clearly know how to connect copper and aluminum wire and do it right. Indeed, with direct contact, copper and aluminum are oxidized, violating the quality and integrity of the twist.

Any conductor (copper, aluminum, steel and others) has a certain electrochemical potential. When the moisture in the air interacts with oxygen, 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 the various conductors. Knowing them, you can choose the right materials that are well connected to each other.

Metal	Copper, its alloys	Lead-tin solder	Aluminum	Duralumin	Steel	stainless steel steel	Zinc coating	Chrome plating	Silver	Carbon (graphite)	Gold Platinum
Copper, 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
mild 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 plating	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 which does not exceed 0.6 mV. Therefore, a 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 choose a kind of gasket between these materials, which optimizes the tension in the bundle.

Considering a copper wire, the best connection option for it would be copper itself and steel (potential 0.1 mV). Likewise with aluminum. Accordingly, in order to connect the copper and aluminum wire correctly, you need to add a gasket (washer) made of steel between the conductors. Also, according to the table, you can choose other combinations of connections.

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

Twisted connection

Twisting is the most common but less reliable way to connect wires.

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

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

With the aim of obtaining a more reliable contact, it is better to refuse to use twisting. But, if you still stop at this connection method, you should adhere to the following rules:

• The different conductors must wrap well around each other.
• Measures are required for additional sealing of 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 wire connection

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

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

• From different metal (for example, copper and aluminum).
• Various thickness (core diameter).
• Multi-core and single-core.

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

Consider the steps for creating a threaded connection:

1. It is necessary to remove from the wire an insulating layer of sufficient length to crimp the live thread of the bolt.
2. Oxidized areas must be cleaned and degreased. And 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 alternately on the screw. Washers must be steel.
4. Finally, the whole structure is fixed 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 out while screwing in, the connection will be optimally fixed.

Terminal block connection

Connecting wires using a terminal block is inferior in reliability to connecting with a screw and a 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 in this way, the ends of the cores are stripped of insulation to a length of 4 - 8 mm (depending on the diameter), inserted into the hole and clamped with the supplied screws.

1. Terminal blocks should never be used in critical and powerful areas. Laying in the plaster under the finishing layer is also not the best option.
2. It is acceptable to use it in viewing 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 loose contacts.
4. When using conductors of various metals, please note that an excessively bare core may have contact with a core threaded from the other side. In this case, partial oxidation and bond weakening will occur.

As an additional precaution, the connection made by the terminal block is recommended to be additionally wrapped with insulating tape. This is due to the fact that a loose contact can lead to an accidental release of a live conductor.

Connection using terminal blocks

Connection using WAGO terminal blocks

The most common type of this connection is terminal blocks with spring clips from the German manufacturer Wago (Vago). They are designed to connect any kind of solid wires (tinned stranded) with a cross section of 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 application. 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 necessary to take into account the load on the lines of the home electrical network and select the 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 the insulation from the conductor by 8 - 10 mm. and insert it into the clamp.

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

powerhouse.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 contacted me with a request to see his outlet. A year after the repair, the outlet began to smell, and over time it also began to warm up. Well, when the socket sparkled, he began to sound the alarm.

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

Never bond aluminum and copper together. Fire not ruled out.

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, then 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, most damaged parts, and cleaned the rest.

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

1 . Two bolts with a diameter of 4 or 5mm;
2 . Four nuts with a diameter of 4 or 5mm;
3 . Eight washers of suitable internal diameter;
4 . Insulating tape;
5 . Copper two-core wire with a cross section of 2.5 squares 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 enters.

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

From above, close the semi-ring with a washer and well tighten with a nut.
Now the aluminum wire must be extended with a piece of copper, so that further connection can be made between copper and copper.

We take a piece of copper wire 15 - 20 cm long, make a half ring, put it on the same bolt, and between two washers well tighten with a nut.

You will get such a "sandwich".

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 any copper can be freely screwed to the resulting two ends.

Let's restore the schema.

The twists made can be irradiated, or you can not irradiate.
Next, we isolate the twists, remove the inside of the box and breed so that they do not interfere with the outlet.

Well, it remains to connect and fix the outlet on the wall.

In such a simple, but at the same time effective way, we bonded copper to aluminum, and at the same time, eliminated a malfunction that could lead to unknown consequences.
Good luck!

sesaga.ru

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

Electrochemical corrosion

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

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

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

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

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

What happens if copper is connected directly to aluminum

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

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

Overview of connection methods

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

Bolted connection

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

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

The connection is made as follows:

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

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

Terminals

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

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

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

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

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

Wago terminal blocks

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

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

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

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

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

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

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

Rivets

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

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

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

soldering iron

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

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

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

Connection quality

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

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

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

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

stranded wires

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

Sleeves

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

Twisting

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

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

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

Note! Twisting is unacceptable in rooms with humid air.

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

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

220.guru

How to connect copper and aluminum wire correctly?

When partially replacing the wiring, extending the conductor or replacing the burnt area, a wire is used. It happens that in their material they do not match. Then it becomes necessary to connect aluminum wires with copper. There are five ways to do this, and each has its own advantages and disadvantages. Some of them require preliminary preparation of the conductor.

Danger of bad wiring

The industry produces two types of wires for domestic purposes, copper and aluminum. The former have less resistance, which allows using a smaller section for the same load. They are more resistant to mechanical stress, this makes it possible to repeatedly twist, not to be afraid that they will break at the place of the incision. The latter have one advantage - comparative cheapness. But sometimes it plays a key role. What can happen if the junction is of poor quality?

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

Methods for joining copper to aluminum

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

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

Wire twisting

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

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

Threaded method

More labor-intensive connection compared to twisting. Requires a tool and some skill. It has greater mechanical strength. On the electrical side, it is better than twisting. Allows you to immediately connect a large number of wires, and of different sections. You can connect both single-core and multi-core.

For connection, a bolt is used, on which conductors are put on 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 superimposed on the last conductor. The whole package is tightened with a nut until the spring washer straightens out. Further pressure may break the conductor.

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. The stranded copper wire also needs to be soldered, then it will not disintegrate during compression.

After assembly, measures must be taken to prevent short circuits with neighboring packages. Over time, it is necessary to check the condition of the spring washer, if it is weakened, tighten the nut. Such a connection prevents sparking, allows you to output wires in different directions. If necessary, it can be easily disassembled and assembled without damaging the conductor.

Terminal method

The terminal connection is made in factories. Has an extensive range. Two groups can be distinguished:

• pads;
• terminal blocks.

pads have different shapes and designs. The bottom line 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 structural rigidity.

The advantage of pads is that no preliminary steps are needed, with the exception of stripping the cores. The connection is fast and does not require any skills. They are indispensable if the conductor is short (connecting a chandelier, restoring a broken wire). If they are located in switchboards, metering boards - 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 stress than a threaded connection;
• each block is designed for a conductor of a certain section;
• it is impossible to connect wires of large and small diameter at the same time;
• take up more space than before.

Terminal blocks have recently found wide application. 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 with a plastic lever. After that, a wire is inserted into the opening. In some embodiments, 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. Designed for single use. If the wire is still 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 training required;
• ease of use;
• the necessary insulation is available.

Disadvantages:

• the method is the most sensitive to mechanical stress;
• compared to other compounds, it is the most expensive;
• sensitive to high current and, according to user comments, does not withstand the regulated load.

One-piece method

Probably the most laborious way. Requires special knowledge and skills. Special tools and fixtures are required. This method includes:

• riveted;
• soldering.

stave very similar to a threaded connection, with the only difference being that a rivet is used instead of a bolt. The ends of the wires are cleaned of insulation and cleaned with sandpaper. When combining aluminum and copper wires, the latter is tinned. This also applies to copper stranded wire. After that, rings are made a little larger in 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 reliability of the connection and its low resistance are needed. It looks like a twist, but the wires are soldered. This cannot be achieved in the usual way for aluminum, so the wires must be prepared.

To do this, you need a solution of copper sulfate, a small non-metallic container, a constant voltage source of 9-24 V. Pour a solution of copper sulfate into the container and lower the previously cleaned conductors to the length of the twist. We connect the copper wire to "+" so that the electrons go 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 that, both wires are covered with a layer of tin. A twist is made in 3 turns for a thick wire and 5 for a thin one (less than 1 mm). All this is carefully soldered. It remains to cover them with waterproof varnish, insulate - and the connection is ready.

Advantages:

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

Disadvantages:

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

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

elektro.guru

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

Almost every electrician will say and agree that electrical is the science of contacts. In practice, this becomes obvious. A large number of problems in the power supply are formed due to a large wiring overload, as well as due to 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 figure is higher than the melting temperature of aluminum itself. Moreover, if you clean the oxide film mechanically, then after a while it appears again.

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

Are there ways to reliably connect aluminum wire then? Let's take a 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 from insulation by 20 mm. After the vein, it is recommended to clean it with a fine-grained sandpaper. Next, twist the bare core into a ring and insert it into the clamping screw, which should be tightly tightened.

Screw connection kit

The downside 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 place.

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 securely held. There are terminal blocks both disposable and reusable. Disposable are used to connect wires, without further disconnection. The wire is inserted into the hole of the clamp, do not pull it back. As for the reusable connection, the wire is easily pulled out by pressing the special lever holding the wire.

Twisting

In rare cases, aluminum wire can be connected by twisting. It should be noted right away that this method is very unreliable, even though it was used relatively often in Soviet times. This is partly due to 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 duration of such a connection depends on various factors, such as current load, humidity and temperature. If the temperature rises, the metal expands, which widens the gap between the wires. This can lead to contact resistance, the contact point will heat up and after that oxidation will form and, in the end, the contact will be completely broken. However, this process continues for a long time, so for temporary connections, the twisting method is acceptable.

When joining aluminum in this way, it is important to adhere to the following rules:

• The wires should evenly wrap around each other.
• If the wire is thick, then there should be no more than three turns, and for a thin one, at least five.
• If copper and aluminum wire are connected, then copper must be tinned.
• It is recommended to use heat shrink 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.
• Having relevant skills.

Consider each method of permanent connection separately.

Welding

Fast and reliable connection method. Moreover, this technology is relevant if a large number of connections should 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.
• After that, carbon electrode welding takes place 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 is dry, 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, special press tongs and sleeves, which are hollow rods, will be required. For crimping, you clean the ends of the wire, insert them into the sleeve and perform crimping in three places. You can also twist the wires additionally.

Crimping set

If the wire is aluminum, then use an aluminum sleeve, for copper - a copper sleeve. If you combine aluminum with copper, then copper-aluminum sleeves are on sale.

aluminum and copper wire

Connecting 2 copper and aluminum wires can cause some problems. The problem lies in the potential difference, the difference of which reaches up to 0.65 mV. With an increase in humidity 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, it is possible to connect aluminum to copper wires.

In this article, we looked at several methods on how to connect wires together. If you know of other methods, then leave comments at the end of this article.

Video

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

kakpravilnosdelat.ru

How to connect copper and aluminum wire

In residential buildings that were built in Soviet times, electrical wiring was carried out with aluminum wires. Professional electricians prefer to make a modern household network with copper wires. Therefore, whether we like it or not, we often face such a problem as connecting copper and aluminum wire. Do not listen to those who will tell you that this cannot be done categorically. Of course, not all methods are suitable for this case, however, connecting electrical aluminum and copper wires is a completely solvable task. The main thing is to do everything right.

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

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

Reasons for incompatibility

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

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

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

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

Bolted connection

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

Of course, it is unlikely that you will be able to use this method to connect wires in an apartment junction box, because now they are produced in miniature sizes, and the resulting electrical assembly will be very cumbersome. But if there are still Soviet-era boxes in your house or when you need to make a connection in a switchboard, then such a bolted method is best suited. In general, it is considered an ideal option when it is necessary to switch absolutely incompatible cores - with different cross-sections, made of different materials, stranded with single-core.

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

You will need to do the following:

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

Most importantly, do not forget to place an intermediate washer between the aluminum and copper wires. If you connect several different conductors, then you can not put an intermediate washer between the cores of the same metal.

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

How to properly bolt the wires is shown in detail in this video:

Clamp "Nut"

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

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

Such clamps are sold at any electrical goods store, they have different types, which depend on the cross section of the wires being connected. The disadvantage of such a device is its non-tightness, that is, there is the possibility of moisture, dust and even small litter. For the reliability and quality of the connection, it is better to wrap the “nut” with insulating tape on top.

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

1. Disassemble the clamp housing, to do this, pry and remove the retaining rings with a thin screwdriver.
2. On the wires to be connected, strip the insulating layer to the length of the dies.
3. Unscrew the fixing bolts and insert the bare conductors into the die slots.
4. Tighten the bolts, position the plate in the compression housing.
5. Close the housing and put on the retaining rings.

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

Terminal block

A cheap and easy solution to the question of how to connect aluminum wires to copper is to use terminal blocks. Buying them now is not a problem at all, moreover, you can buy not a whole section, but ask the seller to cut off the required number of cells. Terminal blocks are sold in different sizes, depending on the cross section of the conductors connected to them.

What is such a block? This is a transparent polyethylene frame designed for several cells at once. Inside each cell there is a tubular brass sleeve. From opposite sides, it is necessary to insert the ends of the wires to be connected into this sleeve and clamp it with two screws.

The use of terminal blocks is very convenient because it is always possible to cut exactly as many cells from it as how many pairs of wires need to be connected, for example, in one junction box.

Using the terminal blocks is very simple:

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

Why do you have to do everything in order? After all, you can immediately unscrew the two screws, insert the wires and tighten. This is to ensure that the copper and aluminum wires do not touch each other inside the brass sleeve.

As you can see, the advantages of terminal blocks are the simplicity and speed of their application. This connection method refers to detachable, if necessary, you can pull out one conductor and replace it with another.

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

There is another feature in the use of terminal blocks. Under the pressure of the screw at room temperature, aluminum can flow. Therefore, a periodic revision of the terminal and tightening of the contact connection, where the aluminum wire is fixed, will be required. If this is neglected, the aluminum conductor in the terminal block will loosen, the contact will weaken, it will start to heat up and spark, which may result in a fire.

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

Self-clamping terminals

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

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

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

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

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

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

Twisted connection

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

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

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

yaelectric.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 must be very tight, and over a fairly large area. This is due to the fact that a fairly large current will flow here. This situation is especially relevant when it is necessary to splice wires through which electricity is introduced into living quarters. How to connect aluminum and copper wire to each other so that the connection is reliable, efficient? You will find answers in this article.

Figure 1. Simple wire connection methods

Why You Can't Just Twist Aluminum and Copper Wires

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

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

That is why it is impossible to connect aluminum and copper wires with a simple twisting method. Many, not knowing this circumstance, still manage to twist. They are attracted by the simplicity of the process, the absence of the need for additional materials, except for insulating tape. At first, such a wire connection will work well. Then, due to the difference in linear expansion coefficients resulting from the diurnal temperature difference, the contact will begin to weaken. This will lead to an increase in resistance, the start of oxidative processes. Subsequently, corrosion destruction will begin.

It must be understood that all of the above will not happen in one day and, perhaps, not in one month. But it will definitely happen. Well, if it ends like this. Because there are cases when fires arise from the spark that appears. How to connect copper and aluminum wires to get a reliable durable contact?

This will require additional equipment. For example, the connection of aluminum and copper wires is possible by twisting, if the copper wire to be connected is first tinned 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 for this case is suitable.

Tinning is mandatory if you have to connect a multi-core cable made of copper with aluminum. You should know that both wires must be wrapped around one another, although they have different degrees of rigidity. You can not wrap one vein around another. The following are methods for twisting and simple connections for wires.

Figure 2. Twisting methods

Connection with threaded devices

This method is the easiest after twisting. True, it requires one bolt, nut, two spring-loaded and three simple washers. Thus, strong connections are obtained, regularly serving for many years. The advantage in this case is the possibility of connecting conductors of different sections, solid, stranded.

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

• one of the wires is stripped of insulation;
• a spring-loaded washer is put on the bolt head, and a simple one on top of it;
• bare 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 thrown onto 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 thread diameter M4 will be optimal. If the copper conductor is stranded, it would be better to solder it by connecting all the cores 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 rivet aluminum and copper wire? This will require a rivet, one spring and one plain washers. An aluminum conductor wrapped around it is put on the rivet head. A spring-loaded washer is put on top. Then a tinned copper core is wrapped around the rivet, on which a simple washer is put on.

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. If necessary, a branch can be drawn from the threaded interface by increasing one more reliable contact. With a rivet, this upgrade option is not possible.

Sockets and clamps with terminals

This is one of the most convenient devices for connecting copper and aluminum wire. Terminals can 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 solder coating.
• In order to connect the wires, it is only necessary to remove the layer of insulation from their ends.
• The pads are conveniently fixed in the wiring.

Figure 4. Sockets and clamps with terminals

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

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

There are no requirements for conductors - they can be made of different alloys, have different 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 fix the conductors, passing through themselves a current of up to 34 amperes. Fixation is made by a special lever, which should be lowered down. In order to pull the core back, the lever must be raised.

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

External connections

All that is listed above is used for splicing inside buildings. But how to connect copper and aluminum cables from the outside? For this, a special clamping mechanism called "Nutlet" is proposed. The clamp body made of plastic reliably protects the place of splicing and branching of conductors from external influences. For reliable contact, several plates are used, made of a metal that is neutral to copper and aluminum.

Figure 5. Wire connector "Nut"

• To remove the insulation, do not use tools such as wire cutters or pliers. Their use can lead to the fact that the cores are damaged. This is especially true for brittle aluminium. Before connecting the wire correctly, it is preferable to strip its cores with a clerical or any other sharp knife. Remember how the pencil is cleaned - 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 from fluxes. Materials such as zinc chloride or hydrochloric acid should not 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 between the electrochemical potentials of 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. Let them cost more, but the materials used in the manufacture will provide reliable contact.

Summary

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

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

For mechanical connections:

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

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

Welding will require the following:

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

For soldering;

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

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

Connection methods

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

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

There are the following ways:

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

Each of these methods has its own characteristics.

Twisting

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

types of twists

Types of twists:

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

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

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

Welding

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

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

Welding has a number of specific features:

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

Spike

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

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

Crimping (crimping method using sleeves)

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

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

This method is most widely used when connecting powerful consumers.

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

Use of terminals

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

Their types:

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

Advantages of terminal clamps:

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

screw connection

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

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

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

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

Spring connection (PPE caps)

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

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

Safety

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

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