How to connect aluminum wire to copper. Ways of connecting wires: twisting, soldering, welding, crimping, terminal block How to join copper and aluminum wire

Modern electrical wiring in an apartment or house is carried out only with copper wires, as the PUE says. But in old houses, wiring was most often done with aluminum wire, and a situation arises in which it is necessary to connect 2 wires from different materials. And in this article, you will learn how to connect copper and aluminum wire in different ways.

Is it possible to twist copper wire with aluminum

Let's start with the fact that is it possible to connect aluminum wires to copper, and will such a connection not lead to a fire? The answer is yes, you can. But let's first get acquainted with these materials.

If you ask yourself which wiring is better, copper or aluminum, then the choice is of course copper. This comes from the technical characteristics of copper, the cross section of the aluminum wire under the same conditions has to be taken more. There are also disadvantages, copper is more expensive. It is easier to distinguish copper wire from aluminum by color, copper has a reddish tint, aluminum is gray, white.

Looking at the electrical performance of metals, there is no question of what conducts current better. Here are some details:

• Resistivity: copper - 0.017 Ohm mm² / m, aluminum - 0.028 Ohm mm² / m.
• Heat capacity: copper - 0.385 J / gK, aluminum - 0.9 J / gK.
• The elasticity of the material: copper - 0.8%, aluminum - 0.6%.

So why can't you twist copper and aluminum wires, because twisting, especially with a small cross section, is the cheapest option in terms of both money and time? The thing is that, when these materials are connected, they create a galvanic couple.

Galvanic couple - 2 metals of various kinds, the combination of which will lead to increased corrosion. Copper and aluminum are such a galvanic pair. The electrochemical potentials of the two metals are too different, so rapid corrosion will increase the resistance at the junction and its heating will follow. For more details on the compatibility of metals, see GOST 9.005-72. Below is a table with some data on metals:

Galvanic compatibility of meltals

There are many ways to achieve high-quality contact between two conductors (soldering, using a simple terminal block, more expensive WAGO terminals, or an ordinary bolt with a nut).

Wire connection

The connection of aluminum and copper wires to each other requires technological solutions, simple twisting is not enough here.

Methods for connecting conductors with different electrochemical potentials:

• By soldering. But not simple soldering.
• Using simple terminal blocks or expensive WAGO. It’s not worth saving here, and if the question is how to properly connect copper and aluminum wires, then it’s better to take WAGO. The advantages of this manufacturer will be described below.
• Using a bolted connection, which has a lot of advantages: cheapness, simplicity and the ability to work with large wires.
• Crimping with sleeves. Requires a specialized tool.

WAGO

WAGO clamps for joining aluminum and copper are very popular, as they are very convenient to use:

1. Push the pressure plates to the side with a click.
2. Insert wires into holes.
3. Put the plates in their places, clamp.

WAGO terminals for connecting copper wire to aluminum are an excellent solution

But now WAGO is casting doubt on its reputation. According to numerous reviews, the spring contact weakens, which leads to burning of the terminal block and its quick replacement.

Wire twisting

Stranding aluminum and copper wire was mentioned earlier as a very unreliable method of connection, but sometimes this is the only way to quickly restore power supply.

A couple of tips before twisting:

• Before twisting the copper wire should be well tinned.
• The amount of twist must be at least 5 turns.
• After work, the joint must be protected with several layers of insulating tape or heat shrink tubing.

Soldering copper to the terminal block

You can solder copper and aluminum together. If everything is clear with copper, then a special flux is needed to solder aluminum. Some electricians simply solder the copper wire to the terminal block.

Flux for aluminum

Terminal blocks

The list of tools and consumables for an electrician includes terminal blocks. Terminal blocks - copper or brass plated with a layer of nickel, designed for wires of a certain section and covered with a layer of insulating plastic. The wires are secured with 2 small screws.

When connecting copper and aluminum terminal blocks, the fixing screws must be correctly tightened. If you overtighten them, you can damage the aluminum conductors, which will not be very good for the further operation of the wiring. Therefore, it is necessary to find a middle ground: tighten not too tight, but achieve high-quality contact.

Bolted connection

If there is no terminal block, soldering iron or WAGO at hand, and the wire cross section is large enough, then you can achieve high-quality with an ordinary bolt.

To connect two wires you will need: a bolt, a nut, 3 washers. Sequencing:

1. At the ends of the wires, make rings of the same diameter as the bolt. For convenience, it is better to use round nose pliers.
2. Put the rings on the bolt in such order that they are between the three washers.
3. Tighten the nut and check the quality of the connection.
4. Apply several layers of insulating tape.

Bolted connection of aluminum and copper

Connection "nut"

"Nut" is another type of terminal block, most often used for branching large wires. It consists of 2 copper plates laid in a plastic case.

A copper and aluminum wire, as well as a branch wire, are placed between the plates. But you can use the "nut" simply as a connecting element. After laying the conductors, the plates are tightened with bolts. As insulation, a plastic case is put on top of the entire structure, consisting of two halves, for fixing which standard screws are used.

The walnut connection is suitable for all types of street connections and branches

Crimping

For this method, you will need special crimping tongs and sleeves. The principle of connecting wires with a sleeve is very simple: on the one hand, an aluminum wire is inserted into the sleeve, on the other, a copper wire, and the sleeve is crimped on both sides with tongs. There are sleeves for wires with a large cross section - from 16 mm 2 to 300 mm 2, but in this case a special hydraulic press is required. The only disadvantage of crimping is the high cost of the tool.

Special sleeve for joining aluminum and copper

Lubricant

To improve the quality of contact, you can use a special lubricant or paste. Usually it is quartz-vaseline paste. Usually it is used to improve the connection of aluminum wires.

But such a paste can be used for all types of connections (threaded, using terminal blocks, crimping), especially if the connection takes place outdoors. Then the contact is affected by additional factors that significantly reduce the durability of the connection. Although the use of grease without insulation is questionable.

Outcome

Based on the foregoing, choose the method that suits you, depending on the place of connection (street, house) and material capabilities.

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

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

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

Reasons for incompatibility

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

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

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

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

Bolted connection

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

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

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

You will need to do the following:

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

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

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

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

Clamp "Nut"

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

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

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

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

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

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

Terminal block

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

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

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

Using the terminal blocks is very simple:

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

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

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

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

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

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

Self-clamping terminals

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

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

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

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

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

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

Twisted connection

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

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

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

Electrical wiring may consist of wires of different materials: aluminum or copper, and in certain situations it may be necessary to combine them. The principle of connection is no different from connecting identical wires, as well as the method of connecting copper and aluminum wire, which can be done in any way. However, a direct connection can hardly be called a reliable and durable connection.

This is because aluminum in the composition with copper oxidizes, and corrosion occurs, which spoils the quality of the connection. Different wires will heat up more and melt under the influence of temperature, so long-term use of the direct method is considered unsafe for humans due to the risk of ignition.

Features of connecting different wires

Most people who have at least something to do with electrical work are aware of the fact regarding the junction of copper and aluminum wires: it is not recommended to connect them. However, many people know about it, but they do it anyway: maybe it will hold out somehow.

As a result, it turns out that the copper-aluminum twist serves a very, very short century. In the case when the connection is placed outdoors or in a room where there is high humidity, the service life of such a pair is significantly reduced.

But situations in which it is required to connect exactly copper and aluminum wires are far from uncommon. In particular, a similar phenomenon has practically become the rule when carrying out repair work in rooms with aluminum wiring.

In such cases, the solution to the problem will be specially made terminal blocks or bolted connections, through which the contact of copper and aluminum wires will be made. Through the use of a clamp or bolt connection, direct contact between the two metals is eliminated. Consider the most popular options for such connectors, without delving into the details of the design.

Perhaps one of the earliest and most tested methods is the use of a nut-type terminal connection. As you might guess, the reason for the name was the external similarity of the shape of the adapter with a nut.

The design of such a connection consists of three plates that clamp the wires together. The advantage of this type of connection is that there is no need to break the line to install the outgoing wire. You just need to unscrew a couple of bolts, insert the desired wire between the plates, and then return the bolts to their place. The outgoing wire is assigned a place between the middle and third plate. After putting it in place, the connection is actually completed.

In second place in popularity are spring terminals for express connections. As the name implies, their use provides the maximum connection speed. Indeed, to make the connection, you only need to strip the ends of the copper and aluminum wires, and then insert them into the holes and fix them.

Inside such a terminal block there is a special lubricant that prevents the oxidation of wires. It should be noted that such adapters are most suitable for lighting circuits or other areas with a small load. For example, using it in a power circuit can cause the contact to overheat and break.

Terminal blocks have also been widely used. It looks like a bar on which there are terminal blocks. To connect a wire to it, you need to strip the conductor, and then fix it in the hole with a mounting screw. Accordingly, another wire is inserted into another hole.

Let's assume a variant in which wires made of copper and aluminum will be connected by a bolted connection. To do this, it is necessary to place a special anodized washer on the bolt between conductors of different metals, which prevents direct contact of materials.

It should be borne in mind that installation work should be carried out by specialists of the appropriate profile. In the future, regular checks of screw and bolt connections should be performed: for aluminum wire it is twice a year, for copper sections - once every 2 years.

Why you can not directly connect copper and aluminum

To do this, it is worth straining your memory and remembering the school course of chemistry and physics. First, let's remember what a galvanic cell is. Simply put, a galvanic cell is a simple battery that generates an electric current. The principle of its appearance is based on the interaction of two metals in the electrolyte. So, twisting between copper and aluminum wire will be the same battery.

Galvanic currents quickly destroy the material. True, in dry air their appearance is excluded. And if you make a twist to the outlet, then it will not fall apart in a few hours. However, subsequently the troubles of such wiring are provided.

Over time, the materials from which the wires are made are destroyed, along with this, the resistance constantly increases. If a powerful current consumer is connected to the outlet, the twist will begin to heat up.

Regular use of such an outlet increases the risk of fire. Therefore, it is strictly forbidden to connect an aluminum conductor with a copper one. However, there are emergency situations when it is simply necessary to make such a connection.

How to connect copper and aluminum wires

It's no secret that copper and aluminum wires are not recommended to be connected. But many, even knowing this, still neglect it, hoping for the Russian "maybe it will pass." As a result, such a twist from a pair of copper-aluminum will not live very long. And if the connection is located on the street or in a room with high humidity, then the life of such a pair is several times shorter.

But quite often there are situations when we need to connect copper and aluminum wiring. Often this situation occurs when repairing electrical wiring in houses where aluminum wiring is laid.

Special terminal blocks and bolted connections will help us get out of this situation, through which we will connect copper and aluminum wires. Using terminal and bolted connections, we do not allow direct contact of the copper-aluminum pair.

Without really going into the design features of the terminal clamps, we will consider the most used of them. One of the old and proven ways to connect wires are nut-type terminal connections. They got their name because of their resemblance to nuts.

Connections of this type consist of three plates, between which, in fact, the wires are clamped. One of the advantages of this type of connection is that there is no need to break the line to connect the outgoing wire. It is enough just to unscrew 2 bolts, insert a wire between the two plates, and tighten the bolts into place. The outgoing wire is inserted between the middle and remaining plate. Everything, the connection is ready.

The next most popular can be called WAGO-type compounds. These connecting terminals allow you to connect aluminum and copper wires. It is enough just to strip the wires by 10-15 mm, insert them into the terminal block hole, and that's it, the next connection is ready to go.

The inside of the terminal block is filled with a special lubricant that prevents the wires from oxidizing. We recommend using this type of connection in lighting circuits. The use of these connections in power circuits is not recommended, since a large load can lead to heating of the springy contacts, and as a result, to poor contact.

Terminal blocks are another popular connection. Outwardly, they are a bar with terminal strips. It is enough to strip the end of the wire, insert it into one hole and clamp it with a screw. The stripped end of the second wire is inserted into the other hole. These terminal blocks also allow you to connect wires from different metals.

Bolted wire connections. This type of connection can also be used if you need to connect copper and aluminum wires. When installing the connection, it is necessary to install an anodized metal washer between the copper and aluminum wires.

All installation work must be carried out by a specialist. All screw and bolt connections must be checked: for aluminum wires - once every six months, for copper - once every two years is enough.

How to solder aluminum to copper? Theoretically it is possible, but practically it makes no sense. Such soldering requires special fluxes, a higher temperature (high risk of overheating the wires) and over time, electrochemical corrosion will develop at the junction.

Twisted connection

Twisting used to be the most common option for connecting wires during installation. This is due to the simplicity of the action, which does not require high qualifications from the performer. However, when connecting wires from dissimilar metals, this option is completely unacceptable!

When temperature fluctuations in the environment occur, a gap appears in the twist between the wires, due to which the contact resistance increases, the connection heats up, and the wires are oxidized. As a result, the contact between the conductors is completely broken.

Naturally, such an event does not occur immediately, but if long-term reliable operation of the power grid is required, then the twist connection cannot be used, it should be replaced with another, more reliable one. Sufficiently reliable contact will be obtained if the copper conductor is first tinned with solder.

In this way, you can twist wires with different diameters, even when one has many wires, and the other has only one. If there are several cores, it is required to pre-coated them with solder, after which one core will be obtained.

In the twisting performed, there must be at least three turns with a thick wire, and at least five if the conductor diameter is up to 1 mm. Twisting is required to be done in such a way that the wires wrap around each other, and not one wire wraps around the other.

If you connect a copper and aluminum conductor with a screw and nuts, you get the most reliable contact that can provide conductivity for the entire life of the wiring. Such a connection is easily disassembled, and also allows you to mount many conductors. Their number is limited only by the length of the screw.

Any combination of metals is successfully fastened with a threaded connection. The basic rule is to prevent direct contact between aluminum and copper, and also to install spring washers under the nuts. To properly organize a threaded connection, it is required to expose the conductors to a length that is four times the diameter of the screw.

If there is oxide on the cores, they are cleaned to a shine, and rings are formed into which a screw can be inserted.

Then put on the screw:
1. spring washer;
2. a simple washer;
3. conductor ring;
4. a simple washer;
5. ring of the second conductor;
6. a simple washer;
7. nut.

By tightening the screw, tighten the entire package until the spring washer is straightened. To connect thin conductors, it is enough to use an M4 screw. With stranded copper wire, it is better to cover the ring with solder first.

Wago clamp connection

One of the novelties of the electrical market is pads (article "Terminals for junction boxes") equipped with a Wago clamp from a German manufacturer.

They come in two versions:
• Disposable constructions - the wire is inserted and after it it is no longer possible to remove it.
• Reusable - there is a lever that allows the insertion and removal of the conductor.

Spring blocks are convenient for connecting wires inside junction boxes, connecting chandeliers. It is enough to insert the wire with force into the hole on the box so that it is fixed securely. The Wago block is a modern device for reliable and quick connection of wires, but its use is more expensive than other options.

One unpleasant moment associated with Wago pads should be taken into account. There are often fakes on sale that look very similar to the original, but of much worse quality. Such clamps will not provide good contact, and sometimes the wire cannot be inserted into them. Therefore, the purchase must be taken very carefully.

Permanent connection

All the advantages of the threaded method have a one-piece connection. Its only drawback is the impossibility of subsequent disassembly without destroying the riveted assembly, as well as the need to have a special tool. To connect the conductors with a rivet, they are prepared in the same way as for a threaded connection. The rings are made such that the rivet in them passes freely.

First, an aluminum conductor is put on the rivet, then a spring washer, then a copper wire, and finally a flat washer. The steel rod of the rivet is placed in the tool and squeezed until its handle clicks. The connection is ready. The reliability of the one-piece connection option is quite high.

In a similar way, the splicing of aluminum wires damaged in the wall during the repair is successfully performed, organizing an additional copper insert. Be sure to securely isolate the exposed parts of the resulting connection.

Electrochemical corrosion

Any electrician will confirm that copper and aluminum cannot be joined together, and such a statement will be correct. What happens when two such different conductors touch? As long as there is no moisture, the connection will be reliable. However, water vapor is always present in the air, which becomes the culprit that the contact is destroyed.

Each conductor has its own electrochemical potential. This property of materials is widely used, on its basis accumulators and batteries are created. However, when moisture penetrates between the metals, a galvanic cell is formed, which is short-circuited.

The current flowing through it destroys one of the metals in the connection. The easiest way out is to cover the copper wire with solder from a mixture of tin and lead, then you can safely allow it to come into contact with aluminum, and using any connection option! Attaching copper wires to old aluminum wiring is not at all difficult. The main thing in this process is to strictly observe the technological requirements.

How to properly connect copper and aluminum wire

It is possible to connect copper and aluminum conductors with a screw, a nut and three washers, one of which is spring-loaded. Strip the connected wires. Put a lock washer on the bolt, then a simple one. Bend the aluminum core with a ring and put it on next. Throw on a simple puck. Put on a copper wire bent by a ring. Now tighten the connection with a nut until the spring washer is fully straightened.

A more convenient way to connect conductors from different materials is terminal blocks. This product has a plastic housing, bar and terminals. It is enough to strip the wire to a length of 5 mm, thread it into the terminal and tighten the screw. The contact of two conductors is excluded by the very design of the terminal block. The connection must be placed in a junction box.

The fastest and easiest way to connect wires is Wago spring terminal blocks. There are disposable and reusable products. As the name implies, the first can be used only once: insert the end stripped of insulation - you're done. To change the network diagram, you will have to cut off the terminal block and connect the cores with another product. Reusable "Vago" allow you to insert and remove the wires repeatedly.

Terminals for connecting aluminum and copper wires

If someone still believes that there is nothing better for connecting wires than stripping their ends with a knife, twisting them, and wrapping them with electrical tape, then he is behind the times. Today there are already a lot of alternative devices that greatly facilitate the process of connecting wires, and at the same time are quite reliable. The times of twists will soon sink into oblivion, because they are being replaced by a variety of terminals.

Why are clamps good? How, for example, to connect an aluminum wire to a copper wire so that the connection is reliable and durable? It is categorically impossible to twist copper with aluminum, because then a galvanic couple is formed, and corrosion will simply destroy the connection, and it doesn’t matter how much current passes through the twist, it will collapse sooner or later, and if the current is higher, switching on and off devices more often, then the twisting resistance will increase faster, over time, the heating of the twisting point will become more and more.

In the end, this is fraught with a fire, or at best - the smell of melted insulation. The terminals in this situation would have saved, and it would not have come to the destruction of the place of contact.

The simplest solution is to put a polyethylene terminal block. Polyethylene terminal blocks are sold today in every electrical store and are not expensive. Inside the polyethylene frame, several brass tubes (sleeves) are arranged in a row, in which the ends of the connected wires are clamped with two screws. If desired, you can cut off as many tubes in polyethylene as you need and connect as many pairs of wires.

However, not everything is so rosy, aluminum flows under the pressure of the screw at room temperature, so periodically, once a year, it will be necessary to tighten the connection. Otherwise, if it comes to connecting copper conductors, everything will be in order.

If the aluminum wire staggering in the terminal block is not tightened in a timely manner, then the end of the wire that has lost its former contact will spark and heat up, and this is fraught with fire. It is impossible to clamp stranded wires into such a terminal block without auxiliary pin lugs, which we will talk about later.

If you simply clamp a stranded wire into such a terminal block, then the pressure of the screw on thin wires, combined with rotation and an uneven surface, will cause part of the wires to become unusable, and this threatens to overheat. If the stranded wire fits tightly along the diameter of the sleeve, this is the most acceptable connection option, because there is less risk of breaking the connection.

As a result, we can conclude that polyethylene terminal blocks are good for single-core, and only for copper wires. If you want to clamp a stranded one, you will have to put on an auxiliary lug, which will be discussed later.

The next option for convenient connecting terminals is terminals on plastic blocks. Such terminal blocks are also equipped with transparent covers that can be removed if desired. Fastening is very simple: the stripped end of the wire is inserted between the pressure and contact plates, and pressed with a screw.

What are the advantages of such terminal blocks? Firstly, unlike polyethylene terminal blocks, plastic terminal blocks have an even steel clamp, there is no direct pressure of the screw on the cores. The clamping part has a recess for the wire. As a result, these terminal blocks are applicable for connecting groups of both solid and stranded wires. Why groups? Because this terminal block can not be cut like polyethylene.

Further - self-clamping terminals (the so-called wags for connecting wires), an example of which is the 773 series from WAGO. These are express terminals for fast, one-time wiring. The wire is pushed all the way inside the hole, and there it is automatically fixed by a pressure plate that presses the wires against a special tinned bar. The clamping force is maintained all the time, thanks to the material of the clamping plate.

These express terminals are disposable, but in principle you can pull out the wire by gently rotating it while pulling it out. But if you pull out the wire, then it is better to make the next connection in a new clamp, fortunately, they are not expensive, 10-20 times cheaper than terminal blocks.

The inner copper plate is tinned and allows fixing even aluminum or copper wires. The clamping force is maintained continuously, and the wire does not have to be pressed once a year, as is the case with terminal blocks.

Inside there is also a lubricant based on quartz sand with technical petroleum jelly, for an abrasive, removing oxide film on the surface of the wire, preventing, thanks to petroleum jelly, its reappearance. These express terminals are transparent and opaque. In any case, plastic does not support combustion.

WAGO branded express clamps are suitable for connections with a prospective current up to 25 A. Terminals from other manufacturers may suffer from heat, for example, the clamping force of the spring contacts will weaken, so use only branded, well-proven terminals.

The 222 series from WAGO is suitable as reusable terminals. These are terminal blocks with lever clamps. Various types of wires can also be clamped here. The fastening process is simple: the lever is raised, the end of the clamped wire is inserted, the lever is pressed - fixation occurs.

This clamp is reusable. When the lever is raised, the fixation is removed, you can pull out one wire and insert another. This terminal type is ideal for multiple reconfiguration of conductor groups. Withstands currents up to 32 amps without overheating. The design of the clamp is a bit similar to a one-time express clamp, the difference is again in the possibility of repeatedly switching the connected conductors.

Next, consider the Scotch-lock type couplings. These are disposable connectors for low current wires. Using adhesive tape, you can connect telephone wires, low-power LED lamps, etc. The essence of this fastener is a mortise contact.

Several wires, right in the insulation, are inserted into the sleeve, then crimped with pliers. Structured cabling installers love scotch locks. Scotch locks allow you to connect wires without having to strip them. The plate with cutting contacts simply cuts into the insulation, and comes into contact with the conductor, with the core.

Scotch locks come in two and three cores. The peculiarity of such terminals is that they are cheap, waterproof, versatile, and do not require stripping the ends, but are crimped with simple pliers. Inside the coupling there is a hydrophobic gel to protect the contacts from moisture and corrosion. If it is necessary to replace the connection, the adhesive tape is simply cut out along with pieces of wire, and a new one is put in.

When you need to connect several wires into one powerful knot, for example, simply combine them, or for laying on a terminal block, sleeves are used. Sleeves are used most often universal, these are usually tinned copper sleeves in the form of tubes, or in the form of flat tips with a mounting hole.

The wires are inserted into the sleeve, and crimped with a special tool - a crimper. The crimper is a crimping tool. The great advantage of the sleeves is that such crimping does not create increased resistance at the junction. Sleeves in the form of a flat tip with a hole are convenient when you need to fix a wire or a bundle of wires to the body with a screw. Simply select a sleeve of a suitable diameter, crimp it, and attach the tip to where you need it.

To connect stranded wires, to combine solid wires with stranded ones, or simply to fix them in terminal blocks, pin sleeve lugs are used. The stranded wire is conveniently inserted into the lug, the lug is crimped together with the wire, after which the stranded wire can be fixed in any terminal block, even in polyethylene, without fear that the connection will be broken.

Decisive here is the correct choice of the diameter of the tip, it must correspond to the total diameter of the crimped, combined into a bundle, lived, so that the wires do not pop out later.
To crimp the pin lugs, you can do with pliers or use a screwdriver and a hammer.

Why is it strictly forbidden to connect copper and aluminum wires directly? Aluminum is a highly oxidizable metal. This is the process of formation of an oxide film on its surface, which has a very high resistance, which naturally cannot but affect the current conductivity of such a connection. Copper wires are less susceptible to oxidation, or rather, the oxide film on them has much less resistance than the oxide film on aluminum wires, so this affects the current conductivity very little.

Therefore, when connecting copper and aluminum wires, electrical contact actually occurs through oxide films of copper and aluminum, which have different electrochemical properties, which can significantly impede current conduction at this junction. On the street, under the influence of atmospheric precipitation and the passage of electric current through the connection, the process of electrolysis occurs. The result is the formation of shells at the junction, heating and sparking of contacts - an increased fire hazard of the connection.

There are the following options for connecting copper and aluminum wires:
1. Connections of copper and aluminum wires outdoors or indoors are allowed only using special adapters - terminal blocks. A good solution for outdoor connections would be to use branch clamps for SIP (“punctures”) with a paste that protects the surface of the wires from oxidation.
2. A good option is branch clamps (“nuts”) - the wires in them are connected through an intermediate plate inside, that is, direct contact of copper with aluminum is excluded.
3. Indoors, it is advisable to use self-clamping with a paste that prevents the oxidation of aluminum wires. This is a fast way to connect copper and aluminum wires without the need for additional insulation. Due to their small size, self-clamping, screw or spring terminal blocks are very suitable for connecting wires in junction boxes.
4. Finally, in the absence of a terminal block or “nut” at hand, situations are different, it is much more reliable, instead of the usual twisting of copper and aluminum wires, to tighten them with a bolt and nut, laying a washer between them, which will exclude direct contact between copper and aluminum. Such a connection, in terms of its reliability of contact, will be inferior to the manufactured terminal blocks or “nuts”, except perhaps for its bulkiness - it is more difficult to place it in a soldering box. When using this method, it is also worth noting the need for good isolation of the connection.

When connecting conductors, it is necessary to take into account many important factors: the material of the current-carrying conductors of the switched wires, their electrochemical compatibility or incompatibility (in particular, copper and aluminum), the cross-section of the wires, the length of the twist, the load of the network, etc.

However, in the regulatory documents regulating the rules for performing electrical work, in particular - PUE (Electrical Installation Rules) it is clearly stated about the ban on connecting wires by twisting: PUE: p2.1.21. Connection, branching and termination of conductors of wires and cables must be carried out by crimping, welding, soldering or clamping (screw, bolt, etc.) in accordance with current instructions.

As you can see, the PUE allows only 4 types of wire connections, and there is no twisting among them (except when the twisting is preliminary, for example, before soldering or welding). Therefore, endless disputes and discussions about the advantages or disadvantages of twists lose all meaning, because not a single fire inspector will approve an electrical installation if the switching of its wires is done with twists.

Soldering or welding significantly increase the installation time, this procedure is much longer than using terminal blocks - you need to remove the insulation from the wires, tin each wire, if it is soldering, connect the welder, then insulate all the wires. If it is necessary to reconnect the wires (for example, add a wire), there are also difficulties - remove the insulation, solder (cook) again. With terminal blocks, everything is much simpler, but the best contact is achieved using welding or soldering.

There are different types of terminal blocks suitable for connecting the wires of the electrical wiring of an apartment or house.

Here are the main and most common among them:
• Self-clamping terminal blocks can have from 2 to 8 places for wires with a minimum cross section of 0.75 mm 2 and a maximum of 2.5 mm 2. Able to withstand loads up to 4-5 kW (24 A). Such terminal blocks are very convenient in installation, greatly reducing its time - there is no need to twist and then insulate the wires. But, they take up more space in junction boxes, in contrast to the twist, which can be given any shape, laid by bending it as you like.
• Connecting screw terminals are designed to connect wires to each other. Usually used for switching wires in junction boxes. Material: polyethylene, polyamide, polycarbonate, polypropylene. For aluminum wires, it is better not to use such terminal blocks - in screw terminal blocks they are highly deformed and can be broken.

Insulating connecting clamps (PPE) are used to connect single-wire conductors of wires with a total maximum cross section of up to 20 mm 2 and a minimum of 2.5 mm 2. They have an insulated body made of polyamide, nylon or refractory PVC, so that the wires do not need further insulation, into which an anodized conical spring is pressed.

When connecting the wires, the insulation is removed from them (by 10-15 mm), collected in one bundle and PPE is wound on them (clockwise) until it stops. PPE caps are very convenient and easy to install, but they lose a lot to terminal blocks as a twist, so it’s still better to give preference.

Calculation of the cross section of wire, cable

The material of manufacture and the cross section of the wires (it will be more correct) are, perhaps, the main criteria that should be followed when choosing wires and cables. Why is the correct choice of wire gauge so important? First of all, because the wires and cables used are the main elements of the electrical wiring of your house or apartment. And it must meet all the standards and requirements of reliability and electrical safety.

The main regulatory document regulating the cross-sectional area of ​​wires and cables is the Electrical Installation Rules (PUE). Incorrectly sized wires that do not match the consumption load can heat up or even burn out, simply unable to withstand the current load, which cannot but affect the electrical and fire safety of your home. The case is very frequent when, for the sake of economy or for some other reason, a wire of a smaller section than is necessary is used.

So, speaking about the wiring of a house or apartment, the application will be optimal: for “socket” - power groups of a copper cable or wire with a core cross section of 2.5 mm 2 and for lighting groups - with a core cross section of 1.5 mm 2. If there are high-power appliances in the house, for example, electric stoves, ovens, electric hobs, then cables and wires with a cross section of 4-6 mm 2 should be used to power them.

The proposed option for choosing cross-sections for wires and cables is probably the most common and popular for apartments and houses. Which, in general, is understandable: copper wires with a cross section of 1.5 mm 2 are able to "hold" a load of 4.1 kW (current - 19 A), 2.5 mm 2 - 5.9 kW (27 A), 4 and 6 mm 2 - over 8 and 10 kW. This is quite enough to power outlets, lighting fixtures or electric stoves. Moreover, such a choice of cross-sections for wires will give some "reserve" in the event of an increase in load power, for example, when adding new "electric points".

Calculation of the cross-sectional area of ​​aluminum conductors of wires and cables. When using aluminum wires, it should be borne in mind that the values ​​​​of continuous current loads on them are much less than when using copper wires and cables of the same cross section. So, for cores of aluminum wires with a cross section of 2 mm 2, the maximum load is a little more than 4 kW (in terms of current it is 22 A), for cores with a cross section of 4 mm 2 - no more than 6 kW.

Not the last factor in calculating the cross section of wires and cables is the operating voltage. So, with the same power consumption of electrical appliances, the current load on the cores of supply cables or wires of electrical appliances designed for a single-phase voltage of 220 V will be higher than for appliances operating on a voltage of 380 V.

In general, for a more accurate calculation of the required cross-sections of the conductors of cables and wires, it is necessary to be guided not only by the load power and the material of manufacture of the conductors; you should also take into account the method of their laying, length, type of insulation, number of cores in the cable, etc.

Any cable product has a conductive core, which is made of copper or aluminum. Since these materials are characterized by excellent return and current conductivity, it is often necessary to connect them during installation and connection. How to connect a copper and aluminum wire without making mistakes will be discussed further.

To deal with all the subtleties of the procedure, you should understand what lies in such a connection. After all, there are different opinions regarding the fact that it is absolutely impossible to connect copper wires with aluminum ones.

Like any other metal, aluminum and copper are oxidized with the participation of oxygen. As a result, an oxide film appears on their surface. And if the copper coating almost does not interfere with the flow of electric current, then the oxide one is a serious barrier to this.

The wire connection of copper and aluminum, in spite of everything, will be the impetus for the interaction of metals. Aluminum is characterized by a higher degree of activity. This means that between the compounds, in the event of moisture, the so-called electrolysis occurs - the transfer of aluminum ions to copper. As a result, the aluminum conductor loses its weight. Shells and voids appear in it, which are also amenable to oxidation and only accelerate electrolysis.

The result is an almost destroyed conductor, which is made of aluminum. As its cross section decreases, the degree of current density increases. In turn, this provokes heating of the metal. There are only two options for the outcome of such a situation: either the aluminum burns out at the connection point, or a fire starts.

Impossible is possible, or how to connect copper and aluminum wire

While some doubt whether it is possible to connect aluminum wires to copper, many successfully do it. Moreover, there are a number of main generally accepted methods, thanks to which it is possible to eliminate contact between materials that act aggressively towards each other. Each of them requires separate attention.

How to connect copper and aluminum using terminal blocks

The terminal block for connecting wires can be equipped with a clamping or bolting mechanism. This design provides connection to two types of materials - aluminum and conductive. They are in contact with each other by means of a steel plate. It is made from a neutral material that does not tend to react with aluminum - often these are brass or tinned copper plates.

The block for wires containing a bolt clamp is characterized by greater reliability and is used in low-voltage power circuits. Often such a clamp is performed using a "nut". It is a small junction box, which is made of dielectric materials. The device got its name due to its shape. Inside it is a block of metal plates, through which contact is provided between copper and aluminum wires.

Each of the above methods is a detachable connection. This means that if necessary, you can repeatedly disconnect and connect them.

When wiring or repairing electrical wiring, when connecting household appliances and a lot of other work, it is required to connect conductors. In order for the connection of wires to be reliable and safe, it is necessary to know the features of each of them, where and when, under what conditions they can be used.

Existing methods of connecting conductors

To connect the wires can be done in several ways:

• welding is the most reliable method, providing high reliability of the connection, but requiring skills and the presence of a welding machine;
• terminal blocks - a simple and fairly reliable connection;
• soldering - works well if the currents do not exceed the normative ones and the connection does not heat up to temperatures above the norm (65 ° C);
• crimping with sleeves - requires knowledge of technology, special pliers, but the connection is reliable;
• the use of spring clips - wago, PPE - quickly installed, subject to operating conditions provide good contact;
• bolted connection - easy to perform, usually used in difficult cases - if it is necessary to switch from aluminum to copper and vice versa.

The specific type of connection is selected based on many factors. It is necessary to take into account the material of the conductor, its cross section, the number of cores, the type of insulation, the number of conductors to be connected, as well as the operating conditions. Based on these factors, we will consider each of the types of connections.

Welding – high reliability in all conditions

When connecting wires by welding, the conductors are twisted, and their end is welded. As a result, a ball of metal is formed, which provides a stable and very reliable connection under any conditions. Moreover, it is reliable not only in terms of electrical characteristics, but also mechanically too - the metal of the connected wires after melting forms a monolith and it is impossible to isolate a separate conductor.

Welding - it is important to heat the metal, but not to melt the insulation

The disadvantage of this type of wire connection is that the connection is 100% one-piece. If you need to change something, you need to cut off the fused piece and redo it all over again. Therefore, for such connections, a certain margin of wires is left - in case of a possible alteration.

Other disadvantages include a welding machine, appropriate electrodes, flux and work skills. In addition, welding takes a lot of time, it is necessary to protect surrounding objects, and it is also inconvenient to work with a welder at a height. Therefore, electricians practice this type of connection in exceptional cases. If you are doing “for yourself” and know how to handle a welding machine well, you can practice on scraps. The trick is not to melt the insulation, but to weld the metal.

After cooling, the welding site is isolated. You can use electrical tape, you can use heat shrink tubing.

Crimping connection of wires

For crimping wires, a special aluminum or copper sleeve is required - it is selected based on the size of the twist (beam diameter), and the material is taken the same as that of the conductors. The wires that are bare and cleaned to a shine are twisted, a tube-sleeve is put on them, which is clamped with special tongs.

Both sleeves and pliers are different, there are several types. Each of them has its own rules of use (the number of wires that can be packed into a sleeve), in which you need to be well versed. It is necessary to pack the wires according to certain rules, measure the size of the resulting bundle, and adjust it to the requirements. All in all, a pretty tedious job. Therefore, this type of wire connection is mainly used by professional electricians, and even more often they switch to spring clips.

Terminal blocks

One of the simplest and most reliable wire connections is through terminal blocks. There are several types, but almost everywhere a screw connection is used. There are sockets of different sizes - for different sizes of conductors, with a different number of pairs - from 2 to 20 or more.

The terminal block itself is a plastic case in which a metal socket or plate is soldered. A bare conductor is inserted into this socket or between the plates, clamped with a screw. After the screw is tightened, it is necessary to pull the conductor well - make sure that it is well clamped. Due to the fact that the connection points remain uninsulated, the scope of the terminal blocks is rooms with normal humidity.

The disadvantage of this connection is that due to the plasticity of metals - especially aluminum - the contact weakens over time, which can lead to an increase in the degree of heating and acceleration of oxidation, and this again leads to a decrease in contact. In general, the connection of wires in screw terminal boxes must be tightened periodically.

Advantages - speed, simplicity, low cost, does not require any skills, except perhaps the ability to use a screwdriver. Another important advantage is that you can easily connect wires of different diameters, single-core and stranded, copper and aluminum. There is no direct contact, therefore there are no risks.

Soldering

First, about soldering technology. The connected conductors are cleaned of insulation, cleaned of oxide film to bare metal, twisted, then tinned. To do this, the conductors are heated with a soldering iron, applied to rosin. It should cover the junction completely. Tinned wires are twisted first with fingers, then squeezed using pliers. Soldering flux can be used instead of tinning. They wet the wires well, but after twisting.

Then, in fact, the soldering process begins: the junction is heated with a soldering iron or a narrow-torch burner. When the rosin or flux begins to boil, take some of the solder on the soldering iron tip, bring it into the soldering area, pressing the tip against the conductors. The solder spreads out, filling the gaps between the wires, making a good connection. When using a torch, the solder is simply added little by little to the torch.

Further, after the soldering place has cooled down, according to the technology, it is necessary to wash off the flux residues (they accelerate oxidation), dry the joint, cover it with a special protective varnish, and then insulate it with electrical tape and / or heat shrink tubing.

Now about the advantages and disadvantages of this method of connecting wires. In low-current systems, soldering is one of the most reliable ways to connect wires. But, when wiring electrical wiring in a house or apartment, it is criticized mercilessly. The thing is that the solder has a low melting point. With the periodic passage of high currents through the connection (it happens if the circuit breakers are incorrectly selected or faulty), the solder gradually melts and evaporates. Time after time, the contact gets worse, the connection heats up more and more. If this process is not detected, it may well end in a fire.

The second negative point is the low mechanical strength of soldering. The point is again in tin - it is soft. If there are a lot of wires in a soldered joint, and if they are still rigid, when trying to pack them, the conductors often fall out of the solder - the elastic force that pulls them out is too great. Therefore, the connection of conductors by soldering when distributing electricity is not recommended for use: it is inconvenient, long and risky.

Spring terminals for connecting wires

One of the most controversial ways to connect wires is with spring clips. There are several types, but the most common two are wago terminal blocks and PPE caps. Externally and by the method of installation, they are very different, but both designs are based on a spring that creates a strong contact with the wire.

There is controversy about this spring. Opponents of using wago say that the spring will weaken over time, the contact will become worse, the connection will start to heat up more and more, which, again, leads to an even faster decrease in the degree of elasticity of the spring. After some time, the temperature may rise so much that the case (plastic) will melt, but what can happen next is known.

Spring clips for electrical wiring - popular wire connection

In defense of the use of spring clamps for connecting wires, if they are used in accordance with the manufacturer's recommendations, problems are very, very rare. Although there are many fakes of both wago and PPE, as well as an abundance of pictures of them in a melted form. But, at the same time, many use them, and, under normal operating conditions, they work for years without any complaints.

Clips for wires wago

They appeared on our market a few years ago and made a lot of noise: with their help, the connection is very fast and easy, while it has high reliability. The manufacturer has specific recommendations for the use of this product:

Inside these devices there is a metal plate, which provides the proper degree of contact. The shape and its parameters of the plates were developed and tested specifically. The tests were carried out on a vibration stand for many hours, then heated-cooled. After that, the electrical parameters of the connection were checked. All tests were passed as "excellent" and branded products always show themselves as "five".

In general, the Wago product range is very wide, but for wiring or connecting household appliances, lighting fixtures, two types of wire clamps are used: the 222 series (detachable) with the ability to remake or change the connection and the 773 and 273 series - which are called one-piece.

Detachable

Spring clamps for electrical wiring Wago 222 series has a certain number of contact pads - from two to five - and the same number of flags-clamps. Before starting the connection, the flags are raised up, the conductors stripped of insulation are inserted into them (up to the stop), after which the flag is lowered. At this point, the connection is considered complete.

wago wire connectors - connection methods

If necessary, you can remake the connection - raise the locking flag and remove the conductor. Convenient, fast and reliable.

The 222 vago series can be used to connect two or three, even five conductors made of copper or aluminum (you can connect different metals in one terminal). Wires can be solid or stranded, but with rigid wires. The maximum section is 2.5 mm 2. Soft stranded wires can be connected with a cross section from 0.08 mm 2 to 4 mm 2.

One-piece

There is another type of clamps that does not provide for the possibility of redoing the connection of wires - the 773 and 273 series. When using these terminals, the work is generally seconds: the stripped wire is inserted into the appropriate socket. The spring present there clamps it, providing contact with the plate. All.

These spring-loaded wire clamps can be used to connect solid aluminum or copper wires with a cross-sectional area from 0.75 mm2 to 2.5 mm2, stranded wires with rigid wires from 1.5 mm2 to 2.5 mm2. Soft stranded conductors cannot be connected using such connectors.

To improve contact, before connecting the wires, it is necessary to clean the oxide film. To prevent further oxidation, wago manufacturers also produce contact paste. It fills the inside of the clamp and it itself corrodes the oxide film, and then protects the wires from further oxidation. In this case, only highly oxidized, dark conductors need to be pre-stripped, and the clamp body is filled with paste.

By the way, manufacturers say that, if desired, the wire can be pulled out of the clamp. To do this, they take the wire with one hand, hold the terminal box with the other and rotate them back and forth with a small range, in opposite directions, stretching in different directions.

Clips for lamps (construction and installation terminals for lamps)

For quick and convenient connection of lamps or sconces, wago has special terminals of the 224 series. With their help, you can connect aluminum or copper wires of different sections and types (solid or stranded with rigid wires). Rated voltage of this connection is 400 V, rated current:

• for copper conductors - 24 A
• 16 A for aluminum.

Cross-section of connected conductors on the mounting side:

• copper 1.0 ÷ 2.5 mm2 - single-core;
• aluminum 2.5 mm2 - single-core.

Cross-section of connected conductors from the chandelier/sconce side: copper 0.5 ÷ 2.5 mm2 - single-core, stranded, tin-plated, crimped.

When connecting copper wires, the use of contact paste is mandatory, and aluminum wires must be manually stripped to bare metal.

This product has two drawbacks. First, the price of original terminals is high. The second - there are a lot of fakes at a lower price, but their quality is much lower and it is they who burn and melt. Therefore, despite the high cost, it is better to buy original products.

PPE caps

PPE caps (stands for "connecting insulating clips") are very easy to use devices. This is a plastic case, inside of which there is a spring that has a conical shape. Conductors stripped of insulation are inserted into the cap, the cap is scrolled clockwise several times. You will feel that it has stopped scrolling, which means the connection is ready.

How to make a wire connection using PPE

These conductor connectors are produced by many manufacturers, there are different sizes, for different diameters and the number of connected conductors. In order for the wire connection to be reliable, the size must be selected correctly, and for this it is necessary to understand the markings.

After the letters of the PPE comes a few numbers. Depending on the manufacturer, the number of digits varies, but they mean the same thing. For example, there is this type of marking: PPE-1 1.5-3.5 or PPE-2 4.5-12. In this case, the number immediately following the letters indicates the case type. "1" is set if the body is an ordinary cone, on the surface of which grooves can be applied - for a better grip. If there is a PPE-2, then there are small protrusions on the case, which are convenient to take with your fingers and twist.

All other figures reflect the total cross section of all conductors that can be connected using this particular PPE cap.

For example, PPE-1 2.0-4.0. This means that the body of the connecting cap is ordinary, cone-shaped. With it, you can connect two conductors with a cross section of at least 0.5 mm 2 (in total they give 1 mm, which corresponds to the minimum requirements - see table). Maximum conductors are included in this cap, the total cross section of which should not exceed 4 mm 2.

Connecting wires using PPE caps

In the second marking option, after the PPE abbreviation, there is only a number from 1 to 5. In this case, you just need to remember which one is useful for which wire section. The data is in another table.

PPE caps and their parameters

By the way, only copper wires can be connected with PPE caps - aluminum conductors, as a rule, are thicker than the maximum allowable for these connectors.

Bolted connection

This connection is assembled from a bolt of any diameter, a suitable nut and one, or better three, washers. It assembles quickly and easily, serves quite a long time and is reliable.

First, the conductors are stripped of insulation, if necessary, the upper oxidized layer is removed. Further, a loop is formed from the cleaned part, the inner diameter of which is equal to the diameter of the bolt. To make it easier, you can wrap the wire around the bolt and twist it (the middle option in the right picture). After all this is assembled in this order:

• A washer is put on the bolt.
• One of the conductors.
• Second puck.
• Another conductor.
• Third puck.
• Screw.

The connection is tightened first by hand, then with the help of keys (you can take pliers). That's all, the connection is ready. It is used mainly if it is necessary to make a connection of wires from copper and aluminum, it can also be used when connecting conductors of different diameters.

How to connect aluminum and copper conductors

By the way, let us recall why it is impossible to directly connect copper and aluminum wires. There are two reasons:

• Such a connection is very hot, which in itself is very bad.
• Over time, contact weakens. This is because aluminum has a lower electrical conductivity than copper, and as a result, when the same currents are passed, it heats up more. When heated, it expands more, squeezing out the copper conductor - the connection gets worse, it heats up more and more.

To avoid such troubles, copper and aluminum conductors are connected using:

• terminal blocks;
• wago;
• bolted connection;
• branch clamps (make wire connections on the street).

Other types of connectors cannot be used.

How to connect wires of different diameters

If it is necessary to connect conductors having different diameters, twisting must not be present to obtain good contact. So you can use the following types:

• terminal blocks;
• wago;
• bolted connection.