What do you need to twist the wires. How to connect wires in a junction box

In stranded wires, the cross section is formed by several, sometimes intertwined with each other, cores. Knowing how to connect stranded wires to each other, you can quite easily do this work yourself and get a strong, absolutely safe contact during operation.

Where are stranded wires used?

Any stranded conductor contains at its base a large number of thin wires. The use of a multi-core cable is relevant in areas that require a large number of bends or, if necessary, pull the conductor through too narrow and long enough holes.

The scope of application of stranded conductors is presented:

extended tees;
mobile lighting devices;
automotive wiring;
connecting lighting fixtures to the electrical network;
connecting switches or other types of leverage to the electrical network.

Flexible stranded conductors can be repeatedly and easily twisted, which does not negatively affect the functionality of the system. Among other things, it is this type of electrical wiring that is distinguished by its plasticity, and greater flexibility and elasticity is given to the wire by weaving a special thread, which is a bit like nylon in strength and composition.

Methods for connecting stranded wires to each other

The methods of electrical installation connections of stranded conductors used today are distinguished by the ability to obtain not only strong, reliable and durable, but also completely safe contact of the cores.

Stranding stranded conductors

This option is the simplest and most intuitive, not requiring the use of special equipment or professional tools.

Twisting is the easiest way to connect stranded wires

The second method consists of the following steps:

Twisting wires by the third method:

There is also a fourth method, which is as follows:

Soldering method

Soldering conductors with a household soldering iron provides high-strength contact and good electrical conductivity. Tinning of stranded conductors is carried out using rosin (flux) and standard solder according to standard technology.

Terminal Type Connections

The use of terminals of various types is the most affordable way to connect stranded wires in everyday life. In most cases, the terminal blocks used are divided into a couple of basic types.

The principle of operation of the clamping terminals involves fixing the wire using a built-in spring mechanism.

Terminals are often used to connect wires.

The screw-type terminal block assumes reliable fixation of all connected stranded wires with a screw. To increase the area of wired contact with a conductive surface, it is required to perform an additional bend of the core.

In the terminal block, the wires are fixed by tightening the screws.

Phased work:

Crimping method

The crimping method involves connecting wires or cables using a copper or aluminum sleeve using special hydraulic or manual crimping pliers.

In this case, the connection is made using a special sleeve

The pressing technology consists in stripping the insulation according to the length of the sleeve, and too thin wires should be connected by twisting. Then all the cables are folded together and placed inside the sleeve, after which a double crimping is performed along the entire length. The method allows to perform a reliable and safe connection of stranded wires made of different types of materials.

Bolted connection

The simplest, but not sufficiently reliable way to connect stranded wires is twisting followed by bolting. This type of plug-in connection is most often used in open wiring conditions.

Bolted connection is the simplest, but not very reliable

To increase the level of reliability of the connection of stranded wires, it is recommended to strip the ends of the insulation, then tin the cleaned sections and fasten them with a bolt.

Application of connecting insulating clamps

PPE elements are used when it is necessary to connect stranded wires with a small cross section (within 25 mm 2). The design feature of this clamp is a plastic housing with a built-in conical spring.

This method is suitable for connecting wires with a small cross section.

Stranded wires are first connected into one bundle using a twist, on which the clamping part is then wound. Among other things, the wire connection does not need additional insulation.

welding method

Permanent connection is the most reliable way when working with stranded wires. With properly performed welding, the general indicators of mechanical strength and contact resistance in terms of reliability do not differ from those of a solid conductor.

Welding wire connection is considered the most reliable

Welding can be performed on alternating and direct current. At the preparatory stage, the wires are stripped of insulation, after which they are twisted and aligned by trimming the ends. To ensure that the conductors do not overheat during the welding process, it is necessary to ensure high-quality heat removal.

Security measures

In order to ensure the safe operation of the connected stranded wires, it is essential to insulate all parts of the electrical wiring without fail. Proper insulation helps to prevent dangerous contact of conductive parts with each other or with the human body. When choosing an insulating material, it is necessary to take into account the operating conditions of the electrical circuit, but in most cases, insulating tape is used for this purpose, as well as a special vinyl or heat shrink tube.

If the connection area is exposed to the negative effects of high-temperature conditions, it is recommended to use varnished cloth or fabric insulating tape as an insulating material. Of no small importance is the correct execution of all stages of electrical installation. Only with a reliable connection and proper connection of all elements of the electrical network can it be possible to minimize the risk of areas with poor contact, as well as prevent local overheating and breaks in electrical wiring.

Multi-core cables are a popular and common option, widely used for arranging electrical wiring for various purposes. The general rules for the separate connection of stranded and solid conductors do not have any differences or features, therefore it is allowed to use twisting, screw clamping, PPE elements, welding and soldering for this purpose.

The topic of connecting wires seems to be quite interesting to consider. For those who are just learning the basics of electrics, this information will be very useful and necessary. After all, you don’t have to be a professional electrician to understand that all wire junctions are a zone of serious danger. As a rule, 90% of all malfunctions and accidents occur precisely in contacts and cable twists.

The connection of wires can be of several types: twisting, using terminal blocks, using contact clamps, etc.

As you understand, there are quite a lot of types of wire connections, but only those connection methods that ordinary consumers can do at home will be considered.

You should start with general information.

When laying or repairing electrical wiring, it is quite often necessary to make all kinds of branches and splicing of wires. During this operation, you should always strive to get a quality connection and good contact. This is really very important, because in places of poor contact, the conductive cores heat up due to an increase in resistance, and this can lead to a fire in the insulation of your conductor and, in some cases, to serious consequences (which we have already mentioned above).

There are several ways to connect wires and cables:

twist.
Terminal blocks with screw terminals.
Contact clamps.
Electric welding.
contact heating method.
Soldering in a twist or in a sleeve.
Crimping in sleeves.

Some of these connection methods require special equipment, at home, terminal clamps, screw terminal blocks and, in a pinch, solderless twisting are best suited for self-connecting wires.

All methods of connecting conductors, which will be discussed below, are almost equivalent. Each of them has its pros and cons. If all your connections are made competently and in good faith, then there should be no problems with them in the future, no matter how you make this connection.
Next, the most common wire connection methods that are applicable at home will be considered.

Wire twisting

This method of connecting wires today is used only in the absence of special tools and devices. In most cases, the wires are simply twisted and wrapped with electrical tape. In some cases, such a connection is not reliable, but under certain conditions, such connections show amazing reliability. To do this, you need to remember a couple of rules: you need to twist copper with copper, aluminum with aluminum and provide a relatively small current to power your chandelier.

In this case, the entire length of your twist should be about 3-4 cm. As you already understood from the above, in no case should aluminum and copper wires be twisted together. In places of such connections, the process of electrolysis always takes place (with the participation of water contained in the air), in which these metals are destroyed. This mainly applies to aluminum. In this process, there is always one rule: the greater the current, the faster the process.

The type of twisting depends mainly on the type and functional purpose of the connection, the diameter and material of the twisted wires. Below, to help you understand this issue, a table of types of twists is provided.

Modern twisting of wires is carried out without the use of pliers. To create it, special connecting polymer caps with a metal spiral inside are used. There are both imported and domestic caps on the market.

A cap (twisting) is the simplest way to connect a TPG with a small section. It is used when you need to connect several ends of a wire. The connection is very simple, the smooth ends of the wires are stripped to a length of about 15 mm, inserted into the cap until it stops and the body is rotated using the wings on the body until a strong connection is obtained. You can check the resulting connection using conventional instrumentation, since at the top of the caps there is a control recess for the probe of the device.

The connection can be screwed on and, in some cases, unscrewed with the same length of the wire ends. But here you should always remember that spring caps are designed for a certain number of wires (this information should be on the cap body or on the package in which the caps were), therefore, when performing this type of work, you should always have a set of different sizes.

When choosing the cap size you need, you can focus on the color scheme. Just when buying caps, carefully study their assortment presented in the store. Pay attention to the color and specifications that should be written on the introduction sheet, and if you need to, remember all this information. In most cases, you can get by with the purchase of red caps - they can be used to twist wires from 0.5 to 12.5 mm².

The next type of wire connection to consider is the connection using terminal blocks.

Connection by terminal blocks

Terminal blocks are a fairly convenient way to connect wires, especially when you have a lot of them.

The block is a dielectric case with screw contacts inside.

The terminal blocks, as you have already seen, have a lot of sockets isolated from each other (usually there are two screws per terminal block). Here all connections are made quite simply. It is only necessary to strip the ends of the cores, insert them into the corresponding hole (towards each other) and tighten the fixing screws. But do not overdo it so as not to cut off these very veins. The terminal blocks are designed for operation in the AC mains with a nominal voltage of 220-230 V and a frequency of 50 Hz.

The pads have holes in the middle of their body. Through these holes, you can fix the terminal blocks on any surface. If you do not need the entire block, you can cut off the extra terminal blocks, focusing on the holes.

You can also use this type of terminal blocks as a dead end. That is, all the cores that you need to connect, you start on one side and strip the cores so that they can be tightened with not one, but two screws. It is better to do this so that the ends of the tightened wires do not stick out from the opposite side of the terminal block. Then take the electrical tape and try to insulate the end so that in the future you yourself will not receive an electric shock.

Although there are dead-end terminal blocks on sale, buying them is not always profitable. It is unlikely that you will purchase an electrical product of large sizes.

And one more thing to consider when working with terminal blocks. If you are trying to connect a stranded wire, then always try to crimp the ends of the stranded wire, since when tightening this wire with screws, there is a high probability that you can cut off a large number of individual strands and thereby reduce its cross section, and this can lead to further unpredictable consequences. One piece of advice is relevant here: when buying terminal blocks, always inspect them carefully and try to buy those where there are pressure plates inside.

Terminal connection

The next type of wire connection, which should be considered in more detail, is the connection with contact clamps (in other words, the use of WAGO terminal blocks, they are also called flat-spring contact clamps).

Currently, wires are increasingly connected with terminal spring clips. In this case, you do not have to twist or solder anything, you just need to strip the ends of the wires by about 12 mm and insert them into the clamp holes.

Scheme of connecting wires with contact clamps: a - connection of an aluminum single-core wire with a pin output: 1 - nut; 2 - split spring washer; 3 - shaped washer; 4 - steel washer; 5 - pin output; b - connection of a two-core wire with a flat contact screw clamp; c - connection of the core with a clamp-type terminal; g - contact spring clip.

Here's what the design will look like.

These terminals are filled with a special contact paste, which, when an aluminum conductor is connected, removes the oxide film from it and prevents re-oxidation. That is, during installation, you can safely connect both a copper conductor and an aluminum conductor to one terminal block.

Many experts scold this type of connection for one reason or another. But still, it is quite reliable and it has a number of advantages:

Conductors are not damaged.
Reliable protection against accidental contact with current-carrying connections.
Each conductor has its own terminal space.
Connecting together both copper and aluminum conductors.
It is possible to measure the electrical parameters of the circuit without breaking the insulation.
Safety and order when using these terminal blocks in wiring boxes.
Short circuit and heating at the connection point are completely excluded.
Clamps of this series are the best option for connecting wires at currents up to 25 A.
Instant installation of conductors.

There are terminal blocks of this type for stranded wires.

There are other connection methods, less popular, that you can do yourself.

Scheme of the contact clamp device: 1 - screw; 2 - spring washer; 3 - washer or base of the contact clamp; 4 - current-carrying core; 5 - stop limiting the spreading of the aluminum conductor.

Screw terminals are contacts in which the wire is fastened with screws. The clamp itself is mounted on the underlying surface with screws. In some cases, screw terminals may look like this:

Cable clamps - these devices help to connect the strands of wires without cutting the TPG. Used to branch wires from the main line.

This kind of compression is a bit outdated. Now they are trying to use a slightly different design, which does not need to be disassembled and when using which it is not necessary to clean the section of the line from insulation, since they are self-piercing. That is, when tightening the nut, which is located on top of the clamp, special teeth pierce the insulation of the conductor and thereby ensure reliable contact. In another hole, you can insert another conductor and thereby make a branch.

Panel terminals or busbars – this connection method is used when you need to connect several conductors. For example, when connecting suitable neutral wires to a common one.

Soldering - connecting wires with a soldering iron and special solders.

Whatever connection you choose, try to do it thoroughly and without haste, so as not to blame yourself in the future if the unexpected happens.

In a field such as electricity, all work must be carried out strictly, accurately and without a single mistake. Some wish to understand such work on their own, not trusting third parties to carry out a responsible mission. Today we will talk about how to properly connect the wires in the junction box. The work must be done with high quality, because not only the performance of electrical appliances in the house depends on it, but also the fire safety of the room.

About junction box

In an apartment or house, wires are routed from an electrical panel to different rooms. Usually there are several connection points: a switch, sockets, and so on. In order for all the wires to be collected in one place, junction boxes were created. They start wiring from sockets, switches and are connected in a hollow housing.

In order not to have to look for where the wires are hidden in the walls during the repair, the electrical wiring is laid on the basis of special rules prescribed in the PUE (Electrical Installation Rules).

Distribution boxes are classified according to the type of attachment. So, there are boxes for outdoor installation and indoor installation. For the second option, it is necessary to prepare a hole in the wall into which the box will be inserted. As a result, the lid of the box is flush with the wall. Often the cover during repair is hidden with wallpaper, plastic. In extreme cases, an outer box is used, which is mounted directly on the wall.

There are round or rectangular junction boxes. In any case, there will be at least 4 exits. Each outlet has a fitting or thread to which a corrugated tube is attached. This is done to quickly replace the wire. The old wire is pulled out, the new wiring is laid. It is not recommended to lay the cable in a strobe on the wall. If the wiring burns out, you will have to gouge the wall, break the finish in order to carry out repairs.

What are junction boxes for?

There are many factors that speak in favor of the existence of junction boxes:

the power system can be repaired in a matter of hours. All connections are available, you can easily find the area where the wires are burned out. If the cable was laid in special channels (corrugated tube, for example), then in an hour you can replace the failed cable;
connections can be inspected at any time. As a rule, wiring problems occur at the junctions. If the socket or switch does not work, but there is voltage in the network, check, first of all, the quality of the connection in the junction box;
the highest level of fire safety is created. It is believed that dangerous places are connections. With the use of the box, they will be in one place.
minimum time and financial costs when repairing wiring. No need to look for wires in the walls that are out of order.

Connecting the wires in the box

There are several ways in which conductor connections can be made in junction boxes. Note that there are simple and complex methods, however, if performed correctly, all options will ensure the reliability of the wiring.

Method number 1. Twisting method

It is believed that the twisting method is used by amateurs. At the same time, it is one of the most reliable and proven options. PUE do not recommend the use of twisting, since the contact between the wires is unreliable. As a result, the conductors can overheat, the room is threatened by a fire. However, twisting can be used as a temporary measure, for example when testing an assembled circuit.

Method number 2. Mounting caps - PPE

Very often, special caps are used for twisting conductors. As a result, it is possible to obtain a reliable connection, with good contact. The outer shell of the cap is plastic (the material is not combustible), and inside there is a metal part with a thread in the form of a cone. The insert increases the contact surface, improving the electrical parameters of the twist. Most often, thick conductors are connected using caps (no soldering is required).

It is necessary to remove the insulation from the wire by 2 centimeters, twist the wires slightly. When the cap is on, it must be turned with force. At this point, the connection can be considered ready.

Before making a connection, you need to count the number of wires. Based on the data obtained (by section), a certain type of caps is selected. The advantage of twisting with plastic caps is that you do not need to spend a lot of time, as with conventional twisting. In addition, the connection is compact.

Method number 3. Connection of conductors by soldering

If the household has a soldering iron, and you know how to work with it, then the wires can be connected using soldering. Before connecting the cores, they need to be tinned. Soldering flux or rosin is applied to the conductor. Next, the heated tip of the soldering iron is immersed in rosin, carried out several times along the wire. A reddish coating should appear.

After the rosin dries, the wires are twisted. With the help of a soldering iron, tin is taken, the twist is heated until the tin flows between the turns. The end result is a quality connection with excellent contact. However, electricians are not very fond of using this connection method. The problem is that it takes a lot of time to prepare. However, if you are doing the work for yourself, you should not spare either effort or time.

Method number 4. Core welding

Using an inverter welding machine, you can connect wires. Welding is used over the twist. On the inverter, you need to set the welding current parameters. There are certain standards for different connections:

- conductor with a cross section of 1.5 sq. mm - 30 A;

- conductor with a cross section of 2.5 sq. mm - 50A.

If the conductor is copper, then a graphite electrode is used for welding. Grounding from the welding machine is connected to the upper part of the resulting twist. An electrode is brought from the bottom of the twist, the arc is ignited. The electrode is applied to the twist for a couple of seconds. After a while, the connection will cool down, then it can be isolated.

Read also: Hidden electrical wiring in a wooden house

Method number 5. Terminal blocks

Another option for connecting conductors in a box is using terminal blocks. There are several types of pads: screw, with clamps, but the principle of the device is identical. The most common is a block with a copper plate for attaching wires. By inserting several wires into a special connector, they can be securely connected. Mounting with a clamp terminal connection is very simple.

In screw terminals, the pads are placed in a plastic case. There are open and closed pads. Closed pads are the invention of a new generation. To make the connection, wires are inserted into the socket and clamped with a screw (using a screwdriver).

However, terminal connections have a disadvantage. It lies in the fact that it is inconvenient to connect several conductors together. Contacts are arranged in pairs. And if you need to connect more than three wires, then several branches are squeezed into one socket, which is very difficult. At the same time, such connections make it possible to operate branches with a high current consumption.

Another type of pads is Wago terminals. Today, two types of terminals are in demand:

- terminals with a flat-spring mechanism. Sometimes they are called disposable, since it is impossible to reuse the terminals - the quality of the connection deteriorates. Inside the terminal there is a plate with spring petals. As soon as the conductor is inserted (it must be single-core only), the tab is pressed out and the wire is clamped. The conductor cuts into the metal. If the conductor is pulled out by force, then the petal will not take its previous shape.

Some terminal connections contain wiring paste internally. Such a connection is used if you need to connect a copper and aluminum wire. The paste protects metals from oxidation by protecting conductors;

- universal terminals with a lever mechanism - this is the best type of connector. The wire, stripped of insulation, is inserted into the terminal, a small lever is clamped. At this point, the connection is considered complete. And if you need to re-connect, add contacts, lift the lever, pull out the wire. The pads can be operated at low current (up to 24 A - with a cross section of 1.5 sq. mm) and at high current (32 A - with a conductor cross section of 2.5 sq. mm). If wires are connected through which a current higher than the specified one will flow, then another type of connection must be used.

Method number 6. Crimping

It is possible to connect the wires in the box by crimping only with the help of special pliers, as well as a metal sleeve. A sleeve is put on the twist, after which it is clamped with tongs. Just this method is suitable for connecting conductors with a large load.

Method number 7. Bolted connection

Connecting multiple wires with bolts is a simple and effective connection method. To complete the work, you need to take a bolt and a few washers with a nut.

It is not enough to know how to connect the wires in the junction box. You need to know which conductors are connected to each other. So, a washer is put on the bolt thread. The core is wound, the second washer is put on, and then the next core. At the end, we put on the third washer and press the connection with a nut. The node is closed with insulation.

There are several advantages of bolting conductors:

- ease of work;

- low cost;

- the ability to connect conductors made of different metals (for example, aluminum and copper).

However, there are also disadvantages:

- fixation of wires - not of high quality;

- to hide the bolt you need to use a lot of insulation;

This article has a somewhat provocative title. I am sure that there will immediately be people who will write instructively, saying that twisting is illegal and wire twisting is prohibited according to the PUE.

Nobody argues with this. If it were not for the fact that, despite everything that is written in the PUE, the vast majority of wire connections on the territory of the former large Soviet country are still made on twists.

I won't claim that it's very good wire twist- this is the most reliable and high-quality way to connect wires, although they constantly try to prove it to me. It seems that someone even measured and compared the voltage drop on the twist and on the whole piece of wire, so it turned out to be less on the twist. Perhaps this is something from the field of mythology among electricians. We will simply proceed from the fact that good twisting can be called one of the stages and a very important element of such methods of connecting wires, such as soldering or welding.

Before discussing further about the correct twist, let's dwell on what will happen if the wires are connected just like that, without technology, "how it happened." In this case, at the point of contact of the two wires occurs. There are two reasons for this - a decrease in the cross-sectional area of \u200b\u200bthe wire at the point of contact (mainly due to microprotrusions during connection) and the presence of an oxide film on the wire cores.

oxide film- the result of the interaction of the atoms of the metal of which the core consists with oxygen in the air. Such an oxide film has a very decent resistivity. The oxide film is absent only in noble metals - gold, platinum, etc. (that's why they are "noble", that they do not react with anyone). In silver, the resistivity of the oxide film is the same as that of the metal itself, so silver is actively used in the contacts of various electrical devices.

When the wire is heated by the current passing through it, the transient contact resistance increases even more, because. the generated heat is not completely removed to the environment, but also heats up the wire itself, including the twist.

As a result, all this can lead to an avalanche-like process, when the place of twisting heats up more and more. Here you have one of the causes of fires due to the so-called "malfunctions in the wiring."

I met one case when an aluminum twist in a neighbor's dacha stood for only one day. The reason for this is not only the presence of poor-quality twisting, but also the material of the conductive core of the wire. already posted on the site.

The most interesting thing is that no circuit breakers and fuses in the electrical panel will help in this case, because. they respond to an increase in current in the circuit. In our case, the current does not change, it just heats up the place of contact between the two wires more and more.

Based on this, we can conclude that a good twist of wires is necessary, first of all, so that the contact contact resistance always remains stable and does not change over time.

So, what does it take to make a good twist of wires?

First you need to remove the insulation without damaging the wire strands. We clean the bare area of \u200b\u200bthe core from dirt with a clean rag soaked in acetone or white spirit. Then we clean the wires with a metal brush or sandpaper to a metallic sheen.

Next, we twist the stripped veins with two pliers. To do this, we bend the ends of the cores at an angle of 90 ° at a distance equal to 7-10 diameters of the core from the insulation cut, and wind them up for each other. We wind 5-7 turns of one core onto another with pliers.

We wind 5-7 turns of another core and seal the connection with pliers, i.e. we tighten the coils of cores with two pliers in opposite directions. Then tightly bend the ends of the wires.

In order to make a branch, it is necessary to wind 10-15 turns of the branch core around the main core. Seal the branch with two pliers, tightening the turns of the core by moving them in opposite directions. Then tightly bend the end of the branch core. After all these operations, the twisting will be mechanically strong and reliable.

There are many other ways to connect wires with a twist. All these methods are given even characteristic names.

For example, here are the methods shown in one well-known book for young electricians:

The option that I described in this article, using two pliers, has been tested by practice and has never failed itself.

After creating a high-quality twist, the wires can be soldered (little used due to labor intensity), welded (in one of the articles on the site it was somehow proved that).

A good twist is also needed, for example, for a more modern and less time-consuming method of connecting wires - when used, which is a good alternative to electrical tape.

In appearance, it looks like a regular cambric, which is put on for twisting with a margin in both directions. Then the heat shrink tube heats up (you can use a regular lighter for this, but it is better to use an electric hair dryer), tightly wraps around the cable and insulates it securely.

Do your twists right!

If you have your favorite wire connection options - share and tell us about it in the comments to the article!

It would seem that it could be easier to connect wires? After all, there are several ways to connect wires. These are twisting wires, soldering wires, welding wires, crimping and connecting wires using a terminal block. Even a schoolboy knows the simplest way to twist conductors. It is necessary to attach together the ends of metal wires, called strands, and twist into one "pigtail", then wrap it with electrical tape. No need for a soldering iron, terminal block, connecting caps and other "unnecessities".
Any “electrician for himself” has mastered such an operation. And, if necessary, he uses this method in his daily practice. For example, it splices the wires of the power cord of a household appliance, tablet adapter or computer after a break.
Russian "techies" use this technology for fastening wires everywhere. That's just in the rules for the installation of electrical installations of PES "twisting", all kinds of "bends" and "riveting" are not provided. There are no such methods of wiring in other regulatory documents. Why?

We often do not think about the consequences of such a “simplification”. Meanwhile, an unreliable contact will let you down at the most inopportune moment, the power supply to consumers / power consumers can always be interrupted. From the “surges” of voltage, a breakdown of the elements of the power cascades of complex household appliances SBT occurs. Even special protection devices used in the most "fancy" models of foreign manufacturers do not save from breakage.

The aiming of short electromagnetic pulses with a voltage of several thousand volts at the electronic filling causes a "harmless" spark at the junctions. At the same time, the standard protection equipment that apartments are now equipped with (RCDs, circuit breakers, fuses) “does not see” such short low-current pulses, so they simply do not work from them, and it is not customary to install special devices for this. Uninterruptible power supplies for computers also did not become a panacea for transient pulses. The occurrence of "pokes" causes malfunctions in the operation of electronic equipment and computer equipment, leads to the failure of electrical components and expensive functional modules.
Overheating at the site of a bad connection leads to even more catastrophic consequences, with the passage of current, a weakened connecting node glows red hot. Often, fires and fires occur from this, causing enormous damage to the owners of the premises. Statistics show that 90% of all electrical wiring malfunctions occur due to twists and poor contact connections of conductors. In turn, the very malfunction of electrical wiring and equipment, according to the Ministry of Emergency Situations, is the cause of one third of the fires occurring in Russia.

However, it so happened historically that several decades ago, in the context of a shortage of electrical fittings / copper conductors, twisting aluminum wires was considered the main method used in electrical work. Twisting as a connection can be used in electrics during repair and restoration work.

How to properly connect wires

How to connect the wires: we start by stripping the insulation. Proper connection of conductors must satisfy three basic requirements:

Ensure reliable contact with a minimum contact resistance between each other close to the resistance of a single piece of wire.
Maintain tensile strength, fracture resistance and vibration.
Connect only homogeneous metals (copper to copper, aluminum to aluminum).

There are several connection methods that meet these requirements. Depending on the requirements for electrical wiring and the possibilities of practical application, the following types of wire connections are used:

All these methods require preliminary preparation of a wire or cable - removal of insulation to expose the wires to be connected. Traditionally, the material of the insulating shell is rubber, polystyrene, fluoroplast. Additionally, polyethylene, silk and varnish serve as insulation inside. Depending on the structure of the conductive part, the wire can be single-core or multi-core.
Single-core means a wire, the cross section of which is formed by an insulating sheath with a metal core or wiring inside.

In a stranded wire, the metal core is formed by several thin wires. They are usually interlaced and represent a strand surrounded on the outside by an insulator. Often, individual veins are coated with polyurethane varnish, and nylon threads are added to the structure between them to increase the strength of the wire. These materials, as well as the fabric braid on the outside, complicate the stripping process.

Depending on the type of connection, 0.2 - 5.0 cm of insulation is removed from each end of the wire. For this, several types of tools are used.
According to a 5-point system, you can evaluate the quality of insulation removal and the degree of protection against notching - damage to the cores by each device:

Insulation/core damage

Monter (kitchen) knife - 3/3
Side cutters (nippers) - 4/3
Stripper - 5/4
Soldering iron or loop burner - 4/4

In low-voltage television / computer networks, coaxial cables are used. During the cutting process, it is important to carefully cut and remove the insulating jacket without damaging the shielding braid. To access the central vein, it fluffs up and is removed, exposing the trunk. After that, the polyethylene insulation is cut with a knife or a special device, the cut is removed from the core.
The bifilar in the screen consists of a pair of wires in the screen, which, in order to access the conductors, is also pre-fluffed into wires, opening access to each core.

Important! A soldering iron should be used to remove the insulating material of enameled wire with a cross section of less than 0.2 mm². Enamel is carefully removed with an emery “zero” by moving the paper along the wires.

How to twist the wires correctly

Most often, twisting is used in the repair of electrical wiring, cords and adapters (including low-current ones) of household appliances and equipment. If we are talking about a home electrical network, then the norms provide for the use of wires in houses with a cross section of a current-carrying core of 1.5–2.0 mm from copper and 2.5–4.0 mm from aluminum. Usually, wires of the VVG and PV brands in a PVC sheath are used for wiring. Power cords of ShVL and ShTB brands with rubber or PVC insulation have a cross section of 0.5 - 0.75 mm.
Step-by-step splicing of wires between each other can be done as follows:

Degrease the bare ends of the wires by wiping with acetone / alcohol.
We remove the varnish layer or oxide film by cleaning the conductors with sandpaper.
We put the ends so that they cross. We wind clockwise at least 5 turns of one core onto another. To make the twist tight, use pliers.
We isolate the open current-carrying parts of the wires with electrical tape, or we wind the insulating cap. They should go beyond the insulation for 1.5–2.0 s to cover the exposed sections of the conductors.

To splice together a stranded stripped wire with a single-core, a different winding technique is used:

A stranded wire is wrapped around a single wire, leaving a free end without winding.
The end of the single-core wire is bent 180 ° so that it presses the twist, then it is pressed with pliers.
The connection point must be firmly fixed with electrical tape. For best performance, an insulating heat pipe should be used. To do this, a piece of cambric of the required length is pulled over the connection. To make it tightly grip the wiring, the tube should be warmed up, for example, with a hairdryer or a lighter.

With a bandage connection, the free ends are placed to each other and wrapped on top with an existing piece of wire (bandage) made of a homogeneous material.
Coupling with a groove provides that before mutual twisting, small hooks are configured from the ends of the wire, they are intertwined with each other, then the edges are wrapped.
There are more complex variations of parallel/series connections. The connection of wires by twisting is used by professional electricians when carrying out restoration work.

Important! Copper and aluminum have different ohmic resistance, they are actively oxidized during interaction, the connection is unstable due to different rigidity, therefore the connection of these metals is undesirable. In case of emergency, the tips to be joined should be prepared - irradiated with tin-lead solder (POS) using a soldering iron.

Why is it better to crimp (crimp) the wires

Crimping of wires is one of the most reliable and high-quality methods of mechanical connections currently used. With this technology, the loops of wires and cables are crimped in the connecting sleeve using press tongs, ensuring tight contact along the entire length.

The sleeve is a hollow tube and can be made independently. For sleeve sizes up to 120 mm², mechanical tongs are used. For large sections, products with a hydraulic punch are used.

During compression, the sleeve usually takes the form of a hexagon, sometimes local indentation is made in certain parts of the tube. In crimping, sleeves made of electrical copper GM and aluminum tubes GA are used. This method allows the crimping of conductors of different metals. This is largely facilitated by the treatment of the constituent components with quartz-vaseline lubricant, which prevents subsequent oxidation. For joint use, there are combined aluminum-copper sleeves or tinned copper sleeves GAM and GML. The crimp connection is used for conductor bundles with a total cross-sectional diameter between 10 mm² and 3 cm².

Soldering as a reliable alternative to twisting

The closest alternative to twisting, which is forbidden for electrical installations, is the connection of wires by soldering. It requires special fixtures and consumables, but provides absolute electrical contact.

Advice! Splicing of wires with an overlap is considered the most unreliable in technology. During operation, the solder crumbles and the connection opens. Therefore, before soldering, apply a bandage, wrap a piece of wire of a smaller diameter around the connected parts, or twist the conductors together.

You will need an electric soldering iron with a power of 60-100 W, a stand and tweezers (thin-nose pliers). The tip of the soldering iron should be cleaned of scale and sharpened, having previously selected the most suitable tip shape in the form of a spatula, and connect the body of the device to the ground wire. From the "consumables" you will need solder POS-40, POS-60 from tin and lead, rosin as a flux. You can use solder wire with rosin placed inside the structure.

If you need to solder steel, brass or aluminum, you will need a special soldering acid.

Important! Connections must not be overheated. Be sure to use a heat sink to prevent the insulation from melting when soldering. To do this, hold the bare wire between the heating point and the insulation with tweezers or thin-nosed pliers.

The cores stripped of insulation should be irradiated, for which the tips heated with a soldering iron are placed in a piece of rosin, they should be covered with a brown-transparent layer of flux.
We place the tip of the soldering iron tip in the solder, grab a drop of the molten one and evenly process the wires one by one, turning and moving along the tip blade.
Attach or twist wires together, fixing motionless. Warm up with a sting for 2–5 s. Treat the areas to be soldered with a layer of solder, allowing the drop to spread over the surfaces. Turn the connected wires over and repeat the operation on the reverse side.
After cooling, the soldering points are isolated by analogy with twisting. In some compounds, they are pre-treated with a brush dipped in alcohol and varnished on top.

Advice! During and after soldering for 5–8 s. the wires must not be pulled and moved, they must be in a fixed position. A signal that the structure has hardened is the acquisition of a matte shade by the surface of the solder (in the molten state it shines).

Still, welding is preferable.

In terms of connection strength and contact quality, welding surpasses all other technologies. Recently, portable welding inverters have appeared that can be carried to the most inaccessible places. Such devices are easily held on the welder's shoulder with a belt. This allows you to work in hard-to-reach places, for example, to weld from a ladder in a junction box. To weld metal wires, carbon pencils or copper-plated electrodes are inserted into the holder of the welding machine.

The main drawback of welding technology - overheating of the parts to be welded and melting of the insulation is eliminated by:

Correct adjustment of the welding current 70–120 A without overheating (depending on the number of wires to be welded with a cross section of 1.5 to 2.0 mm).
The short duration of the welding process is no more than 1–2 seconds.
Tight pre-twisting of wires and installation of a copper heat-dissipating clamp.

When connecting wires by welding, the twisted cores should be bent and be sure to turn up with a cut. An electrode is brought to the end of the wires connected to the ground and an electric arc is ignited. The molten copper flows down in a ball and covers the wire strand with a sheath. In the process of cooling, an insulating belt made of a piece of cambric or other insulating material is put on the warm structure. Lakotkan is also suitable as an insulating material.

Terminal blocks - the most ergonomic electrical installation products

The rules of the PUE, clause 2.1.21, provide for the type of connections using clamps (screws, bolts). There is a connection directly with the help of fasteners “on the fly”, when a screw, a washer is threaded through the loops of each of the wires and fixed with a nut on the reverse side.

Such an installation is wrapped with several turns of electrical tape and is considered quite practical and reliable.
More ergonomic wiring products, called screw terminals. They represent a contact group placed in a housing made of insulating material (plastic, porcelain). Most often, the connection of wires using the terminal blocks is found in junction boxes and switchboards. To connect the wire, you need to insert it into the socket and tighten the screw, the clamping bar will securely fix the core in the seat. Another connected wire is connected to the reciprocal socket, shorted with the first one.

In self-clamping terminal blocks of the WAGO type, the wire is snapped into the socket, a special paste or gel is used for better contact.

Branch clamps are a major version of the screw terminal block with several shorted taps, they are used mainly in the street and places with adverse environmental conditions.

The connecting clamps are an insulating cap with a thread inside, it is screwed onto the twist, simultaneously compressing and protecting against mechanical stress.