What are the twists of wires. Proper twisting of electrical wires: connection methods. Stranded cable twisting

One of the fastest and at the same time the most unreliable ways of splicing wires is twisting the strands. It is popular because it does not require special tools, and only electrical tape is needed to close the junction. You do not need to have special skills, it is enough to know the most common types of twists. However, this method is not without drawbacks.

Why twisting - the main advantages

If you need to connect two copper wires together, they can be soldered. But not everyone has this useful skill, and a soldering iron may not be at hand, for example, if there is a break in the cable of a power tool or a wire in a junction box in the country. Therefore, such a property of copper and aluminum conductors as flexibility is very convenient - they can simply be folded together and twisted in neat turns. In this case, even pliers are not needed if the metal cores of the wires have a small diameter. This concerns not only, but also television cable, antenna, telephone and many others, including computer ones.

Another advantage is the rather high quality of the connection without soldering. If the wire is used to transmit a signal, interference due to twisting usually does not appear, and if it does, then in very rare cases. It is very important that this connection saves time, and sometimes money. In particular, there is no need to wait for the soldering iron to warm up or to equip a special welding inverter for wires; there is no need to tin each core.

If the cores are varnished and do not provide contact, it is enough to simply singe them with a match or a lighter.

Very thin strands easily burn out or become brittle during singeing, which can already be attributed to disadvantages.

What you need to know - the nuances of using twists and their disadvantages

So, we have mentioned some of the difficulties of working with very thin, varnished copper cores. Without stripping, they will not make contact, but simply scorching with an open flame means burning the wire. However, even thick strands are not always easy to handle with conventional splicing. For example, aluminum is quite brittle and too many turns lead to microcracks, which cause the twisted ends to simply break. Approximately the same thing happens in severe frost with a copper core - with a strong tightening of the turns, they burst.

There are also directly opposite nuances, in particular, concerning insufficiently tight twisting of the ends of the wire. Each time, connecting the cores of two cables with a twist, you need to connect the power without insulation and after 30-40 minutes check if the core is heating up. The fact is that with loose contact of the conductors, increased resistance arises and the junction begins to heat up quickly, which can lead to burnout of the splicing of the wires. It should be borne in mind that due to temperature changes, the twisting of wires weakens over time and still starts to heat up.

In order to connect the bare ends of the wire, it is enough to twist them with your fingers, but it is recommended to use pliers to create high-quality tight turns.

It is highly undesirable to interconnect conductors from two different metals, for example, aluminum and copper, but if there is no other option, a special terminal, caps or pads should be used. We also avoid splicing a single-core wire with a stranded one, since they have different resistances, and with the same diameter they are designed for different loads. If you still have to resort to such a connection, calculate the peak power of the current that will pass through the conductors at maximum load. It should be within the allowable range for a weaker wire.

Existing types of twists - a list of commonly used

There are dozens of schemes for interlacing single-conductor and multi-core cables with each other. At the same time, it is extremely important to know that it is always necessary to connect the same type of wires, or use special electrical junction boxes with terminals or screw terminals. The same devices easily combine cores made of different metals. As for twists, there are parallel, serial and branches. The difference between them is in the arrangement of the conductors relative to each other. In the first case, the ends are placed side by side, in the second they are brought together, and in the latter case, we attach the conductor perpendicular to the bare area.

As for the splicing method, there can be quite a lot of room for action. So, for example, multi-core cables can be pre-twisted at the ends and you will correctly twist the wires as if you had solid cores in your hands. But it’s better to splice in a consistent way, after spreading the wires at both ends and then weaving them in oppositely directed turns. Wires with one core each can be twisted in a simple way, with a groove or bandage. We will analyze each of them in more detail.

We twist a stranded wire - the best option

As already mentioned, if there are no terminals, we use twisting, but the main condition for any multi-core cable is the maximum contact of all conductors at the junction. Therefore, having exposed the ends, we twist each of them at the base, a quarter of the length from the insulation, and then spread it with a whisk. We do this with each wire, usually you need to make 2 twists of electrical wires to get plus and minus (or zero and phase), less often 3 - if there is another phase or ground.

For a serial connection, in a neat oncoming movement, we bring the bundles together so that the rims enter one into the other and the wires intersect, even at different arbitrary angles. Next, we begin to twist the cores of one end away from us, and the other - towards ourselves, if you look at the cables from the side. In general, they will curl in the same direction, clockwise, when looking at each rim from the point of connection.

The parallel connection of electrical wires is carried out in almost the same way, only the ends with separated bundles of cores are brought to each other at a slight angle from the side until they intersect. After obtaining the desired contact, we simply weave all the strands into one thick pigtail. Then, of course, it is desirable to fill the resulting twist with tin, having previously tinned it, but if this is not possible, you can wind the insulation, always at least in 2 layers. For this purpose, special tubes are also used, which are put on the wire before connection.

We connect wires with one core - effective ways

The simple parallel option is the fastest. All that is needed is to connect two strands to be twisted together at a certain angle, and then twist them in even turns from the point of intersection. To make a serial connection, you need to slightly bend the bare ends of the wires, bring them together in an oncoming motion so that they intersect. After that, wrap each around the base of the other, one away from you, and the second towards you, if you look at the cable from the side.

Parallel fasteners with a groove are made by twisting one conductor around the other at two points - at the base of the stripped core, closer to the insulation, and near its end, previously slightly bent. This method gives a fairly even and durable installation, consisting, in fact, of two twists. The serial connection is already carried out by the mutual braiding of the cores bent at the ends with the passage of a small section. Again, you will get two twists near the insulation itself.

A bandage is made in cases where the wires are too thick and difficult to twist together. In such a situation, the cores are stripped of insulation and bent at the ends by 90 degrees, after which they are connected to each other in parallel or in series. Then a thinner core is taken, and also necessarily from a wire with one core, and wrapped in even turns around the mounted sections. Then the insulation is applied.

The connection of three wires is no different, you just need to add a third core to one of the first two in a parallel way, and then connect it to each other using any of the options listed above. The same applies to the fork. The only difference between connecting the side core to the bare area is that only it will be wrapped in turns, and the main wire will serve as the base. All of the above methods are suitable, including a bandage in the situation when the core of the attached cable has too large a diameter.

The electrical circuit is placed over the area of ​​virtually the entire frame, providing the room with electricity for household and industrial appliances, depending on the purpose of the building. In fact, a cable is supplied from the central network, which is subsequently placed in the control room, from which several more come out, are bred to different ends of the room and connected to the junction box, from where the final wires come out, which are ultimately connected to sockets, switches, etc. . Right in the distribution. boxes create the greatest number of connections, and sometimes a soldering iron, welding, connectors are not used there, but wire twisting, for the implementation of which special devices, tools are not needed, but only those things that are actually present in everyone (knife, pliers).
Content:

How to make a twist of wires

In order to reduce the actual impossibility of the occurrence and ignition, the twists in the junction boxes must be made with high quality. If a person performs such an action for the first time, for a start it is better to read carefully the rules of such a connection, and only after that begin to work. We will figure out how to make twists correctly, what types of them are and what problems you may encounter when performing these works.

To begin with, it is worth saying that the connection of two wires from different metals with the help of twisting is not recommended. A lot of analytical articles and arguments have been written about this, why this should not be done:

  • different coefficients of thermal expansion (metals react differently to heating and cooling, as a result of which the contact gradually worsens);
  • the appearance of an oxide film on an aluminum wire (it does not allow to fully conduct current, the wire heats up and collapses over time);
  • structural destruction of aluminum during electrolysis (these two metals form a galvanic couple, and after exposure to a humid environment, the metal ends are subject to heating, and subsequent destruction).



Stranding copper and aluminum wires

Do not connect copper and aluminum directly. However, in many homes it is aluminum wires that need to be connected to copper wires, and twisting is sometimes the only way to connect. In this case, it is important to adhere to certain rules that will allow such fastening to last a maximum period.

  • To begin with, it is worth noting that the conductors must be wrapped around each other with high quality. If their diameter is significant, there should be at least 3 turns, and if the diameter is up to 1 mm, in this case it will be necessary to wrap the wire around each other more than five times to ensure high-quality transmission of the electrical flow. Also, after that it is very important to treat the bare surface with a special varnish, which has the properties of resistance to water and moisture.
  • When connecting copper and aluminum wire, it is better to use a special steel plate placed between them. This will avoid their direct contact. Thus, the service life of such a connection will be much longer. If there is no such component at hand, then you can resort to processing bare copper wiring with solder, which will also avoid mechanical contacts between these two metals.
  • The ideal solution for joining copper and aluminum conductors is to pre-solder the copper core. Especially such pre-treatment is often used when connecting a solid and stranded wire, when in this way a wire consisting of several conductors is converted into a solid wire.



Twisting wires of different sections

This type of work implies the unambiguous use of additional means for connection. Such devices can be screw clamps, self-clamping terminals, bolts, copper-tinned tips, holes of the “Nut” type. Also, in order not to buy additional components, you can use soldering or welding, others.

If the difference in the diameter of the wires is insignificant, for example, 4 and 2.5 mm, then it is not so difficult to connect them with a twist. To do this, you need to wrap them with high quality with each other, after which you need to apply welding or soldering. Such a fastening of two conductors will last more than one year without complaints.

In other cases, the twisting of wires will not have reliability and durability. In such situations, you simply cannot do without additional components. In various situations, one or another device is used:

  • if significant, it is best to use a self-clamping terminal;
  • for a branch from the main line to the distribution. the shield uses a branch clamp, which among experts is also called "Nut";
  • to connect wires with a large diameter, a copper-puffer lug is used.

Errors when twisting wires

The most common problem with connecting conductors in this way is winding one wire onto another. This is completely wrong. The wires must evenly wrap around each other, thereby ensuring the reliable passage of electric current and creating mechanical strength so that such a fastening will last for many years.

The length of the twist depends directly on the diameter of the conductors themselves. At the same time, it should be taken into account that the minimum threshold for this characteristic should be at least 3 cm. Otherwise, everything depends on the diameter of the wires: the larger the diameter, the greater the length of the created twist should be, but there are no specifically prescribed rules for this, each specialist decides for himself what this value should be in order for the connection to be reliable and of high quality.

To provide connections and branches during electrical installation operations, twisting of wires is used. Contacts with this method of switching must be reliable. Carrying out work on the installation of wiring of all types - in everyday life or in industry - is subject to a collection of requirements and rules for how to twist the wires correctly. They say that it is impossible for additional resistance to appear at the points of contact between the veins. Neglect of this rule will lead to heating of the contact point.

Connection is carried out in accordance with electrical safety standards using the following methods:

  • twists.
  • Welding.
  • Soldering.
  • Screw clamp.
  • Terminal blocks and blocks.
  • Self-clamping express terminals.
  • PPE caps.

Connecting wires with a twist implies the advantages and disadvantages of the method. There is a PUE regulation to prohibit such an operation. But despite it, twisting is often used.

Twisting contacts occurs during rough installation. This is explained by the need to establish the fact of the correct operation of already mounted connections. Check the integrity of electrical lines, introduce the necessary amendments, install additional devices:

  • switching structures;
  • simple and special sockets;
  • equipment for conversion, voltage stabilization;
  • rectifiers;
  • accounting devices.

Upon completion of the preliminary work, the fully assembled circuit is tested for functionality. In case of incorrect operation of the equipment, lack of electricity find out the cause and site of damage. You have to change faulty nodes, twist the wires correctly.

Correct twisting of wires makes it possible to quickly resume power supply. Depending on the situation, they decide what to do with the elements of accession:

  • The finished combination remains.
  • Improving.
  • It changes to a new one, with a different way of connecting the cores.
  • An elementary set of tools for wire manipulation. It is easy to perform work in the field in the absence of powerful consumers.

Therefore, it is worth considering the maximum number of connected devices, deciding how to properly twist the wires, calculate the appropriate cable cross-section, and further develop the power system in the event of an increase in the number of consumers. Then the mounted soldering will serve reliably for more than one year.

The twisting of cable cores to connect pieces of wiring to each other appeared immediately after the discovery of electricity. At first, this approach suited everyone. But time does not stand still new electrical equipment has appeared, the need for development has increased power networks with increased power and current strength. The question arose of how to twist the wires in the more complicated realities. Twisting ceased to guarantee uninterrupted operation in such conditions. But at the household level, it is widely used and meets the requirements of networks with a low load.

Pros and cons of twists

The advantages of a braided connection are:

  • twisting speed;
  • long service life with high-quality installation;
  • does not require the use of complex tools;
  • ideally serves signaling networks where there is no powerful electrical equipment;
  • if necessary, the contact point can be additionally stretched or soldered;
  • is inexpensive;
  • the tap contains two - four branches at the same time;
  • connection is repeated in case of error or inaccurate execution.

There are also many disadvantages:

  • high-quality insulation;
  • not intended for use in power networks;
  • inconvenient way to assemble wires;
  • when heated, a fire occurs;
  • voltage drop associated with feeder overloads.

Twisting wires with different cores

Such combinations are strictly prohibited for use. It is unacceptable to combine copper and aluminum wire! When touched, these metals enter into a chemical oxidation reaction, galvanized . The contact is broken. With increasing load in the chain, solder erosion accelerates. Connecting in such conditions leads to sad results:

  • heating, sparking and, as a result, a fire;
  • weakening of contact at the solder point;
  • the size of the contact space is reduced;
  • power surges in the circuit section disrupt thermal equilibrium and destroy twisting.

Occurrence of oxide

The influence of air on the conductors oxidizes the junction. For copper and aluminum conductors, such an aggressive environment reduces the service life. The use of expensive metals like silver or gold in conventional schemes it is not economically feasible. The problem is solved by isolating the twists with a quality dielectric material with the correct execution methods. Such measures prolong the trouble-free operation of the soldering point and the entire circuit.

Resistance at the junction of the wires

The result of weak contact between the cable cores is an increase in resistance in this place. There is heating in the transition space and the destruction of the entire connecting circuit. Tight wire bonding will reduce these risks.

Types of connections in electrical circuits

Twisting is classified according to the material of manufacture of the cores participating in the operation, their types, and the method of twisting. The cross-sectional areas, the permissible load must be identical.

Wires with copper conductors allow multiple, up to ten times, torsion without compromising strength and contact. They easily also suitable for triple - quadruple connections. Aluminum cable is not so resistant to mechanical stress. One or two attempts to gossip - and he breaks off.

Cable cores are single and multi-wire. The twisting method must be found taking this feature into account.

For arranging temporary or mobile wiring, a more reusable twisted soft cord is chosen. The stationary and final electrical circuit is made up of a monolithic residential.

Connection of multi-wire cables is allowed. The directories contain data for all types. Materials are selected according to the numbers for mounting from wires with various combinations lived. It is necessary to take into account the cross section according to the current rating. The ways of weaving such endings do not differ.

The connection of wires will last more than one year if the exact order of manufacture is followed during execution.

So we do with the following veins.

TU cambric is displaced to the junction and heated to a monolithic overlay on the area of ​​twisting. In the absence of a tube, insulating tape is used. It is applied in three to four layers in full overlap.

In the absence of special devices for splicing cables, we use twisting. The main requirement is the maximum contact area of ​​the cores at the point of alignment. After stripping, we twist each wire at the sheath by one centimeter. We fluff the bare ends through the hairs. Manipulation is performed with each contact.

Serial connection is carried out by combining opposing beams one into the other, so that wires are intertwined. The twist is made from two sides in opposite directions.

When mounted in parallel, the manipulations are close. The wires fit like a house and the fluffy corollas are braided into a braid. The connections are sealed with pliers and insulated.

The easiest method soldering of single-wire conductors is called parallel. The wires are brought together at an arbitrary angle, the stripped sections are twisted from the point of adhesion.

To build up by the method of simple sequential interlacing, the bare wires are bent, shifted towards the intersection and twisted with a screw in opposite directions.

When one wire is bent and twisted around the second one in 2 places before connection (at the insulation and in the area of ​​its folded edge), the cable is spliced ​​in a way of parallel crossing with the gutter.

Similar consistent twisting is done with a braid of both strands. Two twisted places are formed at the base of the insulating layer.

A brace-assisted connection is required when working with heavy gauge wire or cable. A similar technique also has parallel and sequential versions. The core is pre-prepared from a monolithic wire of a thinner section, soft and made of a material similar to the main cable. The stripped ends are bent at a right angle, brought to each other. The prepared shroud core is wrapped around them in uniform turns.

The connection of an additional wire and a branch for each option occurs in a parallel way. Branching with a bandage differs in that that only the attached process is wrapped around.

With the intensive development of electronic technology, the load on electrical networks increases. The requirements for the reliability of soldering branches of the current supply are also growing. The twist connection is gradually becoming a thing of the past. This is clearly seen in production areas, where installation is carried out in progressive ways, and obsolete splices are replaced.

When installing electrical wiring, special attention is paid to electrical contacts, since the quality and reliability of the entire electrical network as a whole depends on this. An integral part of such contacts is the connection of wires. For this, both modern technologies and old methods are used. Each method has its own disadvantages and advantages. What type of twisting of wires to use is selected from the conditions and possibilities.

Wire Twisting Requirements

Twisting the wires together is the most popular and easiest way, but at the same time the most unreliable. To understand how to twist the wires correctly, it is necessary to imagine what processes can take place at the junction. Over time, as a result of temperature exposure, the clamp loosens. This is caused by the linear expansion of the conductor during the passage of large amounts of current. The contact at the junction is weakened, its resistance increases, and, accordingly, the place of twisting is heated. The wires oxidize and overheat, contact disappears or insulation breakdown occurs, which is fraught with a short circuit and fire.

The requirements for twisting wires are regulated by the rules for the installation of electrical equipment (PUE). The basic rules for any method of connecting wires are to ensure contact without additional resistance. That is, this value at the place of twist must not exceed the minimum the resistance value of the wires themselves. This is also true for the requirements of mechanical strength, the contact point should not be less durable than the strength value of the wires themselves.

Therefore, according to the PUE, simply made connections in the form of twisting during the installation of electrical wiring are prohibited. After twisting, additional operations are required to increase its reliability. It can be soldering, welding, crimping, mechanical clamping.

It is important to note that twisting is applicable only if the conductors to be connected are made of the same material. Otherwise, a chemical compound is formed due to oxidation, which quickly destroys the twist.

There are different types of twists:

  • parallel simple;
  • sequential simple;
  • parallel groove;
  • consistent groove;
  • bandage.

Before starting the connection, it is necessary to prepare the wires. To do this, you will need to remove the insulation over a length of at least 50 mm, clean the bare wire with fine emery, and only then proceed to twisting. Parallel connection applied when it becomes necessary to combine the ends of the wires with each other, for example, in junction boxes. Sequential twisting when making branches.

Parallel Connection Method

Parallel connection is a simple operation that involves a method in which two wires, stripped to the same length, are applied parallel to each other. Next, the bare ends are crossed so that the edges touch each other. Then, with a rotational movement, they begin to twist. Turn in one direction, in which - it does not matter.

The insulated parts of the conductors must not be twisted together. First, the conductors are twisted by hand, forming a direction, and then they are tightened with pliers. At the same time, the ends of the wires are taken with pliers to give uniformity to the twist. The “parallel groove” method implies that during twisting, one core is motionless, and the second braids it. To do this, starting from the end of the insulation, one wire makes three to four turns around the second. We lay the first one with a tight touch parallel to the second and at the end we perform again three to four turns.

Description of the sequential method

Serial simple connection is carried out in a different way. The stripped ends of the wires are not applied to each other, but are located opposite, overlapping. The middle of stripped veins are applied to each other, and then braided in one direction and in the other. In this case, it is necessary that the stripped wires do not fall on the insulation of the opposite wire. When twisting with a groove, each core is braided with the other only at the end of the insulation, and in the middle it passes with a tight touch.

Cable twisting

Runs in parallel , and the sequential method. In the first method, the wires are pressed against each other with an insulating layer, and a third conductor is wound around the stripped conductors with spiral movements. To do this, one end of the additional wire is held with fingers, and the other is wrapped around with the help of pliers, firmly squeezing the wires to be connected to each other. In the second method, the stripped cores are applied in parallel, but opposite each other, not reaching one or two millimeters to the insulation of the opposite wire. Then they are tightly rolled in with an additional conductor.

Stranded cable twisting

With this connection, there are small nuances. To increase the contact area, the same methods are used, but with a preliminary separation of the cores in each wire. After removing the insulation, the cores are bred in each wire, and two to four pigtails are created from them with an equal number of cores in each. Then they are stacked one on top of the other, and the wires are twisted one pigtail from each wire. At the end, the resulting pigtails are intertwined. In this way, the correct twisting of wires with strong mechanical strength and low resistance will be obtained.

The number of turns that is obtained during operation should be more than six. Types of wire connections do not depend on the material used and are performed the same for both aluminum and copper wires. It's important to understand what to twist different types wires cannot be connected to each other, and the aluminum wire may break off if twisted too much. If it is necessary to twist more than two wires, then the process technology will not change.

Additional technological operations

Since the PUE prohibits only twisting, and it is impossible to connect different materials, the twisting process should end with a terminal block or soldering. To make the connection reliable, the following technological operations are used:

  • soldering;
  • welding;
  • screw terminals;
  • crimping in special spring devices;
  • crimping.

Soldering and welding when connecting

The only drawback of this operation is the complexity of the work. Soldering requires tin and flux. When working with copper, rosin is used as a flux, while for aluminum, highly active fluxes containing oleic acid and lithium iodide are used. If a soldering iron with a power of up to 100 W is enough for soldering copper, then aluminum is welded using a gas heater, the heating temperature should be 400-500 degrees. Solder for copper is used lead-tin. And for aluminum with zinc content.

The technology itself is simple, since the thermal conductivity of the twist is greater than that of the solder, then when melted, it goes to the junction, creating a thin layer. When soldering, large flows of solder are not allowed, it should be evenly distributed over the entire surface.

Application of screw terminals

Screw clamps in their principle of operation imply mechanical squeezing of twisted surfaces by means of a bolted connection. For this, steel pads are used. The finished twist or individual strands of wire are placed under a steel washer and compressed by screwing in the screw. In this case, the clamping is carried out both by the washer itself and only by the screw. The first method is better, since the contact surface is larger.

The terminal block itself looks like a plate on an insulator with a group of contacts. With the help of terminal blocks, both copper wires and aluminum wires of different sections are connected.

Use of spring devices

Allows you to make the fastest connection without the use of a tool. Wago terminal blocks are widely used. They are available not only in different sizes, but also for a different number of connected wires. With their help, single-core and multi-core wires of different sections and types are connected. The wires are combined both separately and among themselves. To do this, the terminal blocks have a latch-flag, which allows you to lay the wire and clamp it inside after snapping. Or use a clip-on device.

Using the Wago terminal, aluminum and copper can also be connected to each other. But for this, a special paste is used that prevents air from entering, and the cores of the wires are bred into separate cells.

Crimping of connected cords

If it is necessary to connect wires of large cross section, lugs (sleeves) are used. The wires are stripped and inserted into the sleeves, then with the help of press tongs the sleeve is compressed and the wire is crimped. Such a connection is considered reliable, but requires a specialized tool.

Connecting insulating clamps (PPE) are also considered a kind of crimping. After twisting the wire, depending on the diameter, the caps are screwed on top of the connection, pressing the contact and isolating it.

The last final stage after the connection is made is its thorough isolation. As an insulator, a dielectric electrical tape or a thermotube is used. The insulation should be 2-3 cm larger than the junction itself. The insulation must be of high quality, otherwise there is a possibility of a breakdown between the wires, which will lead to a short circuit.

According to paragraph 2.1.21. PUE, connections of wires and cables must be carried out in one of the following ways: by welding, crimping, using screw or bolted connections, or by soldering in accordance with the current instructions approved in the prescribed manner. As you can see, "twisting" is not mentioned at all here. We can safely conclude: twisting is practically prohibited by the PUE.

However, let's see why the official attitude to twisting is so unambiguous, what may be the reason for its exclusion from the list of allowed methods of connecting wires, because it is quite clear that this was done for a reason. Allowed: crimping, soldering, welding and screw connection. To begin with, we will consider what are the features of the allowed connection methods, and how they differ from twisting.

Soldering and welding

Soldering and welding assume solidity and the maximum possible conductivity of the permanent connection being created. During soldering, the permanent connection formed is formed by interatomic bonds, because when the metals to be joined are heated below their melting point, the solder is already melted, it immediately wets them and flows into the gap, after which it crystallizes.

Welding also involves the establishment of interatomic bonds between the parts to be welded, but here the metals themselves melt or undergo plastic deformation (or undergo simultaneous melting and deformation).

One way or another, now it is clear to us that both soldering and welding of wires make their pairing as complete and high-quality as possible, because the wires are combined at the atomic level, which means that for current they are turned into a single wire, when there are no air gaps at the transition between the parts to be combined, there are no unnecessary intermediate elements that could somehow worsen the conductivity.

Crimping and screw connection

With regard to crimping and screw connection, this implies such a strong pressing of the mating conductors to each other that the quality of the connection is almost identical in terms of conductivity to a welded joint or solder.

Yes, the tensile strength of such a connection may be less than that achievable by welding or soldering, however, the achievable joint conductivity turns out to be almost the maximum possible, since the wires can be said to flow into each other, their metals diffuse. There is not even an intermediate element here - solder, the resistivity of which, in principle, can be greater than the resistivity of the metals of the combined wires.

If the purpose of the connected wires is such that the wires will not carry a significant mechanical load, then crimping or screw connection in terms of conductivity will not yield to welding and soldering.

Why is the twist heated

What about twist? Twisting will not only not allow you to create a reliable, well-conducting contact, it will also not provide strength and will heat up more than the rest of the wire when any significant current passes through it.

This will happen because at the place of twisting the wires are not connected at the atomic level, they only contact with part of their surfaces, and in some places between them there are air gaps in which oxides will necessarily form over time.

In addition, mechanically, the twist will still unwind over time, which will further aggravate the formation of oxidation products.

In the end, due to the combined action of these factors, the contact of the wires in the twist will deteriorate so much that it will be fraught with the formation of sparks and even ignition of the wire insulation.

Of course, if we are talking about a temporary connection of wires, for example, when testing a circuit for switching on some kind of load or when checking a part of some device being repaired, then in these cases no one will forbid you to carefully use elementary detachable connections - twists.

However, one should be aware of the obvious disadvantages of such a solution as twisting and the inevitable long-term consequences of its use. Therefore, please make permanent connections only in the ways permitted by the PUE.

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