Why is it forbidden to twist wires. Correct twist and types of electrical wire connections How to make a twist of 4 6 wires

At least once, but almost everyone had to twist the wires. You will say that this is a fairly simple procedure. On the one hand, indeed, in order to intertwine several cores and put them into a junction box, you do not need to have special skills.

But not everything is so clear! After all, to make a twist of wires is one thing, but to perform it QUALITATIVELY and RELIABLY is a completely different matter.

Unfortunately, homemade twisting of wires often causes electrical wiring to ignite. That is why such a procedure should be approached very responsibly. So that you can be confident in your work and not worry that somewhere you have poorly insulated or twisted the wires not securely enough, we will tell you how to do everything right.

Why can wire twisting be dangerous?

So, let's fix it: twisting wires is rightfully considered the most dangerous connection method. Why?

This is because the degree of contact of two or several conductors at once depends only on the quality of the work you have done. Moreover, over time, weakly bent veins will gradually become even weaker. What is the risk? Well, at least the fact that at high loads of electric current in this zone there will be too weak contact. As a result - heating of the wires, destruction of the insulating layer and a deplorable ending in the form of a short circuit (we are generally silent about fire and electric shock).

According to the rules of the PUE, this method of connecting wires is completely prohibited. Although, of course, almost all electricians resort to a similar method in ordinary everyday work. And this is what practicing professionals say: if you twist the wires correctly and insulate them carefully, you will not have any problems at all. At the same time, the veins themselves can faithfully serve for another couple of decades.

This begs the question - how to make the twisting of wires correctly and "for centuries"? We tell.

Reliable twisting of wires: detailed instructions

For the sake of example, let's take the simplest situation - it is necessary to fasten a pair of single-core wires together (assume that both conductors are made of copper). The course of action is:

We carefully clean both cores with a special tool or a simple knife, removing the insulation by about five centimeters;
Degrease bare contacts with acetone;
We take a piece of sandpaper and clean the ends of the conductors to a pronounced metallic color;
We put the bare veins crosswise and slowly wrap one vein around the other (the procedure is performed using pliers, the number of turns is at least five);
We wind the second core in the same way;
We tightly wrap the twisting zone with electrical tape (it would also be nice to use a heat-shrinkable cambric - a special tube that will protect the bare area from the external environment).

You can safely see that there is nothing complicated in the procedure. The main thing is that we expose sections of wires by at least five centimeters and confidently twist them together with pliers, thereby ensuring strong contact.

Options for twisting single-core wires

What about the more complex situation where you have to twist solid and stranded wires together? Here it is necessary to fulfill the first two points of the above instructions, after which - cross the products between themselves and tightly wind the stranded wire around the single-core (at a distance of a couple of centimeters from its end).

Wrapped up? Then we take the remaining single-core end and bend it in one smooth movement towards the turns of the stranded conductor. When the task is completed, the wires are insulated and placed in a distribution box. Absolutely the same course of action will help with the twisting of two stranded wires.

By the way, what is important - we absolutely do not recommend twisting copper and aluminum wires. This is indicated not only by professional electricians, but also by regulatory documents - the same GOST. You should not make such twists because copper and aluminum have different metal resistance indicators. Also, when they interact, oxidation occurs, and this, in turn, significantly worsens the contact.

There is also the following nuance: copper and aluminum have different physical properties in the sense that one of the metals is hard and the other is soft. This will also have an extremely negative impact on the quality of the contact between the two conductors.

Video about twisting wires

If you want to be sure of the quality of the connection you made, we advise you to read the following recommendations:

Use these tips, they definitely will not interfere with you when performing any electrical work where there is a need to connect wires to each other. What is important to pay attention to - the above methods do not allow you to make the twist waterproof. So if you decide to fasten the cores in the wall under a layer of plaster (besides without a box), be sure to isolate the junctions with cambric.

What is the conclusion?

So we told you about how to make a twist of wires with your own hands. We advise you to resort to this method only as part of the installation of temporary electrical wiring, in other cases, use more modern and safe methods. Also, never forget to turn off the electricity in the house before doing any electrical work. Good luck!

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 completed. 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;

No matter how common various clamps and terminals have been lately, the most popular way to connect wires is elementary twisting. However, you should be aware that the rules for electrical installations prohibit the use of twisting in its pure form (that is, without further soldering or contact welding). You can increase the "legality" of twisting with the help of PPE. You make a twist, and on top of it you wind PPE (connecting insulating clip).

It creates a sufficient contact density and, under different loads and temperature differences, does not allow the contact to weaken. You can choose PPE of the right size, quantity and quality with free delivery.

Types of twists. Twisting errors

First, remember that the wires are aluminum and copper. Copper wires are divided into solid (one solid core) and stranded (flexible).

Monocore is used for stationary connection of equipment. Once laid under the plaster, behind the drywall and forgot about them. Wiggling and bending such wiring is no longer required.

Stranded ones are used for mobile devices or temporary connection of electrical equipment. Where the wiring constantly needs to be moved from place to place, change its location. These are home carrying, household appliances plugged into sockets.

They are also used in the assembly of switchboards, where there is a shortage in free space, and the cores have to be significantly bent in order to lead the devices into the terminals.

Consider first how to properly twist the wires from the monocore. The process here is not intricate and is known to everyone. Two wires are taken, stripped at the ends and begin to twist together.

The Chinese even came up with an assistant-nozzle in this matter to automate the work.

Main features and rules:

⚡ wires must be of the same material (copper or aluminum)
⚡ clean the core by at least 3-4 cm, thereby increasing the usable contact area
⚡ wires run parallel to each other
⚡ both wires must be twisted evenly among themselves
⚡ when twisting with some pliers, hold the place where you start stripping the insulation, and twist at the end with others. The insulated parts of the conductors must not be twisted together.
⚡ the number of turns that should be obtained in the end - from five or more

The twists of aluminum and copper wires are performed in the same way. The difference is that you can spin and twist copper several times, and aluminum 1-2 times. After which they will break off.

And if you need to twist more than two wires, say 4-5? The process is no different:

⚡ with your hands, slowly twist the wires only giving them the shape of a future twist
⚡ take two pliers and, holding the twist at first, tighten the veins at the end
⚡ the length of the stripped areas should also be 3-4cm

There are situations when it is necessary that the twist takes up as little space as possible. Either there is not enough space in the junction box, or it must then be pulled through a narrow hole. In this case, the technology is slightly different.

⚡ put the stripped strands of wires cross on the cross, in the middle of the stripping place
⚡ and begin to twist them so that the ends after folding are equidistant from each other

In terms of quality and reliability, such twists are inferior to conventional ones.

Stranding copper wire with aluminum

It is impossible to twist copper wire and aluminum directly. Such a connection will oxidize and subsequently can lead, at best, to burnout of the contact or, at worst, to a fire. In such cases, you need to use either connectors, or use a third metal - steel, as a gasket between copper and aluminum.

A simple bolt with a nut and washer is taken. The stripped wires are shaped like a ring at the end. And these rings are put on a bolt. Moreover, the wire of the ring must bend in the direction of the thread of the bolt.

The aluminum core is clamped with a steel washer, and a copper one is superimposed on top of this washer. After that, the contact is pulled together with another washer with a nut. That is, to create a normal contact between a copper conductor and an aluminum one, you will need at least a bolt with a nut and 3 steel washers.

Stranded wire twisting

It is possible to apply the previous job descriptions for such strands, but this will not give reliable mechanical contact. Therefore, proceed as follows.

Among the many connection methods, the twisting of electrical wires is the simplest and most easily implemented. This type of connection is not highly reliable, its main advantages are speed of execution and a minimum set of tools during operation. Despite the disadvantages, the twisting of conductive wires remains popular when working at home and in the field.

What the rules say

The Rules of the Electrical Installation Device (PUE) when installing electrical wiring prescribe to connect wires by crimping, welding, soldering, connecting clamps (screw, bolt, etc.). Single-wire wires can be connected by twisting followed by soldering.

In fact, this means that, from the point of view of the PUE, twisting of wires is not allowed. If we are talking about a supervised object, the selection committee will not allow the object, electrical installation or wiring made using such connections to be put into operation.

The reason for the inadmissibility lies in the low reliability. The elasticity of twisted wires weakens over time, the metal of the conductive wires oxidizes. In this case, the quality of contact at the junction deteriorates. The increased resistance of such a section of the circuit works as a heating element, especially when high load currents flow. The conductors begin to heat up, in the worst case, melting and even ignition of the insulation is possible.

The worst situation is when joining dissimilar metals such as copper and aluminum. Due to differences in physical and chemical properties at the points of contact, a rapid increase in contact resistance occurs. The situation is sharply aggravated in the presence of moisture. As a result, the connection of copper and aluminum wires by twisting is directly prohibited by the rules.

However, in practice, in everyday life, this method of connecting the cores remains in demand, as the fastest and easiest.

How to twist electrical wires

If for some reason it was necessary to connect the wires with a twist, it is important to take measures to maximize the sealing of the junction. First, the wires are freed from insulation. The specific length depends on the cross-section, the thinner the wire, the shorter the length of the bare section will be required. On average, at 1.5 mm2, the conductor should be stripped to a length of about 5 cm. In the case of stranded wires, special care should be taken when stripping the insulation, since individual thin strands are easily damaged, thereby reducing the cross section of the conductor. You can remove the insulation with a knife or use a special tool for stripping wires.

The connected cores can be of the same or different cross-section, single-core or multi-core. With a parallel, serial arrangement of wires or with a branch device, the twisting methods can be different, the options are shown in the figure.

To further improve the quality of the connection, with a parallel arrangement of conductors, the use of connecting insulating clamps (PPE) allows.

The clip is a cap made of flame retardant plastic. Inside the cap there is a steel spring. When winding the PPE into a twist, the spring compresses the wires, thereby improving the quality of the contact. The outer plastic sheath serves as insulation for the joint.

In any case, the correct twist of electrical wires is the one that will ensure the tightest possible fit of the conductors to each other. For example, when connecting a thicker single-core wire to a stranded one, you can strengthen the junction by crimping the core itself, as shown in the photo.

Insulation

Insulation plays an important role in the reliability of a connection. It not only protects against short circuits and accidental contact with live parts, but also serves to prevent moisture from entering them. The presence of moisture leads to accelerated oxidation of the metal, deterioration of contact with all the ensuing negative consequences.

The most common method of insulation is wrapping with insulating tape. The tape allows you to isolate connections of any configuration and complexity. Insulating tapes are produced for various conditions, including those designed for use in high temperatures.

Recently, the use of heat shrink tubing has become increasingly popular. This is a tube made of a material that shrinks under the influence of high temperature, tightly covering the insulated parts.

The heat shrink tubing method requires the tubing to be wrapped around the wire beforehand, and is therefore best suited for a series of conductors. The shrinkage temperature is around 120°C. For this purpose, use a building hair dryer, gas burner, in extreme cases, a lighter or matches. It is important to monitor the temperature so as not to melt the insulation with a flame or excessively hot air.

Despite all the shortcomings, the twist connection is popular. In a situation where you need to power an electrical consumer, and there is only a knife or pliers from the tool, twisting is the only available solution. It must be said that in a dry place, a well-made and insulated twist can work for years without a noticeable deterioration in properties. But still, if possible, it will be correct to use another method of connection.

When laying the wiring in the house, you can not do without connecting the wires. After all, a network with branches is laid around the house to power certain electrical appliances.

The need for wiring

Distribution boxes are used to branch the electrical network. But they are intended only to hide the connections of the branches of the electrical network.

The need for a wiring connection is ubiquitous. They connect wiring in different ways in the house, electrical appliances, cars, in general, wherever there are wires.

Now there are several ways to connect the wiring. Each of them has its positive and negative qualities.

The most common ways are:

twist;
Soldering;
Welding;
Use of terminal blocks, blocks;
Use of self-clamping terminal blocks;
Use of connecting insulating clamps (PPE caps).

Twisting

The simplest and most common way to connect wires is the usual twist.

For this type of connection, only a stripping knife and pliers are required from the equipment to ensure a reliable connection. However, in the end, the place of twisting will need to be insulated.

Twisting is done in several ways.

The simplest is the mutual twisting of the stripped ends of the wiring.

For reliability, it is desirable to expose the wires by at least 5 cm. Next, the bare ends are crossed so that the edges of the insulation touch, and then they grab the crosshairs of the wires with the sponges of the pliers and twist them with a rotational movement.

After twisting, the connection is bent to one side so that the twist lies parallel to the wire. Then the connection is isolated.

The second method is also an effective and simple twist.

The stripped ends of the wires in the middle are slightly bent, and in the place of the bend the wires are hooked together.

After the end of one wire is wrapped around the second, it is also done with the other end of the wiring.

For reliability, the windings made can be slightly tightened with pliers. Then everything is isolated.

The next method is a bandage connection. For such a twist, you need a piece of stripped wire.

The two wires to be connected are laid parallel to each other so that the stripped ends touch along their entire length.

Then they are wrapped with the available segment, a kind of bandage is obtained.

The last of the used methods of twisting that can be found is groove twisting.

To perform it, small hooks are made from the ends of the wires, which interlock with each other, and then one end of the wire is wound around the second.

More complex types of wire connections are presented below.

Now about ways to isolate twists.

Often, various types of electrical tape are used for insulation. When using it, it is necessary to wrap not only the place of twisting, it must go on the insulation of the wires for at least 2-3 cm.

This will provide complete insulation, including from moisture.

In addition to electrical tape, it is possible to use thermotubes.

Such a tube of the desired length is put on one of the wires before twisting.

After twisting, the tube is pushed onto the junction. In order for it to tightly wrap around the wiring, it needs to be heated a little, for example, with a lighter.

Due to the heat, the tube will shrink to provide a tight fit.

The positive qualities of twists include ease of implementation with minimal equipment, while they are considered quite reliable.

If good insulation is provided, then the twist can last a long time. Also, the twist itself is a detachable connection, you can twist it at any time.

It is considered more preferable in networks that are not fixed and can sag, which is especially important for cars where vibration constantly affects the wiring.

Among the shortcomings, it is noted that it is impossible to connect wires of different sections, the resistance in such a twist can be very high, which will lead to heating and melting of the insulating layer.

Stranding is difficult to join multi-core cables. They are too soft, so when stretched, the connection may break.

If several insulated cores are used in the wiring, then after insulating each core, the total thickness at the junction can be very large.

This will affect both reliability and increased resistance at the junction of the wires.

Soldering

The next method of connecting wires, which is often used, is soldering.

It is noteworthy that soldering is only an improvement in twist. That is, the wires must be twisted before soldering, and then soldered.

To perform soldering, a soldering iron and solder are used. Thanks to this connection, the stranding strength of a multi-core cable can be significantly increased.

The advantages of soldering include an increase in strength, especially for stranded wires.

After soldering at the junction, the resistance will be much lower, which means that the twist will not heat up.

However, soldering is used only on copper stranded wiring, aluminum soldering does not work.

At the same time, soldering is very fragile, and if it is performed incorrectly, the connection will be unreliable.

Welding

Another way to improve the twist is welding. Again, welding is just a method to increase the reliability of the strand.

It is not applicable for aluminum wires; welding is used only on large-section copper cables.

Reliability in welding is much higher than in soldering. It is a good way to improve the connections in the junction box, but welding is still not very practical.

In addition, it will require special equipment, a welding inverter.

Welding is not used on aluminum wiring, an additional disadvantage is the possibility of weakening the twist, since with strong heating of the wires, which will be necessary during the welding process, it is possible to loosen the twist itself due to a change in the physical properties of the metal.

Soldering and welding cannot be considered separate methods of connection, they only provide additional reliability.

Also, after using a soldering iron or a welding machine, the junction will still have to be isolated.

Terminal blocks and blocks

But the use of terminal blocks and blocks is a completely separate way of connecting wires.

The terminal block and block are a small metal plate with contacts on the edges.

This plate is encased in insulating plastic. Bolts are often used to clamp wires.

The difference between a terminal block and a block comes down to the fact that the terminal block allows you to connect only two wires, and the block is designed for several connections.

Simply put, a block is several terminal blocks connected together, allowing for several separate connections.

To connect two wires, it is enough to clean their ends from insulation, and you don’t need to clean a lot, 0.5 cm is enough, it is only important that the cleaned end reaches the contact.

In this case, the bare wire should not protrude beyond the edges of the terminal block, in order to avoid accidentally touching it.

On the other side of the terminal block, the other end of the wire is fixed. The metal plate will act as a bridge between them.

When using a terminal block, only two wires are connected by them, for the subsequent ones another terminal block is used.

The block also allows you to provide several connections, which, with a large number of wires, will result in more compact dimensions.

Terminal blocks and pads are good because they allow you to interconnect wiring made of different metals and differing in cross section.

In addition, they are detachable, at any time you can disconnect the desired wire. They are good for both solid and stranded wires.

Their disadvantages include the increased dimensions of the connection, especially for the pads.

Hiding terminal blocks and blocks can be very difficult. In addition, conventional terminal blocks will not allow you to make a tie-in into the wiring, twisting this allows. But about the sidebar - a little lower.

Terminal blocks self-clamping

Self-clamping terminal blocks are a variation of conventional terminal blocks. They provide an even faster connection because you don't even need to use a screwdriver.

The contacts in them are spring-loaded, therefore, to connect the cables, it is enough to insert the ends of the wiring into the holes with the contacts.

When installing, you need to overcome the force of the spring, after which it will press the contact to the wire. It is noted that this method is very convenient for stranded wires.

Among the disadvantages of such a connection, one can single out a not particularly reliable connection; it will not be difficult to pull out the wiring from the terminal block. This is especially true for single-core wires of large cross section.

A common disadvantage for terminal blocks is the possibility of moisture getting on the contacts, which can lead to their oxidation and disruption of the connection.

PPE caps

PPE caps are a simple and convenient way to connect. They are produced in three types - without contacts, as well as with clamping and spring-loaded contacts.

Caps without contacts are made of insulating material only. They are designed to isolate the twist.

They are put on top of the twist, protecting it from moisture.