What wires are connected in the junction box. How to connect wires in a junction box according to PUE. Correct pin markings

When connecting wires of different diameters in series, the maximum load current will be determined by the cross-section of the wire with a smaller diameter. For example, a connection was made between copper wires with a diameter of 1.6 mm and 2 mm. In this case, the maximum load current on the electrical wiring, which is determined from the table, will be 10 A, and not 16 A, as for a wire with a diameter of 2 mm.

Connecting electrical wires by twisting

Until recently, twisting was the most common method of connecting wires when doing electrical wiring; due to its accessibility, all it took was a knife and pliers. But, according to statistics, twisting is not a reliable way to connect conductors.

According to the electrical installation rules (PUE), twisted connections when installing electrical wiring are prohibited. But, despite the noted disadvantages, the twisting method is currently widely used. Connecting conductors of low-precision circuits by twisting, subject to certain rules, is quite justified.

The photo on the left shows how twisting is unacceptable. If one conductor is twisted around another, the mechanical strength of such a connection will be insufficient. When twisting wires, you must make at least three turns of wires around each other. In the middle photo, the twisting is done correctly, but a copper conductor is twisted with an aluminum one, which is not permissible, since when copper comes into contact with aluminum, an emf of more than 0.6 mV occurs.

In the photo on the right, the twisting of copper and aluminum wires is done correctly, since the copper wire is tinned with solder before twisting. You can twist several wires together at once; in a junction box, sometimes up to 6 conductors are twisted, wires of different diameters and from different metals, a stranded wire with a single-core wire. Only the stranded wire needs to be made single-core by first soldering it with solder.

Connecting electrical wires by soldering

The connection of copper wires with high-quality soldering is the most reliable and is practically not inferior to a solid wire. All of the above examples of twisted wires, except for aluminum and tinsel, when tinning the conductors before twisting and then soldering them with solder, will be reliable on a par with solid wires. The only drawback is the extra labor involved, but it's worth it.

If you need to connect a pair of wires and the twisted conductors must be directed in different directions, then a slightly different type of twist is used.

By splicing two pairs of double wires in the manner described below, it is possible to obtain a compact and beautiful connection by twisting both single-core and multi-core pairs of conductors. This twisting method can be successfully used, for example, when splicing broken wires in a wall, extending a wire when moving a socket or switch from one place on the wall to another, when repairing or extending the length of a carrying cable.

To obtain a reliable and beautiful connection, it is necessary to adjust the lengths of the ends of the conductors with a shift of 2-3 cm.

Twist the conductors in pairs. With this type of twisting, two turns are enough for a single-core wire, and five for a multi-core wire.

If you plan to hide the twists under plaster or in another inaccessible place, then the twists must be soldered. After soldering, you need to go over the solder with sandpaper to remove any sharp solder icicles that could pierce the insulation and stick out from it. You can do without soldering if the connection is accessible and the currents flowing through the conductors are not large, but the durability of the connection without soldering will be much lower.

Due to the shift of the twisting points, there is no need to insulate each of the connections separately. We attach a strip of insulating tape on both sides along the conductors. Finally, you need to wind three more layers of insulating tape. According to the requirements of the Electrical Safety Rules, there must be at least three layers.

Wires, stringed and soldered in the manner described above, can be safely laid in the wall and plastered on top. Before installation, it is advisable to protect the connection with a vinyl chloride tube placed in advance on one of the pairs of wires. I have done this many times, and the reliability has been confirmed by time.

Connecting wires in junction boxes

When I moved into an apartment built in 1958 and began doing renovations, I was immediately confronted with the blinking of the lighting bulbs in rhythm with the hammer blows on the walls. The primary task of repair arose, carrying out an audit of distribution boxes. Opening them revealed the presence of poor contact in the twisted copper wires. To restore contact, it was necessary to disconnect the twists, clean the ends of the wires with sandpaper and twist them again.

When trying to disconnect, I encountered a seemingly insurmountable obstacle. The ends of the wires broke off even without any effort. Over time, copper lost its elasticity and became brittle. When stripping the wire, the insulation was apparently cut in a circle with a knife blade and notches were made. It was in these places that the wire broke off. The copper became hardened due to temperature fluctuations.

You can restore the elasticity of copper, unlike ferrous metals, by heating it to red and quickly cooling it. But for this case, such a technique is not acceptable. The ends of the wires no longer than 4 cm remained. There was no choice for connection. Just solder.

I exposed the wires with a soldering iron, melted the insulation, tinned them with solder, tied them in groups with tinned copper wire and filled them with solder using a 60-watt soldering iron. The question immediately arises: how to solder the wires in the junction box if the electrical wiring is de-energized? The answer is simple, using a soldering iron powered by a battery.

So I updated the connections in all junction boxes, spending no more than 1 hour on each. I am completely confident in the reliability of the connections made, and this has been confirmed by the 18 years that have passed since then. Here's a photo of one of my boxes.

When leveling the walls with Rotband in the hallway and installing a stretch ceiling, the distribution boxes became a hindrance. I had to open them all, and the reliability of the solder connection was confirmed; they were in perfect condition. That's why I boldly hid all the boxes in the wall.

Connections currently practiced using a Wago flat-spring terminal block greatly reduce the time spent on installation work, but are much inferior in reliability to soldered connections. And if there are no spring-loaded contacts in the block, connections in high-current circuits are completely unreliable.

Mechanical connection of wires

Soldering is the most reliable type of connecting wires and contacts. But it has disadvantages - the connections obtained are not detachable and the work is very labor intensive. Therefore, the most common type of connection of wires to electrical contacts of devices is threaded, screws or nuts. To ensure the reliability of this type of connection, it is necessary to perform it correctly.

Linear expansion due to temperature changes is different for metals. Aluminum changes its linear dimensions especially strongly, then, in descending order, brass, copper, and iron. Therefore, over time, a gap forms between the contact of the connected metals, increasing the contact resistance. As a result, the screws must be tightened periodically to ensure reliable connections.

In order to forget about maintenance, additional slotted washers, called split washers or Grover washers, are installed under the screws. The Grover selects the gaps that arise and thereby ensures high contact reliability.

Often electricians are lazy and do not twist the end of the wire into a ring. In this option, the contact area of the wire with the contact pad of the electrical device will be many times smaller, which reduces the reliability of the contact.

If the formed ring of wire is slightly flattened with a hammer on an anvil, the contact area will increase several times. This is especially true when forming a ring of stranded wire soldered with solder. Instead of a hammer, you can add flatness with a file, grinding off the ring a little at the points of contact with the contacts.

This is how it should be done ideal threaded connection of wires to contact pads of electrical appliances.

Sometimes it is necessary to connect copper and aluminum conductors with each other, or with a diameter of more than 3 mm. In this case, the most accessible is a threaded connection.

The insulation is removed from the wires to a length equal to four screw diameters. If the veins are covered with oxide, then it is removed with sandpaper and rings are formed. A spring washer, a simple washer, a ring of one conductor, a simple washer, a ring of another conductor, a washer and, finally, a nut are put on the screw, screwing the screw into which the entire package is tightened until the spring washer is straightened.

For conductors with a core diameter of up to 2 mm, an M4 screw is sufficient. The connection is ready. If the conductors are made of the same metal or when connecting an aluminum wire to a copper wire whose end is tinned, then there is no need to place a washer between the rings of the conductors. If the copper wire is stranded, then it must first be tinned with solder.

Connecting wires with a terminal block

Connecting wires with low current load can be done using terminal blocks. Structurally, all terminal blocks are designed identically. Thick-walled brass tubes with two threaded holes on the sides of each are inserted into the housing combs made of plastic or carbolite. The wires to be connected are inserted into the opposite ends of the tube and secured.

The tubes come in different diameters and are selected depending on the diameters of the conductors being connected. You can insert as many wires into one tube as its internal diameter allows.

Although the reliability of connecting wires in terminal blocks is lower than when connecting by soldering, much less time is spent on electrical installation. An undeniable advantage of terminal blocks is the ability to connect copper and aluminum wires in electrical wiring, since brass tubes are coated with chromium or nickel.

When choosing a terminal block, you need to take into account the current that will flow through the switched electrical wiring wires and the required number of terminals in the comb. Long combs can be cut into several short ones.

Connecting wires using a terminal block
with Wago flat spring clamp

Terminal blocks with flat spring clamps Wago (Wago) from a German manufacturer are widely used. Wago terminal blocks come in two designs. Disposable, when the wire is inserted without the possibility of removal, and with a lever that makes it easy to both insert and remove wires.

The photo shows a Wago disposable terminal block. It is designed for connecting any types of single-core wires, including copper and aluminum with a cross-section from 1.5 to 2.5 mm 2. According to the manufacturer, the block is designed to connect electrical wiring in junction and distribution boxes with a current of up to 24 A, but I doubt it. I think it’s not worth loading the Wago terminals with a current of more than 10 A.

Wago spring terminal blocks are very convenient for connecting chandeliers and connecting wires in junction boxes. It is enough just to forcefully insert the wire into the hole of the block, and it will be securely fixed. In order to remove the wire from the block, considerable force will be required. After removing the wires, deformation of the spring contact may occur and a reliable connection of the wires when reconnected is not guaranteed. This is a big disadvantage of a disposable terminal block.

A more convenient Wago terminal block is reusable and has an orange lever. Such terminal blocks allow you to connect and, if necessary, disconnect any electrical wires, single-core, multi-core, aluminum in any combination with a cross-section from 0.08 to 4.0 mm 2. Rated for current up to 34 A.

It is enough to remove 10 mm of insulation from the wire, lift the orange lever up, insert the wire into the terminal and return the lever to its original position. The wire will be securely fixed in the terminal block.

The Wago terminal block is a modern tool-free way to connect wires quickly and reliably, but is more expensive than traditional connection methods.

Permanent connection of wires

In some cases, when it is not intended to connect the wires in the future, they can be connected in a permanent way. This type of connection is highly reliable and is advisable in hard-to-reach places, for example, connecting the ends of a nichrome spiral with copper current-carrying conductors in a soldering iron.

Connecting thin wires by crimping

A simple and reliable way to connect wire cores is crimping. Wire strands are inserted into a piece of copper or aluminum tube, depending on the metal of the wires being connected, and the tube is pressed in the middle with a tool called a press pliers.

Crimping can be used to connect both single-core and stranded wires in any combination. The diameter of the tube must be selected depending on the total cross-section of the conductors. It is desirable that the conductors fit tightly. Then the connection reliability will be high. If in a stranded wire the conductors are twisted together, then it is necessary to develop and straighten them. There is no need to twist the wire strands together. The prepared conductors are inserted into the tube and crimped with press pliers. The connection is ready. All that remains is to insulate the connection.

Crimping tips are available for sale, already equipped with an insulating cap. Crimping is performed by compressing the tube together with the cap. The connection is immediately isolated. Since the cap is made of polyethylene, during crimping it is deformed and held securely, ensuring reliable insulation of the connection.

The disadvantage of joining by crimping is the need for special press jaws. You can make your own pliers using pliers with side cutters. You need to round the side cutter blades and make a groove in the middle. After such modification of the pliers, the edges of the side cutters will become blunt and will no longer be able to bite, but only squeeze.

Connecting wires of larger cross-sections by crimping

To connect electrical wires with a larger cross-section, for example, in power panels of houses, special lugs are used, which are crimped using universal press pliers, for example, the PC, PKG, PMK and PKG types.

To crimp each standard size of tip or sleeve, it requires its own matrix and punch, a set of which is usually included in the set of pliers.

To crimp a tip onto a wire, the insulation is first removed from the wire, the wire is tucked into the hole in the tip and inserted between the matrix and the punch. The long handles of the press pliers are used to squeeze. The tip is deformed, crimping the wire.

In order to correctly select the matrix and punch for the wire, they are usually marked and branded press pliers on the matrix have an engraving for crimping what section of wire the matrix is intended for. The number 95 embossed on the tip means that this matrix is designed for crimping into the tip of a wire with a cross-section of 95 mm 2.

Connecting wires with a rivet

It is made using screw connection technology, only a rivet is used instead of a screw. Disadvantages include the impossibility of disassembly and the need for special tools.

The photo shows an example for connecting copper and aluminum conductors. More details about connecting copper and aluminum conductors are described in the website article “Connection of aluminum wires”. In order to connect the conductors with a rivet, you need to first put an aluminum conductor on the rivet, then a spring washer, then a copper one and a flat washer. Insert a steel rod into the rivet gun and squeeze its handles until it clicks (this cuts off the excess steel rod).

When connecting conductors from the same metal, there is no need to place a split washer (grower) between them, but put the groover on the rivet first or second to last; the last one must be an ordinary washer.

Connecting broken wires in the wall

Repairs should begin with very careful removal of the plaster in the area of damaged wires. This work is done with a chisel and hammer. As a chisel when laying electrical wiring in the wall, I usually use the rod from a broken screwdriver with a sharpened end of the blade.

Connecting copper wires broken in the wall

Take a piece of copper wire with a cross-section no less than the cross-section of the broken wire. This piece of wire is also covered with a layer of solder. The length of this insert must ensure an overlap of at least 10 mm over the connected ends of the wires.

The insert is soldered to the connecting ends. Solder should not be skimped. Next, the insulating tube is moved so as to completely cover the joint. If a sealed, moisture-resistant connection is required, then before putting on the tube, the soldered joint must be coated with silicone.

Connecting aluminum wires broken in the wall

A prerequisite for obtaining a reliable mechanical connection of aluminum wires is the use of a Grover-type washer. The connection is assembled as follows. A groover is put on the M4 screw, then an ordinary flat washer, rings of connected wires, then a simple washer and a nut.

Step-by-step instructions for connecting broken wires in a wall are outlined in the article “Connecting broken wires in a wall”

Connecting wires with slip-on terminals

Widely used in household appliances and cars is the detachable connection of conductors using slip-on terminals, which are placed on contacts 0.8 mm thick and 6.5 mm wide. Reliability of fixation of the terminal is ensured by the presence of a hole in the center of the contact and a protrusion in the terminal.

Sometimes the conductors break off, and more often the terminal itself burns due to poor contact and then it becomes necessary to replace it. Typically, the terminals are pressed onto the ends of the conductors using special pliers. Crimping can also be done with pliers, but you don’t always have a new replacement terminal on hand. You can successfully use a used one by installing the terminal using the following technology.

First you need to prepare the old terminal for reinstallation. To do this, holding the terminal with pliers at the press-in point, you need to use an awl or a screwdriver with a thin tip to move the tendrils that compress the insulation apart. Next, the wire is bent many times until it breaks off at the point where it exits the press fit. To speed things up, you can trim this area with a knife.

When the wire is separated from the terminal, a needle file prepares a place for soldering it. You can completely grind it off until the remaining wire is free, but this is not necessary. It turns out to be a flat platform.

The resulting area is broken through with solder. The conductor is also stripped and tinned with solder using a soldering iron.

All that remains is to attach the conductor to the prepared terminal area and warm up the soldering irons. The antennae that fix the wire are bent after soldering the wire to the terminal, since if they are crimped before soldering, the antennae will melt the insulation.

All that remains is to pull on the insulating cap, put the terminal on the desired contact and check the reliability of the fixation by tugging on the wire. If the terminal has come off, then it is necessary to tighten its contacts. A home-made terminal attached to a wire by soldering is much more reliable than one obtained by crimping. Sometimes the cap is put on so tightly that it cannot be removed. Then it needs to be cut and after installing the terminal, cover it with insulating tape. You can also stretch a piece of vinyl chloride or heat-shrinkable tube.

By the way, if you hold a vinyl chloride tube in acetone for about five minutes, it increases in size by one and a half times and becomes plastic, like rubber. After the acetone evaporates from its pores, the tube returns to its original size. About 30 years ago, I insulated the bases of light bulbs in a Christmas tree garland in this way. The insulation is still in excellent condition. I still hang this garland of 120 6.3 V light bulbs on the Christmas tree every year.

Splicing stranded wires without twisting

Stranded wires can be spliced in the same way as single-core wires. But there is a more advanced method, in which the connection is more accurate. First you need to adjust the lengths of the wires with a shift of a couple of centimeters and strip the ends to a length of 5-8 mm.

Fluff the slightly cleaned areas of the pair to be joined and insert the resulting “panicles” into each other. In order for the conductors to take a neat shape, they need to be tied together with a thin wire before soldering. Then lubricate with soldering varnish and solder with solder.

All conductors are soldered. We clean the soldering areas with sandpaper and insulate them. We attach one strip of electrical tape on both sides along the conductors and wind a couple more layers.

This is what the connection looks like after covering it with insulating tape. You can further improve the appearance if you use a file to sharpen the solder joints on the insulation side of adjacent conductors.

The strength of connected stranded wires without twisting by soldering is very high, as the video clearly demonstrates. As you can see, the connection can withstand the weight of the monitor 15 kg without deformation.

Connecting wires with a diameter of less than 1 mm by twisting

Let's consider twisting thin conductors using the example of splicing twisted pair cables for computer networks. For twisting, thin conductors are stripped of insulation for a length of thirty diameters with a shift relative to adjacent conductors and then twisted in the same way as thick ones. The conductors must wrap each other at least 5 times. Then the twists are bent in half with tweezers. This technique increases mechanical strength and reduces the physical size of the twist.

As you can see, all eight conductors are connected by twisting with a shift, which makes it possible to do without isolating each of them separately.

All that remains is to tuck the conductors into the cable sheath. Before refueling, to make it more convenient, you can tighten the conductors with a roll of insulating tape.

All that remains is to secure the cable sheath with insulating tape and the twist connection is complete.

Connecting copper wires in any combination by soldering

When connecting and repairing electrical appliances, you have to lengthen and connect wires with different cross-sections in almost any combination. Let's consider the case of connecting two stranded conductors with different cross-sections and number of cores. One wire has 6 conductors with a diameter of 0.1 mm, and the second has 12 conductors with a diameter of 0.3 mm. Such thin wires cannot be reliably connected with simple twisting.

With the shift, you need to remove the insulation from the conductors. The wires are tinned with solder, and then the smaller gauge wire is wound around the larger gauge wire. It is enough to wind a few turns. The twisting area is soldered with solder. If a direct connection of wires is required, the thinner wire is bent and then the connection is insulated.

Using the same technology, a thin stranded wire is connected to a single-core wire with a larger cross-section.

As is obvious, using the technology described above, you can connect any copper wires of any electrical circuits. At the same time, we must not forget that the permissible current strength will be determined by the cross-section of the thinnest wire.

TV coaxial cable connection

There are three ways to extend or splice a coaxial television cable:
– TV extension cable, commercially available from 2 to 20 meters
– using an adapter TV F socket - F socket;
- soldering with a soldering iron.

Tinsel wire connection
twisted with single-core or stranded conductor

If it is necessary to give the cord very high flexibility and at the same time greater durability, the wires are made using a special technology. Its essence lies in winding very thin copper ribbons onto a cotton thread. This kind of wire is called tinsel.

The name is borrowed from tailors. Gold tinsel is used to embroider the ceremonial uniforms of high-ranking military officers, coats of arms and much more. Copper tinsel wires are currently used in the production of high-quality products - headphones, landline phones, that is, when the cord is subjected to intense bending during use of the product.

In a cord of tinsel conductors, as a rule, there are several and they are twisted together. It is almost impossible to solder such a conductor. To attach tinsel to the contacts of products, the ends of the conductors are crimped into the terminals with a special tool. To make a reliable and mechanically strong twist connection without tools, you can use the following technology.

The insulation is removed from the 10-15 mm tinsel conductors and the conductors with which it is necessary to connect the tinsel to a length of 20-25 mm with a shift using a knife in the manner described in the site article “Preparing wires for installation”. The tinsel thread is not removed.

Then the wires and the cord are applied to each other, the tinsel is bent along the conductor and the wire core is tightly wound onto the tinsel pressed against the insulation. It is enough to make three to five revolutions. Next, the second conductor is twisted. You will get a fairly strong twist with a shift. Several turns of insulating tape are wound and the twisted connection of the tinsel to a single-core wire is ready. Thanks to shear twisting technology, the connections do not need to be separately insulated. If you have a heat-shrinkable or polyvinyl chloride tube of suitable diameter, you can put on a piece of it instead of insulating tape.

If you want to get a straight connection, you need to rotate the single-core wire 180° before insulating it. The mechanical strength of the twist will be greater. The connection of two cords with tinsel-type conductors to each other is carried out using the technology described above, only for wrapping, a piece of copper wire with a diameter of about 0.3-0.5 mm is taken and at least 8 turns must be made.

When building a house or renovating a new apartment, the first stage is to install a household electrical network. Deciding where sockets, switches, junction boxes and chandeliers will be installed is a small part of the total required amount of work. The most important thing is to lay a network around the house with many branches for lighting and connecting household appliances. Such a network is carried out with electrical wires, which must be selected according to the cross-section according to the expected load and laid according to certain standards. Here we will talk about how to properly connect the wires in the junction box.

There are many options for connecting wires, but among them it is impossible to single out just one and call it ideal. Something more convenient and simpler, but not recommended by the Electrical Installation Rules (PUE). Some method is suitable for single-core wires, but not suitable for multiple wires. But more complex methods guarantee the quality and reliability of contacts. All methods of connecting electrical wires in a junction box have their advantages and disadvantages. Let's look at each of them in more detail.

Twisting method

The most common and simplest option is twisting. For it you will need only two tools - a knife, with which you can strip the insulation on the conductors, and pliers to ensure reliable twisting.

Connection principle

This method is often called “old-fashioned”; electricians have been using it for decades, despite the fact that it is not recommended to connect wires this way according to the Electrical Code. It is often used as a temporary option, for example, when you need to check how the wiring diagram in the junction box works. Subsequently, the places of twisting are replaced with more reliable types of connections.

The essence of the method is that several wires are twisted together. It is important that all connected wires are twisted together at the same time; twisting one around another is not allowed.

The whole job is incredibly simple. First, the insulating layer is cut off with a knife from the wire cores to the same length (10-30 mm). Then it is twisted using pliers and insulated from above. There are many options for twisting, the most common of which are:

Mutual twisting.
Bandage connection.
Twisting with a groove.

Let's explain in a little more detail using a very simple example. Place each wire to be twisted next to each other so as to align them with the removed layer of insulation (in this case you will have to cut off 40-50 mm). At the end of the connected wires, make a 1 cm bend at 90 degrees. Hold the insulating layer with one hand, grab the bend with the other hand and begin to make rotational movements clockwise. Some people ask the question, can it be turned counterclockwise? It’s possible, but backwards is somehow not very accepted; the whole world is used to existing by the clock. If at the end it is already difficult to twist your fingers, do it with pliers.

You can connect 5-6 wires in this way, but then it will be difficult to twist, you need to make the bend longer (by 20 mm) and immediately perform rotational movements with pliers. When a beautiful, even twist is obtained, the bend is cut off.

Important to remember! It is necessary to wrap insulating tape not only around the twisting area itself, but also to go 2-3 cm above the wire insulation. This will prevent moisture from entering and provide more reliable insulation.

A thermal tube can also be used as an insulating layer at the twisting site. Keep in mind that it must be put on one of the wires to be connected in advance. When the twist is ready, the tube is pushed onto this place. If you heat it around the edges, then due to the influence of temperature, the heat tube will shrink and tightly wrap around the wires.

How to properly twist wires is described in detail in this video:

Advantages

The most important advantage of this method is its ease of operation.

The second advantage of twisting is the absence of any material costs.

If there is a need for this, then several wires can be twisted at the same time using this method, but their total number should not be more than six.

Flaws

The main disadvantage of twisting is unreliability. And we know that in electrical engineering such a concept is not allowed.

In the main regulatory document for electricians, the PUE, in the section where all permitted types of wire connections are listed, the twisting method is not mentioned, and accordingly it is not recommended for use. That's right, experts cannot accept a connection that is sensitive to pulse current and has high transient resistance.

With the twisting method, the contact area of the cores is small, which results in unreliable contact. As the load increases, the conductors will heat up more, and the contact connection will become weaker, which will ultimately lead to burnout.

Twisting cannot be used to connect cores made of different materials (copper and aluminum).

Remember! If you use twisting as a permanent connection method, you take full responsibility for possible consequences.

Welding method

For more reliable contact, the connecting wires are welded in the junction box. With this option, the ends of the cores are fused and form a single whole, which is a guarantee of safety and reliability. Solid contacts do not oxidize and welded joints do not weaken over time.

The disadvantage of welding is that you must be able to handle special equipment, or you will have to invite a professional.

Required Tools

In addition to being able to cook, you will need:

knife (to remove the insulating layer from the cores);
sandpaper (to clean the surfaces to be joined);
welding inverter;
gloves (protect hands during welding);
goggles or mask (protect eyes during welding work);
graphite (carbon) electrode;
flux to protect the melt from air.

Welding joint algorithm

Remove 70-80 mm of insulation from the cores with a knife.
Use sandpaper to clean the wires until they are shiny.
Using the method described above, twist the wires; its length should be at least 50 mm.
Carefully hook the grounding clamp to the top of the twist.
Place the electrode at the bottom of the twist, lightly touch it to ignite the arc, and remove it. Welding of wires occurs literally in a few fractions of a second.
After this, let the welding area cool down and insulate the connection.

Another important question is how many amperes to set on the welding machine? For conductors with a cross section of 1.5 mm 2, 30 A of welding current will be sufficient, for 2.5 mm 2 - 50 A.

Welding twists in a junction box is clearly shown in this video:

Soldering method

No less reliable than welding is soldering the connected wires in the junction box.

The essence of the soldering method is similar to welding work, only now instead of an inverter apparatus with electrodes, solder with a soldering iron is used. You will also need rosin or soldering flux. There is one small nuance: before twisting the cores, they must be tinned. To do this, heat up the soldering iron, dip it in rosin and run it over the wires stripped of the insulating layer several times until a characteristic reddish tint appears.

Now do the twist as we described above. Take the solder to the soldering iron and heat the twisted area until the tin melts and begins to fill the space between the turns. Thus, the twisted area is enveloped in tin, which ensures correct connection of the wires and reliable contact in the box.

Most often, copper conductors are soldered this way. But there is a special solder that can be used to do the same with aluminum conductors.

Soldering twists using the method of immersion in a sleeve with molten tin is shown in this video:

Terminal blocks

Connecting wires in a junction box is greatly facilitated by using terminal blocks.

The modern market provides a wide range of pads, which differ both in design features and sizes, as well as in price. The terminal itself can be small or large, it all depends on the cross-section of the connecting wires. However, structurally they are all built on the same principle.

As a rule, terminal blocks are sold in sections, but sometimes they are also bought individually, asking the seller to cut off the required quantity.

Device

The terminal block is a transparent plastic casing, inside of which there is a brass sleeve. It is these sleeves that differ in diameter, depending on what cross-section of the core the block is designed for. There are two threaded holes in the sleeve; screws are screwed into them to clamp the wires.