Maximum number of wires in a twist. The principle of connecting wires. Method

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Twisting wires is the simplest and at the same time the most “dangerous” way to connect them. More than 80% of all fires that occur as a result of short circuits in electrical wiring occur through the fault of installers who connect wires by twisting. The use of this type of connection is not provided for by any normative document, operating on the territory of the Russian Federation. Nevertheless, correct twist wires are not much inferior in reliability to a terminal or even a welded connection.

In order to correctly connect wires (cables) by twisting, you must have at least general ideas about the properties of the materials being joined. It is not allowed to twist aluminum and copper wires together. The difference in electrical conductivity of these metals leads to an increase in temperature at the junction. In addition, aluminum is chemically more active than copper, and therefore more susceptible to all types of corrosion. This is especially true for rooms with high humidity - baths and kitchens (condensation formed at the junction leads to electrochemical corrosion aluminum). There are many ways to twist wires, but their classification can be divided into 2 large groups:

1. Parallel twisting is one of the most simple ways. It is best used for connection aluminum wires with single-wire conductors.

Bandage twisting of aluminum wire is suitable for conductors with a large cross-section. The wire for wrapping the bandage should also be aluminum.

Twisting with a groove is suitable if you need to make a branch.

But it should be remembered that if there is a heavy load on the network at the branching point of the wire, the temperature may rise so much that the insulation will melt and a short circuit will occur. For branching it is better to use terminal strips.

2. Twisting a copper wire is a more complex operation, since the copper conductors used in everyday life are most often wires with stranded cores. “Pigtail” is the most reliable, although not common, method. The wire strands are woven together, and the “tails” remaining after twisting are cut off with scissors.

The bare ends of the wires must be treated with fine-grained sandpaper before twisting. To insulate the twisted area, it is best to use PVC electrical tape Russian production(Intek, Polymerplast, Avalon). Cheaper Chinese analogues do not have sufficient heat shrinkage; their glue dries faster. Therefore, they do not provide sufficient protection of the connection from moisture. In addition to insulating tape, you can use a connecting insulating clip - PPE (manufactured in Russia).

It will be better if the twisted aluminum wire is insulated with the help of PPE, since aluminum is a soft metal, the connection is easily deformed and loses strength. The steel spring inside the cap will constantly keep the conductors in a “compressed” state. The twisting of the wires should be as tight as possible; pliers should be used to “tighten” (even if the wires are of small cross-section). If you see that the insulation at the twisted point has changed color and structure or feel heat from the connection point, you need to turn off the power and reconnect the wires.

Alternative ways to connect wires

Terminal blocks and clamps
The reliability and safety of the wire connection directly depends on its density. The closer the surfaces of the conductors are to each other, the less the connection will “heat up”. In terms of density, a terminal connection is inferior only to a welded one. Twisting copper wire with aluminum is undesirable due to the high difference in the redox potential of these metals.

In the terminal block, this problem is solved with the help of brass plates. There are self-clamping and screw terminal blocks. For electrical installation in typical apartment 4 and 6 pair screw terminals produced by IEK (Russia) and three-conductor terminals WAGO (Germany) are suitable. It is better not to use screw terminal blocks to connect aluminum wires due to the high ductility of aluminum. If the screw is tightened too much, it may simply “cut” the wire. Self-clamping terminal blocks can be used for all types of connections. Low price The use of these parts pays for itself many times over in the reliability of the electrical network. Saving 200 - 300 rubles on terminal blocks for electrical installation in an apartment does not justify the risks associated with fire and failure of expensive equipment.

Solder connections
Connecting wires by twisting has one significant drawback - insufficient density. Because of this, the bare conductor at the junction is covered with an oxide film (copper is slower, aluminum is faster), which prevents the passage through it electric current. This process is a kind of time bomb - every year the contact area of “pure” conductors becomes smaller, and the resistance and temperature at the connection site become greater. When the temperature gets high enough to melt the insulation, a short circuit occurs. In order to prevent the metal at the junction from coming into contact with atmospheric oxygen, you can use lead-tin solder. To do this, the wires are first twisted in the usual way, preferably in a parallel way or in a pigtail, after which the joint is evenly covered with solder using a soldering iron. After the solder has cooled, the joint is wrapped with insulating tape.

How to connect a single-core and stranded wire so that this does not lead to problems in the future, and the contact connection serves us for many years? And in general, how to make connections correctly various types wires?

We will try to answer all these questions in our article, and we will also analyze what such rules are associated with and what dangers are hidden behind an incorrect connection.

First of all, let's look at what the requirements for high-quality contact connections are related to. It is not without reason that clause 2.1.21 of the PUE separately stipulates methods for connecting wires, and allows only screw or bolt clamps, crimping, welding or soldering.

This is primarily due to the fact that these types of connections can provide the required level of durability and reliability of the connection. After all, any electrician will tell you that more than 90% of all damage occurs at contact connections, and that is why so much attention is paid to them.
After all, what is a poor-quality contact connection is a connection that has a high contact resistance. And since we have resistance, this means heating.

As we remember from the physics course, any conductor in a heated state has greater resistance than a conductor with a lower temperature. Therefore, an avalanche-like process results. A poor-quality contact connection causes the conductor to heat up and its resistance increases even more. As a result, it heats up even more until it reaches the point where it simply melts.
As a result, our main task is to ensure minimum resistance between the two conductors being connected. This is achieved by ensuring the proper area of contact between the two conductors, as well as by ensuring the maximum possible contact between them.
Let's immediately look at why we will not consider the question of how to twist single-core wires or their multi-core counterparts. After all, when the right approach, and by twisting it is possible to ensure a sufficient area of contact and compression of the conductors with each other.

The fact is that in any case, the contact connection will be subject to temperature influences. That is, it will heat up and cool down. And as we know, heating leads to expansion of materials, and cooling, accordingly, to contraction. As a result, our contact connection, which is not fixed by any third element, can quickly become of insufficient quality.

Note! Surely each of you can give dozens and hundreds of examples where twisting has lasted for decades, and even now looks better than screw or bolt connections. But, as they say, exceptions to the rule only confirm the rule itself. According to statistics, twisted joints are damaged much more often than other types of joints.

Correct connection of conductors

Now we can talk about how to correctly connect a single-core and stranded wire, two single-core or two stranded wires. And also, which type of connection for each of these types will be optimal, and which should be used only with certain restrictions.

Connection using the compression method

By compression method, PUE means screw or bolt connection of conductors. The same type of connection includes the now popular Wago terminals, which use the compression method through the use of springs or special mechanisms.

On this moment The compression method is one of the most popular joining methods. After all, the price of terminals based on this method is one of the lowest. The installation process is simple and does not require additional equipment, and the method itself is quite reliable.

For wires of small cross-section, the screw connection method is mainly used - or the compression method using a special mechanism. The essence of the screw method is that two conductors are installed in a brass tube, which are then each clamped with its own screw.
This method is well suited for connecting two single-core copper conductors. If aluminum is used, then this material is softer, and when clamping it with a screw, you can either critically reduce its cross-section or completely crush it. Therefore, for aluminum wires, the use of this method is undesirable, or it should be used with extreme caution.

In the photo - a tip for a stranded wire

Using a screw clamp to connect multi-core wires is also associated with the possibility of breaking individual wires that make up the conductor in whole or in part during the process of tightening the screw. To protect the wires from mechanical influences, special tips should be used.
Using special lugs, stranded wires can be connected both to each other and between single-core wires using screw terminals.

There are screw terminals with a special clamping pad, which provides clamping over the entire cross-section of the brass tube. In this case, the use of special lugs for stranded wires is not necessary.

As for Wago terminals and the like. There is still debate among electricians about their reliability and durability. Some argue that the use of springs in terminals is not the best option, others that it is very convenient and the springs are quite reliable.

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

About the distribution box

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

So that during repairs you do not have to look for where the wires are hidden in the walls, 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 fastening. So, there are boxes for external mounting and indoor installation. For the second option, you need to prepare a hole in the wall into which the box will be inserted. As a result, the box lid is located flush with the wall. Often the cover is hidden with wallpaper or plastic during repairs. As a last resort, an outer box is used, which is attached directly to 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 and new wiring is laid. It is not recommended to lay the cable in a groove on the wall. If the electrical wiring burns out, you will have to dig into the wall and disturb the finish in order to carry out repair work.

What are distribution 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 accessible, you can easily find the area where the wires have burned out. If the cable was laid in special channels (corrugated tube, for example), then the failed cable can be replaced in an hour;
Connections can be inspected at any time. As a rule, wiring problems occur at the connection points. If the socket or switch does not work, but there is voltage in the network, first check the quality of the connection in the junction box;
is created highest level fire safety. It is believed that dangerous places are connections. Using a box will keep them in one place.
minimal time and financial costs when repairing wiring. There is no need to look for broken wires in the walls.

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 correct execution all options will ensure reliability of electrical wiring.

Method number 1. Twisting method

It is believed that the twisting method is used by amateurs. At the same time, this is one of the most reliable and proven options. PUE do not recommend using twisting, since the contact between the wires is unreliable. As a result, the conductors may overheat, putting the room at risk of 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 flammable), and inside there is a metal part with a cone-shaped thread. The insert increases the contact surface, improving electrical parameters twists. Most often, thick conductors are connected using caps (no soldering required).

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

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

Method No. 3. Connecting conductors by soldering

If you have a soldering iron on your household and you know how to work with it, then the wires can be connected by soldering. Before connecting the wires, 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 and passed along the wire several times. A reddish coating should appear.

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

Method number 4. Welding cores

Using an inverter welding machine you can connect the wires. Welding is used over twisting. You need to set the parameters on the inverter welding current. 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. On top part The resulting twist is connected to the grounding from the welding machine. An electrode is brought from below the twist and an arc is ignited. The electrode is applied to the twist for a couple of seconds. After some time, the connection will cool down, then it can be insulated.

Read also: Hidden electrical wiring in a wooden house

Method No. 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 reliably connected. Installation using a clamp terminal makes the connection very simple.

IN screw terminals The pads are placed in a plastic case. There are open and closed type. Closed pads are a new generation invention. To make a 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. The 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 high current consumption.

Another type of terminals 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 should only be single-core), the petal is pressed out and the wire is clamped. The conductor cuts into the metal. If you pull out the conductor by force, then the petal will not take its previous shape.

Some terminal connections contain wiring paste inside. This connection is used if you need to connect copper and aluminum wire. The paste protects metals from oxidation, protecting conductors;

- universal terminals with a lever mechanism - this is the most best view connector. The wire, stripped of insulation, is inserted into the terminal and a small lever is clamped. At this point the connection is considered complete. And if you need to reconnect, add contacts, lift the lever and 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 that specified will flow, then a different type of connection must be used.

Method number 6. Crimping

The wires in the box can only be connected by crimping using special pliers and a metal sleeve. A sleeve is put on the twist, after which it is clamped with pliers. This method is suitable for connecting conductors with a large load.

Method No. 7. Bolted connection

Connecting multiple wires using bolts is easy and effective method connections. To complete the work, you need to take a bolt and several washers with a nut.

It is not enough to know how to connect the wires in a 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 screwed on, the second washer is put on, and then the next core is put on. At the end, put on the third washer and press the connection with a nut. The node is closed with insulation.

There are several advantages bolted connection conductors:

- ease of work;

- low cost;

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

However, there are also disadvantages:

— fixation of wires is not of high quality;

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

No matter how widespread they are Lately a variety of clamps and terminals; the most popular way to connect wires is simple twisting. However, you should know that electrical installation rules prohibit the use of twisting in pure form(i.e. no further soldering or welding of the contact). You can increase the “legality” of twisting with the help of PPE. You make a twist, and on top of it you screw the PPE (connecting insulating clip).

It creates sufficient contact density and, under different loads and temperature changes, does not allow the contact to become loose. Choose PPE the right size, quantity and quality with free shipping Can .

Types of twists. Errors when twisting

Firstly, remember that wires come in aluminum and copper. Copper wires are divided into monocore (one solid core) and multicore (flexible).

Monocores are used for stationary connection of equipment. Once I laid it under the plaster, behind the drywall and forgot about them. There is no longer any need to move or bend such wiring.

Multi-core cables are used for mobile devices or temporary connection of electrical equipment. Where wiring constantly needs to be moved from place to place, its location must be changed. These are home carriers, Appliances plugged into sockets.

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

Let's first consider how to properly twist wires from a single core. The process here is not complicated and is known to everyone. Take two wires, strip them at the ends and begin to twist each other.

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

Main features and rules:

⚡ wires must be made of the same material (copper or aluminum)
⚡ strip the core at least 3-4 cm, thereby increasing usable area contact
⚡ wires are laid parallel to each other
⚡ both wires must be twisted evenly together
⚡ When twisting, use some pliers to hold the place where you start stripping the insulation, and use the other to twist at the end. The insulated parts of the conductors must not be twisted together.
⚡ the number of turns that should end up being five or more

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

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

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

There are situations when it is necessary for twisting to take as long as possible less space. 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.

⚡ place the stripped wire strands crosswise in the middle of the stripping area
⚡ 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.

Twisting copper wire with aluminum

Copper and aluminum wires cannot be twisted 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 spacer between copper and aluminum.

Take a simple bolt with a nut and washer. The stripped wires are shaped into a ring at the end. And these rings fit on the bolt. Moreover, the wire of the ring should bend in the direction of the bolt thread.

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

Twisting stranded wires

You can apply the previous descriptions of work for such conductors, but this will not provide reliable mechanical contact. Therefore, proceed as follows.

First of all, you must understand that different conditions may be applied Various types connections. And their choice depends on the specific task at hand.

For example, it is much more convenient to connect small-section wires up to 2.5 mm2 in a compact junction box with terminal blocks or clamps. But if we're talking about about a groove or cable channel, then the sleeves come first here.

Let's consider the three most simple and at the same time reliable types of connections.

Let's start with the connection type PPE. It stands for:

WITH unifying

AND insulating

Z pressure

It looks like a simple cap. Comes in different colors.

Moreover, each color means that it belongs to specific sections of the cores.

The cores are inserted into this cap and twisted together.

How to do it correctly, first twist the wires and then put on the cap or twist them directly with the PPE itself, is discussed in detail in the article “.”

As a result, thanks to PPE, you get a good old twist, only immediately protected and insulated.

On top of that, it has a spring-loaded contact that prevents it from coming loose.

In addition, this process can be slightly automated by using an attachment for PPE for a screwdriver. This is also discussed in the above article.

The next type is Wago terminal blocks. They also come in different sizes, and different quantities connected wires - two, three, five, eight.

They can connect both monocores and stranded wires together.

Moreover, this can be implemented as in different types Vago, and in one single thing.

For stranded ones, the clamp must have a latch-flag, which open state allows you to easily insert the wire and clamp it inside after snapping it into place.

According to the manufacturer, these terminal blocks in home wiring can easily withstand loads of up to 24A (lights, sockets).

There are some compact specimens also available for 32A-41A.

Here are the most popular types Wago clamps, their markings, characteristics and for what cross-section they are designed:

Series 2273 Series 221-222 Series 243 Series 773 Series 224

There is also an industrial series for cable cross-sections up to 95mm2. Their terminals are really large, but the principle of operation is almost the same as that of small ones.

When you measure the load on such terminals, with a current value of more than 200A, and at the same time you see that nothing is burning or heating, many doubts about Wago products disappear.

If you have original Vago clamps, and not a Chinese counterfeit, and the line is protected by a circuit breaker with a correctly selected setting, then this type of connection can rightfully be called the simplest, most modern and convenient to install.

Violate any of the above conditions and the result will be quite natural.

Therefore, there is no need to install wago at 24A and at the same time protect such wiring with a 25A automatic. In this case, the contact will burn out if overloaded.

Always choose the right terminal blocks for your car.

As a rule, you already have automatic machines, and they primarily protect the electrical wiring, and not the load and the end consumer.

There is also enough old look connections, such as terminal blocks. ZVI – insulated screw clamp.

In appearance, this is a very simple screw connection of wires to each other. Again, it comes in different sections and different shapes.

Here they are specifications(current, cross-section, dimensions, screw torque):

However, ZVI has a number of significant disadvantages, due to which it cannot be called the most successful and reliable connection.

Basically, you can only connect two wires to each other in this way. Unless, of course, you specifically choose large pads and shove several wires there. What to do is not recommended.

This screw connection works well for monocores, but not for stranded flexible wires.

For flexible wires, you will have to press them with NShVI lugs and incur additional costs.

You can find videos online where, as an experiment, transition resistances on different types of connections are measured with a microohmmeter.

Surprisingly, the lowest value is obtained for screw terminals.

But we should not forget that this experiment refers to “fresh contacts.” Try making the same measurements after a year or two of intensive use. The results will be completely different.

Copper and aluminum connection

Often a situation arises when it is necessary to connect a copper conductor to an aluminum one. Because Chemical properties Copper and aluminum are different, then direct contact between them, with access to oxygen, leads to oxidation. Often even copper contacts on circuit breakers susceptible to this phenomenon.

An oxide film forms, resistance increases, and heating occurs. Here we recommend using 3 options to avoid this:

They remove direct contact between aluminum and copper. The connection occurs through steel.

The contacts are separated from each other in separate cells, plus the paste prevents the access of air and prevents the oxidation process from developing.

The third simple way to connect conductors is crimping with sleeves.

GML sleeves are most often used for joining copper wires. Deciphered as:

G Ilsa

M single

L narrowed

For connecting pure aluminum - GA (aluminum sleeve):

To switch from copper to aluminum, special adapters GAM:

What is the crimping method? Everything is quite simple. Take two conductors and strip them to the required distance.

After this, on each side of the sleeve, the conductors are inserted inside, and the whole thing is crimped with press pliers.

Despite its obvious simplicity, there are several rules and nuances in this procedure, if not followed, you can easily ruin a seemingly reliable contact. Read about these mistakes and rules on how to avoid them in the articles “” and “”.

To work with conductors of large sections 35mm2-240mm2, a hydraulic press is used.

Up to cross-sections of 35mm2, you can also use a mechanical one with a large span of handles.

The sleeve must be crimped two to four times, depending on the cross-section of the wire and the length of the tube.

The most important thing in this work is to choose the correct sleeve size.

For example, when connecting a monocore, the sleeve is usually taken to a smaller cross-sectional size.

And in this way you can connect several conductors at one point at the same time. In this case, only one sleeve will be used.

The main thing is to completely fill its internal space. If you are crimping three conductors at the same time, and you still have voids inside, then you need this free space“clog” with additional pieces of the same wire, or conductors of a smaller cross-section.

Sleeve crimping is one of the most versatile and reliable connections, especially when it is necessary to extend the cable, including the input cable.

In this case, the insulation turns out to be almost equivalent to the main one, when also using the outer tube HERE as a casing.

Of course, you won’t use either PPE or Wago for these purposes, but GML cartridges are just the thing! At the same time, everything comes out compact and can be easily reduced, either in a groove or in a cable channel.

Welding and soldering

In addition to all the above connection methods, there are two more types that experienced electricians rightfully consider the most reliable.

And even with its help it is not always possible to connect an aluminum monocore wire with a flexible copper stranded one. In addition, you are forever tied to an outlet or extension cord.

What if there is no voltage or generator nearby?

At the same time, on the contrary, 90% of electrical installers have elementary press pliers. It is not necessary to purchase the most expensive and sophisticated ones for this.

For example, batteries. It’s convenient, of course, just walk and press a button.

The Chinese counterparts also cope well with their task of crimping. Moreover, the entire process takes no more than 1 minute.