How to twist wires in a junction box. Types of connection of electrical wires in a junction box

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.

Read also:

Experts say that even for a temporary connection of wires, all work must be carried out according to the rules. It should be noted that regardless of the number of cores in the conductor, the twisting methods are approximately the same. However, there are some differences. If stranded wires are connected, then you should adhere to the following rules:

- it is necessary to clean the insulation of the conductor by 4 cm;

- we unwind each conductor by 2 centimeters (along the veins);

- a connection is made to the junction of non-untwisted cores;

- you need to twist the cores only with your fingers;

- in the end, the twist is tightened with the help of pliers, pliers;

- bare electrical wires are covered with insulating tape or heat shrink tubing.

It is much easier to use twist when connecting solid wires. After the conductors have been stripped of insulation, they must be twisted by hand along their entire length. After that, with the help of pliers (2 pieces), the conductors are clamped: with the first pliers - at the end of the insulation, and with the second - at the end of the connection. We increase the number of turns on the connection with the second pliers. The connected conductors are insulated.

Method number 2. Mounting caps - PPE

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

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

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

Method number 3. Connection of conductors by soldering

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

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

Method number 4. Core welding

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

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

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

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

Read also: Hidden electrical wiring in a wooden house

Method number 5. Terminal blocks

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

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

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

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

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

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

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

Method number 6. Crimping

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

Method number 7. Bolted connection

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

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

There are several advantages of bolting conductors:

- ease of work;

- low cost;

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

However, there are also disadvantages:

- fixation of wires - not of high quality;

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

The correct connection of the wires in the junction box is in many ways the key to the reliability of your electrical network. Indeed, unlike the connections in the switchboard, distribution boxes, or as they are also called, junction boxes are more closed for maintenance and contact connections are much more difficult to check here. That is why, even at the stage of installation, their quality and correctness should be given maximum attention.

Before connecting the wires in the junction box, we advise you to study the rules for their installation. After all, it is important not only to qualitatively connect the wires to each other, but also to correctly bring them into the junction box, and also conveniently position them for possible inspection or repair.

Rules for installing wires in a junction box

First of all, let's look at the rules for arranging and installing wiring in a distribution network. After all, it is with this factor that any installation begins.

So:

• First of all, it should be remembered that no more than eight groups of wires are allowed in one strobe, box or pipe.
• All connections must be made in accordance with paragraph 2.1.17 - 2.1.30 of the PUE. These paragraphs provide for a range of restrictions. First of all, remember that the wire in front of any contact must have a margin sufficient for at least one reconnection.
• Before connecting the wires in the junction box, make sure that they are not under tension.. Or that this tension will not occur during temperature changes.
• Any wire connections must be accessible for repair and inspection.. At the same time, these places should be organized in such a way that inspection is not hindered by structural elements.
• Any connection must be insulated. However, this insulation must correspond to the level of basic insulation. To achieve these parameters, it is better to use electrical tape or heat shrink.
• The junction boxes themselves must be made of non-combustible or slow-burning materials. like in the video. This is especially true for the installation of wiring on combustible structures, which are subject to additional requirements.

Options for connecting wires in a junction box

First of all, let's look at how to connect wires in a junction box. After all, it is contact connections that are often the most vulnerable point of any electrical network, and any flaws appear very quickly.

According to clause 2.1.21 of the PUE, all connections of wires and cables must be made by welding, soldering, crimping, screw or bolt clamping. Other connection methods, especially twisting, are not allowed. Based on this, let's consider each of the possible connection methods separately.

So:

• The most reliable is the connection of wires by welding.. It has the lowest transient resistance, as a result of which there is practically no increased heating. In addition, over time, such a connection does not lose its properties.

Welding of wires in the junction box is carried out using a special welding transformer and a carbon electrode. The cost of such products is high enough for a simple replacement of wiring in an apartment, so you can often find home-made devices. Usually these are transformers up to 600 W and voltage 9 - 36V.

• In second place in terms of reliability is the connection by soldering. This method is more affordable for home use because it does not require special equipment other than a conventional soldering iron.

Soldering wires in the junction box is carried out according to the usual technology and does not impose special requirements. The only thing worth paying attention to is the quality of such connections. Indeed, in the case of heating, the tin heats up quickly enough and the contact will disappear. In order to prevent this, soldering is often combined with a twist connection.

• Crimping wires has become increasingly popular in recent years. Indeed, a large number of fairly cheap tools for crimping wires have appeared on the market, and the price of consumables for this method is quite low.

• But the most common is still the method of screw or spring clamp cores. A huge number of tires and terminals on the market now allow for a fairly reliable connection of wires.

More and more powerful electrical appliances appear in our homes: coffee makers, kettles, air conditioners, boilers, etc. All this greatly increases the load on the home power supply network. The first thing that reacts to increases in circuit current is the wire connections. They are the first to lead to fires if they are not made in the appropriate way. And if there are several of them, and even in a closed junction box, then the total heat generated is summed up and increased. This means that the junction box is a particularly important and responsible node in terms of network load capacity.

I will tell you three reliable ways to connect the wires in the junction box, which I use myself and recommend to others.
The first in reliability is the welding of wires. It is produced by a special welding machine using a graphite or tungsten electrode. In view of the melting of the metal, the structures are mixed and the wires become one. If possible, use it.

• The most reliable connection ever.

• Requires special equipment.

• Very reliable connection with the proper length of the soldered twist.
• Available to most home masters.

• Time consuming and not always applicable.
• Applicable to copper wires only.

The third most reliable method is crimping wires with tips. In view of its speed and reliability, it is often used by electricians when laying wiring in new homes.

• Very fast, requires a minimum of time to create a reliable connection.
• Suitable for aluminum and copper wires.

• It is necessary to have special crimping pliers and tips.

Conclusion

Content:

Electrical wiring is an integral part of the installation of any electrical network. The electrical network ensures the distribution of electricity. Sections of wires may be under a layer of plaster. But they can be laid in one way or another on the surface of walls and ceilings. In any case, they must be securely connected to each other. To do this, junction boxes are installed in certain places.

Following their installation, wiring is done. Previously, before connecting consumers, a wire connection diagram is prepared. If you have to hear such a name as a disconnection scheme, it means that you are talking about supplying power to several consumers. Switching the junction box does just that. The wiring diagram in the junction box always contains the main supply wire.

Junction boxes are where the wires of sockets, switches and other loads are connected. This is the node in which the branching of the wiring takes place. Electricians have coined the word "disconnect" applied to such a junction. It is exclusively colloquial and is not used in technical literature.

The connection of wires in a round junction box is usually used for wires of hidden electrical wiring. The installation site in this case is easier to prepare using an electric drill with a special drilling fixture.

The shape of the box in relation to the manufacturability of its installation for outdoor wiring is not so important. However, a rectangular box provides more space and may be preferable for this reason. Next, we will tell readers how to connect the wires in the junction box.

Connection methods

The connection of wires in the box is carried out in two main ways:

• twisting of connected cores (twisting);
• using special accessories. These wire connectors in the junction box are referred to as terminal blocks and blocks. All connectors make electrical contacts using a screw or spring clamp.

It is not difficult to twist even several strands of wires wound into a junction box. Twisting is the simplest fixed contact. But the simplicity of obtaining the result has a bad effect on the quality of this contact. The main disadvantages of simple twisting are as follows:

• relatively small contact area (especially for large cross-section conductors);
• lack of compensation for oxidation and weakening of the compression of the contacting cores.

Therefore, conventional twisting should only be used for low electrical loads in the range of 100–300 W. Before connecting the wires in the junction box, it is necessary to correctly determine the length of the contact of the cores. If it is impossible to accurately predict what currents will pass through the twist, its quality must be improved in one of the following ways:

• cover with solder (solder);

• weld strands.

In addition to welding and soldering, special accessories are often used that fix the contact of the cores. Of these, you can

• use a crimping cap screwed onto the twisted wires.

The cap is also called a connecting insulating clip - PPE

If it is necessary to mount a powerful consumer of electricity, it is allowed to use caps and long twists formed with their help. How this is done is shown in the images below.

• Use a sleeve that compresses either twisted or even conductors;

• use tips;

• connect the wires with a terminal block;

• use terminal blocks of a suitable design.

Comparison of methods

The images provided above clearly demonstrate that the connection of the cores can be made in several ways. Therefore, we will now consider their disadvantages and advantages.

Electricity is so familiar to modern life that it is almost impossible to imagine how to do without it. If you can wash or grind the meat manually, then the TV, computer, mobile phone on coals, like an iron, will not work. Electricity in every home is already a necessity, and it is supplied there by wires from external networks. At the entrance to each apartment or individual house there is a junction box, from which the wires of the internal electrical wiring depart.

The need for a junction box

First of all, junction boxes ensure fire safety. The greatest danger from the point of view of fire is the junction of the wires. Due to the high resistance in places of insufficient tight contact, heating of the wiring occurs in this place, which can lead to a fire when in contact with combustible wall materials.

The junction box eliminates the fire hazard by isolating the wire connection.

In addition, the junction box plays a functional role. Access to the wire connections hidden in it is much easier and more convenient than if the connection of each wire was hidden in the wall in deep strobes that had to be opened, breaking the wall decoration, when repairing the wiring.

And even the outer junction box looks aesthetically pleasing compared to a bunch of cables sticking out of the wall.

Special Electrical Installation Rules (PEU) regulate the correct connection of electrical conductors by welding, soldering, crimping or using screw and bolt clamps.

The rules do not stipulate the most common connection method - twisting. Although a properly performed twist is more reliable than a bad solder connection. Selecting a connection method depends on several factors:

• joined materials. It can be aluminum, copper, or a combination;
• the number of wires in the connection. You can connect not only two, but also three, four or more wires;
• section and number of cores.

Twisted connection

To make this connection, you need strip the ends, carefully twist them with pliers and insulate the place of twisting. Very simple and cost-free. But such a connection weakens over time due to the residual elastic deformation of the material, which means that the resistance in the connection increases and the contact begins to heat up until destruction and ignition. Therefore, in no case should wiring with twisting be laid on combustible substrates, for example, in a wooden house. And one more prohibition - weak protection against moisture does not allow such a connection to be made in rooms with high humidity.

In order for the twist to be of high quality, from the wires you need strip insulation up to 80 mm length wires, fold them perpendicular to each other if there are two of them, and in parallel if there are three or more, and twist tightly. The remaining ends of the wires must be removed with wire cutters with a helical movement, as if smearing the material of the wires one into the other. The total length of the finished twist should be at least ten, and preferably fifteen core diameters.

If special caps or a heat-shrinkable tube (cambric) are used for insulation, then they are put on the wire before twisting. It is recommended to put on the heat shrink tube twice, and lay the insulating tape in at least three layers. Whatever insulating material is chosen, it must also capture the wires' own insulation to protect it from moisture and its slipping.

Connection by soldering or welding

This method is the best in terms of manufacturability and reliability, but requires some skills to make a good connection.

Before soldering, the wires must be thoroughly cleaned of insulation and oxides, irradiated if necessary and twisted not as tightly as with simple twisting, coated with flux and soldered. Soldering can connect both copper and aluminum wires with a suitable flux and solder. Do not use an active acid flux, as it destroys the connection, remaining on the bare wires. The junction is isolated in the usual way.

With undeniable advantages, this method has quite significant disadvantages:

• the need for skills in work, the complexity of the process;
• use of a special tool;
• one-piece connection, that is, for repair it must be completely removed;
• an increase over time in the resistance in the connection, which worsens the electrical conductivity and increases the voltage loss in the network.

Welding - even more reliable connection method than soldering, but it requires a welding machine with personal protective equipment and welding skills, which is much less common in everyday life. Unless you need to independently perform electrical work in a country house, then the purchase of an inverter-type welding machine will be economically justified. Welding inverters are small-sized, have a wide range of welding current regulation, and provide stable arc burning with low power consumption. For welding copper wires, carbon-copper electrodes or carbon rods from conventional AA batteries are used.

The preparation for welding differs only in the density of the twist and in that the free ends of the two strands, even if there are more of them in the connection, are straightened and pressed parallel to each other to facilitate the formation of a ball of melt. Then the twist is placed in a welding clamp (ordinary old pliers) and the ends of the wire are welded with a carbon electrode to the main twist for two to three seconds so that the insulation does not melt. After cooling, the weld isolated in the usual way..

Often there is a temptation not to wait for natural cooling, but to use cold water to speed up the wiring process. But cold water causes the appearance of microcracks in the material, which naturally affects the quality of the connection.

Crimping

This method of connecting electrical wires uses special tubular sleeves or lugs. The industry produces sleeves for wires from 2.5 to 240 mm², and it is very important to choose the right connector for a particular connection. Required to complete the work special tool. It can be a swaging press or tongs, mechanical, electrical or hydraulic.

Having chosen a suitable sleeve and adjusted the tool, the insulation is removed from the wires, the ends are cleaned and quartz-vaseline paste is applied to them, the connector is put on and crimped. If the tool is simple, then you need to perform several compressions at some distance from each other. Using a good tool, you can crimp the sleeve in one go. At the end, the usual isolation of the junction is performed.

The wires to be connected can be inserted into the connector from opposite sides so that their joint is located approximately in the middle of the sleeve. It can be convenient to insert both wires on the same side, while the total cross-sectional area of ​​​​all wires should be less than the cross-section of the sleeve. High-quality installation and reliable insulation are the positive aspects of using crimping. But There are some negatives too:

• the sleeve is deformed during crimping and its reuse is impossible;
• the need for a special tool for crimping the sleeve, fitting it in length and stripping the insulation from the wire;
• for crimping the connection of copper and aluminum wire, a rather rare special sleeve is needed;
• quite a lot of time for the installation of electrical wiring.

Connecting insulating clips (PPE)

The clamp is cap with square steel wire coiled into a spiral cone. For aluminum wires, the cone is filled with a special paste that prevents oxidation of the bare ends. The information on the package with clamps will allow you to choose the right size of PPE in accordance with the cross-sectional area and the number of connected conductors.

To connect the wires, their ends are stripped to a distance slightly less than the depth of the cap, put together, twisted slightly and the cap is screwed on top. It is not necessary to strip bare wires from oxides, since this work is performed by the edges of the spring, and its turns tightly press the wires to each other.

The use of such connectors is technologically advanced, they not only connect the wires, but also isolate the junction, however, they do not provide the contact area, as when twisting with soldering. The bright colors of the caps help to mark zero, phase and ground during installation if the wires are not color-coded. The disadvantages include:

• gradual weakening of the spring over time, and, consequently, an increase in contact resistance and voltage losses in the network;
• restrictions on the number of connected wires, you can connect two with a cross section of 4 mm² or four with a cross section of 1.5 mm²;
• impossibility of mixed connections.

Bolted connections

Bolt connection is a simple, reliable and effective way. You just need to have a short bolt with a small section, three washers and a nut. True, it takes a lot of electrical tape for such a connection, and it is not used in the junction box because of its bulkiness. A washer is put on the bolt, then a stripped wire is wound, another washer (if copper and aluminum are connected), a second wire, a washer and the nut is tightly tightened.

Screw terminals

Screw terminals allow fast and neat installation. They are widely used when connecting to the wires of lamps, switches, sockets. With their help, you can connect copper and aluminum, while no insulation of the connections is required.

The disadvantages of screw clamps include:

• the need for crimping or soldering a multi-core cable before installation;
• the need for periodic maintenance of the connections, since the screws need to be tightened, that is, they need access.

Clamp "nut"

Such a connector is named for its shape. It is a cable clamp with special plates in which the grooves for the wires are made, and four screws in the corners. The wires are stripped, inserted under the plate and fixed with screws. Then a carbolite shell is put on. With this clamp you can join copper and aluminum, the insulation is sufficiently reliable, the installation process is simple and does not cause difficulties. Basically, such a branch connection is used to drain to apartments from a common aluminum riser. But besides tightening the threaded connections, there is another drawback - the dimensions, due to which the “nut” does not fit into the junction box.

Terminal blocks

Connection using terminal blocks is used in junction boxes, when installing lamps, sockets and switches. Terminal blocks are small in size, easy to fit in a box. A brass bushing is inserted into a small plastic case, into which screws are screwed on both sides. Stripped conductors are inserted from the ends of the block and clamped with screws with force. For wires of different sections, pads with different inlets are designed. The quality of such a connection is high, installation is easy, dissimilar materials can be connected, but there are significant disadvantages of terminal blocks:

• connection of only two wires;
• the poor quality of the pads themselves, due to which disturbances in the network are possible;
• care is needed when mounting aluminum and stranded wires so as not to damage the contact due to the brittleness of the metal.

Terminals WAGO

This relatively new type of connection using insulated spring clamps is by far the most reliable and safe. Disputes over the reliability of connections using WAGO terminals can be associated either with fakes on the market, or with the wrong choice of terminal for a specific load. International certificates and approvals protect the reputation of these products. Their only drawback is high price.

The special screwless spring mechanism makes the installation of connections simple and fast. The terminals can be reusable with a special lever that clamps the wire and releases it if necessary. Disposable terminals fix the core with some effort, but, according to the manufacturers, it is impossible to release it.

For installation, you only need to strip the ends of the wires and insert them into the clamp.

Advantages of WAGO terminals:

• the possibility of mounting dissimilar metals;
• the possibility of fixing more than two wires at the same time;
• neat fixation of thin wires;
• good connection quality;
• compact dimensions.

Connection of wires in the junction box

Of all the listed methods of connecting wires in the junction box, “nut” and bolted connections are not used for one reason - large dimensions. All other methods have the right to life.

It remains to clarify two points, which method to use to connect a large (three, four, five) number of wires and what to do if you need to connect wires of different sections.

For connecting wires of different cross-sections, WAGO terminals or a cheaper option are well suited - conventional terminal blocks. But for a large number of conductors in a junction box, you can use several options, depending on the conditions and cost of installation:

• WAGO terminals;
• crimping;
• soldering;
• PPE;
• twist.

Naturally, it is most preferable to use WAGO terminals, and last but not least, twist.

When choosing a solution, it is necessary first of all to ensure the safety and reliability of the operation of electrical networks, then durability and cost follow. And it is very important that the wire connections, no matter how they are made, are accessible for inspection and maintenance.