The electrical network got its name for a reason. It, like a spider web, covers all the premises, ensuring the operation of the equipment. Junction boxes are used to distribute energy between individual connection points (sockets, switches). One cable goes to them, and several go out. A prerequisite for the safe operation of the electrical network is to twist the wires correctly and accurately. This can be done in different ways.
In order to better understand how to do the twisting correctly, we will figure out what options exist, the order, and the features of their implementation. Electricity refers to communications that "do not forgive" mistakes. The result of illiterate actions is a breakdown of the device, a short circuit, a fire. Often novice craftsmen ask: is it possible to independently connect the wires in the junction box? Of course, but before that, you should take the time to study the rules, features of electrical work.
Ways to connect wires
There are various methods of tightening wires in a junction box: crimping, welding, soldering, various clamps. Some of them require more time, special materials, devices. Others are easier to implement, but inept actions greatly reduce their reliability.
Twisting is popular with craftsmen. PUE classifies it as unreliable methods that do not guarantee the reliability of contact. Usually it is used as a temporary option, for example, when checking the operability of a circuit. In addition, it is considered preferable for sagging, loose networks. Advantages:
- ease of execution;
- minimum of tools;
- easy to disconnect if necessary.
Among the shortcomings, one can single out the complexity of working with wires of different cross-sections: the difference in resistances leads to heating of the insulation, its gradual melting. They try not to use the method for multicore cables, since there is a high probability of breaking the circuit.
Do not twist copper and aluminum wires: the result will be unreliable, the point of contact will become a source of increased resistance.
The easiest way is to twist the wires by twisting the previously stripped ends. From the tools you will need a knife, pliers. A section of the core 5 cm long is preliminarily cleaned of insulation. The bare ends are crossed, bringing the individual parts as close as possible. Then the crosshair is rotated with pliers, it is bent in any direction parallel to the main line, and it is isolated.
Types of wire connections
You can use another option, when the stripped ends are bent in the middle, interlocked. Then the veins are wrapped around each other. For reliability, they are crimped with pliers, insulated. Electricians know a variety of stranding methods: parallel or sequential shroud, groove. Correct twisting should ensure the most complete fit of the cores.
For insulation, electrical tape is usually used. It is necessary that it should go over the insulation at least 2-3 cm. You can use a thermotube. It is preliminarily put on the cable, then shifted, closing the point of contact. The tube should grip the wiring tightly, so it is slightly warmed up.
For crimping, a special sleeve is required, matched to the size of the bundle and the material of the cable. The stripped ends of the core are inserted into the sleeve, crimped with press pliers, and insulated.
In terms of reliability and quality, welding gives the best result. In fact, a one-piece structure is obtained, which is protected from oxidation and rupture. To complete, you will need a welding machine, carbon electrode, flux. Step-by-step implementation instructions:
- strip the ends of the cable from insulation, bring them to a shine with sandpaper;
- twist the wiring;
- fill the recess of the electrode with flux;
- weld on a contact point.
The resulting "ball" is cleaned of flux, varnished. Similar actions are performed when soldering. Here the contact provides the solder melted with a soldering iron.
Strands of copper and aluminum wires
Much has been written about why copper and aluminum should not be interconnected. The consequence of such contact is its heating, subsequent combustion. There are several reasons for this behavior of metals:
- The difference in the coefficients of thermal expansion. Metals expand in different ways when heated, contract when cooled. Therefore, their connection is gradually deteriorating.
- Formation of an oxide film on aluminum. The film prevents the passage of current, the conductor heats up, the bond is gradually destroyed.
- Disruption of the structure of aluminum during electrolysis. Copper and aluminum form a galvanic pair. Under the influence of moisture, the dissociation of ions begins, which leads to the destruction of the metal. The resulting shells, voids conduct current poorly, cause heating.
The presence of aluminum wiring in houses makes it necessary to combine it with new copper conductors. Using simple rules, you can avoid heating the contact and ensure its reliability. When twisting, it is important to wrap wires around each other. The number of turns - for a thick wire more than 3, for a thin one (less than 1 mm) - at least 5. The finished connection is sealed with a protective varnish that is resistant to water.
The method in which the copper is pre-plated with solder provides maximum reliability. This creates a reliable contact between single and stranded conductors. To do this, the stranded core must first be plated with solder, it will become single-core.
To make the contact detachable, use a bolt, nuts, spring washers. All elements are alternately put on the rod, avoiding the combination of copper wires and aluminum. For example: a conductor with a diameter of less than 2 mm will fit perfectly on an M4 bolt.
The development of electrical engineering has brought new comfortable ways to work with different materials. An example is a terminal block. Its advantages:
- comfortable;
- reliable;
- excludes contact of bare areas.
The end of the core is stripped of insulation (about 5-10 mm), inserted into the hole, clamped with a screw. The terminal box is irreplaceable when restoring a broken circuit, connecting a chandelier. In a wall, it can only be placed in a junction box.
The Wago terminal block is very popular. It is disposable, reusable (with a lever). The terminal block works simply: the cable is inserted with effort, it is fixed. Disadvantage: More expensive than other traditional products.
Danger of twisting copper and aluminum wires
Twisting wires of different cross-sections
Often the master is faced with the task of connecting wires of different diameters in the junction box. This can be done in several ways: twisting followed by soldering (welding), screw clamps, self-clamping terminals, bolts, nut-type taps, tinned copper lugs.
The easiest way is to twist wires in a box that are close in thickness (for example, 4 and 2.5). With a big difference, it is difficult to ensure high-quality contact. The veins must wrap tightly around each other, then they are welded or sealed. A strong connection will last more than one year without complaints.
A secure contract between conductors of adjacent cross-section creates a screw clamp ZVI. Cables are started from different sides, each is clamped with a separate screw. The choice of the clamp is made taking into account the characteristics of the conductors, the permissible current. Implementation principle:
- strip the ends by 2-3 cm;
- insert them into the box;
- tighten the screws.
With a large cross-section of wires, you can twist them using the Wago self-clamping terminal. Its peculiarity is the presence of special nests for each core. The marking of the terminal body will help you figure out how many wires can be twisted, what section.
The permanent contact of the wires in the junction box guarantees a bolted connection. It allows you to fasten two, three or more conductors with nuts, washers, bolts. Step-by-step mounting instructions:
- strip the vein by 3 cm (you should get a full turn);
- prepare a ring from a core in diameter;
- put a washer on the bolt, a ring of one conductor, another washer, a ring of the second conductor;
- put the next washer, tighten with a nut.
So you can connect several cores together. Their number is limited only by the length of the rod.
The question often arises: how to twist the wires together to branch off the trunk line in the switchboard? The solution is most often a branch squeeze, in common parlance - "nut". It allows, without cutting the line, to branch off a line from it. To do this, the right place of the main part is cleaned of insulation, the clamp is fixed, an additional "branch" is inserted. It can also be used to connect two separate cables. When choosing a "nut", it is necessary to know the cross-section of the trunk cable and branch. With the help of a clamp, you can connect a copper wire to an aluminum one.
The walnut body is leaking. To protect it from moisture, dust, debris, it should be insulated.
The clamp connection procedure is simple:
- disassemble the case by removing the retaining rings with a screwdriver;
- strip the insulation (the length corresponds to the dimensions of the die);
- loosen the mount;
- insert the cores into special grooves on the dies;
- carefully (not overtightening) tighten the bolts;
- put the die in the case;
- close the housing, install the retaining rings.
To work with a thick cable, you will need copper-tin lugs, crimping pliers. The connection turns out to be cumbersome, so you will need to provide enough space for it in the box. A tip is put on each core, crimped, fixed with a bolt with a nut, washer, insulated (with electrical tape, thermotube)
Reliable wire connection
Errors when twisting wires
A common mistake when twisting is wrapping one wire around the other. This option does not provide the required mechanical strength. The conductors should wrap around each other evenly. It is unacceptable to wind a thin conductor onto a thick one; it will not be possible to achieve a snug fit.
The length of the twist depends on the cross-section of the wires. It should be at least 3-5 cm. Variants of grip with a ring, loose fit, not twisted are unacceptable.
The direct connection of copper to aluminum leads to a rapid destruction of the contact. Craftsmen often forget to install an intermediate plate to prevent direct metal contact.
When laying wiring in a house, you cannot do without connecting wires. After all, a network with branches is being laid around the house to power certain electrical appliances.
Need for wiring connection
Junction boxes are used for branching the electrical network. But they are intended only to hide the connections of the branches of the electrical network.
The need for wiring connections is ubiquitous. They connect wiring in a house, electrical appliances, a car in different ways, in general, wherever there are wires.
Now there are several ways to connect the wiring. Each of them has its own positive and negative qualities.
The most common ways are:
- Twisting;
- Soldering;
- Welding;
- Use of terminal blocks, blocks;
- Use of self-clamping terminal blocks;
- Use of connecting insulating clamps (PPE caps).
Twisting
The simplest and most common way to connect the wires is the usual twisting.
For this type of connection from the equipment, only a knife for stripping the insulation and pliers are required to ensure the reliability of the connection. However, at the end, the place of twisting will need to be insulated.
Twisting is done in several ways.
The simplest is the mutual twisting of the stripped ends of the wiring.
For reliability, it is advisable to strip the wires by at least 5 cm.Further, the bare ends are crossed so that the edges of the insulation touch, and then they grip the crosshairs of the wires with pliers and twist them with a rotational motion.
After twisting, the joint is bent to one side so that the twist lies parallel to the wire. Then the connection is isolated.
The second method is also effective and simple twisting.
The stripped ends of the wires are slightly bent in the middle, and in the place of the bend, the wires are hooked together.
After the end of one wire is wrapped around the second, it is also made with the other end of the wiring.
For reliability, the windings made can be tightened slightly with pliers. Then everything is isolated.
The next way is a bandage connection. For such a twist, you need a piece of stripped wire.
The two wires to be connected are laid parallel to each other so that the stripped ends touch along the entire length.
Then they are wrapped with the existing segment, a kind of bandage is obtained.
The last of the used methods of twisting that can be found is twisting with a groove.
To complete it, small hooks are made from the ends of the wires, which are interlocked with each other, and then one edge of the wire is wound around the other.
More complex types of wire connections are presented below.
Now about the ways to isolate the twists.
Often, different types of electrical tape are used for insulation. When using it, it is necessary to wrap not only the place of twisting, it must go over the insulation of the wires at least 2-3 cm.
This will provide complete insulation, including from moisture ingress.
In addition to electrical tape, it is possible to use thermotubes.
Such a tube of the required length is put on one of the wires before twisting.
Already after twisting, the tube is pushed onto the junction. In order for it to grip the wiring tightly, it needs to be slightly heated, for example, with a lighter.
Temperature will cause the tube to shrink to provide a tight grip.
The positive qualities of twists include ease of implementation with minimal equipment, while they are considered quite reliable.
If good insulation is provided, the twist can last for a long time. Also, the twist itself is a detachable connection, you can twist it at any time.
It is considered more preferable in networks that are not secured and can sag, which is especially important for cars where vibration is constantly exposed to the wiring.
Among the shortcomings, it is noted that it is impossible to connect wires of different cross-sections, the resistance in such a twist can be very high, which will lead to heating and melting of the insulating layer.
It is difficult to twist multi-core cables together. They are too soft, so the connection may break when stretched.
If several insulated conductors are used in the wiring, then after each conductor is insulated, the total thickness at the junction can be very large.
This will affect both reliability and increased resistance at the junction of the wires.
Soldering
The next method of connecting wires, which is often used, is soldering.
It is noteworthy that soldering is just an improvement in twist. That is, the wires must be twisted before soldering and then soldered.
For soldering, a soldering iron and solder are used. Thanks to this connection, the twisting strength of the multi-core cable can be significantly increased.
The advantages of soldering include an increase in strength, especially for stranded wires.
After soldering at the junction, the resistance will be much lower, which means that the twist will not heat up.
However, soldering is used only on copper stranded wiring, aluminum cannot be soldered.
At the same time, soldering is very fragile, and if it is performed incorrectly, the connection will be unreliable.
Welding
Welding is another way to improve stranding. Again, welding is just a method of increasing the reliability of the stranding.
It is not applicable for aluminum wires, welding is used only on copper cables of large cross-section.
Welding reliability is much higher than soldering. It is a good way to improve the connections in the junction box, but welding is still not very practical.
In addition, it will need special equipment, a welding inverter.
Welding is not used on aluminum wiring, an additional disadvantage is the possibility of weakening the twist, since with strong heating of the wires, which will be necessary during the welding process, the twist itself may weaken due to a change in the physical properties of the metal.
Soldering and welding cannot be considered separate connection methods, they only provide additional reliability.
Also, after using a soldering iron or welding machine, the joint will still have to be insulated.
Terminal blocks and strips
But the use of terminal blocks and blocks is already a completely separate way of connecting wires.
The terminal block and block is a small metal plate with contacts at the edges.
This plate is enclosed in insulating plastic. Bolts are often used to clamp the wires.
The difference between a terminal block and a block boils down to the fact that the terminal block allows you to connect only two wires, and the block is designed for multiple connections.
To put it simply, a block is a series of terminal blocks connected together to provide several separate connections.
To connect two wires, it is enough to clean their ends from insulation, and you do not need to clean much, 0.5 cm is enough, it is only important that the cleaned end reaches the contact.
In this case, the bare wire should not protrude beyond the edges of the terminal block, in order to avoid accidentally touching it.
On the other side of the terminal block, the other end of the wire is fixed. The metal plate will act as a bridge between them.
When using a terminal block, they connect only two wires, for the subsequent ones, one more terminal block is used.
The block allows you to provide several connections, which, with a large number of wires, will result in a more compact size.
Terminal blocks and blocks are good because they allow you to connect together wiring made of different metals and differing in cross-section.
In addition, they are detachable, you can disconnect the desired wire at any time. They are good for both solid and stranded wires.
Their disadvantages include the increased dimensions of the connection, especially for the pads.
It can be very difficult to hide terminal blocks and strips. In addition, ordinary terminal blocks will not allow you to insert into the wiring, twisting allows this. But about the sidebar - just below.
Self-clamping terminal blocks
Self-clamping terminal blocks are a kind of conventional terminal blocks. They provide an even faster connection since you don't even need to use a screwdriver.
The contacts in them are spring-loaded, therefore, to connect the cables, it is enough to insert the ends of the wiring into the holes with contacts.
When installing, it is necessary to overcome the force of the spring, after which it will press the contact to the wire. It is noted that this method is very convenient for stranded wires.
Of the disadvantages of such a connection, one can single out a not particularly reliable connection; it will not be difficult to pull out the wiring from the terminal block. This is especially true for single-core wires of large cross-section.
A common disadvantage for terminal blocks is the possibility of moisture getting on the contacts, which can lead to their oxidation and disruption of the connection.
PPE caps
PPE caps are a simple and convenient way to connect. They are produced in three types - without contacts, as well as with clamping and spring-loaded contacts.
Caps without contacts are made only of insulating material. They are designed to isolate the twist.
They are put on top of the twist, protecting it from moisture.
It would seem that what could be simpler than connecting wires? After all, there are several ways to connect wires. These are wire twisting, wire soldering, wire welding, crimping and connecting wires using a terminal block. Even a schoolboy knows the simplest way of twisting conductors. It is necessary to attach together the ends of metal wires, called veins, and twist into one "pigtail", then wrap with electrical tape. No need for a soldering iron, terminal block, connecting caps and other "unnecessary".
Any “his own electrician” has mastered such an operation. And, if necessary, he applies this method in his daily practice. For example, splices the wires of a power cord of a household appliance, tablet adapter or computer after a break.
Russian "techies" use this technology of fastening wires everywhere. Here are just in the rules for the installation of electrical installations PES "twists", all kinds of "bends" and "rivets" are not provided. There are no such methods of wiring in other regulatory documents. Why?
We often do not think about the consequences of such a "simplification". Meanwhile, an unreliable contact will fail at the most inopportune moment, the power supply to consumers / electrical receivers can always be cut off. From "surges" of voltage there is a breakdown of the elements of power cascades of complex household appliances SBT. Even special protection devices used in the most "sophisticated" models of foreign manufacturers do not save from breakdown.
The induction of short electromagnetic pulses with a voltage of several thousand volts on the electronic filling causes "harmless" sparking at the joints. At the same time, the standard protection equipment with which apartments are now equipped (RCDs, circuit breakers, fuses) do not "see" such short low-current impulses, so they simply do not work, and we do not customize to install special devices for this. Uninterruptible power supplies for computers also did not become a panacea for transient impulses. The appearance of "pokes" causes malfunctions in the operation of electronic equipment and computer equipment, leads to the failure of electrical components and expensive functional modules.
Overheating in the place of a bad connection leads to even more catastrophic consequences, when the current passes, the weakened connecting node becomes red-hot. Often from this occur fires and fires, causing enormous damage to the owners of premises. Statistics show that 90% of all wiring faults occur due to twists and poor contact connections of conductors. In turn, the very malfunction of electrical wiring and equipment, according to the Ministry of Emergency Situations, is the cause of one third of fires occurring in Russia.
However, it so happened historically that several decades ago, in the face of a shortage of electrical accessories / copper conductors, twisting of aluminum wires was considered the main method used in electrical work. Twisting as a connection can be used in electrical engineering when carrying out repair and restoration work.
How to connect the wires correctly
How to connect the wires: start by stripping the insulation off. Correct connection of conductors must satisfy three basic requirements:
- Provide reliable contact with a minimum contact resistance between themselves close to the resistance of a single piece of wire.
- Maintain tensile strength, fracture and vibration resistance.
- Connect only homogeneous metals (copper to copper, aluminum to aluminum).
There are several connection methods that satisfy these requirements. Depending on the requirements for wiring and the possibilities of practical application, the following types of wire connections are used:
All these methods require preliminary preparation of the wire or cable - stripping the insulation to expose the wires to be connected. Traditionally, the material of the insulating shell is rubber, polystyrene, fluoroplastic. Additionally, polyethylene, silk and varnish are used as insulation inside. Depending on the structure of the conductive part, the wire can be solid or stranded.
A single-core wire means a wire, the cross-section of which is formed by an insulating sheath with a metal core or a wire inside.
In a stranded wire, the metal core is formed by several thin wires. They are usually intertwined and present as a bundle surrounded by an insulator on the outside. Often, individual veins are covered with polyurethane varnish, and nylon threads are added to the structure between them to increase the strength of the wire. These materials, like the fabric braid on the outside, complicate the stripping process.
Depending on the type of connection, 0.2 - 5.0 cm of insulation is removed from each end of the wire. For this, several types of tools are used.
According to a 5-point system, it is possible to assess the quality of stripping and the degree of protection against notching - damage to the cores by each device:
Insulation / core damage
Monter's (kitchen) knife - 3/3
Side cutters (nippers) - 4/3
Stripper - 5/4
Soldering iron or loop burner - 4/4
In low-current television / computer networks, coaxial cables are used. During the cutting process, it is important to carefully cut and remove the insulating jacket without damaging the braided shield. To access the central vein, it is fluffed up and removed, exposing the trunk. After that, the polyethylene insulation is cut with a knife or a special device, the cut is removed from the core.
The bifilar in the screen consists of a pair of wires in the screen, which is also preliminarily fluffed into wires to access the conductors, opening access to each core.
Important! To remove the insulating material of the enameled wire with a cross section of less than 0.2 mm², a soldering iron should be used. The enamel is carefully removed by means of an emery "zero" by moving the paper along the wires.
How to twist wires correctly
Most often, twisting is used to repair electrical wiring, cords and adapters (including low-current ones) of household appliances and equipment. If we are talking about a home electrical network, then the norms provide for the use in houses of wires with a current-carrying conductor section of 1.5–2.0 mm made of copper and 2.5–4.0 mm made of aluminum. Usually, wires of the VVG and PV brands in a PVC sheath are used for wiring. Power cords of the ShVL and SHTB brands with rubber or PVC insulation have a cross section of 0.5 - 0.75 mm.
Step-by-step splicing of wires together can be done as follows:
- Degrease the bare ends of the wires by wiping with acetone / alcohol.
- Remove the varnish or oxide layer by sanding the conductors with sandpaper.
- We apply the tips so that they cross. We wind at least 5 turns of one core to another in a clockwise direction. To make the twist tight, use pliers.
- We isolate the open current-carrying parts of the wires with electrical tape, or screw on an insulating cap. They should go behind the insulation for 1.5–2.0 s to cover the bare sections of the conductors.
For splicing a stranded stripped wire with a single-core wire, another winding technique is used:
- A single wire is twisted with a stranded wire, leaving a free end without winding.
- The end of the single-core wire is bent 180 ° so that it presses the twist, then pressed with pliers.
- The connection point must be firmly fixed with electrical tape. For best performance, an insulating heat pipe should be used. For this, a piece of cambric of the required length is pulled over the joint. In order for it to grip the wiring more tightly, the tube should be warmed up, for example, with a hairdryer or a lighter.
With a bandage connection, the free ends are placed next to each other and wrapped from above with an existing piece of wire (bandage) made of a homogeneous material.
Coupling with a groove provides that before mutual twisting, small hooks are configured from the ends of the wire, they are interlocked with each other, then the edges are wrapped.
There are more complex types of parallel / serial connections. The connection of wires by the twisting method is used by professional electrical repairers when carrying out restoration work.
Important! Copper and aluminum have different ohmic resistance, they actively oxidize when interacting, the connection is fragile due to different hardness, therefore, the connection of these metals is undesirable. In case of emergency, the ends to be connected should be prepared - irradiated with tin-lead solder (POS) using a soldering iron.
Why is it better to crimp (crimp) the wires
Crimping of wires is one of the most reliable and high-quality methods of mechanical connections that are currently used. With this technology, the cables and wires are crimped in the connecting sleeve using press tongs, ensuring tight contact along the entire length.
The sleeve is a hollow tube and can be manufactured independently. For sleeve sizes up to 120 mm², mechanical pliers are used. For large cross-sections, products with a hydraulic punch are used.
When crimped, the sleeve usually takes the shape of a hexagon, sometimes local indentation is made in certain parts of the tube. In crimping, sleeves made of electrical copper GM and aluminum tubes GA are used. This method allows crimping conductors made of different metals. This is largely facilitated by the treatment of the constituent components with quartz-vaseline lubricant, which prevents subsequent oxidation. For joint use, there are combined aluminum-copper sleeves or tinned copper sleeves GAM and GML. The crimp connection is used for wire bundles with a total cross-sectional diameter between 10 mm² and 3 cm².
Soldering as a reliable alternative to twisting
The closest alternative to twisting, prohibited for wiring, is the connection of wires using the soldering method. It requires special tools and consumables, but provides absolute electrical contact.
Advice! Overlapping wire splicing is considered the most unreliable technology. During operation, the solder crumbles and the connection opens. Therefore, before soldering, apply a bandage, wrap a piece of wire of a smaller diameter around the parts to be connected, or twist the conductors together.
You will need a 60-100 W electric soldering iron, a stand and tweezers (thin nose pliers). The tip of the soldering iron should be cleaned of scale, sharpened by selecting the most suitable tip shape in the form of a spatula, and connect the device body to the ground wire. From "consumables" you will need POS-40, POS-60 from tin and lead, rosin as a flux. Solder wire with rosin placed inside the structure can be used.
If you need to solder steel, brass or aluminum, you need a special soldering acid.
Important! Do not overheat the junction points. In order not to melt the insulation when soldering, be sure to use a heat sink. To do this, hold the bare wire between the heating area and the insulation with tweezers or pliers.
- The conductors stripped of insulation should be irradiated, for which the tips heated with a soldering iron are placed in a piece of rosin, they should be covered with a brown-transparent layer of flux.
- We place the tip of the soldering iron tip in the solder, grab a drop of the melted one and evenly process the wires alternately, turning and moving along the blade of the tip.
- Attach or twist the wires together, fixing them firmly. Warm up with a sting for 2–5 s. Treat the areas to be soldered with a layer of solder, allowing the drop to spread over the surfaces. Turn the wires to be connected and repeat the operation on the reverse side.
- After cooling, the soldering points are insulated by analogy with twisting. In some compounds, they are pre-treated with a brush dipped in alcohol and varnished on top.
Advice! During and after soldering within 5–8 s. wires must not be tugged or wiggled, they must be in a stationary position. The signal that the structure has hardened is the acquisition of a matte shade by the surface of the solder (in the molten state, it shines).
Still, welding is preferable
Welding surpasses all other technologies in connection strength and contact quality. Recently, portable welding inverters have appeared that can be carried to the most inaccessible places. Such devices are easily held on the welder's shoulder using a strap. This makes it possible to work in hard-to-reach places, such as welding from a ladder in a junction box. For welding metal wires, carbon pencils or copper-plated electrodes are inserted into the holder of the welding machine.
The main disadvantage of welding technology - overheating of the parts to be welded and melting of the insulation is eliminated by:
- Correct adjustment of the welding current 70-120 A without overheating (depending on the number of welded wires with a cross-section of 1.5 to 2.0 mm).
- The short duration of the welding process is no more than 1-2 seconds.
- Tight preliminary twisting of wires and installation of a copper heat sink clamp.
When connecting wires by welding, the twisted cores should be bent and cut upwards. An electrode is brought to the end of the wires connected to the mass and an electric arc is ignited. Molten copper flows down in a ball and covers the wire strand. In the process of cooling, an insulating belt made of a piece of cambric or other insulating material is put on the warm structure. Varnished cloth is also suitable as an insulating material.
Terminal blocks - the most ergonomic wiring products
The rules of the PUE, clause 2.1.21 provide for the type of connections using clamps (screws, bolts). There is a connection directly by means of fasteners "on the weight", when a screw, a washer is threaded through the loops of each of the wires and is fixed with a nut from the back side.
Such an installation is wrapped in several turns of electrical tape and is considered quite practical and reliable.
More ergonomic wiring products, called screw terminal blocks. They represent a contact group located in a housing made of insulating material (plastic, porcelain). The most common connection of wires by the method using terminal blocks is found in junction boxes and electrical panels. To connect the wire, you need to push it into the socket and tighten the screw, the clamping bar will securely fix the core in the seat. Another wire to be connected is connected to the mating socket, shorted to the first.
In self-clamping terminal blocks of the WAGO type, the wire is snapped into the socket; for better contact, a special paste or gel is used.
Tap-off clamps represent the capital version of the screw terminal block with several short-circuited taps, used mainly on the street and in places with unfavorable environmental conditions.
The connecting clamps represent an insulating cap with a thread inside, it is screwed onto a twist, at the same time squeezing and protecting from mechanical stress.
Among the many connection methods, twisting electrical wires is the simplest and easiest to implement. This type of connection does not differ in high reliability, its main advantages are in the speed of implementation and the minimum set of tools during operation. Despite the disadvantages, the twisting of conductive conductors remains popular when working at home and in the field.
What the rules say
The Electrical Installation Rules (PUE) when installing electrical wiring prescribe to connect wires by crimping, welding, soldering, connecting clamps (screw, bolt, etc.). Single-wire wires are allowed to be connected by twisting followed by soldering.
In fact, this means that from the point of view of the PUE, twisting of wires is not allowed. If we are talking about a supervised facility, the selection committee will not allow the facility, electrical installation or wiring made with the use of such connections into operation.
The reason for the inadmissibility lies in low reliability. The elasticity of the twisted wires weakens over time, the metal of the conductive conductors is oxidized. In this case, the quality of contact at the junction is deteriorated. The increased resistance of such a section of the circuit works as a heating element, especially when high load currents are flowing. The conductors begin to heat up, in the worst case, melting and even ignition of the insulation is possible.
The situation is worst when joining dissimilar metals such as copper and aluminum. Due to the differences in physical and chemical properties at the points of contact, there is a rapid increase in the transient resistance. The situation is aggravated sharply in the presence of moisture. As a result, the twisting of copper and aluminum wires is directly prohibited by the rules.
However, in practice, in everyday life, this method of connecting veins remains in demand as the fastest and simplest.
How to twist electrical wires correctly
If, for any reason, it was necessary to connect the wires with a twist, it is important to take measures to seal the junction as much as possible. First, the wires are freed from insulation. The specific length depends on the cross-section, the thinner the wire, the shorter the length of the bare section will be required. On average, at 1.5 mm2, the conductor should be stripped to a length of about 5 cm. In the case of stranded wires, be especially careful when stripping the insulation, since individual thin veins can be easily damaged, thereby reducing the conductor cross-section. You can remove the insulation with a knife or use a special wire stripper.
The conductors to be connected can be of the same or different cross-section, single-core or multi-core. With a parallel, serial arrangement of wires or with a branch device, the twisting methods can be different, the options are shown in the figure.
To further improve the quality of the connection, with a parallel arrangement of conductors, the use of connecting insulating clamps (PPE) allows.
The clamp is a flame retardant plastic cap. There is a steel spring inside the cap. When the PPE is screwed onto the twist, the spring compresses the wires, thereby improving the quality of the contact. The outer plastic sheath serves as insulation for the joint.
In any case, the correct twisting of electrical wires is the one that will ensure the most tight fit of the conductors to each other. For example, when connecting a thicker single-core wire with a stranded one, you can strengthen the connection by crimping the core itself, as shown in the photo.
Insulation
Insulation plays an important role in the reliability of the connection. It not only protects against short circuits and accidental contact with live parts, but also serves to prevent moisture from entering them. The presence of moisture leads to accelerated oxidation of the metal, deterioration of contact with all the ensuing negative consequences.
The most common insulating method is with insulating tape. The tape allows you to isolate connections of any configuration and complexity. Insulating tapes are manufactured for various conditions, including those designed for use in high temperatures
Recently, the use of heat shrink tubing has become more and more popular. This is a tube made of a material that shrinks under the influence of high temperature, tightly covering the insulated parts.
The method of insulating with heat shrink tubing requires that the tubing be put on the wire beforehand, therefore it is best suited for sequential arrangement of conductors. The shrinkage temperature is around 120 ° C. For this purpose, a building hair dryer, a gas burner, or, in extreme cases, a lighter or matches are used. It is important to monitor the temperature so as not to melt the insulation with a flame or excessively hot air.
Despite all the disadvantages, the twist connection is popular. In a situation where you need to power a power consumer, and there is only a knife or pliers from the tool, twisting is the only available solution. I must say that in a dry place, a well-made and insulated twist can work for years without noticeable deterioration in properties. But still, if possible, it will be correct to use another connection method.
The laying of electrical wiring in the house involves the connection of wires; it will be necessary to make branches from the main network, which are necessary to provide power to electrical appliances.
How to make the right wiring connection
Connecting wires is required everywhere in rooms, in cars, devices and mechanisms, wherever there are wires. The following methods are used today:
- Twisting;
- Welding;
- Soldering;
- With the help of special blocks, terminal blocks;
- With self-clamping terminal blocks;
- With PPE caps.
What you need to know about twisting
Take a close look at the photo of the wire twist, you will see that it can be done in different ways. You will need to prepare tools: a knife to strip the insulation, pliers to make the connection secure, and you will also need electrical tape to isolate the twist.
Method - twisting the wiring with protected ends
Strip the wires at least 5 cm, cross the ends unprotected with insulation, clamp the resulting cross with pliers and twist them together, performing a rotational movement.
A common method is grooving
To get started, check out the sequence of steps on how to twist wires with your own hands. Bend the ends of the wire into small hooks, hook them together, wind one wire around the other.
Insulate the resulting twist to ensure human safety, contact reliability, prevent current leakage and eliminate short circuits.
Professionals say that these types of wire twisting can be made more durable by using the following guidelines:
Twisted contacts are additionally connected by soldering or welding, as a result, the contact acquires maximum reliability, it is almost impossible to break it. It is preferable to use soldering when both cores of the connection have a large cross-section.
WAGO terminals greatly facilitate connection, making it more efficient, they are needed when you have to figure out how to twist copper wires with aluminum ones. The whole procedure will take place quickly enough, while the "vagi" allow you to connect the conductors of different cross-sections, the contact will be reliable and durable.
If the DIYer is faced with the task of connecting wires in an electrical outlet or lamp, use the WAGO terminal blocks.
Thanks to PPE clamps, the reliability of the connection increases significantly, it becomes as safe as possible. These products have a low price, so they are available at any electrical store.
Wires twisted together should not be immediately covered with a junction box. It is better to observe how the power grid works for several hours, after which it is recommended to check the temperature at the attachment point. If the connection is very hot, you need to do everything again: most likely, the contacts turned out to be unreliable.
The twist itself is not waterproof, so it is better to take a box to connect the veins inside the wall, if without it, then the twisted wires will need to be insulated with cambric.
It remains for you to determine for yourself which twisting method is better, and consider methods for isolating the knots.
What a DIY Craftsman Should Know About Soldering and Welding
Soldering is considered simply an improvement in twist, first the wires are twisted, and then they are soldered using a soldering iron with solder. Soldering advantages:
- Increasing the strength of the twist;
- Reduced resistance, which means the twist point will not heat up.
Copper stranded wiring can be easily soldered, but this method is not suitable for all wires, with the exception of twisting aluminum wires. Since soldering is fragile, you must not be negligent when performing it, otherwise you will get a poor-quality connection.
Welding is another way to improve twisting, it increases reliability, but it is also not suitable for aluminum wires. It is used for multicore copper cables with a large cross-section, the reliability of welding is considered higher compared to soldering.
When using welding, the possibility of weakening the twist cannot be ruled out; under the influence of high temperatures, the performance characteristics of the metal can change.
Isolation methods
Insulation of wires is performed using various types of electrical tape, it is necessary to insulate the place of twisting and a piece of insulated wires equal to at least 2 or 3 cm.Then it will be possible to make high-quality insulation that protects against unwanted ingress of moisture on the contacts, and for this purpose, special thermal tubes are additionally used.
Insulation with thermotube
The tube with the desired length is put on one core before twisting.
Twisting is performed, after which the thermotube is shifted to the place where the contacts are connected.
It is necessary that the tube adheres to the wiring as tightly as possible, so it is heated slightly with a lighter. Under the influence of high temperature, the thermotube will shrink, and it will be possible to ensure a tight girth of the wiring.
The advantages of all kinds of twists are the simplicity of their execution, despite the minimum equipment, they have proven to be quite reliable connections.
When good quality insulation is made, for which good duct tape has been used, the twist will last long enough. Such a connection is convenient in operation: it is detachable, which means that if necessary, the wires can simply be twisted again.
Twisting is used in loose electrical wiring that sags, this method was adopted by motorists, in the car, the wiring is constantly exposed to vibration.
Among the disadvantages of twisting, the following should be noted:
It is not possible to connect conductors with different cross-sections, in such a connection, as a rule, there is a very high resistance, which is the reason for the constant heating of the wires and the melting of their insulating layer.
Stranded cables are difficult to twist together, which are soft and may break under any tension.
When there are multiple insulated wires in a wiring, because each core is individually insulated, the overall thickness can be very large.
Twisting is not suitable when it is necessary to connect wires made of different materials - copper and aluminum.
When choosing a method, it is important to take into account all sorts of nuances, only then will it be possible to get a high-quality connection with your own hands. Twisting must be done after disconnecting the power supply for safety reasons.
Photo of twisting wires
