All electrical engineering, since the time of Faraday, uses wires. And for as many years as wires have been used, electricians have been faced with the problem of connecting them. This article explains what methods there are for connecting conductors, and the advantages and disadvantages of these methods.
Twist connection
The easiest way to connect wires is twisting. Previously, this was the most common method, especially when wiring in a residential building. Now, according to the PUE, connecting wires in this way is prohibited. The twist must be soldered, welded or crimped. However, these methods of connecting wires begin with twisting.
In order to perform high-quality twisting, the connected wires must be cleared of insulation to the required length. It ranges from 5 mm when connecting wires for headphones to 50 mm if it is necessary to connect wires with a cross-section of 2.5 mm². Thicker wires are usually not twisted together due to their high rigidity.
Wires are stripped sharp knife, insulation stripping pliers (ISR) or, after heating with a soldering iron or lighter, the insulation is easily removed with pliers or side cutters. For better contact bare areas are cleaned sandpaper. If the twist is supposed to be soldered, then it is better to tin the wires. Wires are tinned only with rosin and similar fluxes. This cannot be done with acid - it corrodes the wire and it begins to break at the soldering site. Even washing the soldering area in a soda solution doesn’t help. Acid vapors penetrate under the insulation and destroy the metal.
The stripped ends are folded parallel into one bundle. The ends are aligned together, the isolated part is held firmly with your hand, and the entire bundle is twisted with pliers. After this, the twist is soldered or welded.
If there is a need to connect the wires to increase the total length, then they are folded opposite each other. The cleaned areas are placed crosswise on top of each other, twisted together by hand and tightened tightly with two pliers.
You can only twist wire made of the same metal (copper with copper, and aluminum with aluminum) and of the same cross-section. Twisting wires of different sections will turn out uneven and will not provide good contact and mechanical strength. Even if it is soldered or crimped, these types of wire connections will not ensure good contact.
How to connect electrical wires by soldering
Compound electrical wires soldering is very reliable. You can solder untwisted wires, but such soldering will be fragile due to the fact that the solder is a very soft metal. In addition, it is very difficult to lay two conductors parallel to each other, especially when suspended. And if you solder on some kind of base, the rosin will stick the soldering area to it.
A layer of rosin is applied to the pre-tinned and twisted conductors with a soldering iron. If another flux is used, it is applied in the appropriate manner. The power of the soldering iron is selected based on the cross-section of the wire - from 15 W when soldering headphones to 100 W when soldering twisted wires with a cross-section of 2.5 mm². After applying the flux, tin is applied to the twist with a soldering iron and heated until the solder completely melts and flows into the twist.
After the soldering has cooled, it is insulated with electrical tape or a piece of heat-shrinkable tubing is put on it and heated with a hairdryer, lighter or soldering iron. When using a lighter or soldering iron, be careful not to overheat the heat shrink.
This method reliably connects wires, but is only suitable for thin wires, no more than 0.5 mm², or flexible ones up to 2.5 mm².
How to connect headphone wires
Sometimes the cable near the plug breaks off in working headphones, but there is a plug from faulty headphones. There are also other situations in which it is necessary to connect the wires in the headphones.
To do this you need:
- cut off a broken plug or an unevenly torn cable;
- strip the external insulation by 15–20 mm;
- determine which of the internal wires is common and check the integrity of all conductors;
- trim internal wiring according to the principle: do not touch one, common by 5 mm and the second by 10 mm. This is done to reduce the thickness of the connection. There can be two common conductors - each earphone has its own. In this case they are twisted together. Sometimes a screen is used as a common conductor;
- strip the ends of the wires. If varnish is used as insulation, it will burn off during the tinning process;
- tin the ends to a length of 5 mm;
- put a piece of heat-shrink tubing on the wire 30 mm longer than the expected length of the connection;
- put pieces of thinner heat-shrinkable tube 10 mm long on the long ends, do not put on the middle (general) ends;
- twist the wires (long with short, and middle with middle);
- solder the twists;
- bend the soldered twists outward to the unprotected edges, slide pieces of thin heat-shrinkable tubing onto them and heat it with a hairdryer or lighter;
- Slide a larger diameter heat-shrinkable tube onto the joint and warm it up.
If everything was done carefully and the color of the tube was matched to the color of the cable, then the connection will be invisible and the headphones will work no worse than new ones.
How to brew twist
For good contact, the twist can be welded with a graphite electrode or gas burner. Torch welding has not become widespread due to the complexity and the need to use gas and oxygen cylinders, so this article only talks about electric welding.
Electric welding is performed using a graphite or carbon electrode. Graphite electrode is preferable. It is cheaper and provides best quality welding Instead of a purchased electrode, you can use a rod from a battery or a brush from an electric motor. It is better not to use copper electrodes. They often get stuck.
For welding, you first need to make a twist 100 mm long, so that the finished one turns out to be about 50. The protruding wires need to be trimmed. For welding, it is best to use an inverter welding machine with adjustable current. If this is not the case, then you can take a regular transformer with a power of at least 600 W and a voltage of 12–24 V.
Near the insulation, “ground” or “minus” is connected using a thick copper clamp. If you simply wrap a wire around a twist, the twist will overheat and melt the insulation.
Before starting welding, it is necessary to select the current. The required current varies depending on the number and thickness of the wire that makes up the twist. The welding duration should be no more than 2 seconds. If necessary, welding can be repeated. If everything was done correctly, then a neat ball will appear at the end of the twist, soldered to all the wires.
How to connect wires by crimping
Another way to connect wires is crimping. This is a method in which a copper or aluminum sleeve is placed on the wires or cables to be connected, and then crimped with a special crimper. For thin sleeves, a manual crimper is used, and for thick ones, a hydraulic one is used. This method can even connect copper and aluminum wires, which is unacceptable with a bolted connection.
To connect using this method, the cable is stripped to a length greater than the length of the sleeve, so that after putting on the sleeve, the wire sticks out 10–15 mm. If thin conductors are connected by crimping, then twisting can be done first. If the cable has a large cross-section, then, on the contrary, in the stripped areas it is necessary to align the wire, fold all the cables together and give them round shape. Depending on local conditions, the cables can be folded with the ends in one direction or in the opposite direction. This does not affect the reliability of the connection.
A sleeve is tightly placed on the prepared cables or, when laid in opposite directions, the wires are inserted into the sleeve from both sides. If there remains in the sleeve free place, then it is filled with pieces of copper or aluminum wire. And if the cables do not fit in the sleeve, then a few wires (5–7%) can be cut off with side cutters. In the absence of a sleeve the right size You can take a cable lug by sawing off the flat part of it.
The sleeve is pressed 2–3 times along its length. The crimping points should not be located at the edges of the sleeve. It is necessary to retreat 7–10 mm from them so as not to crush the wire during crimping.
The advantage of this method is that it allows you to connect wires of different sections and from different materials, which is difficult with other connection methods.
A fairly common connection method is a bolted connection. For this type you need a bolt, at least two washers and a nut. The diameter of the bolt depends on the thickness of the wire. It should be such that a ring can be made from the wire. If wires of different sections are connected, then the bolt is selected according to the largest one.
To implement bolted connection the end is cleared of insulation. The length of the stripped part should be such as to make a ring that fits onto the bolt using round pliers. If the wire is stranded (flexible), then the length should allow, after making the ring, to wrap the free end around the wire near the insulation.
In this way, you can connect only two identical wires. If there are more of them, or they are different in cross-section, rigidity and materials (copper and aluminum), then it is necessary to install conductive, usually steel washers. If you take a bolt of sufficient length, you can connect any number of wires.
Terminal block connection
A development of the bolted connection is the terminal connection. Terminal blocks come in two types - with a rectangular pressure washer and with a round one. When using a terminal block with a pressure washer, the insulation is removed to a length equal to half the width of the terminal block. The bolt is released, the wire is slipped under the washer and the bolt is clamped again. On one side, you can connect only two wires, preferably of the same cross-section and only flexible or only single-core.
Connecting to a terminal block with a round washer is no different from using a bolted connection.
The connection of the wires is reliable, but cumbersome. When connecting wires with a cross-section of more than 16 mm², the connection is unreliable or the use of lugs is necessary.
Self-clamping terminal blocks WAGO
In addition to terminal blocks with bolts, there are also terminal blocks with clamps. They are more expensive than usual, but they allow the connection to be made much faster, especially in connection with the new requirements of the PUE and the ban on twisting.
Most famous manufacturer Such terminal blocks are made by WAGO. Each terminal is a separate device with several holes for connecting wires, each of which is inserted into a separate wire. Depending on the version, it connects from 2 to 8 conductors. Some types are filled inside with conductive paste for better contact.
They are available for both detachable and permanent connections.
The stripped wire is simply inserted into the terminals for a permanent connection and spring tendrils fix the wire inside. Only hard (single-core) wire can be used.
In terminals for detachable connections, the wire is clamped using a folding lever and spring clamp, allowing you to easily connect and disconnect wires.
Since the wires do not touch each other, the terminals allow you to connect wires of different sections, single-core to stranded, copper to aluminum.
This method of connecting conductors has proven to work best at low currents and is most widespread in lighting networks. These terminals are small in size and easily fit into adapter boxes.
How to connect electrical wires with lugs
Another way is to use tips. The tip looks like a piece of tube, cut and turned flat on one side. A hole for a bolt is drilled in the flat part. The lugs allow you to connect cables of any diameter in any combination. Connect if necessary copper cable with aluminum, special tips are used, in which one part is copper and the other is aluminum. It is also possible to place a washer, brass or tinned copper, between the tips.
The ferrule is pressed onto the cable using a crimper, similar to how wires are connected using crimping.
Soldering tips
Another way to use the tip is to solder it. To do this you need:
- stripped copper cable;
- tip designed for soldering. It is distinguished by a hole near the flat part and a thinner wall;
- bath of molten tin;
- a jar of phosphoric acid;
- a jar of soda solution.
Carefully! Wear protective glasses and gloves!
In order to solder the tip, the cable is cleared of insulation along the length of the tubular part and inserted into the tip. The tip is then sequentially immersed in phosphoric acid, into molten tin for a time sufficient for the acid to boil away and the solder to flow into the tip. This is checked by periodically briefly removing it from the solder. After impregnating the tip and cable with solder, the tip is dipped in a soda solution. This is done to neutralize acid residues. The cooled tip can be washed clean water and ready for further work. Such a tip can be connected to aluminum busbars and lugs without the use of adapter washers.
Connectors for cables and wires
Cables can also be connected using special connectors. These are sections of pipe in which threads are cut and bolts are screwed in. There are detachable connectors, in which the bolts are unscrewed, and permanent ones. In permanent connectors, the bolt heads break off after clamping. There are also connectors designed to connect wires and cables of different sections. The cables are inserted end-to-end into the connectors, facing each other.
Connectors used on air lines power transmission, consist of two halves connected by bolts. The wires are laid in special grooves towards each other, parallel to each other, after which both halves are clamped with bolts.
Connecting wires and cables using couplings
If the cable to be connected is in the ground, water or rain, then conventional methods of isolating the connection are not suitable. Even if you apply a layer to the cable silicone sealant and compress it with heat shrink tube, this will not guarantee tightness. Therefore, it is necessary to use special couplings.
Couplings are available in plastic and metal casings, poured and heat-shrinkable, high-voltage and low-voltage, regular and small-sized. The choice of coupling depends on the specific operating conditions and the presence or absence of mechanical loads.
Connecting wires and cables is one of the most important points during electrical installation. Therefore, all methods of connecting electrical wires must ensure good contact. Poor contact or poor insulation may result in short circuit and fire.
Video on the topic
Power terminal
Soldering wires in headphones
It often happens that wires of different sections come into the junction box and they need to be connected. It seems like everything should be simple here, as with connecting wires of the same section, but there are some peculiarities here. There are several ways to connect cables of different thicknesses.
Remember that you cannot connect two wires of different sections to one contact in a socket, since the thin one will not be pressed tightly by the bolt. This will lead to poor contact, high contact resistance, overheating and melting of the cable insulation.
How to connect wires of different sections?
1. By twisting with soldering or welding
This is the most common way. You can twist wires of adjacent sections, for example 4 mm 2 and 2.5 mm 2. Now, if the diameters of the wires are very different, then good twisting will no longer work. When twisting, you need to make sure that both wires wrap around each other. Do not allow a thin wire to wrap around a thick one. This may result in poor electrical contact. Do not forget about further soldering or welding. Only after this will your connection work for many years without complaints.
2. Using screw clamps ZVI
I already wrote about them in detail in the article: Methods of connecting wires. Such terminal blocks allow you to insert a wire of one cross-section on one side, and a different cross-section on the other side. Here each core is clamped with a separate screw. Below is a table that will help you choose the right screw clamp for your wires.
| Screw clamp type | Permissible continuous current, A | |
| ZVI-3 | 1 - 2,5 | 3 |
| ZVI-5 | 1,5 - 4 | 5 |
| ZVI-10 | 2,5 - 6 | 10 |
| ZVI-15 | 4 - 10 | 15 |
| ZVI-20 | 4 - 10 | 20 |
| ZVI-30 | 6 - 16 | 30 |
| ZVI-60 | 6 - 16 | 60 |
| ZVI-80 | 10 - 25 | 80 |
| ZVI-100 | 10 - 25 | 100 |
| ZVI-150 | 16 - 35 | 150 |
As you can see, using ZVI you can connect wires of adjacent sections. Also remember to look at their amperage rating. The last digit in the screw terminal type indicates the amount of permissible continuous current that can flow through this terminal.
We strip the conductors to the middle of the terminal...
We insert them and tighten the screws...
3. Using Wago universal self-clamping terminals.
Wago terminal blocks have the ability to connect wires different sections. They have special sockets where each wire “sticks” into. For example, you can connect a 1.5 mm 2 wire into one hole of the clamp, and 4 mm 2 into the other, and everything will work properly.
According to the manufacturer's markings, terminals of different series can be used to connect wires of different sections. See table below:
| Wago terminal series | Cross-section of connected conductors, mm 2 | Permissible continuous current, A |
| 243 | 0.6 to 0.8 | 6 |
| 222 | 0,8 - 4,0 | 32 |
| 773-3 | 0.75 to 2.5 mm 2 | 24 |
| 273 | 1.5 to 4.0 | 24 |
| 773-173 | 2.5 to 6.0 mm 2 | 32 |
Below is an example with series 222...
4. Using a bolted connection.
A bolted connection of wires is a composite connection consisting of 2 or more wires, a bolt, a nut and several washers. It is considered reliable and durable.
Here it goes like this:
- we strip the core by 2-3 centimeters, so that it is enough for one full revolution around the bolt;
- we make a ring from the core according to the diameter of the bolt;
- take the bolt and put it on the washer;
- We put a ring of conductor of the same section on the bolt;
- then put on the intermediate washer;
- put on a ring made of a conductor of a different cross-section;
- We put the last washer and tighten the whole thing with a nut.
In this way, you can simultaneously connect several wires of different sections. Their number is limited by the length of the bolt.
5. By squeezing the branch “nut”.
I wrote about this connection in detail with photographs and corresponding comments in the article: Connecting wires using nut-type clamps. Let me not repeat myself here.
6. Using tinned copper tips through a bolt with a nut.
This method is well suited for connecting large cross-section cables. For this connection it is necessary to have not only TML tips, but also crimping pliers or Hydraulic Press. This connection will be a little bulky (long), may not fit into some small junction box, but still has the right to life.
It's easy to connect here. A ferrule is placed on each core, they are crimped and connected using a bolt with a nut and washers. This area is then insulated using insulating tape or heat-shrinkable tubing (it must be placed over the wire before connection).
Unfortunately, I didn’t have a thick wire and the necessary tips on hand, so I made a photo from what I had. I think you can still understand the essence of the connection from it.
I think I've listed everything. If you know other ways to connect wires of different sections, then write in the comments.
Let's smile:
There are two people sitting in the cell:
- Why are you imprisoned?
- For murder.
- How much did they give?
- 7 years. What are you for?
- For poaching.
- How many?
- Fifteen.
- Who were you hunting for?!
- I’m walking, so I’m hunting, I see a telegraph pole, an eagle is sitting on the pole. Well, I'm a doublet...
- So what?! 15 years for an eagle? Did you even kill him?
- Yeah... shot, claws in one direction, pliers in the other.
To ensure that the power supply in your homes is always of high quality, uninterrupted and reliable, it is very important when installation work connect the wires correctly. There are a lot of methods, we will consider each in detail separately with its advantages and disadvantages, with step by step instructions perform switching. We will also pay attention to the eternal question of electricians - how to connect wires whose cores are made of different metals(for example, copper and aluminum).
Removing the insulating layer from the wires
I would like to immediately dwell on a question that will be common to any method. Before connecting the wires into a common electrical unit, they must be stripped of the top insulating layer.
This can be done using a mechanic's knife. This method is simple, but there is a high probability of damage to the conductor. To do everything correctly, you must strictly follow the step-by-step instructions:
- Place the wire on some flat surface (such as a table).
- Press it with your left index finger.
- Right hand take a knife and lightly press it into the insulating sheath of the wire. To avoid snagging the metal core, position it towards the cut at an angle. If the angle is right, there is a possibility of a circular cut in the core, as a result of which it may subsequently break.
- Hold the knife in this position. Using the index finger of your left hand, slowly twist the conductor one full turn, thus cutting the insulation around the entire circle.
- All that remains is to pull off the cut piece of insulation.
Professional electricians now necessarily have in their arsenal such a device as a stripper. This is a multifunctional tool that can be used to strip insulation from a wire or cut a cable. It can be simple, semi-automatic or automatic. The most important thing is that when stripping the insulation with a stripper, the conductor is not damaged. For everyone standard diameter The core of such a tool has a calibrated hole with a cutting edge.
The length to which wire cores need to be stripped is different for each connection method.
Twist
Let's start with the simplest and known method– twists. It can also be called the oldest; it’s not for nothing that electricians call twisting the “old-fashioned method.”
We will not tell you that such a connection of wires is durable and reliable. According to the main document in electrical engineering, PUE (“Rules for Electrical Installations”), twisting is generally prohibited, despite the fact that half a century ago it was used everywhere. The fact is that in those days the load in the apartments consisted only of lighting, radio or television. Considering what the current load is in modern apartments with a huge amount household appliances used daily, then no old insulation, core cross-sections or methods of connecting wires are any longer suitable.
Nevertheless, we will talk about twisting, and even first of all, because it is the main stage of such connection options as welding and soldering.
Positive sides
The most important advantage of twisting is that it requires absolutely no material costs. All you need is a knife to remove the insulating layer from the wire cores and pliers to make the connection.
The second indisputable advantage of twisting is its ease of execution. You don’t need any special knowledge or skills; it can be done by anyone who has ever held pliers in their hands.
Several wires can be connected simultaneously in a twist, but their total number should not exceed six.
Negative sides
The main disadvantage of twisting is its unreliability; it weakens over time. This is due to the fact that there is residual elastic deformation in the cable or wire cores. At the point of twisting, the contact resistance increases, which can lead to contact failure and heating. IN best case scenario, you will detect this in time and re-seal the connection; in the worst case, a fire may occur.
Electrical wires made of different metals cannot be connected using twisting. As an exception, you can twist copper and aluminum wire, but only if the copper core is first tinned with solder.
In electrical engineering there are concepts of detachable or permanent connection. So twisting does not apply to one or the other. A detachable connection is characterized by the fact that its ends can be disconnected many times. This cannot be fully done in twisting; every time after the next unwinding and twisting of the cores, they will deteriorate. It is also impossible to call twisting a permanent connection, because it does not contain the concepts of strength, reliability and stability necessary for this. This is another disadvantage of the twist connection.
Installation
If for some reason you do not have the opportunity to use other methods of connecting electrical wires, you can use twisting, just do it well. Very often it is used as a temporary option and is subsequently replaced by more in reliable ways switching
How to connect wires using twist? To begin with, the cores are stripped to 70-80 mm. The main thing is to twist all switched conductors into one single twist at the same time, and not wind one around the other.
Many people mistakenly begin to twist the wires together from the place where the insulating layer ends. But it is better in this place to clamp both wires with one pair of pliers, and with the other, grab the ends of the wires and perform rotational movements in a clockwise direction.
If the wire cross-section is small, you can twist it by hand. Align the conductors along the cut of the insulation and hold them firmly in this place with your left hand. Bend all switchable ends into one single bend at an angle of 90 degrees (a bend length of 10-15 mm will be enough). Hold this bend with your right hand and rotate clockwise. This must be done firmly and firmly. If it is already difficult to twist your hands at the end, use pliers as described above. As soon as the twist becomes smooth and beautiful, you can trim the bend.
You can connect several wires this way, but then to make it easier to twist them, make the bend longer, somewhere around 20-30 mm.
How to properly twist wires is shown in this video:
There is also a way to twist wires using a screwdriver, see about it here:
For information on twisting wires using a special tool, see here:
Now the resulting twist must be carefully insulated. Electrical tape is used for this. Do not spare it, wind it in several layers, and insulate not only the connection itself, but also step 2-3 cm over the core insulation. This way, you will ensure the insulating reliability of the twist and protect the contact connection from moisture.
You can also insulate the connection of wires using heat pipes. The main thing is not to forget to put the tube on one of the cores to be connected in advance, and then push it into the place where it is twisted. When exposed to heat, the thermal tube shrinks, so slightly heat its edges and it will firmly grip the wire, thereby providing reliable insulation.
If the twist is done well, there is a chance that it will serve you long years, provided that the load current in the network is normal. But it’s still better not to stop at this stage and strengthen the joint by welding or soldering.
Soldering
Soldering is when electric wires connected using molten solder. This type of connection is most suitable for copper wires. Although there are now various fluxes for aluminum, experienced electricians prefer to refrain from such soldering. But if necessary, you can use special fluxes and even solder copper and aluminum.
Positive sides
This type of connection cannot be compared with twisting; soldering is much more reliable (in terms of reliability it is second only to welding).
Using soldering, you can connect stranded and single-core wires, as well as wires of different sections.
This type of connection does not require any maintenance throughout the entire period of operation.
Soldering is considered low in cost, the only equipment you need is a soldering iron, and flux and solder are very inexpensive, and their consumption is quite negligible.
Negative sides
The disadvantages of this method include high labor intensity. Soldering requires certain preparatory work, wire strands must first be tinned before twisting. The surfaces to be soldered must be free of oxides and absolutely clean before starting work.
And of course, you need experience in using a soldering iron, that is, the person who will connect the wires using the soldering method must have a certain qualification. Indeed, during the soldering process it is very important to maintain the necessary temperature regime. An underheated soldering iron will not heat the connection well; overheating is also unacceptable, because the flux will burn out very quickly, not having time to do its job.
Soldering is a slow process, but this disadvantage is compensated by the reliability of the contact connection.
Installation
The step-by-step soldering process is as follows:
- Remove the insulation from the cores by 40-50 mm.
- Sand the bare areas of the wires until they shine using sandpaper.
- Dip a heated soldering iron into rosin and move it over the cleaned surfaces several times.
- Perform a twist.
- Bring the soldering iron tip to the solder.
- Now immediately heat the twist with solder, the tin should melt and fill the gaps between the turns.
- Thus, the entire twist is enveloped in tin, after which it is allowed to cool.
- Wipe the hardened solder with alcohol and insulate it.
Soldering wires with a soldering iron is shown in this video:
Soldering wires using a gas soldering iron:
Soldering twists by immersion in molten solder:
Welding
In order for the connection of electrical wires to be as reliable as possible, the considered twisting method must be subsequently secured by welding. It is similar to soldering, only now a welding machine is used instead of a soldering iron.
Positive sides
This method is most preferable to all others, since it meets all regulatory requirements in terms of reliability and quality.
The welding method is based on contact heating of the ends of the wires with a carbon electrode until a ball (contact point) is formed. This ball is obtained as a single unit from the fused ends of all connected cores, which ensures safe and reliable contact; it will not weaken or oxidize over time.
Negative sides
The disadvantage of welding is that such work requires certain knowledge, experience, skills and special equipment; you often have to turn to specialists.
Installation
In order to connect wires using welding, you will need the following devices, tools and materials:
- welding inverter with a power of at least 1 kW, its output voltage must be up to 24 V;
- carbon or graphite electrode;
- goggles or eye mask;
- welding leather gloves to protect hands;
- a mechanic's knife or stripper for removing the insulating layer from conductors;
- sandpaper (for cleaning the conductive surfaces to be connected);
- insulating tape for further insulation of the welding joint.
The sequence of work is as follows:
- Free each connected wire from 60-70 mm of insulation.
- Sand the exposed wires until they are shiny using sandpaper.
- Twist, after biting, the length of its ends should be at least 50 mm.
- Attach grounding clamps to the top of the twist.
- To ignite the arc, bring the electrode to the bottom of the twist and lightly touch the connected wires with it. Welding happens very quickly.
- It turns out to be a contact ball, give it time to cool, and then insulate it with tape.
As a result, an almost solid wire is obtained at the end, that is, the contact will have the lowest transition resistance.
If you connect copper wires in this way, then choose a carbon-copper electrode.
I would like to recommend that if you purchase a welding machine (it will be useful not only for connecting wires, but also for many other purposes), then choose the inverter option. With small dimensions, weight and electrical energy consumption, it has a wide range of adjustment welding current and produces a stable welding arc. And this is very important to be able to regulate the welding current. If you choose it correctly, the electrode will not stick and the arc will hold steady.
Watch how welding is done in this video:
We looked at the main types of wire connections. Now let’s briefly talk about methods that are used less frequently, but also guarantee quality and reliability.
Crimping
For this method, special tubular sleeves or lugs are used, with which the wires to be connected are crimped and crimped. The essence of the method is the joint deformation of the sleeve and the cores inserted into it. When deformed, the sleeve contracts and puts pressure on the conductive surfaces. The conductors engage in mutual adhesion, which ensures reliable electrical contact.
The advantage of such a connection is its reliability, and also the fact that it can be classified as “set and forget”; it does not require maintenance.
But along with positive aspects Crimping also has a number of disadvantages. First, a special tool is required (a crimping press or mechanical or hydraulic pliers). Secondly, the quality of the connection directly depends on the correctly selected sleeve (it is selected depending on the number of cores being connected and their cross-section).
Before connecting two wires using crimping, they are not only stripped of insulation, but also lubricated with a special paste. Aluminum is treated with quartz-vaseline paste; it removes the oxide film and prevents it from appearing again. For copper conductors, quartz impurities are not needed; technical petroleum jelly is sufficient. It is needed to reduce friction. Lubrication also minimizes the risk of damage to the cores during deformation.
Next, the cores must be inserted into the sleeve until they mutually stop, and alternate crimping is performed on both sides. The pressed joint is insulated using insulating tape, varnished cloth or a thermal tube.
How to connect wires with sleeves is shown in these videos:
Bolted connection
Bolts for connecting wires used to be often used, now this method is more characteristic of circuits with high voltage. The contact is reliable, but the electrical unit connected in this way is too cumbersome. Until recently, large distribution boxes were installed in apartments; at least somehow, such a connection could be placed in them. Modern boxes are smaller and are not designed for switching wires using this method.
But you definitely need to know about it, because this is one of the ways to solve the eternal problem of connecting conductors made of various metals. The bolt contact is ideal for switching completely incompatible cores - thin and thick, aluminum and copper, single-core and stranded.
The wire strands must be stripped and the ends twisted into rings. A steel washer is put on the bolt, then rings of wires to be connected are put on (this is the case when they are made of homogeneous metal), then another steel washer follows and everything is tightened with a nut. If aluminum and copper wires are connected, another additional washer must be placed between them.
The advantages of this connection are its simplicity. If necessary, the bolted structure can always be unscrewed. If necessary, you can add more wire strands (as long as the bolt length allows).
The most important thing in this type of connection is to prevent direct contact between copper and aluminum, and do not forget to place an additional washer between them. And then such a switching unit will serve for a long time and reliably.
Modern technologies
In many cases, the methods discussed are gradually becoming a thing of the past. They were replaced by factory wire connectors, which made installation and switching work much easier and faster:
- Terminal blocks, inside of which there are tubular brass sleeves. Stripped wire strands are inserted into these tubes and secured by tightening the screws.
- PPE caps, inside of which there are compression springs. The cores are inserted into the cap and then turned clockwise with little effort, thereby reliably compressing the connected wires inside.
- Self-clamping terminals. It is enough to place the wiring in them, and there it is automatically fixed due to the pressure plate.
- Lever-type terminal blocks. Such connecting element reusable. It is enough just to lift the lever, insert the conductor into the contact hole and lower the lever back, reliable fixation is ensured.
We do not talk in detail about all existing terminal blocks, since there is a separate article about this, where each type of wire clamp is discussed in detail.
We hope that we have clearly explained to you how to connect the wires correctly. Choose the method that suits you best. When choosing, take into account the cross-section and material of the conductors, the location of the connection (outdoors or indoors), and the amount of load current that will flow in this electrical circuit.
It would seem that what could be simpler than connecting wires? After all, there are several ways to connect wires. This includes twisting wires, soldering wires, welding wires, crimping and connecting wires using a terminal block. Even a schoolboy knows the easiest way to twist conductors. You need to put the ends of the metal wires, called strands, together and twist them into one “pigtail”, and then wrap them with electrical tape. There is no need for a soldering iron, terminal block, connecting caps and other “unnecessaries”.
Any “own electrician” has mastered this operation. And, when the need arises, he applies this method in his daily practice. For example, it splices the power cord wires of a household appliance, tablet or computer adapter after a break.
Russian “technicians” use this technology for fastening wires everywhere. It’s just that the rules for constructing electrical installations of PES do not provide for “twisting”, all kinds of “bends” and “rivets”. There are no such methods of electrical installation in other regulatory documents. Why?
We often don’t think about the consequences of such a “simplification”. Meanwhile, no reliable contact fails at the most inopportune moment, the supply of power to consumers/electrical receivers may always be cut off. Voltage “surges” cause breakdown of the elements of the power cascades of complex SBT household appliances. They don’t even save you from breakdown special devices protection used in the most sophisticated models of foreign manufacturers.
Induction of short electromagnetic pulses with a voltage of several thousand volts onto electronic stuffing causes “harmless” sparking at the joints. At the same time, the standard protection equipment that apartments are now equipped with (RCD, circuit breakers, fuses) such short low-current pulses are not “seen”, so they simply do not trigger, and we do not customarily install special devices for this. Sources uninterruptible power supply Computers also did not become a panacea for transient impulses. The occurrence of “poke” causes malfunctions in the operation of electronic equipment and computer equipment, leading to failure of electrical components and expensive functional modules.
Overheating at the site of a poor connection leads to even more catastrophic consequences; when current passes, the weakened connecting node becomes red-hot. This often causes fires and fires, causing enormous damage to the owners of the premises. Statistics show that 90% of all electrical 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 the fires that occur in Russia.
However, it so happened historically that several decades ago, in conditions of a shortage of electrical accessories/copper conductors, twisting aluminum wires was considered the main method used in electrical installation work. Twisting as a connection can be used in electrical engineering when carrying out repair and restoration work.
How to connect wires correctly
How to connect the wires: we start by removing the insulation. Correct connection of conductors must satisfy three basic requirements:
- Ensure reliable contact with a minimum transition resistance between each other, close to the resistance of a single piece of wire.
- Maintain tensile strength, fracture resistance 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 wiring requirements and capabilities practical application, the following types of wire connections are used:
All these methods require preliminary preparation wire or cable - stripping the insulation to expose the connected cores. Traditionally, rubber, polystyrene, and fluoroplastic are used as insulating shell materials. Additionally, polyethylene, silk and varnish serve as insulation inside. Depending on the structure of the conductive part, the wire can be single-core or multi-core.
By single-core is meant a wire whose cross-section is formed by an insulating sheath with a metal core or wiring inside.
In a stranded wire, the metal core is formed by several thin wires. They are usually intertwined and represent a lay, surrounded on the outside by an insulator. Often individual veins become covered 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 process of removing the insulation.
Depending on the type of connection, 0.2–5.0 cm of insulation is removed from each end of the wire. Several types of tools are used for this.
Using a 5-point system, you can evaluate the quality of insulation removal and the degree of protection against cutting - damage to cores by each device:
Damage to insulation/core
Monter (kitchen) knife – 3/3
Side cutters (nippers) - 4/3
Stripper - 5/4
Soldering iron or electric 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 shielding braid. To access the central vein, it is fluffed up and removed, exposing the trunk. After which the polyethylene insulation is cut with a knife or a special device, the trim is removed from the core.
The bifilar in the screen consists of a pair of wires in the screen, which, in order to access the conductors, is also pre-fluffed into wires, allowing access to each core.
Important! To remove the insulating material of an enameled wire with a cross-section of less than 0.2 mm², a soldering iron should be used. The enamel is carefully removed using sandpaper and moving the paper along the wires.
How to twist wires correctly
Most often, twisting is used in the repair of electrical wiring, cords and adapters (including low-current) household appliances and equipment. If we are talking about the home electrical network, then the standards provide for the use in homes of wires with a current-carrying core cross-section of 1.5–2.0 mm made of copper and 2.5–4.0 mm made of aluminum. Typically, wires of the VVG and PV brands in a polyvinyl chloride 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.
You can splice the wires together step by step as follows:
- Degrease the bare ends of the wires by wiping with acetone/alcohol.
- We remove the varnish layer or oxide film by sanding the conductors with sandpaper.
- Apply the ends so that they intersect. We wind clockwise at least 5 turns of one core onto another. To make the twist tight, use pliers.
- We insulate the open current-carrying parts of the wires using electrical tape, or screw on an insulating cap. They should extend beyond the insulation for 1.5–2.0 s to cover the exposed areas of the conductors.
To splice a stranded stripped wire with a single-core wire, another winding technique is used:
- A single wire is wrapped with a stranded wire, leaving the end free 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 better efficiency an insulating heat pipe should be used. To do this, a piece of cambric of the required length is pulled over the connection. To make it grip the wiring more tightly, the tube should be heated, for example, with a hair dryer or lighter.
With a bandage connection, the free ends are placed next to each other and wrapped on top 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 interconnected, then the edges are wrapped.
There are more complex varieties of parallel/serial connections. Connecting wires using the twisting method is used by professional electrical repairmen when carrying out restoration work.
Important! Copper and aluminum have different ohmic resistances; when they interact, they actively oxidize; due to different hardnesses, the connection turns out to be fragile, so the connection of these metals is undesirable. In case of emergency, the ends to be connected should be prepared - tinned with tin-lead solder (PLS) using a soldering iron.
Why is it better to crimp (crimp) wires?
Wire crimping is one of the most reliable and high-quality methods of mechanical connections currently used. With this technology, loops of wires and cables are crimped into a connecting sleeve using press pliers, ensuring tight contact along the entire length.
The sleeve is a hollow tube and can be made independently. For liner sizes up to 120 mm², mechanical pliers are used. For large sections, products with a hydraulic punch are used.
When compressed, 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 of 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. Wire connections using the crimp method are used for conductor 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, which is prohibited for electrical installation, is to connect wires using the soldering method. It requires special tools and Supplies, but provides absolute electrical contact.
Advice! Overlapping wire soldering is considered the most unreliable in 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 being connected, or twist the conductors together.
You will need an electric soldering iron with a power of 60–100 W, a stand and tweezers (pliers). The soldering iron tip should be cleaned of scale, sharpened, having first selected the most suitable tip shape in the form of a spatula, and the device body should be connected to the ground wire. Among the “consumables” you will need POS-40, POS-60 solder from tin and lead, rosin as a flux. You can use solder wire with rosin placed inside the structure.
If you need to solder steel, brass or aluminum, you will need a special soldering acid.
Important! Do not overheat the junction points. To prevent the insulation from melting when soldering, be sure to use a heat sink. To do this, hold the bare wire between the heating point and the insulation with tweezers or needle-nose pliers.
- The wires stripped of insulation should be tinned, 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 into the solder, grab a drop of molten solder and evenly process the wires one by one, turning and moving along the tip blade.
- Attach or twist the wires together, securing them motionless. Warm up with the tip for 2–5 s. Treat the areas to be soldered with a layer of solder, allowing the drop to spread over the surfaces. Turn over the wires to be connected and repeat the operation on the reverse side.
- After cooling, the soldering joints are insulated in the same way as twisting. In some compounds, they are pre-treated with a brush dipped in alcohol and coated with varnish.
Advice! During and after soldering for 5–8 s. The wires cannot be pulled or moved, they must be in a stationary position. A signal that the structure has hardened is when the solder surface acquires a matte tint (it shines in the molten state).
But welding is still preferable
In terms of connection strength and contact quality, welding surpasses all other technologies. Recently, portable welding inverters, which can be transferred to the most inaccessible places. Such devices are easily held on the welder's shoulder using a belt. This allows you to work in hard to reach places, for example, welding from a stepladder in a distribution box. To weld metal cores, 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 being welded and melting of the insulation - is eliminated using:
- Correct adjustment of the welding current 70–120 A without overheating (depending on the number of welded wires with a cross-section from 1.5 to 2.0 mm).
- The duration of the welding process is no more than 1–2 seconds.
- Tightly pre-twist the wires and install a copper heat sink clamp.
When connecting wires by welding, the twisted wires should be bent and the cut side must be turned upward. An electrode is brought to the end of the wires connected to ground and the electric arc is ignited. The molten copper flows down in a ball and covers the twisted wire with a sheath. During the cooling process, an insulating belt made from a piece of cambric or other insulating material is put on the warm structure. Lacquered fabric is also suitable as an insulating material.
Terminal blocks are the most ergonomic electrical installation products
The PUE rules, clause 2.1.21 provide for the type of connections using clamps (screws, bolts). There is a connection directly using hanging fasteners, when a screw and washer are threaded through the loops of each wire and secured with a nut on the reverse side.
This installation is wrapped with several turns of electrical tape and is considered quite practical and reliable.
Electrical installation products called screw terminal blocks are more ergonomic. They represent a contact group housed in a housing made of insulating material (plastic, porcelain). The most common way to connect wires using terminal blocks is in distribution boxes and electrical panels. To connect the wire, you need to insert it into the socket and tighten the screw, clamping bar will securely fasten the core to the seat. Another connecting wire is connected to the mating socket, short-circuited with the first one.
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.
Branch clamps represent a permanent version of a screw terminal block with several short-circuited taps; they are used mainly on the street and in places with unfavorable conditions environment.
The connecting clamps are an insulating cap with a thread inside; it is screwed onto the twist, simultaneously compressing and protecting from mechanical stress.
Today, a bunch of different ways to connect have been invented. But, for some reason, the “bite off, twist and wrap with electrical tape” method does not give up its position.
But there are also things that are fundamentally wrong.
The reason is that twisting two wires from different materials, for example, copper and aluminum, is absolutely not correct. The fact is that when an aluminum wire oxidizes, galvanic steam is released, which will eventually break the connection. And the more current passes through this connection, the sooner it will fail. And, if the load on the wires is not constant, then constant heating and cooling will only worsen the condition of the wiring.
Connecting wires this way can be dangerous. So, sparks in a connection can lead to a fire.
Fortunately, there is a sure way out of the situation.
For example, here’s a thing called a polyethylene terminal block:
You can buy such a simple contraption at any hardware store. And if you pull the brass sleeve out of it, you can clearly see how the wires are connected:
You need to insert the ends into it and tighten the screws:
When folded, that is, in normal form, it looks like this:
And, by the way, each insulating segment can be disconnected from each other. So, at first glance everything is perfect and simple, but no. And here there were shortcomings.
If you clamp an aluminum wire, you need to make sure that it doesn’t turn out like this: 
This clear example the fact that aluminum cannot be clamped, and if this happens, then the terminals need to be changed once a year. Otherwise, the contact will heat up and this will lead to a fire.
Do not clamp multi-core wires in the sleeve. You may be unlucky and something you already know about will happen.
It's important to choose right size sleeves to match the diameter of the wire, otherwise it may fall out or break if pinched.
When buying a terminal block, do not be fooled by the inscriptions on it. They are lying. It is better to divide the current into 2 or 3 sleeves.
And as practice says, it is better not to buy such terminals at all. And if you use it, then only to connect something small, a light bulb, for example.
The same goes for unnamed Chinese gizmos. It's better to be safe than sorry. Therefore, buy terminals from normal, proven manufacturers, such as: Tridonik, ABB, Legrand, Verit
TB Series Terminal Blocks
Made of hard black plastic, they have a lid. This one is already much better than the previous one.
The inside consists of two screws and a plate:
Here you need to wrap it around the screw and press it with a plate:
It’s a good thing, because here the wires are clamped by an iron plate, and not by the screw itself, which is undoubtedly a big plus.
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The surface is such that it does not increase the clamping surface by much, which means that both stranded and single-core can be clamped. But still, aluminum ones should be checked from time to time. What's bad about these terminals is that they don't share. And there are hardly any less than 6 pieces.
Self-clamping terminals (WAGO, REXANT 773 series)
They look like this:
Extremely convenient clamps. What you need is to simply strip the wire and push it in until it stops:
Inside that terminal there is this thing, where the blue arrow indicates a pressure plate, and the orange arrow indicates a small bar made of tinned copper:
This is what happens when a wire is inserted into it:
That is, the wire is pressed tightly against the bar with a plate and holds it there constantly, preventing it from falling out.
You can even push an aluminum wire into this terminal without fear.
Here are exactly the same, but transparent terminals:
The advantage of them is that through the translucent walls you can see how deep the wiring is inserted. This terminal is suitable for 4 kW. However, there is one big BUT. This means that only original WAGO terminals have such capabilities. For the rest, the maximum current is limited to a lower value.
WAGO 222 Series Terminals
Such terminals will be indispensable if there are wires different diameters and from different materials.
These terminals have levers:
When the lever is raised, you need to insert the wires and fix it by lowering the lever:
You can replace the wire by lifting the lever and pulling it out. Smart thing, conducts current up to 32A.
