When installing electrical wiring in a house or apartment, connecting the wires is the most important point. For trouble-free and safe power supply, you will need a reliable and high-quality connection of wires.
A careless attitude towards connecting wires and cables can lead to very bad consequences. It would seem that there is nothing complicated in connecting the wires, twist them, wrap them with electrical tape and everything is ready, but everything is not so simple... as popular wisdom says "Electrics is the science of contacts", and the connection of wires and cables must be carried out with all responsibility, since the percentage of accidents and damage in power supply systems due to poor-quality connection of wires is very high. No matter how good the electrical contact between the wires is, wire connections have higher resistance, which means they heat up more. And the worse the contact, the more it heats up, which will ultimately lead to melting of the insulation, a short circuit, and then a fire.
In practice, several methods of connecting wires are used, I will tell you about the most common ones.
Connecting wires by twisting
Connecting wires twisted, widespreadeverywhere, but if we turn to the main book of electricians PUE, then according to:
clause 2.1.21 “Connection, branching and termination of cables and wire cores must be done by soldering, welding, crimping or clamping (screw, bolt, etc.)”
As we can see, there is no twisted connection of wires at this point, which means twisting of wires is prohibited. But twists have always been, are and will be used to connect wires when installing electrical wiring. Yes, and well-made twisting can last for decades, but the connection of wires by twisting must be done efficiently. The technology for connecting wires and cables by twisting is quite simple:
- the twist length must be at least 4-5 cm;
- The connected wires, stripped of insulation, must be cleaned of the oxidized film, for example, with an ordinary knife or sandpaper;
- It is necessary that the connected wires wrap around each other evenly and tightly, ensuring sufficiently reliable contact.
One “but”, problems may arise when handing over the electrical installation to the fire inspectorate, because... Connecting wires by twisting according to the PUE is prohibited. However, this applies mainly to industrial consumers, retail premises, etc.; a fire inspector will not come to your apartment or private house to inspect it.
Connecting wires by twisting- This forced measure, when there is nothing else left, it is better to use wire connections using the methods described below.
Connecting wires by soldering
If solder twisted wires, then we get the connection of wires soldering, which guarantees reliable and high-quality contact, which has a fairly low contact resistance, high conductivity and mechanical strength. But it is important to solder the wire connection correctly; for this you need:
- tin the connected wires with rosin (flux);
- the solder should flow into the twist;
- After the solder has cooled, you can sand it with sandpaper, because sharp edges of the solder can pierce the insulation;
- insulate the wire connection.
But such connection of wires by soldering is very labor-intensive and requires certain skills. TO negative sides of soldering wire connections, I would classify:
- need for isolation;
- complexity (not everyone knows how to solder well), and even for those who are good at soldering, doing this, for example, while standing on a stepladder or ladder, to put it mildly, is not very convenient;
- if a mistake was made when connecting the wires, it will not be easy to separate them after soldering, so it is better to leave a larger supply of wires and cables;
- high time consumption.
Connecting wires by welding
Connecting wires welding provides even better electrical contact between wires. But here everything is even more confusing than with soldering wires, since you need to have:
- welding transformer;
- welding skills;
- masks (goggles) for welding, special gloves, electrodes;
- construction hair dryer for heat shrink tube.
Wire connection by welding, you can perform only from homogeneous metals. Such a connection of wires can be found infrequently, our people do not really like difficulties, and many electricians do not like this method of connecting wires due to the large investment of time, but it is worth noting that connecting wires by welding is faster than soldering.
Connecting wires by crimping
Connecting wires crimping, consists of compressing the connecting sleeve (aluminum or copper tube) into which the wires are inserted with special press pliers. The wires are first stripped of insulation to the length of the sleeve, then we place the wires inside the sleeve and crimp it in two or three places for reliability. If the sleeve is much larger than the wires that need to be crimped, then you can stuff the sleeve with additional wires. We insulate the resulting wire connection using crimping tape, or better yet, heat-shrink tubing + hair dryer.
Sleeves for connecting wires by crimping, there are copper, aluminum and copper-aluminum, i.e. Crimping can be used to connect copper and aluminum wires.
Connecting wires using crimping is quite reliable if done correctly. Your skills in connecting wires using crimping will also be useful when, for crimping NShVI bushings.
The disadvantages include the cost of pressing pliers for connecting wires by crimping and sleeves, the inseparability of connecting wires by crimping, i.e. they crimped the wire in the sleeve and “forgot” about it.
Bolted connection of wires and cables
Bolted connection wires, as a rule, are used when connecting wires made of different metals, that is, if we have one wire made of copper and the second of aluminum, a steel washer must be placed between them.
This connection of wires turns out to be very cumbersome, it is inconvenient to place it in junction boxes and insulate it. Periodic broaching is required.
Connecting wires with screw terminals
Connecting wires screw terminal blocks, as well as bolted, can be used to connect wires made of different metals. This wire connection meets the requirements of the PUE, but requires periodic tightening of screws in terminals that weaken over time, which means the contact itself weakens, which can close over time.
Periodic pulling the screw connection of wires involves, What connection access in a box should always be open, which will not look very nice in an apartment or private house. Also, when tightening the screw, you can damage the wire itself, especially the softer aluminum one. And if you need to connect a stranded wire, then you need to either solder the stripped ends of the wire or crimp it with tubular lugs.
Connecting wires with PPE caps
Connecting wires PPE caps(Connection Insulating Clamps). PPE are plastic caps with a conical spring inside, which, when twisted, compresses and secures the wires, and the plastic PPE cap itself insulates the connection of the wires and is fire and mechanical protection.
This wire connection is quick and simple; to perform it correctly you need:
- strip the insulation from wires and cables to a length slightly shorter than the length of the PPE cap itself;
- fold them into a bundle, precisely into a bundle, and not twist them;
- use your hands to twist the PPE clockwise onto the bundle of wires;
- tighten the PPE using pliers.
The advantages of such a connection wires and cables are obvious (no special tools required, no need for additional insulation, quick and easy), but there are also disadvantages:
- Do not connect stranded wires;
- the quality of such a connection will be worse than those listed above, so I would recommend using these clamps for small loads, for example, in lighting circuits.
PPE caps are divided according to the total cross-section of the wires to be twisted and are designated by numbers from 1 to 5, which indicate the number of wires to be twisted and their cross-section.
Connecting wires with self-clamping (spring) terminals
Well, in conclusion, let’s look at the simplest, most effective, convenient, and most importantly fast connection of wires - self-clamping (spring) terminals. Spring terminals from Wago are widely used, which allow you to connect wires:
- without having any special skills;
- there is no need to purchase special tools (soldering iron, welding transformer, press pliers);
- some Wago terminals have a special paste that allows you to connect copper and aluminum wires and prevents oxidation;
- no additional insulation required;
- quick disconnection of the connection (press the lever and pull out the desired wire).
Wago terminals are produced for connecting wires and cables from 0.75 to 4 sq.mm., the number of connected wires is from 2 to 8. Wago terminals
Wago terminal blocks were invented in Germany. Perhaps the most significant disadvantage is their price, the average cost of a Wago terminal block for 3 wires will be approximately 11-12 rubles, so if there are a lot of distribution boxes, then the total cost of Wago terminal blocks will be considerable. You should not use Wago terminals when installing wiring with loads of more than 16 A. In general, it is better to use them maximum on the lighting line for electrical wiring in a private house or apartment, and choose Wago terminal blocks with a margin of at least a step higher.
The article describes various methods of connecting wires when installing electrical wiring.
Electrical wiring requires reliable connection of wires. In the sixties and seventies of the twentieth century, during the construction of “Khrushchev’s” houses, wiring, purely for economic reasons, was carried out with aluminum wire.
All connections in this wiring were made by twisting, which were insulated with black fabric tape, and could last ten years or more without requiring any maintenance or preventive maintenance. Of course, if the twisting was performed according to all the rules. Therefore, old electricians claim that there is simply no more reliable connection than twisting.
They are partly right. In those days, there was no other method, and it was not required, since apartments did not yet have such an abundance of electrical and electronic equipment as they do now. The power of refrigerators, washing machines, irons and electric kettles of that time was much lower than modern ones. And not all of them had refrigerators, televisions and washing machines.
And such electricity consumers as air conditioners and computers were not used in apartments at all. They simply hadn't been invented yet. Therefore, it was possible to carry out the wiring with aluminum wires, as well.
Requirements for modern wiring
In modern conditions, wiring is most often done with copper wires, which allows you to connect a load of almost any power. Various methods are now used to connect wires. This is stipulated in the electrical installation rules (PUE). They literally say this: quote.
PUE: clause 2.1.21. Connection, branching and terminating of wires and cables must be carried out using crimping, welding, soldering or clamping (screw, bolt, etc.) in accordance with current instructions.
From this paragraph of the rules it follows that it is impossible to connect wires by twisting, it simply is not in the specified paragraph. If a fire inspector accepts the wiring, then he simply will not accept the wiring made using the twisting method, and it will have to be redone. Twists are permissible only as a temporary connection before welding, which will be discussed in the next article.
Connecting wires using clamps
According to the specified paragraph of the PUE, for connecting wires there are currently terminal blocks, which should be used. The most common are three types of terminal blocks. These are self-clamping, screw and connecting insulating clamps. Figure 1 shows a self-clamping terminal block.
Figure 1. Self-clamping terminal block
Self-clamping terminal blocks are designed for connecting wires with a cross-section of up to 2.5 mm2, their operating current reaches up to 24A, which allows you to connect a load of up to 5KW. The number of places in such terminal blocks is from 2 to 8, which significantly speeds up the installation of wiring in general. True, compared to twisting, they take up more space in junction boxes, which is not always convenient.
The design of screw terminal blocks is shown in Figure 2.
Figure 2. Screw terminal block
This type of terminal blocks is the most common and therefore used more often than other types. Their main area of application is connecting wires in junction boxes. However, if the wiring is done with aluminum wire, you should refrain from using such terminal blocks, since when tightening the screws it is possible to pinch and break the soft aluminum wire.
The third type of mechanical wire connectors is connecting wires. Their appearance is shown in Figure 3.
Figure 3. PPE clamps
This clamp is a plastic case, inside of which there is an anodized conical spring. To connect the wires, they are stripped to a length of about 10 - 15 mm and folded into a common bundle. Then the PPE is screwed onto it, rotating clockwise until it stops. With their help, it is possible to connect several single wires with a total area of 2.5 - 20 mm2. Naturally, the caps in these cases are of different sizes.
Such clamps speed up installation and, due to the insulated housing, do not require additional insulation. True, their connection quality is somewhat lower than that of screw terminal blocks. Therefore, other things being equal, preference should still be given to the latter.
Connecting wires by soldering
Connecting wires by soldering and welding is more reliable than using terminal connectors of various designs. Copper wires lend themselves best to soldering, and although there are currently various fluxes for soldering aluminum, it is better to refrain from such soldering.
Compared to welding, it is simpler and more accessible: it does not require expensive equipment, is less fire hazardous, and the skills needed to perform good quality soldering will require more modest skills than when performing a welded joint.
If soldering twists is done from time to time, for example, you decide in your apartment, then it is quite possible to get by with a power of at least 100 W. When you have to solder twists almost every day, as regards your main or additional work, it is better to use the same hundred-watt soldering iron after first modifying its tip, as indicated in Figure 4.
Figure 4. Reworking the soldering iron tip
To do this modification, you should remove the soldering tip from the soldering iron body and grind it off with a file or cut off its working wedge-shaped part with a hacksaw. After this operation, drill a hole with a diameter of 6 - 7 mm to a depth of 30 - 40 mm in the copper tip.
Although special precision when drilling in this case is not required, if possible, it is better to trim the end and drill a hole on a lathe.
After installing the tip back into the soldering iron, the hole must be tinned from the inside, just as is done for a simple soldering iron. Thus, a small-sized tin bath is obtained.
Before soldering, of course, the insulation is first removed from each wire to a length of 40..50 mm, and each individual wire is stripped to a metallic shine, after which it is tinned.
To do this, melt a small amount of solder in the hole of the soldering rod, then add a little rosin and immerse the wire in the hole. If there is some kind of liquid flux, for example, a solution of rosin in alcohol, then simply lubricate the wire with liquid flux and dip the wire into the molten solder.
Then carefully twist the tinned wires, cut the ends at the same level and, holding them with pliers, dip them into the soldering bath.
In such a device it is possible to solder a twist of 4 - 6 cores with a cross-section of up to 2.5 mm2. In this case, the twist should be held in the hole of the tip for about 3 - 4 seconds to fully warm up. The soldering should air cool and have a shiny, contoured appearance.
When using pine rosin as a flux, the solder joint does not need to be washed. If you use other fluxes, you must act in accordance with the instructions attached to them.
It is completely unacceptable to cool the soldering with water to speed up the process: this leads to the formation of microcracks and, naturally, deterioration in the quality of the connection.
It is best to insulate the twists using an appropriate diameter, heating it with a technical hair dryer. If you don’t have a tube, you can use regular electrical tape, wrapping it in at least three layers.
To ensure that the power supply in your homes is always of high quality, uninterrupted and reliable, it is very important to correctly connect the wires during installation work. There are a lot of methods, we will consider each in detail separately with its advantages and disadvantages, with step-by-step instructions for performing 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.
- With your right hand, take the 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 each standard core diameter, 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 most well-known method - twisting. 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 the Construction of 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 apartments consisted only of lighting, radio or television. If you consider the current load in modern apartments with a huge number of household appliances used daily, then no old insulation, core cross-sections and 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 aspects
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.
Negatives
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 the best case, 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 reliable switching methods.
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 twisting is done well, there is a chance that it will serve you for many 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 electrical wires are joined 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 aspects
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.
Negatives
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. After all, during the soldering process it is very important to maintain the required temperature conditions. 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 aspects
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.
Negatives
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:
- Remove 60-70 mm of insulation from each wire to be connected.
- 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 welding current adjustment 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 this video to see how welding is performed:
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 enter into 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 the 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 different 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. This connecting element is 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.
When connecting wires of different diameters in series, the maximum load current will be determined by the cross-section of the wire with a smaller diameter. For example, a connection was made between copper wires with a diameter of 1.6 mm and 2 mm. In this case, the maximum load current on the electrical wiring, which is determined from the table, will be 10 A, and not 16 A, as for a wire with a diameter of 2 mm.
Connecting electrical wires by twisting
Until recently, twisting was the most common method of connecting wires when doing electrical wiring; due to its accessibility, all it took was a knife and pliers. But, according to statistics, twisting is an unreliable way to connect conductors.
According to the electrical installation rules (PUE), twisted connections when installing electrical wiring are prohibited. But, despite the noted disadvantages, the twisting method is currently widely used. Connecting conductors of low-current circuits by twisting, subject to certain rules, is quite justified.
The photo on the left shows how twisting is unacceptable. If one conductor is twisted around another, the mechanical strength of such a connection will be insufficient. When twisting wires, you must make at least three turns of wires around each other. In the middle photo, the twisting is done correctly, but a copper conductor is twisted with an aluminum one, which is not permissible, since when copper comes into contact with aluminum, an emf of more than 0.6 mV occurs.
In the photo on the right, the twisting of copper and aluminum wires is done correctly, since the copper wire is tinned with solder before twisting. You can twist several wires together at once; in a junction box, sometimes up to 6 conductors are twisted, wires of different diameters and from different metals, a stranded wire with a single-core wire. Only the stranded wire needs to be made single-core by first soldering it with solder.
Connecting electrical wires by soldering
The connection of copper wires with high-quality soldering is the most reliable and is practically not inferior to a solid wire. All of the above examples of twisted wires, except for aluminum and tinsel, when tinning the conductors before twisting and then soldering them with solder, will be reliable on a par with solid wires. The only drawback is the extra labor involved, but it's worth it.
If you need to connect a pair of wires and the twisted conductors must be directed in different directions, then a slightly different type of twist is used.
By splicing two pairs of double wires in the manner described below, it is possible to obtain a compact and beautiful connection by twisting both single-core and multi-core pairs of conductors. This twisting method can be successfully used, for example, when splicing broken wires in a wall, extending a wire when moving a socket or switch from one place on the wall to another, when repairing or extending the length of a carrying cable.
To obtain a reliable and beautiful connection, it is necessary to adjust the lengths of the ends of the conductors with a shift of 2-3 cm.
Twist the conductors in pairs. With this type of twisting, two turns are enough for a single-core wire, and five turns for a multi-core wire.
If you plan to hide the twists under plaster or in another inaccessible place, then the twists must be soldered. After soldering, you need to go over the solder with sandpaper to remove any sharp solder icicles that could pierce the insulation and stick out from it. You can do without soldering if the connection is accessible and the currents flowing through the conductors are not large, but the durability of the connection without soldering will be much lower.
Due to the shift of the twisting points, there is no need to isolate each of the connections separately. We attach a strip of insulating tape on both sides along the conductors. Finally, you need to wind three more layers of insulating tape. According to the requirements of the Electrical Safety Rules, there must be at least three layers.
Wires spliced and soldered in the manner described above can be safely laid in the wall and plastered on top. Before installation, it is advisable to protect the connection with a vinyl chloride tube placed in advance on one of the pairs of wires. I have done this many times, and the reliability has been confirmed by time.
Connecting wires in junction boxes
When I moved into an apartment built in 1958 and began doing renovations, I was immediately confronted with the blinking of the lighting bulbs in rhythm with the hammer blows on the walls. The primary task of repair arose, carrying out an audit of distribution boxes. Opening them revealed the presence of poor contact in the twisted copper wires. To restore contact, it was necessary to disconnect the twists, clean the ends of the wires with sandpaper and twist them again.
When trying to disconnect, I encountered a seemingly insurmountable obstacle. The ends of the wires broke off even without any effort. Over time, copper lost its elasticity and became brittle. When stripping the wire, the insulation was apparently cut in a circle with a knife blade and notches were made. It was in these places that the wire broke off. The copper became hardened due to temperature fluctuations.
You can restore the elasticity of copper, unlike ferrous metals, by heating it to red and quickly cooling it. But for this case, such a technique is unacceptable. The ends of the wires no longer than 4 cm remained. There was no choice for connection. Just solder.
I exposed the wires with a soldering iron, melted the insulation, tinned them with solder, tied them in groups with tinned copper wire and filled them with solder using a 60-watt soldering iron. The question immediately arises: how to solder the wires in the junction box if the electrical wiring is de-energized? The answer is simple, using a soldering iron powered by a battery.
So I updated the connections in all junction boxes, spending no more than 1 hour on each. I am completely confident in the reliability of the connections made, and this has been confirmed by the 18 years that have passed since then. Here's a photo of one of my boxes.
When leveling the walls with Rotband in the hallway and installing a stretch ceiling, the distribution boxes became a hindrance. I had to open them all, and the reliability of the solder connection was confirmed; they were in perfect condition. That's why I boldly hid all the boxes in the wall.
Connections currently practiced using a Wago flat-spring terminal block greatly reduce the time spent on installation work, but are much inferior in reliability to solder connections. And if there are no spring-loaded contacts in the block, they make connections in high-current circuits completely unreliable.
Mechanical connection of wires
Soldering is the most reliable type of connecting wires and contacts. But it has disadvantages - the inseparability of the resulting connections and the high complexity of the work. Therefore, the most common type of connection of wires to electrical contacts of devices is threaded, screws or nuts. To ensure the reliability of this type of connection, it is necessary to perform it correctly.
Linear expansion due to temperature changes is different for metals. Aluminum changes its linear dimensions especially strongly, then, in descending order, brass, copper, and iron. Therefore, over time, a gap forms between the contact of the connected metals, increasing the contact resistance. As a result, the screws must be tightened periodically to ensure reliable connections.
In order to forget about maintenance, additional slotted washers, called split washers or Grover washers, are installed under the screws. The Grover selects the gaps that arise and thereby ensures high contact reliability.
Often electricians are lazy and do not twist the end of the wire into a ring. In this option, the contact area of the wire with the contact pad of the electrical device will be many times smaller, which reduces the reliability of the contact.
If the formed ring of wire is slightly flattened with a hammer on an anvil, the contact area will increase several times. This is especially true when forming a ring of stranded wire soldered with solder. Instead of a hammer, you can add flatness with a file, grinding off the ring a little at the points of contact with the contacts.
This is how it should be done ideal threaded connection of wires to contact pads of electrical appliances.
Sometimes it is necessary to connect copper and aluminum conductors with each other, or with a diameter of more than 3 mm. In this case, the most accessible is a threaded connection.
The insulation is removed from the wires to a length equal to four screw diameters. If the veins are covered with oxide, then it is removed with sandpaper and rings are formed. A spring washer, a simple washer, a ring of one conductor, a simple washer, a ring of another conductor, a washer and, finally, a nut are put on the screw, screwing the screw into which the entire package is tightened until the spring washer is straightened.
For conductors with a core diameter of up to 2 mm, an M4 screw is sufficient. The connection is ready. If the conductors are made of the same metal or when connecting an aluminum wire to a copper wire whose end is tinned, then there is no need to place a washer between the rings of the conductors. If the copper wire is stranded, then it must first be tinned with solder.
Connecting wires with a terminal block
Connecting wires with low current load can be done using terminal blocks. Structurally, all terminal blocks are designed identically. Thick-walled brass tubes with two threaded holes on the sides of each are inserted into the housing combs made of plastic or carbolite. The wires to be connected are inserted into the opposite ends of the tube and secured.
The tubes come in different diameters and are selected depending on the diameters of the conductors being connected. You can insert as many wires into one tube as its internal diameter allows.
Although the reliability of connecting wires in terminal blocks is lower than when connecting by soldering, much less time is spent on electrical installation. An undeniable advantage of terminal blocks is the ability to connect copper and aluminum wires in electrical wiring, since brass tubes are coated with chromium or nickel.
When choosing a terminal block, you need to take into account the current that will flow through the switched electrical wiring wires and the required number of terminals in the comb. Long combs can be cut into several short ones.
Connecting wires using a terminal block
with Wago flat spring clamp
Terminal blocks with flat spring clamps Wago (Wago) from a German manufacturer are widely used. Wago terminal blocks come in two designs. Disposable, when the wire is inserted without the possibility of removal, and with a lever that makes it easy to both insert and remove wires.
The photo shows a Wago disposable terminal block. It is designed for connecting any types of single-core wires, including copper and aluminum with a cross-section from 1.5 to 2.5 mm 2. According to the manufacturer, the block is designed to connect electrical wiring in junction and distribution boxes with a current of up to 24 A, but I doubt it. I think it’s not worth loading the Wago terminals with a current of more than 10 A.
Wago spring terminal blocks are very convenient for connecting chandeliers and connecting wires in junction boxes. It is enough just to forcefully insert the wire into the hole of the block, and it will be securely fixed. In order to remove the wire from the block, considerable force will be required. After removing the wires, deformation of the spring contact may occur and a reliable connection of the wires when reconnected is not guaranteed. This is a big disadvantage of a disposable terminal block.
A more convenient Wago terminal block is reusable and has an orange lever. Such terminal blocks allow you to connect and, if necessary, disconnect any electrical wires, single-core, multi-core, aluminum in any combination with a cross-section from 0.08 to 4.0 mm 2. Rated for current up to 34 A.
It is enough to remove 10 mm of insulation from the wire, lift the orange lever up, insert the wire into the terminal and return the lever to its original position. The wire will be securely fixed in the terminal block.
The Wago terminal block is a modern tool-free way to connect wires quickly and reliably, but is more expensive than traditional connection methods.
Permanent connection of wires
In some cases, when it is not intended to connect the wires in the future, they can be connected in a permanent way. This type of connection is highly reliable and is advisable in hard-to-reach places, for example, connecting the ends of a nichrome spiral with copper current-carrying conductors in a soldering iron.
Connecting thin wires by crimping
A simple and reliable way to connect wire cores is crimping. Wire strands are inserted into a piece of copper or aluminum tube, depending on the metal of the wires being connected, and the tube is pressed in the middle with a tool called a press pliers.
Crimping can be used to connect both single-core and stranded wires in any combination. The diameter of the tube must be selected depending on the total cross-section of the conductors. It is desirable that the conductors fit tightly. Then the connection reliability will be high. If in a stranded wire the conductors are twisted together, then it is necessary to develop and straighten them. There is no need to twist the wire strands together. The prepared conductors are inserted into the tube and crimped with press pliers. The connection is ready. All that remains is to insulate the connection.
Crimping tips are available for sale, already equipped with an insulating cap. Crimping is performed by compressing the tube together with the cap. The connection is immediately isolated. Since the cap is made of polyethylene, during crimping it is deformed and held securely, ensuring reliable insulation of the connection.
The disadvantage of joining by crimping is the need for special press jaws. You can make your own pliers using pliers with side cutters. You need to round the side cutter blades and make a groove in the middle. After such modification of the pliers, the edges of the side cutters will become blunt and will no longer be able to bite, but only squeeze.
Connecting wires of larger cross-sections by crimping
To connect electrical wires with a larger cross-section, for example, in power panels of houses, special lugs are used, which are crimped using universal press pliers, for example, the PC, PKG, PMK and PKG types.
To crimp each standard size of tip or sleeve, it requires its own matrix and punch, a set of which is usually included in the set of pliers.
To crimp a tip onto a wire, the insulation is first removed from the wire, the wire is tucked into the hole in the tip and inserted between the matrix and the punch. The long handles of the press pliers are used to squeeze. The tip is deformed, crimping the wire.
In order to correctly select the matrix and punch for the wire, they are usually marked and branded press pliers on the matrix have an engraving for crimping what cross-section of wire the matrix is intended for. The number 95 embossed on the tip means that this matrix is designed for crimping into the tip of a wire with a cross-section of 95 mm 2.
Connecting wires with a rivet
It is made using screw connection technology, only a rivet is used instead of a screw. Disadvantages include the impossibility of disassembly and the need for special tools.
The photo shows an example for connecting copper and aluminum conductors. More details about connecting copper and aluminum conductors are described in the website article “Connection of aluminum wires”. In order to connect the conductors with a rivet, you need to first put an aluminum conductor on the rivet, then a spring washer, then a copper one and a flat washer. Insert a steel rod into the rivet gun and squeeze its handles until it clicks (this cuts off the excess steel rod).
When connecting conductors made of the same metal, there is no need to place a split washer (grower) between them, but put the groover on the rivet first or second to last; the last one must be an ordinary washer.
Connecting broken wires in the wall
Repairs should begin with very careful removal of the plaster in the area of damaged wires. This work is done with a chisel and hammer. As a chisel when laying electrical wiring in the wall, I usually use the rod from a broken screwdriver with a sharpened end of the blade.
Connecting copper wires broken in the wall
Take a piece of copper wire with a cross-section no less than the cross-section of the broken wire. This piece of wire is also covered with a layer of solder. The length of this insert must ensure an overlap of at least 10 mm over the connected ends of the wires.
The insert is soldered to the connecting ends. Solder should not be skimped. Next, the insulating tube is moved so as to completely cover the joint. If a sealed, moisture-resistant connection is required, then before putting on the tube, the soldered joint must be coated with silicone.
Connecting aluminum wires broken in the wall
A prerequisite for obtaining a reliable mechanical connection of aluminum wires is the use of a Grover-type washer. The connection is assembled as follows. A groover is put on the M4 screw, then an ordinary flat washer, rings of connected wires, then a simple washer and a nut.
Step-by-step instructions for connecting broken wires in a wall are outlined in the article “Connecting broken wires in a wall”
Connecting wires with slip-on terminals
Widely used in household appliances and cars is the detachable connection of conductors using slip-on terminals, which are placed on contacts 0.8 mm thick and 6.5 mm wide. Reliability of fixation of the terminal is ensured by the presence of a hole in the center of the contact, and a protrusion in the terminal.
Sometimes the conductors break off, and more often the terminal itself burns due to poor contact and then it becomes necessary to replace it. Typically, the terminals are pressed onto the ends of the conductors using special pliers. Crimping can also be done with pliers, but you don’t always have a new replacement terminal on hand. You can successfully use a used one by installing the terminal using the following technology.
First you need to prepare the old terminal for reinstallation. To do this, holding the terminal with pliers at the press-in point, you need to use an awl or a screwdriver with a thin tip to move the tendrils that compress the insulation apart. Next, the wire is bent many times until it breaks off at the point where it exits the press fit. To speed things up, you can trim this area with a knife.
When the wire is separated from the terminal, a needle file prepares a place for soldering it. You can completely grind it off until the remaining wire is free, but this is not necessary. It turns out to be a flat platform.
The resulting area is broken through with solder. The conductor is also stripped and tinned with solder using a soldering iron.
All that remains is to attach the conductor to the prepared terminal area and heat it with a soldering iron. The antennae that fix the wire are bent after soldering the wire to the terminal, since if they are crimped before soldering, the antennae will melt the insulation.
All that remains is to pull on the insulating cap, put the terminal on the desired contact and check the reliability of the fixation by tugging on the wire. If the terminal has come off, then it is necessary to tighten its contacts. A home-made terminal attached to a wire by soldering is much more reliable than one obtained by crimping. Sometimes the cap is put on so tightly that it cannot be removed. Then it needs to be cut and after installing the terminal, cover it with insulating tape. You can also stretch a piece of vinyl chloride or heat-shrinkable tube.
By the way, if you hold a vinyl chloride tube in acetone for about five minutes, it increases in size by one and a half times and becomes plastic, like rubber. After the acetone evaporates from its pores, the tube returns to its original size. About 30 years ago, I insulated the bases of light bulbs in a Christmas tree garland in this way. The insulation is still in excellent condition. I still hang this garland of 120 6.3 V light bulbs on the Christmas tree every year.
Splicing stranded wires without twisting
Stranded wires can be spliced in the same way as single-core wires. But there is a more advanced method, in which the connection is more accurate. First you need to adjust the lengths of the wires with a shift of a couple of centimeters and strip the ends to a length of 5-8 mm.
Fluff the slightly cleaned areas of the pair to be joined and insert the resulting “panicles” into each other. In order for the conductors to take a neat shape, they need to be tied together with a thin wire before soldering. Then lubricate with soldering varnish and solder with solder.
All conductors are soldered. We clean the soldering areas with sandpaper and insulate them. We attach one strip of electrical tape on both sides along the conductors and wind a couple more layers.
This is what the connection looks like after covering it with insulating tape. You can further improve the appearance if you use a file to sharpen the solder joints on the insulation side of adjacent conductors.
The strength of connected stranded wires without twisting by soldering is very high, as the video clearly demonstrates. As you can see, the connection can withstand the weight of the monitor 15 kg without deformation.
Connecting wires with a diameter of less than 1 mm by twisting
Let's consider twisting thin conductors using the example of splicing twisted pair cables for computer networks. For twisting, thin conductors are stripped of insulation for a length of thirty diameters with a shift relative to adjacent conductors and then twisted in the same way as thick ones. The conductors must wrap each other at least 5 times. Then the twists are bent in half with tweezers. This technique increases mechanical strength and reduces the physical size of the twist.
As you can see, all eight conductors are connected by twisting with a shift, which makes it possible to do without isolating each of them separately.
All that remains is to tuck the conductors into the cable sheath. Before refueling, to make it more convenient, you can tighten the conductors with a roll of insulating tape.
All that remains is to secure the cable sheath with insulating tape and the twist connection is complete.
Connecting copper wires in any combination by soldering
When connecting and repairing electrical appliances, you have to lengthen and connect wires with different cross-sections in almost any combination. Let's consider the case of connecting two stranded conductors with different cross-sections and number of cores. One wire has 6 conductors with a diameter of 0.1 mm, and the second has 12 conductors with a diameter of 0.3 mm. Such thin wires cannot be reliably connected by simple twisting.
With the shift, you need to remove the insulation from the conductors. The wires are tinned with solder, and then the smaller gauge wire is wound around the larger gauge wire. It is enough to wind a few turns. The place of twisting is soldered with solder. If a direct connection of wires is required, the thinner wire is bent and then the connection is insulated.
Using the same technology, a thin stranded wire is connected to a single-core wire with a larger cross-section.
As is obvious, using the technology described above, you can connect any copper wires of any electrical circuits. At the same time, we must not forget that the permissible current strength will be determined by the cross-section of the thinnest wire.
TV coaxial cable connection
There are three ways to extend or splice a coaxial television cable:
– TV extension cable, commercially available from 2 to 20 meters
– using an adapter TV F socket - F socket;
- soldering with a soldering iron.
Tinsel wire connection
twisted with single-core or stranded conductor
If it is necessary to give the cord very high flexibility and at the same time greater durability, the wires are made using a special technology. Its essence lies in winding very thin copper ribbons onto a cotton thread. This kind of wire is called tinsel.
The name is borrowed from tailors. Gold tinsel is used to embroider the ceremonial uniforms of high-ranking military officers, coats of arms and much more. Copper tinsel wires are currently used in the production of high-quality products - headphones, landline phones, that is, when the cord is subjected to intense bending during use of the product.
In a cord of tinsel conductors, as a rule, there are several and they are twisted together. It is almost impossible to solder such a conductor. To attach tinsel to the contacts of products, the ends of the conductors are crimped into the terminals with a special tool. To make a reliable and mechanically strong twist connection without tools, you can use the following technology.
The insulation is removed from the 10-15 mm tinsel conductors and the conductors with which it is necessary to connect the tinsel to a length of 20-25 mm with a shift using a knife in the manner described in the site article “Preparing wires for installation”. The tinsel thread is not removed.
Then the wires and the cord are applied to each other, the tinsel is bent along the conductor and the wire core is tightly wound onto the tinsel pressed against the insulation. It is enough to make three to five revolutions. Next, the second conductor is twisted. You will get a fairly strong twist with a shift. Several turns of insulating tape are wound and the twisted connection of the tinsel to a single-core wire is ready. Thanks to shear twisting technology, the connections do not need to be isolated separately. If you have a heat-shrinkable or polyvinyl chloride tube of a suitable diameter, you can put on a piece of it instead of insulating tape.
If you want to get a straight connection, you need to rotate the single-core wire 180° before insulating it. The mechanical strength of the twist will be greater. The connection of two cords with tinsel-type conductors to each other is carried out using the technology described above, only for wrapping, a piece of copper wire with a diameter of about 0.3-0.5 mm is taken and at least 8 turns must be made.
Connecting wires is probably the most critical area of work when installing electrical networks. The higher the load on the area, the higher the requirements for connecting wires will be - that’s why you need to use the most effective techniques, methods and devices.
We will analyze the most popular methods of connecting electrical conductors, paying attention to their advantages and disadvantages. In addition, I will give examples of the implementation of techniques most often used in the installation of electrical networks.
Overview of the main connection methods
Installation without the use of additional parts
The connection of electrical network wires must meet a number of requirements:
- reliable mechanical fixation of two conductors;
- ensuring conductivity between two conductors(the higher the conductivity, the better);
- minimizing resistance at the joint area;
- no increase in resistance during long-term operation.
Today, when installing electrical networks, a variety of types of wire connections are used, which make it possible to implement the above requirements at different levels. They can also be classified in different ways, but for the convenience of analysis I will single out only two large groups: connections with and without additional devices.
If we need to connect two wires, and we do not plan to use any other devices (except, of course, insulation), then the list of methods will be limited. Wires can be twisted, soldered or welded. These are the three methods we will analyze.
Without the use of special devices, conductors are mounted as follows:
- Twist- the easiest, fastest and cheapest way. The ends of the wires are stripped of insulation, then twisted together in a spiral, after which the exposed sections of the conductor are re-insulated.
Main disadvantage Such a connection consists in a gradual drop in conductivity. The contact point oxidizes over time, the heating of the conductors increases, and as a result, the reliability of the fixation decreases. The higher the current in the network, the higher the risk of fire at the twisting point, while the circuit breaker is almost guaranteed not to work.
In the modern “Rules for Electrical Installations” (PUE from 2009, Chapter 2, clause 2.1.21), such an installation method as fixing wires by twisting is absent in principle. If in earlier editions this method could be used for joining wires with a cross-section of up to 10 mm 2, then with the increase in the average load on the network, twisting was abandoned. Now it is used only as one of the stages of installation of soldered, welded or other connections.
- Welding wires- in the opinion of most electricians (I completely share!) the most reliable method. In welding, the conductors are first twisted to increase the contact area and then welded using alternating current.
Copper is very easy to work with, but when installing aluminum wires, it is advisable to use flux to remove the oxide film from the metal surface. The resistance at the welding site remains constant and does not increase over time, so the site will last a very long time.
- Soldering- another fairly effective method of installing connections. When soldering a copper wire, it is cleared of insulation, the junction is tinned, after which the conductors are twisted. The twisted section is soldered with solder and rosin, and you must try to solder the joint without gaps or sag.
From my point of view, soldering is less reliable compared to welding. On the other hand, when installing wiring yourself, a soldering iron is much easier to find than a welding machine. And the safety margin for household needs of a soldered connection is quite sufficient!
Connection using additional parts
A variety of devices can be used to connect wires while maintaining maximum conductivity of the area. This includes both the simplest crimp sleeves and complex terminals that allow installation in literally seconds.
What parts can be used to connect wires?
- Sleeves for crimping. The crimp sleeve is a hollow cylinder made of soft metal. During installation, the wires are stripped, brought together, and then a connecting sleeve is put on their ends. The part is clamped with a special tool, which allows you to tightly fix the conductors and prevent their displacement relative to each other.
- Branch clamps. They are used to form taps from the main conductor with voltages up to 660 volts without violating its integrity. Contact is ensured by a clamping platform made of anodized steel, which is placed on the stripped section of the cable and secured with four screws. The connection of the wires is protected by a housing made of dielectric material (carbolite or analogues).
- Self-insulating (PPE) caps. A popular device that is suitable only for low-current circuits. The PPE cap is a plastic cone with a clamping spring inside. When connecting, the conductors are twisted, after which a cap is screwed onto the twist. Despite the fact that the spring, in theory, should keep the twist from loosening the contact, it is not very reliable.
- Terminal blocks. A fairly reliable and simple device, which consists of a plastic insulating body, copper contacts with screw fastenings. When connecting a wire to a terminal, its end is stripped, inserted into the hole in the block and pressed against the contact plate with a screw.
The quality of the connection directly depends on the condition of the terminal block itself. In some cheap varieties, due to thermal expansion of materials, the thread weakens over time, and the contact has to be “tightened.” Other pads have a risk of breaking the contact if the screw is over-tightened.
- Spring terminals (WAGO and analogues). They are used to secure a section as quickly as possible: remove the insulation from the wire, insert the wire into the hole in the terminal - the spring fixes it with sufficient strength. There are also varieties with clamping levers that allow you to securely fix soft metal conductors - these are the ones I use most often.
The main disadvantage of such products is the relatively high price. A high-quality WAGO self-clamping terminal block costs from 7 to 25 rubles, depending on the configuration. If you need to make a lot of such connections, a decent amount will accumulate.
A few words about copper and aluminum
When describing methods for installing electrical networks, one cannot help but pay attention to such a delicate issue as twisting copper and aluminum wires. Probably everyone who is even remotely related to this area knows that these materials cannot be directly combined.
There are several reasons:
- Temperature deformation. Aluminum and copper have different coefficients of thermal expansion. This means that when the current is turned on, they heat up differently, and cool down differently when turned off. As a result, periodic on-off switching leads to loosening of the connection and a decrease in contact density.
- Oxidation. Over time, a film of oxides forms on the surface of aluminum, which is characterized by poor conductivity. As a result, resistance increases, and with it heating.
Yes, both of these factors can be compensated for: the first by tight clamps, the second by the use of special lubricants. But let's be honest: who does this and when when equipping the simplest twists?
- Electroplating. Copper and aluminum are a galvanic pair. This means that when these metals combine, the resulting oxides will disintegrate into charged ions, and the higher the humidity in the room, the more active the process will be. As a result of electrolysis, the reliability of the connection will decrease - primarily due to the appearance of voids, and then due to the resulting heating.
Taking these arguments into account, I strongly do not advise connecting a copper wire to an aluminum one without the use of “intermediaries” - terminals, adapters, clamps and other devices.
Algorithms for installing basic connections
Method 1. Twisting with soldering and heat shrink tube
Different methods of connecting electrical wires require different approaches. In this section, I will provide step-by-step instructions for the most commonly used circuits.
Let's start with the simplest one - twisting. Yes, it is not very reliable, but it can be successfully used in low-current circuits. And if you solder the contact point, then you can use conductors almost everywhere.
| Illustration | Execution technique |
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Stripping conductors.
Using a special tool or a sharp knife, remove the insulation from the ends of the conductor. We need to expose about 25mm of wire. |
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Preparation of insulation.
From a heat-shrinkable tube of the required diameter, cut a fragment, the length of which will be approximately twice the length of the connected section. We put the tube on one of the conductors and move it to the side so that it does not interfere with us. |
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Twisting.
We twist the sections of the conductor, cleared of insulation, together. When installing single-core conductors, make sure that they are connected in a spiral, and not one wrapped around the other. First, we “fluff” the stranded wires, then weave the strands together and twist them in a spiral. |
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Soldering.
Using a soldering iron on medium heat, carefully solder the connection. When soldering, make sure that the solder evenly fills the voids between the individual cores in the twist. |
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Insulation.
We move the thermal insulation tube onto the soldered or twisted area so that it completely covers it and extends into isolated areas on both sides. |
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Insulation seal.
Using a hair dryer (better) or a regular lighter (worse, but still possible), we heat the heat-shrink tube until its diameter decreases and it crimps the entire length of the connection. |
Method 2. Installation with crimping
The connection of conductors in the junction box can be made by crimping. To do this, we will need special crimp sleeves and a tool that allows us to fix them on the wires.
Installation instructions using crimp sleeves:
| Illustration | Execution technique |
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Removing general insulation.
Using a sharp knife, we cut the insulating casing on the wires leading into the junction box. We remove the insulation and sort the wires by color, collecting them into groups. It will be much more convenient to work this way. |
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Stripping conductors.
Using a special tool or knife, remove the insulating layer of the conductors. It is advisable to remove a little less than can fit into the crimp sleeve - this will make it easier to insulate. |
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Putting on the sleeve.
Conductors that require connection into one group are assembled together without twisting. We put a sleeve on the conductors, pushing its edge onto the insulated area. |
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Crimping.
Using a special tool, we crimp the wires. We compress the sleeve in at least two places, and then check the strength of fixation. |
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Connection of remaining conductors.
We repeat the operations for the remaining groups of conductors. |
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Insulation.
We put a heat shrink tube on each group of wires with an installed crimp sleeve. We heat the insulation to compact it along its entire length. |
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Installation of the second insulation circuit.
We bend the free ends of the heat-shrinkable tubes. We put larger diameter tubes on top. |
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Insulation seal.
As in the first case, we warm up the heat-shrinkable tubes with a hairdryer. By contracting, they will fix the bent ends of the insulation, ensuring maximum tightness. |
Method 3. Twisting with welding
The most reliable type of connection without additional parts is welded. It can be used where the contact point is subject to severe loads.
You can install wires in junction boxes using welding as follows::
| Illustration | Execution technique |
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Preparing the wires.
We take the wires out into the junction box, after which we remove the outer insulation and disassemble them into cores. We clean the ends of the cores, forming sections 50–70 mm long that are free from insulation. We collect wires by color to facilitate the formation of twists. |
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Formation of twists.
We bring all the wires of the same color together, fold them in parallel and bend the edge by about 1 cm. Holding the bent part, twist the wires in a spiral. To increase the reliability and compaction of the twist, we make the last few turns using pliers. |
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Preparing the welding machine.
You can weld wires with almost any household appliance - the power is quite enough. For welding, it is advisable to use graphite (special insert, brush from the engine, rod from the battery). |
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Welding wires.
We install one clamp on the twist at the top, and use the second clamp with a graphite insert to carry out welding, starting from the bottom of the twist. At the same time, we make sure that the connection does not overheat and begin to collapse. We thoroughly boil all connections. |
After this, we just need to insulate all stripped sections of the wire. This is done using insulating tape, heat-shrinkable tubes or special caps.
Method 4. Connecting copper and aluminum using a screw
Above, I noted that it is impossible to directly connect copper and aluminum. And yet, sometimes it is necessary to establish reliable contact between such conductors - for example, when “splicing” old and new wiring.
If we have two solid wires, then the easiest way to connect them is using a clamping screw:
| Illustration | Execution technique |
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Formation of end rings.
We strip the ends of both wires by about 30–40 mm. Using pliers, we make “ears” on both wires. The diameter of the ring should match the diameter of the screw that will be used for the connection. |
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Installing the bolt.
We use an M4 bolt as a connecting element. We put a washer of such a diameter on the rod under the cap that it completely covers the end ring of the wire. We put the wire with the ring on the bolt so that when the fastening is tightened, the bent part does not open, but, on the contrary, bends even more. |
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Forming a connection.
Cover the first wire with a second washer of suitable diameter. Then we put a second wire on the rod - also with a ring. We cover it with a third washer, and install a Grover (spring washer) on top, which will prevent the mount from unwinding. |
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Tightening the fastening.
We install the nut on top and tighten the fasteners, holding the screw head with a screwdriver. When fixing, you need to tighten the fastener tightly, but without excessive force, otherwise there is a risk of damaging the soft conductor. This is especially true for copper stranded wires. |
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Insulation.
We insulate the joint using either tape or large-diameter heat-shrink tubing. When using a heat-shrinkable tube, it is advisable to additionally secure its edges to the left and right of the contact point. |
Method 5. Using terminal blocks
The use of terminal blocks of different types allows not only to connect copper and aluminum wires, but also makes it possible to create detachable connections.
These parts are used as follows:
| Illustration | Execution technique |
| Regular terminal block | |
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Stripping wires.
We clean the ends of the connected wires. In this case, approximately 5–7 mm must be removed from the insulation - this is quite enough for reliable contact inside the terminal block. |
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Preparing the terminal block.
We cut off a fragment from the product with the required number of contacts. We loosen the mounting screws of the terminal block, opening the holes for installing the wires. |
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Installation of the first wire.
On one side, insert the stripped ends of the wire into the holes, pushing them so that they do not reach the middle. Using a screwdriver, tighten the mounting screws, clamping the wire inside the block. |
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Installation of the second wire.
We repeat the operations for the second wire. We make sure that the wires inside the block do not touch each other. |
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Shutdown.
We check the reliability of the connection, and then isolate the contact point, protecting it from moisture and dust. |
| Spring terminal block WAGO 222 | |
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Preparation for installation.
We clean the wires intended for installation in the same way as for installation using a terminal block. We lift the clamping lever on the terminal block, opening the hole for installing the conductor. |
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Wire installation.
We insert the conductor into the hole, pushing it all the way. Make sure that the wire inside the device is not bent. |
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Fixation of the conductor.
Lower the clamping lever. In this case, the contact plate inside the terminal block rises, clamping the conductor and securely fixing it inside the device due to spring action. |
Conclusion
A reliable and safe connection of wires can be ensured in different ways. The options given above are quite sufficient to perform the most common types of work. If you need additional information, watch the video in this article or ask a question in the comments!