We have long and universally switched to copper wires in home electrical wiring. But the likelihood of docking with aluminum conductors from the past is still high. This usually occurs when replacing or repairing existing electrical wiring that was previously installed. However, aluminum is also contained in the new SIP wire (self-supporting insulated wire), which is now customary to make connections from the pole to the house. Everything would be fine, but aluminum and copper are not “friends” at the molecular level, and we have to solve this problem on our own. Let's see which method suits you best.
Twisting is not the best method
In the old days, ordinary twisting was used when connecting home wiring wires. This was a familiar procedure, and no additional devices were required at all. Quite often, this method is used now, because it is difficult to refuse simple and quick solutions. If you still have to twist, then try to minimize the risks: the wires must be tightly wrapped around each other. A method is completely unacceptable when one core is straight, and the second wraps around it - such a connection will be initially defective.
In the connection, the number of turns is selected in accordance with the diameters of the cores. If the diameter is less than 1 mm, we make 5-6 turns. When twisting wires of larger diameter, three turns are sufficient. After tight twisting, it is necessary to seal the connection with a protective varnish with waterproof properties.
The easy way with screws
wires from different materials can be successfully connected with screws and nuts. It is convenient that such a connection, if necessary, is quickly disassembled and redone again. With proper execution, the threaded connection will be quite high quality and durable. The attractiveness of this option is the possibility of simultaneously connecting several wires, the number of which can only be limited by the length of the screw itself.
The screw method is well suited for connecting wires with different numbers of cores and different diameter. The main thing is that there is no conflict approach between wires from different materials. Washers are used for separation. The procedure is simple: we remove the sheath from the cable to the required length, and then we make wire rings according to the diameter of the screw. We sequentially put a spring washer, a ring of wire, a washer, a ring of the next conductor, etc. on the screw rod. At the end of the assembly, tighten the nut until the spring washers are completely straightened.
When there is a rivet on hand
This method of docking resembles a bolted one, but instead of a nut and a bolt, a blind rivet is used, which forms a permanent connection. But after fixing, it will no longer be possible to fix the connection without “surgical” removal of the assembly. From the stripped ends of the wires we make rings with the same diameter as the rivet. In connection we use galvanized washers. Having strung the assembly, we pull out the rivet and we get a very high-quality connection. But it can only be used inside the mounting box.
Connect with terminal block
A fairly popular method of connecting conductors with special terminal blocks, of course, loses to screw in reliability, but it makes it possible to connect wires as quickly and simply as possible. To do this, it is enough to remove the insulation from the connected ends of the wires by about 5 mm, insert them into the terminal block and tighten with a screw. Tighten the aluminum soft wire with little effort.
Terminal blocks are convenient to use when connecting a chandelier to aluminum wires. Periodic twists often lead to a break in such wires, which is why almost nothing remains of their original length over time. In such cases, the block helps out, since only the short end of the wire is enough to connect with it. Terminal splicing is well suited for broken wires laid in the wall, when laying new wiring is difficult, and the remaining length of the wires is clearly not enough for connections in other ways. But such pads can only be plastered when they are installed in a junction box.
Using spring clips
Relatively recently, modified terminals with spring clips have appeared. There are disposable express terminals in which the wires are fixed without the possibility of their further removal, and reusable - with a lever that allows you to get and insert the wires repeatedly. The most popular so-called terminal blocks German company Wago with paste, specially designed for joining copper to aluminum. Disposable ones allow you to connect single-core wires with a cross section of 1.5 to 2.5 mm 2, and manufacturers allow their load up to 24 A. But professional electricians still do not recommend supplying current above 10 A to such terminals. Strictly speaking, Wago terminal blocks are best used only in lighting fixtures. With increased load, the contact spring overheats, and the contacts between the conductors are critically violated.
Reusable express terminals are equipped with a pressure lever (usually orange) and can connect wires with any number of cores and a cross section up to 4 mm 2. The maximum current for them is allowed up to 34 A. If the terminals without levers simply snap into place, then for reusable ones you need to lift the lever up to the stop, insert the wire and slowly lower the lever. As a result, the cores will be securely fixed. The cost of such a connection will be much more than the dubious twist, but the work is done quickly and without the use of any additional tools.
Pay attention to the "nuts"
This practical type of connecting (branching) clamps is successfully used on the facades of private houses, when it is necessary to switch from aluminum overhead wiring to noble copper inside the house, since aluminum is prohibited from entering the house by the rules. This is where simple and reliable clamps come in handy in a rounded black polycarbonate case, popularly called nuts for their resemblance.
Inside the case there are two steel dies and an intermediate plate, which we compress with screws after installing the wires. Dissimilar wires here do not conflict on an electrochemical occasion - they are located on different "floors" of the clamp, not touching at all and honestly performing their current-carrying function. To get into internal parts squeezing, it is necessary to disassemble its body by removing the two retaining rings on the sides. In the dies we will see prudently stamped grooves for conductors of a certain section. It remains only to choose the right size depending on the cross-section of the cores, so that the connection is strong and reliable.
You can also use branch clamps in cases where you do not want to violate the integrity of the cable. After all, it is known that the more connected breaks in the power circuit, the lower its reliability. And if it is a grounding cable, then it cannot be categorically broken at all. Here reliable "nuts" will come to your aid. But in connecting copper and aluminum wires, special care must be taken so that our stay in the house is safe and comfortable.
It would seem that it could be easier connections wires? After all, there are several ways to connect wires. These are twisting wires, soldering wires, welding wires, crimping and connecting wires using a terminal block. Even a schoolboy knows the simplest way to twist conductors. It is necessary to attach together the ends of metal wires, called strands, and twist into one "pigtail", then wrap it with electrical tape. No need for a soldering iron, terminal block, connecting caps and other "unnecessities".
Any “electrician for himself” has mastered such an operation. And, if necessary, he uses this method in his daily practice. For example, splicing the wires of the power cord household appliance, tablet or computer adapter after a break.
Russian "techies" use this technology for fastening wires everywhere. That's just in the rules for the installation of electrical installations of PES "twisting", all kinds of "bends" and "riveting" are not provided. There are no such methods of wiring in other regulatory documents. Why?
We often do not think about the consequences of such a “simplification”. Meanwhile, an unreliable contact will let you down at the most inopportune moment, the power supply to consumers / power consumers can always be interrupted. From the "surges" of voltage, a breakdown of the elements of the power cascades of a complex household appliances SBT. Even special protection devices used in the most "fancy" models of foreign manufacturers do not save from breakage.
The aiming of short electromagnetic pulses with a voltage of several thousand volts at the electronic filling causes a "harmless" spark at the junctions. At the same time, the standard protection equipment that apartments are now equipped with (RCDs, circuit breakers, fuses) “does not see” such short low-current pulses, so they simply do not work from them, and it is not customary to install special devices for this. Uninterruptible power supplies for computers also did not become a panacea for transient impulses. The occurrence of "pokes" causes malfunctions in the operation of electronic equipment and computer equipment, leads to the failure of electrical components and expensive functional modules.
Overheating at the site of a bad connection leads to even more catastrophic consequences, with the passage of current, a weakened connecting node glows red hot. Often, fires and fires occur from this, causing enormous damage to the owners of the premises. Statistics show that 90% of all electrical wiring malfunctions 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 occurring in Russia.
However, it so happened historically that several decades ago, in the context of a shortage of electrical accessories / copper conductors, twisting aluminum wires was considered the main method used in electrical work. Twisting as a connection can be used in electrics during repair and restoration work.
How to properly connect wires
How to connect the wires: we start by stripping the insulation. Proper connection of conductors must satisfy three basic requirements:
- Provide reliable contact with a minimum contact resistance between each other close to the resistance of a single piece of wire.
- Maintain tensile strength, fracture resistance and vibration.
- Connect only homogeneous metals (copper to copper, aluminum to aluminum).
There are several connection methods that meet these requirements. Depending on the wiring requirements and possibilities practical application, the following types of wire connections are used:
All these methods require preliminary preparation of a wire or cable - removal of insulation to expose the wires to be connected. Traditionally, the material of the insulating shell is rubber, polystyrene, fluoroplast. 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.
Single-core means a wire, the cross section of which 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 interlaced and represent a strand surrounded on the outside by an insulator. Often, individual veins are coated with polyurethane varnish, and nylon threads are added to the structure between them to increase the strength of the wire. These materials, as well as the fabric braid on the outside, complicate the stripping process.
Depending on the type of connection, 0.2 - 5.0 cm of insulation is removed from each end of the wire. For this, several types of tools are used.
According to a 5-point system, you can evaluate the quality of insulation removal and the degree of protection against notching - damage to the cores by each device:
Insulation/core damage
Monter (kitchen) knife - 3/3
Side cutters (nippers) - 4/3
Stripper - 5/4
Soldering iron or loop burner - 4/4
In low-voltage television / computer networks, they use coaxial cables. 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 fluffs up and is removed, exposing the trunk. After that, the polyethylene insulation is cut with a knife or a special device, the cut is removed from the core.
The bifilar in the screen consists of a pair of wires in the screen, which, in order to access the conductors, is also pre-fluffed into wires, opening access to each core.
Important! A soldering iron should be used to remove the insulating material of enameled wire with a cross section of less than 0.2 mm². Enamel is carefully removed with an emery “zero” by moving the paper along the wires.
How to twist the wires correctly
Most often, twisting is used in the repair of electrical wiring, cords and adapters (including low-current ones) of household appliances and equipment. If we are talking about a home electrical network, then the norms provide for the use of wires in houses with a cross section of a current-carrying core of 1.5–2.0 mm from copper and 2.5–4.0 mm from aluminum. Usually, wires of the VVG and PV brands in a PVC sheath are used for wiring. Power cords of ShVL and ShTB brands with rubber or PVC insulation have a cross section of 0.5 - 0.75 mm.
Step-by-step splicing of wires between each other can be done as follows:
- Degrease the bare ends of the wires by wiping with acetone / alcohol.
- We remove the varnish layer or oxide film by cleaning the conductors with sandpaper.
- We put the ends so that they cross. We wind clockwise at least 5 turns of one core onto another. To make the twist tight, use pliers.
- We isolate the open current-carrying parts of the wires with electrical tape, or we wind the insulating cap. They should go beyond the insulation for 1.5–2.0 s to cover the exposed sections of the conductors.
To splice together a stranded stripped wire with a single-core, a different winding technique is used:
- A stranded wire is wrapped around a single wire, leaving a free end without winding.
- The end of the single-core wire is bent 180 ° so that it presses the twist, then it is pressed with pliers.
- The connection point must be firmly fixed with electrical tape. For best performance, 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 tightly grip the wiring, the tube should be warmed up, for example, with a hairdryer or a lighter.
With a bandage connection, the free ends are placed 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 interlock with each other, then the edges are wrapped.
There are more complex variations of parallel/series connections. The connection of wires by twisting is used by professional electricians when carrying out restoration work.
Important! Copper and aluminum have different ohmic resistance, they are actively oxidized during interaction, the connection is unstable due to different rigidity, therefore the connection of these metals is undesirable. In case of emergency, the tips to be joined should be prepared - irradiated with tin-lead solder (POS) using a soldering iron.
Why is it better to crimp (crimp) the wires
Crimping of wires is one of the most reliable and high-quality methods of mechanical connections currently used. With this technology, the loops of wires and cables are crimped in the connecting sleeve using press tongs, ensuring tight contact along the entire length.
The sleeve is a hollow tube and can be made independently. For sleeve sizes up to 120 mm², mechanical tongs are used. For large sections, products with a hydraulic punch are used.
During compression, the sleeve usually takes the form 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 the crimping of conductors from different metals. This is largely facilitated by the treatment of the constituent components with quartz-vaseline lubricant, which prevents subsequent oxidation. For joint use, there are combined aluminum-copper sleeves or tinned copper sleeves GAM and GML. The crimp connection is used for 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 forbidden for electrical installations, is the connection of wires by soldering. It requires special equipment and Supplies, but provides absolute electrical contact.
Advice! Splicing of wires with an overlap 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 connected parts, or twist the conductors together.
You will need an electric soldering iron with a power of 60-100 W, a stand and tweezers (thin-nose pliers). The soldering iron tip should be cleaned of scale and sharpened, having previously selected the most suitable shape tip in the form of a spatula, and connect the body of the device to the ground wire. From the "consumables" you will need solder POS-40, POS-60 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! Connections must not be overheated. Be sure to use a heat sink to prevent the insulation from melting when soldering. To do this, hold the bare wire between the heating point and the insulation with tweezers or thin-nosed pliers.
- The cores stripped of insulation should be irradiated, for which the tips heated with a soldering iron are placed in a piece of rosin, they should be covered with a brown-transparent layer of flux.
- We place the tip of the soldering iron tip in the solder, grab a drop of the molten one and evenly process the wires one by one, turning and moving along the tip blade.
- Attach or twist wires together, fixing motionless. Warm up with a sting for 2–5 s. Treat the areas to be soldered with a layer of solder, allowing the drop to spread over the surfaces. Turn the connected wires over and repeat the operation on the reverse side.
- After cooling, the soldering points are isolated by analogy with twisting. In some compounds, they are pre-treated with a brush dipped in alcohol and varnished on top.
Advice! During and after soldering for 5–8 s. the wires must not be pulled and moved, they must be in a fixed position. A signal that the structure has hardened is the acquisition of a matte shade by the surface of the solder (in the molten state it shines).
Still, welding is preferable.
In terms of connection strength and contact quality, welding surpasses all other technologies. Recently, portable welding inverters that can be moved to the most inaccessible places. Such devices are easily held on the welder's shoulder with a belt. This allows you to work in hard-to-reach places, for example, to weld from a ladder in a junction box. for welding metal conductors into the holder welding machine carbon pencils or copper-plated electrodes are inserted.
The main drawback of welding technology - overheating of the parts to be welded and melting of the insulation is eliminated by:
- Correct adjustment of the welding current 70–120 A without overheating (depending on the number of wires to be welded with a cross section of 1.5 to 2.0 mm).
- The short duration of the welding process is no more than 1–2 seconds.
- Tight pre-twisting of wires and installation of a copper heat-dissipating clamp.
When connecting wires by welding, the twisted cores should be bent and be sure to turn up with a cut. An electrode is brought to the end of the wires connected to the ground and an electric arc is ignited. The molten copper flows down in a ball and covers the wire strand with a sheath. In the process of cooling, an insulating belt made of a piece of cambric or other insulating material is put on the warm structure. Lakotkan is also suitable as an insulating material.
Terminal blocks - the most ergonomic electrical installation products
The rules of the PUE, clause 2.1.21, provide for the type of connections using clamps (screws, bolts). There is a connection directly with the help of fasteners “on the fly”, when a screw, a washer is threaded through the loops of each of the wires and fixed with a nut on the reverse side.
Such an installation is wrapped with several turns of electrical tape and is considered quite practical and reliable.
More ergonomic wiring products, called screw terminals. They represent a contact group placed in a housing made of insulating material (plastic, porcelain). The most common way to connect wires using terminal blocks is found in junction boxes and electrical panels. To connect the wire, you need to insert it into the socket and tighten the screw, the clamping bar will securely fix the core in the seat. Another connected wire is connected to the reciprocal socket, shorted with the first one.
In self-clamping terminal blocks of the WAGO type, the wire is snapped into the socket, a special paste or gel is used for better contact.
Branch clamps are a major version of the screw terminal with several shorted taps, used mainly in the street and places with adverse environmental conditions.
The connecting clamps are an insulating cap with a thread inside, it is screwed onto the twist, while compressing and protecting against mechanical stress.
First of all, you must understand that in different conditions may apply different types connections. And their choice depends on the specific task.
For example, it is much more convenient to connect wires of small cross sections up to 2.5 mm2 in a compact junction box with terminal blocks or clamps. But if we are talking about a strobe or a cable channel, then sleeves come out on top here.
Consider the three most simple and at the same time reliable types of connections.
Let's start with a PPE type connection. It is decoded as:
- WITH connecting
- AND insulating
- Z excitement
It looks like a simple cap. There are different colors. 
Moreover, each color means belonging to specific sections of the veins.
Cores are inserted into this cap and twisted together. 
How to do it right, first twist the cores and then put on a cap or twist them directly with the PPE itself, is discussed in detail in the article “.” 
As a result, thanks to PPE, you get the good old twist, only immediately protected and insulated.
On top of that, with a spring-loaded contact that does not allow it to loosen. 
In addition, this process can be slightly automated by using a PPE attachment for a screwdriver. This is also covered in the article above. 
The next view is the Wago terminal blocks. They are also different sizes, and for a different number of connected wires - two, three, five, eight.
They can join together both monocores and stranded wires.
Moreover, this can be implemented as different types Vago, and in one single. 
For multi-wire, the clamp should have a latch-flag, which, when open, allows you to easily insert the wire and clamp it inside after snapping. 
These terminal blocks in home wiring, according to the manufacturer, can easily withstand loads up to 24A (light, sockets).
There are separate compact specimens on 32A-41A. 
Here are the most popular types of Wago clamps, their marking, characteristics and for what section they are designed:
Series 2273 Series 221-222 Series 243 Series 773 Series 224
There is also industrial series for cable sections up to 95mm2. Their terminals are really large, but the principle of operation is almost the same as that of the small ones. 
When you measure the load on such clamps, with a current value of more than 200A, and at the same time you see that nothing is burning or heating, many doubts about Wago products disappear.
If you have original Vago clamps, and not Chinese fake, and at the same time the line is protected by a circuit breaker with a correctly selected setting, then this type of connection can rightfully be called the simplest, most modern and easy to install.
Violate any of the above conditions and the result will be quite natural. 
Therefore, you do not need to set wago to 24A and at the same time protect such wiring with an automatic 25A. The contact in this case will burn out during overload.
Always choose the right vago terminal blocks.
Automatic machines, as a rule, you already have, and they protect primarily the electrical wiring, and not the load and the end user.
There are also enough old view connections, such as terminal blocks. ZVI - insulated screw clamp.
In appearance, this is a very simple screw connection of wires to each other. Again, it happens under different sections and various shapes.
Here are their technical characteristics (current, cross section, dimensions, screw torque): 
However, ZVI has a number of significant drawbacks, due to which it cannot be called the most successful and reliable connection.
Basically, only two wires can be connected to each other in this way. Unless, of course, you don’t specifically choose large pads and shove several wires there. What to do is not recommended. 
Such a screw connection is well suited for solid conductors, but not for stranded flexible wires.
For flexible wires, you will have to press them with NShVI lugs and incur additional costs. 
You can find videos on the network where, as an experiment, the transient resistances on different types of connections are measured with a microohmmeter.
Surprisingly, but smallest value obtained from screw terminals.
But we should not forget that this experiment refers to "fresh contacts". And try to make the same measurements after a year or two of intensive use. The results will be completely different.
Combination of copper and aluminum
Often there is a situation where it is necessary to connect copper wire nick with aluminum. Because Chemical properties copper and aluminum are different, then direct contact between them, with the access of oxygen, leads to oxidation. Often even copper contacts on circuit breakers are subject to this phenomenon. 
An oxide film is formed, resistance increases, and heating occurs. Here it is recommended to use 3 options to avoid this:
They remove direct contact between aluminum and copper. Communication occurs through steel.
The contacts are separated from each other in separate cells, plus the paste prevents air from entering and prevents the oxidation process from developing.
The third simple way to connect conductors is crimping with sleeves.
GML sleeves are most often used for joining copper wires. Deciphered as:
- G ilza
- M single
- L narrowed
To connect pure aluminum - GA (aluminum sleeve):
For the transition from copper to aluminum, special GAM transitions:
What is the pressing method? Everything is quite simple. Take two conductors, strip to the required distance.
After that, on each side of the sleeve, the conductors are inserted inside, and the whole thing is crimped with press tongs. 
With obvious simplicity, there are several rules and nuances in this procedure, if not followed, you can easily ruin a seemingly reliable contact. Read about these mistakes and rules on how to avoid them in the articles ” ” and ” ”.
To work with conductors of large sections 35mm2-240mm2, a hydraulic press is used. 
Up to sections of 35mm2, you can also use a mechanical one with a large span of handles. 
The sleeve must be crimped two to four times, depending on the cross section of the wire and the length of the tube. 
The most important thing in this work is to choose the right size of the sleeve.
For example, when connecting monofilament, the sleeve is usually taken to the size of a smaller section.
And in this way, you can connect several conductors at the same time at the same point. In this case, only one sleeve will be used. 
The main thing is to completely fill its internal space. If you crimp three conductors at the same time, and you still have voids inside, then you need to “fill in” this free space with additional pieces of the same wire, or conductors of a smaller cross section.
Sleeve crimping is one of the most versatile and reliable connections, especially when it is necessary to extend the cable, including the lead one.
In this case, the insulation turns out to be almost equivalent to the main one, while also using the outer tube HERE as a casing.
Of course, you will not use either PPE or Wago for these purposes, but the GML sleeves are the very thing! At the same time, everything comes out compactly and easily decreases even in a strobe, even in a cable channel.
Welding and soldering
In addition to all the above connection methods, there are two more types that experienced electricians rightfully consider the most reliable.
And not always, even with its help, it is possible to connect an aluminum solid wire with a flexible copper stranded wire. In addition, you are forever tied to an outlet or extension cord.
And if there is no voltage or generator nearby at all? 
At the same time, elementary press tongs, on the contrary, are present in 90% of electrical installers. It is not necessary to purchase the most expensive and fancy ones for this. 
For example, batteries. Convenient of course, go and just press the button.
The Chinese counterparts also cope well with their task of crimping. Moreover, the whole process takes no more than 1 minute.
When it is required to connect 2 different sections of the wire together, it is necessary, in addition to high-quality contact, to obtain sufficient strength of the section where these wires are connected to each other.
If we take into account the regulatory documents that are in force on the territory of our country, then it is permissible to connect aluminum wires to each other using various methods:
- Welding.
- Crimping.
- Soldering.
- Connection using .
Despite the fact that all these connection methods specified in the regulatory documents are presented as universal, not every one of them will be suitable when working with aluminum wires.
First of all, this is due to the characteristics of such a material as aluminum, in particular, with its technical specifications. As is known from the school chemistry course, on the surface of aluminum there is always an oxide film formed as a result of direct contact with atmospheric oxygen.
It is unable to conduct electricity through itself. In addition, the oxide film has quite heat melting - in the region of 2000 degrees. This figure is much higher than the melting point of aluminum itself.
If you remove this film mechanically, then it will very quickly reappear. It should be noted that the presence of this film during aluminum soldering greatly interferes with the process of connecting the aluminum core to the solder. Also, it can cause difficulties when welding wires, because due to its presence, various inclusions occur, due to which the quality of the contact is greatly reduced.
Additional characteristics of a material such as aluminum include increased brittleness and fluidity. In this regard, when connecting aluminum wires, care should be taken in advance that they are located so that the possibility of mechanical impact on this area is completely excluded.
It is worth noting that when connecting wires using a standard bolt clamp, it will have to be tightened periodically, as the metal will gradually flow out from under the bolt. As a result, the connection will become weaker.
Twisting
Aluminum wires are often interconnected by twisting. This is the simplest, but also the most dangerous method of connecting wires to each other.
The sequence of actions when using this technology will be as follows:
- First, the insulation is removed from the wires approximately 4-5 cm on each side. It is most convenient here to use a special tool designed specifically for this purpose.
- Now the contacts should be degreased. To do this, they will have to be wiped with a cloth previously moistened with acetone.
- sandpaper remove the oxide film from the surface of the metal, that is, they clean it until a metallic sheen is obtained.
- Wires cross each other, after which one of the cores is twisted as tightly as possible onto the other with the help of pliers.
- Second wire in the same way it is wound on the first one.
- The twist should now be insulated with insulating tape. Professional electricians also recommend using a special heat shrink tube or cambric. With it, you can qualitatively protect the bare area from the negative effects of the external environment.
In principle, the technology is quite simple. It is only necessary to remember that the cores need to be bared by at least 4-5 cm, and the twisting should not be done manually, but only with the help of pliers, so that the wires fit as close to each other as possible.
If this is not done, then the result will be a loose contact, due to which the area can become very hot. In turn, this effect causes a short circuit, and in some cases even a fire.
Threaded connection
This type of connection can be very reliable if done correctly. It should be noted that aluminum has the highest linear expansion, and therefore a gap appears between the connected wires over time, which worsens their contact with each other. To prevent a short circuit, you need to tighten these screws from time to time.
To get rid of this need, install special washers with cuts or grovers. They choose the resulting gaps and several times increase the reliability of the connection.
On the screw, the wires will need to be wound so that the area of \u200b\u200bcontact with the contact pad is much higher. Professional electricians often do this: they flatten this ring on an anvil to increase the contact area.
The technology for making a high-quality threaded connection of wires begins with the removal of insulation from them at a distance equal to 4 screw diameters. Cleaned areas are degreased.
Then you need to bend their tips so that rings form.
The elements are put on the screw in the following sequence:
- Spring washer.
- Standard puck.
- Ring of the first wire.
- Another standard washer.
- Ring of the second wire.
- Screw.
This whole system is tightened until the spring washer is in a straightened state. In principle, if both wires are made of aluminum, then a standard washer can not be laid between them.
We use terminal blocks
If aluminum wires have a slight current load, then they can be interconnected using terminal blocks. Despite the fact that the appearance of such products may vary greatly, the principle of their work is the same.
The body of the pads is made of plastic or carbolite. It contains tubes with thick walls made of brass. There are threaded holes on the sides. Connected wires are inserted into opposite ends, which are fixed with screws. It should be noted that it is allowed to insert as many wires into one brass tube as will fit there.
This is not a very reliable connection compared to soldering, however, on installation work takes several times less time. In addition to connecting conductors made of the same material, it is permissible to use different wires in terminal blocks.
Permanent connection
If in the future it is not planned to disassemble the wire connection, then the so-called one-piece methods can be used. These methods are among the most reliable. It is desirable to use them, first of all, in hard-to-reach places.
One of the easiest methods of permanent connections is crimping. To do this, an aluminum tube of a suitable diameter is taken, the wires are twisted together, inserted into this tube and clamped with press tongs. It is best here that the conductors enter as tightly as possible.
Only in this case the connection will be the most durable. It is worth noting: if the wires enter the tube quite tightly, then you don’t even have to twist them together. At the last stage, the connection is isolated.
Today on sale you can find special tips for the manufacture of this connection, which already have an insulating cap. It shrinks together with the tip and wraps around the wires, blocking any access to them.
To obtain a high-quality one-piece connection, you need to have special pliers that will not bite, but only squeeze. If they are not available, then standard pliers are quite suitable.
Soldering and welding
Soldering wires allows you to get a fairly high-quality and one-piece connection. However, when connecting aluminum wires, you should be aware of the presence of an oxide film on them, due to which the solder will not adhere too well.
To prevent the occurrence of such a defect, you need to follow a certain sequence of actions:
- Connected sections of wires treated with a special flux, which removes the oxide film from the surface.
- Solder is handled as carefully as possible so that it has the largest area of \u200b\u200bcontact with the wires.
- When the connection area cools down, it is desirable to process it with sandpaper to remove sharp edges that can damage the insulating layer.
- Wires in without fail isolate.
Soldering requires certain skills.
It should be said that this method has several negative points:
- He has to be isolated.
- The method itself is rather complicated., especially if you have to solder wires under the ceiling, standing on a stepladder.
- If an error was made in the course of work, then fixing it will be quite problematic.
- It takes a lot of time to work.
Welding is somewhat similar to soldering wires, but it is performed much faster. In order to obtain a quality connection, the electrode is brought to the connection area for only 1-2 seconds. Both ends of the wire are pretreated with flux to remove the oxide film.
If there is no experience in this area, then initially you should practice on twists prepared in advance, but not connected to the system.
After the welding process is completed, the twists are passed with a special solvent and varnished. The result is a quality connection that can last for a long period of time, as this method allows you to prevent the occurrence of overheating. Accordingly, such an area will need to be isolated.
Alternatives
flat spring clamp The wires can be connected to each other with a rivet. In principle, this technology is similar to screw technology, only here a rivet is taken instead of a screw. The end result is a non-separable connection.
This connection is quite simple: both conductors are put on the rivet through the spring washer, then it is inserted into the riveter and the handles are brought together until a click is heard.
Also, there is a special flat-spring clamp. Such products are disposable and reusable, when the wire can be both inserted and removed. However, it should be remembered that such clamps are made of plastic, so it is undesirable to use them for currents above 10 A.
Working with them is very simple: the wires are stripped and inserted into the clamp until it clicks. It is impossible to pull them out without using a special lever. It is also desirable to isolate this section of the wire.
Connection Features
Aluminum wires are best placed in special ones, to which they must fit in corrugated sleeves. This is especially important when laying outdoors or in the case of wiring in a damp room such as a bathroom.
In general, when connecting aluminum wires that will function outdoors, care must be taken that moisture does not approach the connection areas.
Otherwise, a short circuit cannot be avoided. It is very convenient in this case to use the technology of welding wires, since the subsequent use of a special varnish makes it possible to exclude the effect of water on the junction, and the insulating layer additionally protects against electric shock.
- Professional electricians It is not recommended to connect aluminum and copper wires together. This is due to many reasons, the most important of which is the different resistance of metals. In addition, when interacting with each other, copper and aluminum oxidize very quickly, which causes heating of the wires, significantly worsens the contact. In addition, their rigidity is different, which greatly complicates the work.
- You can, if necessary, combine certain methods of connecting wires. In particular, twisting goes well with soldering or welding. The result is a very reliable and one-piece contact that will last for a long time.
Any cable consists of aluminum or copper conductors. The rules for the installation of electrical installations, the usual twisting of such wires is strictly prohibited. But there are situations during installation when there are no options other than how to connect aluminum and copper wire. There are many such possibilities. It remains only to choose an affordable and safe one.
Electrochemical destruction of metals
The opinion about the impossibility of combining aluminum and copper is often mentioned. This is true from the analysis of the chemical compatibility of metals. In the world modern technologies you can find dozens of conjugations of metal pairs.
There is the concept of the difference in electrochemical potentials, the indicators of which are summarized in a special reference table. From it, if necessary, take indicators and are determined with compatibility:
- Copper - lead-tin solder 25 mV.
- Aluminum - lead-tin solder 40 mV.
- Copper - steel 40 mV.
- Aluminum - steel 20 mV.
- Copper - zinc 85 mV.
In order to imagine what is happening, it is necessary to understand the reactions that electrodes of various metals enter into when they come into contact.
In the absence of moisture, the reliability of contact is undeniable. But there is no ideal environment. The humidity of the atmosphere always has a negative effect on the quality of the joints. Any conductor has a certain electrochemical potential. This property is used in practice in the operation of batteries.
Getting on the contact planes from various compounds, water creates a short-circuited galvanized medium. One electrical conductor begins to deform. The material from which it is made is also subject to destruction.
Methods for connecting wires from different metals
Technological rules allow direct connection of different metal conductors with an electrochemical potential coefficient of more than 0.6 millivolts. According to tabular data, for a bond of aluminum and copper, it is 0.65 mV, which makes this combination unacceptable. However, there are ways to correctly interconnect the differing wires.
Cable connection by twisting
most famous, but an unreliable reception is called twisting. This method does not require special skills and is easy to manufacture. For these reasons, it is used quite often. Before connecting the aluminum wire with copper, you need to imagine what is happening in a similar combination with temperature changes and precipitation:
- There is a gap in the connection.
- Increased resistance at the ligament point.
- Heat.
- Cable oxidation, contact destruction.
To ensure a secure relationship, this method is not suitable. Although if you perform certain operations, in some cases you can use twisting to connect aluminum and copper wires:
Threaded wire connection
A similar method is performed by clamping the ends of the cable into a bolted fastener. Exactly this reliable connection aluminum and copper wires to each other. It guarantees tight contact for the entire period of use of the twist. Replacing bolts of different lengths makes it possible to combine an unlimited number of cables:
- Different section.
- Multiwire and monolithic.
- With washers to prevent direct contact with copper and aluminum conductors.
Procedure:
- Cut off the insulating coating to the length required for fasteners.
- Sand and degrease cleaned areas. Irrigate multi-wire cable. Connect the cores with a thread through steel washers.
- Tighten the nut firmly.
- Shock absorbers are placed in front of the outer washers to prevent pinching and breaking of the wire. When crimped, it straightens and the connection is fixed.
Connecting different cables with a terminal block
Splicing cables through terminal connections has received in end times wide use. Although the quality of contact it is inferior to the bolt one, there are also undeniable advantages:
- The wires are connected randomly.
- There is no need to make connecting rings and put on tips.
- Design features terminal blocks do not allow wire short circuit.
- Contact isolation is not required.
- The work on connecting the terminal contacts is simple.
The ends of the wires are exposed by about five millimeters, inserted into the clamp and pulled through. This method is indispensable when connecting aluminum cables, the cores of which break from repeated bends.
Repair of damaged cables using terminal blocks is also the only acceptable one due to the short length of the wires. After splicing, a junction box is mounted.
Of the numerous connecting devices, not the last place is occupied by the German spring terminal blocks Vago of the company of the same name. They are both disposable and with a clip for repeated splicing of the wire. Such terminal blocks are used when working with single-wire wires with a cross section of one and a half to two and a half squares from any metals in insulating boxes. According to the passport, they are designed for twenty-four amperes in terms of load. Contacts are treated with a special composition to prevent oxidation.
These are the easiest devices to use. The wire is stripped and forcefully inserted into the block. The fixation is secure. It is possible to get the wire with a well-applied effort. The spring block is destroyed and reuse is impossible, which is the biggest drawback of this product.
Reusable terminal blocks Wago with an orange lever are designed for the use of wires of any type with a cross-sectional area of \u200b\u200bup to four square millimeters and currents up to thirty-four amperes. Apply repeatedly until completely worn out.
The method of application is available to anyone. The insulation is stripped to a distance of about ten millimeters, the lever rises, the wire is placed in the channel and the lever slams shut. The connection is fixed.
Vago terminal blocks are effective devices for installation of electrical networks. They do not require the use of special tools, but are quite expensive.
Monolithic connection method
The technique for making such a connection is similar to a threaded one. A rivet and a special device - a riveter are used as a fastener. The rivet is a hollow aluminum rod thickened on one side. A wire pin with a hat is placed in it. When passing through the cavity, it creates a thickening on one side. Then the pin breaks off, forming a rivet.
If you do not take into account the price of the riveter, this method of contact becomes the most affordable, apart from twisting. The disadvantage of such contact is the one-time use and the impossibility of separation if the work is done by mistake.
The use of special copper sleeves will be another way to permanently combine conductors. They are produced various sizes, for each section of the cable its own. The bare ends of the wires are threaded into them and crimped with special tongs. This method is the most compact along with twisting.
Connecting wires by soldering
If there is a desire, then dissimilar wires can be soldered. This method must take into account certain technological features. Before the wires are properly connected, aluminum and copper must be prepared for soldering. Copper does not require special tricks. Another thing is aluminum wire. On its surface, under the influence of ambient air, an oxide film is formed - an amalgam. It resists chemical attack and solder does not stick to it.
To neutralize it, you will have to make a simple device. The tip of the aluminum wire is cleaned and treated with a solution of copper sulfate. A battery is taken and its minus is attached to this conductor. The copper wire is fixed on the plus at one end, and the other is dipped into the same solution. After a certain period of time, aluminum will be covered with a copper coating and will become available for soldering.
Specifics of connections for outdoor installation
Electrical connections in outdoor installations are exposed to various weather conditions. Insulation requirements are more stringent. In order to prevent shorting, a Nut clamping kit is used.
In its plastic shell there are metal clamps in which the wires are connected by tightening the screws. The body halves are tightly compressed with screws or spring rings. Such a cocoon guarantees protection from external weather fluctuations. This is a rather large-sized connection, but in outdoor conditions this is not critical.
