How to properly connect aluminum and copper wires to each other
When installing electrical wiring, sometimes the question arises about connecting copper and aluminum wires. This issue is especially relevant during electrical work in old housing stock, where the main part of the electrical networks is made of aluminum wire. How to connect aluminum and copper wires to avoid problems with electrical wiring will be discussed later in this review.
What is the difficulty of connecting copper and aluminum wiring directly
As is known, the cause of problems in the direct connection of copper and aluminum is electrocorrosion processes.
In a dry environment, nothing will happen even with direct contact, but with increased humidity, a short-circuited galvanic cell is formed at the junction, in which the metals begin to play the role of a battery with a “plus” and a “minus”.
The metal itself practically melts, resulting in a network rupture with a possible short circuit and insulation fire. Which in turn can lead to a fire.
In order to avoid this, various types of contact devices are used to indirectly connect copper and aluminum wiring.
All connection methods can be divided into 2 groups based on the presence of wire contact:
- There is direct contact between the wires: twisting, crimping, connection with rivets, strips.
- There is no direct contact between the wires: threaded fixation, connection with various types of terminal blocks.
Important! To connect aluminum and copper wires, it is recommended to use methods from the second group. It is allowed to use connections from group 1 provided that the copper wire is processed. For example, it can be tinned with solder.
Twist
The main method of connecting wires at home, it is quite convenient in that it does not require special tools and equipment. But in the case of connecting aluminum and copper wires, this method must be used extremely carefully, observing the following conditions:
- A twisted connection is made by mutually twisting both ends of the wire with each other; wrapping the end of one wire around the other is not allowed;
- It is recommended to tin the copper cable with tin or solder before twisting; this point is especially important for stranded copper wire;
- A protective moisture-resistant coating must be applied to the connection between aluminum and copper wires.
There are three main types of twist: simple, bandage and groove twist. It should be noted that bandage twisting will give the best results. When performing twisting, it is worth considering that the number of turns directly depends on the diameter of the wiring, so for a wire up to 1 mm in diameter it is necessary to make at least 5 turns, for large sections at least three turns. In addition to moisture insulation, one should not forget about the electrical insulation of the twist; for this you can use special tips.
High-quality twisting will last quite a long time, but only the use of an indirect connection can provide a true guarantee.
How to make a twist correctly
First you need to prepare the ends of the wires. To do this, remove the insulation at a distance of 3–5 cm from the edge of the cable. It should be noted that the heat-shrink tube is placed on one of the wires, before twisting, upon completion of all operations, the tube is moved to an open place and fixed there. After cleaning the ends, you need to twist the wires according to the proposed diagram. In this case, it is necessary to ensure that the cores are wrapped around each other, and that one cable core does not overlap another.
To make it easier to twist a multi-core copper cable, its cores can and should be tinned. It should also be noted that tinning copper in any case increases the reliability of the twisted connection. After twisting, the connection point must be coated with moisture-resistant varnish. Electrical insulation can be done using heat shrink tubing or cap caps with a soft clamp or cone spring.
Insulation of wire ends with caps with a cone spring
Important! Unless absolutely necessary, it is not recommended to use twisting to connect copper and aluminum cables. Currently, there are many safer and more reliable ways to combine copper and aluminum into one network.
Crimping
In this case, a metal or plastic sleeve or tip is placed on the twisted connection, which is fixed to the connection with press pliers, a special crimping tool. Fixation in this case is carried out by crimping the connection with the sleeve material. The sleeves are a metal tube with insulation made of PVC materials. The nozzles are usually plastic caps into which the compound is inserted, after which the cap is crimped with press jaws.
Separately, it is necessary to note the connection using cap attachments with a clamping ring or cone spring. In this case, after twisting the wires, a cap is put on the twist, after which it is screwed onto the connection with rotational movements, after which it is simply crimped with pliers. In this case, a ring of soft metal inside the cap tightly compresses the junction. This crimping option is quite accessible for household use.
Threaded fixation
A reliable, although somewhat cumbersome, way of connecting copper and aluminum wiring is a threaded connection; in this case, the cores are clamped with a nut on a threaded base. In order to avoid direct contact, a washer is placed between the exposed ends of the cores.
The advantages of this connection method are simplicity and versatility. In this way, you can connect several electrical wires of different cross-sections. But at the same time, this type of connection is quite cumbersome, and it is also very inconvenient to isolate. But, at the same time, this type of connection requires only a bolt and nut.
First of all, the ends of the wire are prepared. The insulation is removed at a distance of 1–1.5 cm from the cut, after which rings with a diameter slightly larger than the diameter of the bolt or rivet are made from the exposed wires.
These rings are used to attach the wire to the rivet or threaded part of the bolt. A spring washer is placed between the aluminum and copper cable; this is necessary to ensure that there is no direct contact between these metals.
After which the connection is fixed by tightening the nut or a riveter.
It is worth noting that this option is suitable for splicing wires of sufficient length; when saving length, which is often found when connecting lighting electrical equipment to the short ends of an aluminum wire, as is often the case in old apartments, it is better to use terminal boxes.
Connecting copper and aluminum wires with rivets
The clamping of the wires in this case is carried out by a wedged rivet, consisting of a tube and a core, fixed with a rivet gun. To connect, prepared conductors with wound rings are placed on a rivet tube with a gasket - a steel washer. After which the rivet is crimped with a rivet tool, the core wedges the rivet tube, thereby compressing the metal cores among themselves, thereby fixing the cable cores.
The contact in this case is permanent, but at the same time strong and reliable. For this type of connection, you need a special tool - a riveter, and skills to work with it. This method is used mainly for working with wire breaks and splicing wire ends in hard-to-reach places.
Connection with two steel strips
You can connect copper and aluminum wires in this tricky way, which also requires pre-treatment of the copper wire with tinning: clamp the wires with two steel strips with bolts at the edges. Advantages of the method: the ability to connect several branches of wiring at once, without increasing the length of the bolt. In this case, the bare ends of the cores are placed between the slats. The method is applicable for wires of the same cross-section.
Important! The connection with two steel strips requires mandatory external insulation, as well as preparation of the copper wire by tinning.
Wire clamp with metal plate
Terminal blocks and terminal boxes
Convenient and reliable connection method. The terminal block is a strip of insulating material in which sockets for wires are located. The wires are fixed in the sockets using clamping bolts. An important feature in our case is the absence of contact between the wires. To connect copper and aluminum wires, you only need a screwdriver.
The terminal box is a system of several separately located terminal blocks, combined into one structure and having several terminals.
The advantages of this connection method are:
- Easy to install, all you need is an electrician's knife to strip the ends of the wire and a screwdriver to tighten the screws;
- Reliability of insulation, very often when using a terminal block or terminal box, additional insulation is not required;
- Undemanding to the length of the wire; 1–2 cm of wire is enough to fix the wire in the terminal box.
At the same time, to install hidden wiring in the wall, the terminal block requires the installation of a distribution box. Without a distribution box, installation of hidden wiring is unacceptable. But in this case, you can use a terminal box for flush mounting.
When working with the terminal box, it is important to carefully fix the ends of the wire in the socket, especially for aluminum wires. This is especially important when installing the box outdoors or indoors where temperature fluctuations are possible.
Connection with spring and self-clamping terminal blocks
Currently, both reusable and single-use terminal blocks and terminal blocks are produced.
- spring terminal blocks and reusable terminal blocks have a retaining spring that can be loosened by lifting a lever located on the device body. This allows you to remove or insert the wire without any effort. Lowering the lever securely fixes the cable cores;
- Single-use terminal blocks automatically clamp the wire when inserting it into the socket; removing the wire will require physical force, which can damage the clamping spring, so their single use is recommended.
Both reusable and single-use terminal blocks are produced in a wide range, including with a different number of connected wiring branches, designed to fix wires with a cross-section from 0.08 mm² to 6 mm². Including in the form of ready-to-install terminal boxes. This method of connecting aluminum and copper wires is currently the most optimal in terms of reliability and ease of use.
Section of the spring terminal block and placement of the connection in the junction box
Terminal boxes with spring clamps were first produced by the German company Wago, from which they got their name, but currently there are a large number of analogues, including counterfeit ones. For this reason, it is necessary to purchase spring terminal boxes only from electrical stores. When purchasing terminal boxes on the market, there is a high probability of purchasing low-quality products that do not meet the stated requirements.
Self-clamping terminal block WAGO
To fix the wires in the terminal box, it is necessary to prepare the wires; to do this, remove the insulation from their ends; the size of the exposed part must be at least 0.5 cm.
After that, the open part of the cable core is inserted into the desired socket of the terminal box and fixed in it using a spring clip or screw.
It should be noted that mounting in a terminal box usually does not require additional insulation, but at the same time, when they are located in a wall, a distribution box is required. Thus, spring terminal blocks have a number of advantages over other types of connections due to ease of connection.
conclusions
In this way, it is quite possible to connect copper and aluminum wire, but it is necessary to take into account the location of the cable and the environment. Copper and aluminum can only be connected by twisting in a dry room. If the humidity in the room increases, this connection may become unusable and, moreover, cause a fire. The most optimal method today is to connect electrical wiring using spring terminal blocks.
The main advantage of this method is stable fixation in any environmental conditions. Despite all the advantages of a screw terminal block, threaded or rivet connection, when operating under conditions of sudden temperature changes, the contact under the screw may weaken.
Due to the difference in temperature expansion of the metals of the wires. These changes may result in loss of contact or short circuit.
Thus, with all the variety of methods for connecting copper and aluminum wiring, the safest method at the moment is the use of self-clamping terminal blocks.
Source: https://ProFazu.ru/provodka/montazh/kak-soedinit-alyuminievyj-i-mednyj-provod.html
How to correctly connect aluminum wires with copper wires in electrical wiring
In apartments of old buildings, the electrical wiring is often made of aluminum wires connected to each other by twisting. When connecting lamps to aluminum wiring, installing additional sockets and other electrical equipment, it is necessary to take into account that with increased humidity, the contact resistance between aluminum and copper wires increases over time. This leads to heating of the junction and destruction of the contact.
To reliably connect copper and aluminum wires to each other, you must follow simple rules, which will be discussed.
Methods for connecting
aluminum wires to copper
Connecting copper wires to existing wiring made of aluminum wires is not as difficult as it seems at first glance. The main thing is to follow the technology.
Twist connection
Twisting, although currently prohibited by the PUE rules, is one of the most common methods of connecting wires in everyday life, due to its simplicity and does not require additional costs. But when connecting dissimilar metals, twisting is also the least reliable method of connecting conductors.
When the ambient temperature fluctuates, due to the linear expansion of metals, a gap forms between the twisted wires, the contact resistance increases, heat begins to be generated, the wires oxidize, and ultimately the contact between the conductors is completely broken. Of course, this happens after more than one year, but, nevertheless, if reliable long-term operation of the electrical wiring is planned, then it is better to replace the twisted wire connection with a more reliable one, for example, a threaded one or using terminal blocks.
But if there is a need to twist the wires, then the twisting must be done in such a way that the conductors wrap around each other, and not one wraps around the other. The photo on the left shows twisting, which is unacceptable, since it will not ensure sufficient mechanical strength of the connection. Twisting a copper conductor and an aluminum one without taking measures to additionally seal it is unacceptable. The twist can be sealed with any waterproof protective varnish.
The most reliable connection between copper and aluminum conductors will be achieved if the copper wire is first tinned with solder. In the right photo, the copper and aluminum wires are twisted correctly.
Wires of different diameters can be connected, stranded wire with single-core wire. Only the stranded wire must first be tinned with solder, thus making it single-core.
There must be at least three turns in the twist for a thick wire and at least five for a thin wire with a diameter of less than 1 mm.
Threaded connection
of aluminum wires with copper
Connecting wires, when done correctly, with screws and nuts is the most reliable and can ensure proper contact throughout the life of the wiring and connected electrical appliances.
Easily disassembled and allows you to connect any number of conductors, limited only by the length of the screw. Using a threaded connection, you can successfully connect wires in any combination, aluminum and copper, thin and thick, stranded and single-core.
The main thing is to avoid direct contact between copper and aluminum wires and install spring washers.
In order to make a threaded connection, it is necessary to remove the insulation from the conductors to a length equal to four screw diameters; if the wires are oxidized, then clean the metal until it shines and form rings. Next, 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.
Currently, the method of connecting wires using a terminal block has become widespread. Of course, this type of wire connection is inferior in reliability to a connection using a screw and nut, but it has a number of advantages.
Allows you to reliably and quickly connect aluminum and copper wires to each other in any combination; there is no need to form rings at the ends of the wires, and there is no need to insulate the connection, since the design of the terminal block prevents the bare sections of the wires from accidentally touching each other.
To connect a wire to the terminal block, just strip its end of insulation to a length of 5 mm, insert it into the hole and tighten it with a screw. The screw must be tightened with considerable force, this is especially important when connecting aluminum wires.
The terminal block is indispensable when connecting the chandelier to short aluminum wires coming out of the ceiling. From repeated twisting, aluminum wires break off and become short.
Even if the aluminum conductor is only one centimeter long, you can reliably connect the chandelier using the terminal block.
A terminal block is very convenient for connecting aluminum and copper wires broken in the wall, since the length of broken wires for connection by other methods is insufficient. But hiding the terminal block under the plaster without placing it in a distribution box is not permissible.
Connecting aluminum to copper wires
using a Wago flat-spring terminal block
Currently, 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 reusable, with a lever that allows you to repeatedly insert and remove wires.
The photo shows a Wago disposable terminal block. They are designed for connecting any types of single-core wires, including copper and aluminum wires with a cross-section from 1.5 to 2.5 mm2. 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 5 A.
Wago spring terminal blocks are very convenient for connecting chandeliers, connecting wires in junction and distribution 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 with this terminal 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, stranded, aluminum in any combination with a cross-section from 0.08 to 4.0 mm2. 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 aluminum wires with copper
A permanent connection of wires has all the advantages of a threaded connection, with the exception of the possibility of disassembling and reassembling the connection without destroying the rivet and the need for a special tool for making the rivet - a riveter.
Today, rivets are widely used for permanently connecting thin-walled structural parts when creating partitions and interiors in any premises.
Speed, strength, low price and ease of riveting are the main advantages of this type of permanent connection.
The operating principle of the riveter is simple: retracting and cutting a steel rod threaded through a tubular aluminum rivet with a head. The rod has a thickening and when it is pulled into the rivet tube, it expands it. Rivets come in different lengths and diameters, so you can choose any one.
In order to connect the conductors with a rivet, you need to prepare them in the same way as for a threaded connection. The diameters of the rings should be slightly larger than the diameter of the rivet. The optimal rivet diameter is 4 mm. First, an aluminum conductor is placed 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). The connection is ready.
The reliability of threaded and permanent connections with rivets is quite high. This connection method can be successfully used to splice, for example, aluminum conductors damaged during repair work in a wall with an additional insert. You just need to take care of good insulation of the exposed areas of the connections.
You can find other types and methods of connecting wires on the page “How to properly connect electrical wires.”
There is an opinion that it is unacceptable to connect aluminum and copper wires directly together and this is indeed a scientifically proven fact. Is it possible to connect a copper wire to a galvanized terminal? Of course, you cannot immediately give an answer, but in a minute you will be able to navigate this issue no worse than an experienced chemist.
What happens when two different current conductors come into contact? If there is no moisture, the connection will always be reliable. But there is always water vapor in the atmospheric air, which is the culprit for the destruction of contacts. Each current conductor has a certain electrochemical potential. This property of metals is widely used in technology, for example, thermocouples are made.
But if water gets between the metals, it forms a short-circuited galvanic cell, current begins to flow, and just as one of the electrodes is destroyed in the galvanic bath, so one of the metals in the connection is destroyed. The electrochemical potential of each conductive material is known, and knowing the value, you can accurately determine which materials can be connected to each other.
Table of electrochemical potentials (mV)
arising between connected conductors
According to the requirements of the standard, mechanical connection between materials is allowed, the electrochemical potential (voltage) between them does not exceed 0.6 mV. As can be seen from the table, the reliability of contact when connecting copper to stainless steel (potential 0.1 mV) will be much higher than with silver (0.25 mV) or gold (0.4 mV)!
And if a copper wire is coated with tin-lead solder, then you can safely connect it with aluminum in any mechanical way! After all, then the electrochemical potential, as can be seen from the table, will be only 0.4 mV.
Source: https://YDoma.info/ehlektrotekhnika/vybor-podgotovka-montazh-provoda/electricity-soedinenie-alyuminievyh-provodov.html
How to properly connect copper and aluminum wire
Aluminum electrical wiring can often be found in older buildings. Now everyone understands that this is not the best metal for current. Today, during a major renovation, all the wiring of an old building is usually changed. However, with partial repairs, it becomes necessary to connect aluminum and copper wires.
Is it possible to connect aluminum wires to copper
First of all, you need to return to the school curriculum in chemistry and physics. There is such a thing as a “galvanic cell” - a simple battery that generates electric current. It is formed by the interaction of metals in an electrolyte. Twisting copper and aluminum cable wiring will essentially be the same battery.
Wire connections
Galvanic current quickly destroys metal. Despite the fact that it does not form in dry air, and the twist in the socket will not fall apart in a day, problems are guaranteed when the wiring is used for a long time.
After a few months or years, the wires will begin to deteriorate - this will lead to an increase in resistance. When a powerful current consumer is connected to the outlet, the twist will overheat. If such a connection is used regularly, there is a risk of fire.
Wiring fires
Regulations prohibit the direct twisting of aluminum and copper conductors. However, in emergency situations, the transition must be made, so you need to follow certain rules.
What happens when copper and aluminum come into contact?
Any metal, including copper and aluminum, oxidizes when exposed to oxygen. This leads to the formation of an oxide film on the surface of the material. In the case of copper, it does not prevent the passage of electric current, but the film on aluminum increases its resistance.
If wires are connected, dissimilar metals will begin to interact tightly. Aluminum is considered more active, therefore, when moisture accumulates at the joints (it is present in the air in any case), the process of electrolysis begins, that is, aluminum ions are gradually transferred to copper.
Metal twisting
As a result, one of the conductors loses its mass. Voids and breakdowns form in aluminum - they also oxidize, which speeds up the electrolysis process. The speed of the process also depends on the volume of moisture. Towards the end of the reaction, an almost destroyed aluminum conductor is obtained - its cross-section decreases, and the current density increases. As already described above, the metal heats up and there is a risk of fire.
Rules for connecting copper wires to aluminum
There are safe ways to connect copper and aluminum wires:
Bolted connection
This method is considered the most affordable, reliable and simple. For arrangement you will need:
- Bolt;
- Screw;
- Steel washers (several pieces);
- Wrench.
It is unlikely that it will be possible to use this method to connect wires in an apartment junction box - today they are made too small, and the finished connecting unit is quite large.
However, if a Soviet-era box is installed in the building or you have to work in a distribution panel, then the bolt method is the best solution.
It is considered to be the ideal solution if you have to connect completely incompatible cores - with different cross-sections, from different materials, multi-core/single-core.
Important! The bolt method allows you to connect more than 2 conductors (their number depends on the length of the bolt).
Connection device process:
- Each of the wires will have to be stripped of the insulation layer - 2-3 cm from the edge.
- A ring is assembled from the cleaned ends around the circumference of the bolt so that they can be put on it without any problems.
- Next, a bolt is taken, and a washer is put on it, after which a ring of copper wire, then a second washer, a ring of aluminum conductor, and finally a third washer, the entire resulting structure is tightened with a nut.
- Finally, you need to secure the connection using insulating tape. It is important not to forget that there is an intermediate washer between the aluminum and copper. If you plan to work with several different conductors, then a washer is not necessary between conductors of the same material.
Bolted connection
A special advantage of this method is the versatility of the connection. It can be untwisted and re-twisted at any time and, if you need to add wires, or change the connection diagram.
Terminals
Another cheap and easy connection method is terminal blocks. They are easy to find and buy, especially considering that they are often not sold in whole sections, but are cut in the quantity required for work. The pads come in different sizes, which directly depends on the cross-section of the conductors.
Terminals
Terminal blocks for connecting aluminum and copper wires are a plastic frame with several cells. Inside each is a brass tubular sleeve. The stripped ends of the wires are threaded into the terminal from different sides and clamped with screws. Connection arrangement:
- Loosen the clamp, releasing one part of the sleeve in order to thread the bare part of the wire into the sleeve.
- At the end of the conductor, strip the insulation by 5–6 mm. The wire is inserted into the block, the screw is clamped, fixing the metal to the sleeve. The fastening must be tightened firmly, but not too tightly, otherwise it will break the core.
- Similar steps for connecting a copper wire - only on the opposite side of the terminal.
Important! All stages of work must be carried out sequentially, despite the fact that it is physically possible to loosen both screws, thread the wires and tighten them at once. This is necessary so that the copper and aluminum do not touch ends inside the sleeve.
The main advantage of the terminals is the simplicity of their design and speed of installation. The method is called detachable - one of the conductors can be pulled out without any problems to connect the other.
Lever terminals
The pads are not suitable for working with stranded wires. In this case, you will first have to mount the sleeve tip, which is crimped with a bundle of cores.
Another feature of the terminals is that under screw pressure at room temperature, aluminum sometimes leaks. This leads to the need to regularly check the pads and tighten the contacts. If this is not done, the contact weakens, the connection heats up and sparks - there is a risk of fire.
Wago terminal blocks
A quick and easy connection method - the wires must first be stripped and inserted into the terminals until they stop. There they are automatically fixed using a pressure plate - it strongly presses the material against the tire. The transparent terminal housing allows you to control the passage of the conductor. The problem with this method is the disposability of such devices.
If you need a reusable clamp, then it is better to buy lever terminals. The lever is raised to clear the passage into the hole - the stripped wire is inserted there. The lever is then lowered to lock the wire inside the terminal. This is a detachable connection of copper and aluminum - if necessary, the lever rises to reach the conductor out.
Interesting! WAGO self-clamping devices are very popular and trusted in the market. The company produces a special series of terminals equipped with Alu-plus contact paste. This is a mixture that protects aluminum and copper contacts from corrosion. The model can be distinguished by the special “Al Cu” marking.
Self-clamping structures are very easy to use. The terminal itself indicates how long the core insulation needs to be stripped.
Rivets
Rivets are used to create a permanent connection, which has the same advantages as a threaded connection, but does not require disassembly and reassembly without destroying the rivet and requires a special tool - a connector.
Today, the method is more often used to connect thin-walled elements when forming partitions and the interior of different rooms. Electricians choose rivets because of their low cost, durability, and ease of installation.
Rivets
The principle of installing an electrical connection is simple: a metal rod threaded through a tubular rivet with a head is pulled in and cut. The rod has a thickening - it expands the rivet as it passes through the tube. Retainers come in different lengths and sizes.
Before connecting the wires, they must be prepared in the same way as in the case of a threaded bundle. The diameters of the rings should be slightly larger than the diameters of the rivets - the optimal is 4 mm. An aluminum core is first put on the rivet, then a spring washer, then a copper conductor and a second washer. A steel rod is threaded into the electrical installation and the tool is clamped until it clicks (this is how excess steel is cut off). All is ready.
Connections, both threaded and permanent, are characterized by reliability. This method is used to splice, for example, aluminum wiring damaged during repair work. It is imperative to insulate exposed areas.
Soldering iron
Soldering wires consisting of different metals is a completely feasible solution, if you take into account certain operating rules. Copper does not cause difficulties when soldering, which cannot be said about aluminum. An amalgam is formed on its surface, which is characterized by strong chemical resistance - it does not provide the solder with proper adhesion.
Soldered wires
To work with two dissimilar metal wires, you will have to prepare a solution of copper sulfate, a Krona battery and a piece of copper wire. The future soldering area is carefully cleaned on the aluminum core. Then a solution of copper sulfate is applied to this place.
Copper wiring is connected to the positive pole of the Krona battery and immersed in vitriol solution. An aluminum conductor is connected to the negative pole. After some time, a copper layer will be deposited on the aluminum - solder clings to it without problems.
Adapters for connecting from aluminum to copper
Sleeve adapters for crimping are considered the most reliable and high-quality connection. Special copper-aluminum models are made, into which 2 wires are inserted, after which they are processed with a press. However, it should be noted that the sleeves require sections starting from 16 mm2, while in residential buildings from 1.5 to 4 mm2 are used. Therefore, it is better to connect using a standard aluminum sleeve. Pressure testing occurs according to the following algorithm:
- We strip the ends of the copper conductor with lead-tin solder - this helps prevent metal-to-metal contact.
- Get rid of aluminum oxide film.
- Pass the wires through from different ends and crimp them.
- Wrap the connections with electrical tape or heat shrink followed by heating.
Important! If excessive crimping is done inside the structure, the soldered layer at the copper end may be damaged, so the size of the sleeve and matrix must match the core.
The good thing about the adapter from aluminum to copper is that it can be embedded under the plaster without fear of the wiring catching fire. However, implementation will require a press, which entails certain costs.
Sleeves
It is recommended that when carrying out work, all electrical wiring is intact, without breaks or connections - this reduces the risk of fire. However, if there is an urgent need to join a copper and aluminum core, then you need to take into account all the recommendations and choose one of the most optimal methods.
Source: https://rusenergetics.ru/provoda-i-kabeli/kak-soedinit-medniy-i-alyuminieviy
Connecting aluminum and copper wires to each other
Modern electrical wiring in an apartment or house is carried out only with copper wires, as the PUE says. But in old houses, wiring was most often done with aluminum wire, and a situation arises in which it is necessary to connect 2 wires of different materials. And in this article you will learn how to connect copper and aluminum wire in different ways.
Methods for connecting copper and aluminum wires
Is it possible to twist copper wire with aluminum
Let's start with the fact that is it possible to connect aluminum wires with copper wires, and will such a connection not lead to a fire? The answer is yes, you can. But let's first get acquainted with these materials.
If you ask yourself which wiring is better, copper or aluminum, then the choice is, of course, copper. This comes out of the technical characteristics of copper; the cross-section of aluminum wire under the same conditions has to be taken larger. There are also disadvantages: copper is more expensive. It is easier to distinguish copper wire from aluminum by color; copper has a reddish tint, aluminum is gray and white.
Having looked at the electrical performance of metals, the question of which conducts current better disappears. Here's some information:
- Resistivity: copper – 0.017 Ohm mm²/m, aluminum – 0.028 Ohm mm²/m.
- Heat capacity: copper - 0.385 J/gK, aluminum - 0.9 J/gK.
- Elasticity of the material: copper – 0.8%, aluminum – 0.6%.
So why can’t you twist copper and aluminum wires, because twisting, especially with a small cross-section, is the cheapest option in terms of both money and time? The thing is that these materials, when connected, create a galvanic couple.
Galvanic pair - 2 metals of different kinds, the connection of which will lead to increased corrosion. Copper and aluminum are just such a galvanic pair. The electrochemical potentials of the two metals are too different, so rapid corrosion will increase the resistance at the junction and subsequent heating. More details about the compatibility of metals are indicated in GOST 9.005-72. Below is a table with some data on metals:
Galvanic compatibility of meltals
You can achieve high-quality contact between two conductors in different ways (soldering, using a simple terminal block, more expensive WAGO terminals, or an ordinary bolt and nut).
Connecting wires
Connecting aluminum and copper wires to each other requires technological solutions; simple twisting is not enough.
Methods for connecting conductors with different electrochemical potentials:
- By soldering. But not simple soldering.
- Using simple terminal blocks or expensive WAGO. There is no point in saving money here, and if the question is how to properly connect copper and aluminum wires, then it is better to take WAGO. The advantages of this manufacturer will be described below.
- Using a bolted connection, which has many advantages: low cost, simplicity and the ability to work with large cross-section wires.
- Crimping with sleeves. Requires specialized tools.
WAGO
WAGO clamps for joining aluminum and copper are very popular, as they are very convenient to use:
- Click the pressure plates to the side.
- Insert wires into holes.
- Place the plates in their places and clamp them.
WAGO terminals for connecting copper wire to aluminum are an excellent solution
But now WAGO is casting doubt on its reputation. According to numerous reviews, the spring contact weakens, which leads to burning of the terminal block and its rapid replacement.
Twisting wires
Twisting aluminum and copper wires was previously mentioned as a very unreliable connection method, but sometimes this is the only way to quickly restore power supply.
A couple of tips before twisting:
- Before twisting, the copper wire should be well tinned.
- The amount of twist must be at least 5 turns.
- After work, the joint must be protected with several layers of insulating tape or heat shrink tubing.
Soldering copper to the terminal block
You can solder copper and aluminum together. If everything is clear with copper, then for soldering aluminum you need a special flux. Some electricians simply solder copper wire to the terminal block.
Flux for aluminum
Terminal blocks
The list of electrician tools and consumables includes terminal blocks. Terminal blocks are copper or brass coated with a layer of nickel, designed for wires of a certain cross-section and covered with a layer of insulating plastic. The wires are secured with 2 small screws.
When connecting copper and aluminum terminal blocks, the locking screws must be properly tightened. If you tighten them, you can damage the aluminum conductors, which will not have a very good effect on the further operation of the electrical wiring. Therefore, it is necessary to find a middle ground: not tighten too tightly, but achieve high-quality contact.
Nut connection
"Nut" is another type of terminal block, most often used for branching large-gauge wires. It consists of 2 copper plates placed in a plastic case.
Copper and aluminum wire, as well as a branch wire, are placed between the plates. But you can simply use the “nut” as a connecting element. After laying the conductors, the plates are tightened with bolts. As insulation, a plastic case is placed over the entire structure, consisting of two halves, for fastening which standard screws are used.
Walnut connection is suitable for all types of street connections and branches
Lubrication
To improve the quality of contact, you can use a special lubricant or paste. Usually this is quartz vaseline paste. It is usually used to improve the connection of aluminum wires.
But this paste can be used for all types of connections (threaded, using terminal blocks, crimping), especially if the connection takes place outdoors. Then the contact is affected by additional factors that significantly reduce the durability of the connection. Although the use of lubricant without insulation raises doubts.
Bottom line
Based on all of the above, select the method that is suitable for you, depending on the location of the connection (street, house) and material capabilities.
Source: https://domashnysvet.ru/elektroprovodka/coedinenie-alyuminievyx-i-mednyx-provodov
Is it possible to connect aluminum wires with copper wires, how to do it correctly
When carrying out various electrical installation work, beginners often have a question: is it possible to connect aluminum wires with copper wires?
If so, what should you consider? Or is it better not to?.. Well, we can dwell in more detail on these and other related issues.
And yet, is it possible to connect aluminum wires with copper
Generally speaking, in case of emergency, this can still be done. But, as they say, be careful.
Twisting is a common option for connecting wires when installing electrical wiring, but when connecting wires made of dissimilar metals, this option is completely unacceptable.
In the old days, many self-taught electricians got by by simply twisting copper and aluminum wires together, then wrapping the whole thing in blue electrical tape - and nothing, it worked. For the time being, true. It was in the most literal sense - Russian roulette. After all, it was impossible to say in advance exactly when it would “explode.”
It could have blown through, but such a twist could have led to huge troubles and even cost the lives of the whole family. In order to understand what, strictly speaking, the danger is, you can recall the basic concepts from the school course in physics and chemistry. First of all, aluminum and copper have different characteristics in terms of resistivity.
Moreover, the lower the resistance of the conductor, according to Ohm’s law, the greater the current strength at a constant voltage. Since the voltage in the household network usually remains unchanged - it is the usual 220 volts - the electric current begins to gain strength. If it flows from a conductor of greater resistance to a conductor with less, then a jump in current strength begins to be observed in the latter.
As a result, the conductor heats up with less resistance - and a fire is almost guaranteed. The risk increases significantly during regular voltage surges - which, it’s no secret, is common in domestic power grids.
However, the difference in resistivity can be leveled out if conductors of different cross-sections are used.
After all, the larger the cross-sectional area of the conductor, the lower the resistance, and vice versa. Therefore, a wire made of a material with lower resistance should simply be thicker - and the problem is solved?
Copper and aluminum cannot be combined together, because... The presence of humidity and water vapor in the air is one of the factors that destroys contacts.
Not resolved at all. After all, the second danger is that conductors made of different materials are subject to so-called electrochemical corrosion over time in an oxygen environment. The situation is aggravated by the direct connection of aluminum and copper wire. As a result, a galvanic couple is formed, which will gradually destroy the conductor.
To prevent this from happening, you need to ensure that the environment is completely dry. However, in practice this is not possible. After all, there is always moisture in the air. Especially when it comes to a bathroom or shower.
Finally, even the strongest twist will come apart over time if dissimilar materials are used.
Indeed, due to the difference in resistance, there will also be a difference in temperature for one and the other conductor. They will expand at different speeds, which, when the current consumer is periodically turned on and off, will be tantamount to pulling the twist back and forth.
Of course, not in a couple of hours or even in a couple of days, but sooner or later there will be a breakdown in contact between the conductors - and sparking wiring in this case is far from the biggest nuisance.
Note! Direct twisting of wires made of copper and aluminum is today strictly prohibited by all known rules. A conscientious master will never allow himself anything like this.
However, this does not mean that there are no ways to solve the problem of connecting copper and aluminum wires to each other.
How to connect dissimilar conductors using the threaded method
Connecting copper and aluminum wires with a screw and nuts is the most reliable contact, capable of ensuring conductivity for the entire life of the electrical wiring.
One of the possible options, which allows for a high-quality connection of not only copper and aluminum wires, but also any dissimilar conductors in general, is the threaded connection method. It is done using a screw and nuts.
Moreover, the number of conductors is limited in practice only by the length of the screw itself onto which the wires are attached. In this way, it will be possible to combine almost all known types of conductors - of different thicknesses and made of different materials, with different numbers of cores, etc.
To successfully complete this type of connection, you will need:
- Remove the insulating layer from the wires to a length that will be equal to four diameters of the screw on which the bait is applied;
- Next, you should make sure that the cores themselves have not undergone oxidation. Otherwise, you need to clean them to a metallic shine;
- Now you need to form rings from the bare metal part of the conductor;
- At the next stage of work, a spring washer is put on the screw, then a regular washer - and a ring from one conductor. Again, a simple washer is placed on it, and then you can put on a ring from another conductor;
- A fastening nut is screwed onto the resulting “sandwich”. It must be screwed until the spring washer straightens.
The basic rule is to prevent direct contact between aluminum and copper, and to install spring washers under the nuts.
As practice shows, for a standard wire with a diameter of 2 millimeters it will be enough to take an M4 screw.
If stranded copper wire is used, it must be properly tinned with solder before starting work.
How to connect dissimilar wires using terminal blocks
Although the method described above ensures reliability if implemented correctly, today they are increasingly resorting to another method - through a connection using the so-called terminal block.
It is worth noting that, although in terms of reliability of fastening the terminal block is inferior to a threaded connection, the implementation of fastening in this way is more convenient and faster. There is no need to form any rings, carry out final insulation, etc. After all, the entire design of such a block assumes that the wires are in an isolated position.
In order to connect the wires using a terminal block, you will need to strip their ends of insulating material to a length of about 5 millimeters. Then the bare end of the wire is simply inserted into the hole on the block - and clamped using the supplied screw. In this case, you need to screw with noticeable force.
This is especially true for aluminum wires. Indeed, due to the expansion of the material due to heating of the wire, the connection may weaken over time.
A common option is to connect wires made of different metals using a block.
- For example, if you have to connect a chandelier with a shortened aluminum wire. As a result of repeated twisting, aluminum wires may break off - and then only a block will help;
- Or if you have to connect copper and aluminum wires broken inside the walls. After all, the length of the broken wires is not sufficient to form not only a twist, but also to make a threaded connection. In this case, the lack of length will be compensated by the terminal block.
Connecting the block terminal with a Wago flat spring clamp
Particularly worth noting is the so-called Wago spring clamp, which is used in terminal blocks of conventional German production. Moreover, such blocks can be in reusable and disposable versions. In the first case, it will be possible to open the lock many times and change the wires if necessary, but in the second case, the wire is placed in the block only once, and it is impossible to remove it again.
Wago terminal blocks are designed for connection with a current strength of up to 24 amperes, as the manufacturer assures. But practice shows that it is better not to risk a current of more than 5 amperes.
If you use a Wago lock, insert the stripped end of the wire 10 mm into the hole in the block - and it will be fixed inside.
In order to remove the wire, you will need to apply quite a lot of force.
Terminal blocks from the world leader WAGO have long been known as a reliable device for quick installation of electrical wiring.
Permanent connection of wires using the rivet method
This method will require the purchase of a special rivet machine. In this case, the wires are prepared in exactly the same way as for a threaded type of connection. As for the diameter of the rings, it should be slightly larger than the diameter of the rivet itself.
Typically the diameter of each rivet is 4mm. First, an aluminum conductor is put on it, then a spring washer, then a copper wire should be put on - and a flat washer on it.
Now the rivet rod is inserted into the machine - and the handle is clamped until a characteristic click is heard, which indicates that the connection is ready for use.
Manual riveter is a professional hand tool for installing threaded (nut) rivets and screw rivets.
What do experts recommend?
Evgeniy Valerievich Sukhorukov, electrician: If you use removable type threaded screw connections, you will need to monitor them at least once a year for loosening.
Elena O., sales consultant: It’s not worth purchasing a terminal block with a margin of wire thickness. If you have doubts about whether the wire will fit into the hole, it is better to cut a sample and bring it with you to the store.
Results
Source: http://79w.ru/elektrosnabzhenie/provodka/mozhno-li-soedinyat-alyuminievye-provoda-s-mednymi-kak-pravilno-eto-delat
How to connect copper and aluminum wire
In residential buildings that were built in Soviet times, electrical wiring was carried out with aluminum wires. Professional electricians prefer to make a modern household network with copper wires.
Therefore, whether we like it or not, we often have to face the problem of how to connect copper and aluminum wire. Don’t listen to those who tell you that you absolutely can’t do this.
Of course, not all methods are suitable for this case, however, connecting electrical aluminum and copper wires is a completely solvable task. The main thing is to do everything correctly.
These two metals have different chemical properties, which affects the quality of their connection. But there were smart heads who figured out how to connect two conductors, while eliminating direct contact between them.
We will look at all existing options for how you can connect copper and aluminum wires, but first, let's figure out why this cannot be done with ordinary twisting and what is the reason for this incompatibility?
Reasons for incompatibility
The main reasons for the undesirable connection between these two metals lies in the aluminum wire.
the result of twisting copper and aluminum is overheating of the connection, melting of the insulation, the possibility of fire
There are three reasons, but they all lead to the same result - over time, the contact connection of the wires weakens, begins to overheat, the insulation melts and a short circuit occurs.
- Aluminum wire has the ability to oxidize when exposed to moisture in the air. This happens much faster when in contact with copper. The oxide layer has a resistivity value greater than that of the aluminum metal itself, which leads to excessive heating of the conductor.
- Compared to copper conductor, aluminum is softer and has lower electrical conductivity, due to which it heats up more. During operation, the conductors heat up and cool down many times, resulting in several cycles of expansion and contraction. But aluminum and copper have a large difference in the magnitude of linear expansion, so a change in temperature leads to a weakening of the contact connection, and weak contact is always the cause of strong heating.
- The third reason is that copper and aluminum are galvanically incompatible. If you twist them, then when an electric current passes through such a unit, even with minimal humidity, a chemical electrolysis reaction will occur. This, in turn, causes corrosion, as a result of which the contact connection is again broken, and as a result, heating, melting of the insulation, short circuit, and fire.
Walnut clip
Another good way to connect copper and aluminum wires is to use nut clamps. It is more correct to call this device a branch compressor. It was already the electricians who nicknamed it “the nut” because of its external resemblance.
It is a dielectric polycarbonate housing, inside of which there is a metal core (or core). The core is two dies, each of which has a groove for a certain cross-section of the conductor, and an intermediate plate, all of which are connected to each other with bolts.
Such clamps are sold in any electrical goods store; they have different types, which depend on the cross-section of the wires being connected. The disadvantage of such a device is that it is not sealed, that is, there is the possibility of moisture, dust and even small debris getting in. For reliability and quality of connection, it is better to wrap the “nut” with insulating tape on top.
The process of connecting wires using this compression is as follows:
- Disassemble the compression housing; to do this, pry up and remove the retaining rings using a thin screwdriver.
- On the wires to be connected, strip the insulating layer to the length of the dies.
- Unscrew the fixing bolts and insert the exposed conductors into the die grooves.
- Tighten the bolts, position the die in the compression housing.
- Close the housing and install the retaining rings.
A practical example of using a nut clamp is shown in this video:
Terminal block
A cheap and simple solution to the question of how to connect aluminum wires to copper wires is the use of terminal blocks. Buying them now is not a problem at all; moreover, you can buy not a whole section, but ask the seller to cut off the required number of cells. Terminal blocks are sold in different sizes, depending on the cross-section of the conductors connected to them.
What is such a block? This is a transparent polyethylene frame designed for several cells at once. Inside each cell there is a brass tubular sleeve. From opposite sides, the ends of the wires to be connected must be inserted into this sleeve and clamped with two screws.
The use of terminal blocks is very convenient because you can always cut off exactly as many cells from it as there are pairs of wires that need to be connected, for example, in one junction box.
Using the terminal blocks is very simple:
- Unscrew one clamping screw, thereby freeing one side of the sleeve for the conductor to pass into it.
- On the cores of the aluminum wire, strip the insulation to a length of 5 mm. Insert it into the terminal, tighten the screw, thereby pressing the conductor to the sleeve. The screw should be tightened firmly, but do not force it too hard, so as not to break the core.
- Do the same operations with the copper wire, inserting it into the sleeve from the opposite side.
Why do you have to do everything one by one? You can immediately unscrew two screws, insert the wires and tighten them. This is done to ensure that the copper and aluminum wires do not touch each other inside the brass sleeve.
As you can see, the advantages of terminal blocks are their ease and speed of use. This connection method is a detachable one; if necessary, you can remove one conductor and replace it with another.
Terminal blocks are not entirely suitable for connecting stranded conductors. In order to do this, you must first use ferrules that will crimp the bundle of cores.
There is one more feature in the use of terminal blocks. Under screw pressure at room temperature, aluminum can flow. Therefore, periodic inspection of the terminal and tightening of the contact connection where the aluminum wire is fixed will be required. If this is neglected, the aluminum conductor in the terminal block will become loose, the contact will weaken, begin to heat up and spark, which may result in a fire.
How to connect wires using a terminal block is shown in this video:
Self-clamping terminals
It is even faster and easier to connect aluminum and copper conductors using self-clamping terminals.
The stripped conductors must be inserted into the terminal holes until they stop. There they will be automatically fixed with the help of pressure plates (it will firmly press the conductor to the tinned busbar). Thanks to the transparent housing of the terminal block, you can check whether the core has fully entered the terminal. The disadvantage of such devices is that they are disposable.
If you want a reusable clamp, use lever terminals. The lever rises and releases the entrance to the hole into which the stripped core must be inserted. After which the lever is lowered back, thereby fixing the conductor in the terminal. This connection is detachable; if necessary, the lever is raised and the wire is removed from the terminal.
Self-clamping terminals “WAGO” have proven themselves best in the electrical goods market. The manufacturer produces a special series of terminals that contain “Alu-plus” contact paste.
This substance protects the contact junction between aluminum and copper from the manifestation of electrolytic corrosion processes. You can distinguish these terminals by the special marking on the packaging “Al Cu”.
Using such terminals is also extremely simple.
The clamp itself indicates how long the insulating layer of the conductor needs to be stripped.
The advantages and disadvantages of using WAGO terminal blocks are described in this video:
How best to connect aluminum and copper cable: methods
- Types of cable connections
- What is the best way to connect aluminum cable cores?
How best to connect an aluminum cable: methods
When connecting wires, you need to understand how to do it correctly. Otherwise, the wires may quickly burn out or there will be poor contact, which will lead to the electrical wiring starting to get very hot.
This is especially true for connecting aluminum wires, which cannot be soldered with tin and rosin (mmasvarka.ru). And, of course, you probably know that twisting copper and aluminum wires is not recommended.
Firstly, such a connection will oxidize, which will lead to loss of contact, and secondly, it will become very hot, which can lead to the wire burning out.
Types of cable connections
You can connect aluminum wires to each other in different ways, namely:
- Twisting method. However, this method of connecting aluminum wires has one significant drawback. Aluminum wire is very sensitive to bends, etc. Therefore, it can break in places where it is twisted;
- For bolt and nuts. A more reliable method of connecting aluminum wires than the one described above. To do this, take a bolt and several nuts with washers, between which one and the other end of the wires being connected is clamped. In this case, the connection is quite reliable and durable. Its only disadvantage is that it is bulky, and often open, without any insulation;
- Pads. Universal devices for connecting wires, and those can be made of dissimilar metals;
- By means of a sleeve. You can connect aluminum wires using a small tube for this purpose, which is crimped after two or more wires have been laid in it. Before this, it is recommended to twist the aluminum wires together and then crimp them using a sleeve.
Let's take a closer look at how exactly aluminum cables are connected using all of the above methods.
What is the best way to connect aluminum cable cores?
Twisting aluminum wires - with proper winding, this connection method will last at least 50 years. Twisting of wires can be different, for example, as in the pictures. The second connection method is certainly much better and more reliable.
Bolted connection - take a long bolt and wrap one end of an aluminum wire around it, closer to the head. Then a washer is put on the bolt, and the end of the other wire is wound behind it. After this, everything is tightened with one or two washers. Bolts, washers and nuts are best used to connect wires made of dissimilar metals, such as aluminum and copper.
Terminals and blocks are an equally popular way to connect aluminum wires. This method is fast and reliable, as well as the ability to connect copper and aluminum wires. Today there is a wide variety of terminal blocks, for example, Wago, and simpler ones in design.
Sleeve connection - with this method, two wires are twisted together and then crimped using a cable sleeve. For greater reliability, the sleeve is crimped not with pliers, but with press tongs specially designed for this purpose.
To make a sleeve to connect two wires, you can use a copper tube to connect the air conditioner. The sleeve must have a length of at least 5-7 cm, and its diameter depends on what cross-section of the cable will need to be connected (crimped).
Source: https://mmasvarka.ru/kak-luchshe-soedinit-alyuminievyj-kabel.html
How to combine copper with aluminum - the better and more reliable
Almost everyone already knows that aluminum wiring is a legacy of the last century, and it must be changed when renovating an apartment. Few people carry out major repairs and forget about it.
However, there are situations when the repair is carried out partially, and there is an urgent need to connect an aluminum wire with a copper one or simply extend them by adding a few extra centimeters of wire.
However, aluminum and copper are not galvanically compatible. If you connect them directly, it will be something like a mini battery.
When current passes through such a connection, even with minimal humidity, an electrolytic chemical reaction occurs. Problems will definitely show themselves sooner or later.
Oxidation, weakening of the contact, its further heating with melting of the insulation. Transition to a short circuit or burnout of the core.
What such contact can ultimately lead to, look at the photo.
How to make such a connection competently and reliably to avoid problems in the future.
Here are some common methods that electricians use. True, not all of them are convenient for working in installation boxes.
Let's take a closer look at each of them and choose the most reliable one, which does not require subsequent maintenance or revisions.
Here a steel washer and bolt are used for connection. This is one of the most proven and simple methods. The truth is that it turns out to be a very large design.
For installation, twist the ends of the wires into rings. Next, select the washers.
They must be of such a diameter that the entire eye of the wire is hidden behind them and cannot contact another conductor.
The most important thing is how to position the ring. It must be put on so that when tightening the nut, the eye does not unfold, but rather is pulled inward.
Steel washers between conductors made of different materials prevent oxidation processes. In this case, do not forget about installing the engraver or spring washer.
Without it, contact will weaken over time.
The fact is that metals whose electrochemical potential of the connection does not exceed 0.6 mV can be safely connected to each other.
Here is a table of such potentials.
As you can see, copper and zinc have as much as 0.85 mV here! This connection is even worse than direct contact between aluminum and copper conductors (0.65 mV). This means the connection will not be reliable.
However, despite the simplicity of the threaded assembly, the end result is a large, awkward structure, shaped like a beehive.
And it’s not always possible to stuff this whole thing into a shallow socket. Moreover, even in such a simple design, many manage to screw it up.
The consequences will not keep you waiting in a very short time.
Another method is to use a nut-type connecting clamp.
It is often used to branch off a supply cable with a much larger cross-section than a tap.
Moreover, it does not even require cutting the main wire. It is enough to remove the top layer of insulation from it. Some have found a use for it to connect the input cable to the SIP.
However, you shouldn't do this. Why, read the article below.
But again, nuts are not suitable for junction boxes. Moreover, sometimes such clamps burn out. Here is a real review from a user on one of the forums:
There are a series of special clamps that can be used to join copper to aluminum.
Inside these terminals there is antioxidant paste.
However, disputes about the 100% reliability of such clamps, especially for sockets and not lighting groups, have not subsided to this day. When installed in a limited space, the contact may weaken, which will inevitably lead to burnout.
Moreover, this can happen even at a load below the minimum for which Vagos are designed. Why and when does this happen?
The fact is that when the connected conductors are compressed, a small gap appears between the pressure plate and the contact point. Hence all the heating problems.
Here is a very clear video that explains this problem without further ado.
This method has one significant disadvantage. Most of the pads sold are of very poor quality.
Some people get clever and, in order to avoid direct contact between copper and aluminum, the copper core is soldered to the side of such a clamp, rather than inserted inside.
True, the terminal will have to be disassembled for this. In addition, reliable aluminum contact under the screw without revision does not last very long.
The screws will need to be tightened every six months to a year. The frequency of revision work will directly depend on the load and its fluctuations during periods of maximum and minimum.
Forget to tighten up and expect trouble. And if this entire connection is hidden deep in the socket, then getting into it every time is not a very convenient task.
Therefore, the most reliable method available is crimping. Here we will not consider the use of specialized copper-aluminum sleeves GAM, since they start from sections of 16mm2.
For home wiring, as a rule, you need to increase the wires by 1.5-2.5 mm2 no more.
Let's consider the most common case that occurs in panel houses. Let's say you need to power one or more additional outlets from an existing aluminum outlet in a through niche.
For extensions, take a FLEXIBLE copper wire with a cross section of 2.5 mm2. This will reduce the mechanical impact on the aluminum core when you lay the wires in the socket box.
Strip the ends of the copper wire.
Further, for such a connection they must be soldered. This will prevent direct contact between copper and aluminum in the sleeve. For soldering, it is convenient to use a homemade crucible, which is a slightly modified soldering iron in the shape of a hatchet.
In this case, before soldering with flux, remove the oxide layer from the core.
The tinning process itself involves dipping the wire into a special hole in the soldering iron filled with tin.
After the core has cooled, the remaining flux is removed with a solvent.
Next, move on to the aluminum wires sticking out of the wall. Carefully clean their ends and also remove the oxide layer.
To do this, you can use oxide conductive paste. The same paste is used when installing modular pin grounding systems.
https://www.youtube.com/watch?v=ZH1ZLOYL_xo
It is designed to work in any conditions and eliminates the further appearance of oxide on the surface of the wire. Keep in mind that the oxide film can subsequently have a resistance several times greater than the aluminum itself.
And without removing it, all your further work will go down the drain.
Moreover, the melting point of such a film reaches 2000 degrees (versus approximately 600C for Al). After all the preparatory work, insert the wires into the GML sleeve from both sides. All that remains is to crimp this connection.
Some people will have a logical question: will the solder layer on the core be pressed through during crimping? Then it turns out that all tinning manipulations will be in vain.
The main thing here is to choose the correct cross-section of the sleeve and die of the tool for crimping.
In this case, the soft solder will, as it were, seal the contact spot of the copper-aluminum connection. And without oxygen access to this point, contact erosion will not be observed.
Be careful; when working with aluminum conductors, you must act with extreme caution, as this is a very brittle material. One careless movement and you are guaranteed to have a broken wire.
After crimping, it is necessary to insulate this connection with adhesive heat shrink.
It is the adhesive type that will ensure 100% tightness and prevent the flow of oxygen to the contact areas. In order not to risk burning the insulation, it is better to heat the heat shrink with a hair dryer rather than with a lighter or portable torch.
The resulting bundle of wires must be placed in the electrical box with great care, since aluminum does not like sharp bends.
Since the extended copper wires are flexible, you put insulated NShVI lugs on the ends of these conductors.
Only after this can they be safely inserted into the terminal blocks of the sockets and the screws tightened.
Of course, this is not the only way to extend aluminum wires, but it is one of the simplest (as opposed to welding or soldering) and reliable (as opposed to twisting). More details
If you have the slightest opportunity to change the entire aluminum wiring, be sure to do it, do not skimp on your safety.
Source: https://domikelectrica.ru/kak-soedinit-med-s-alyuminiem/
