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 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.
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/
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.
Bolted connection
Bolted connection of aluminum wires to copper is considered the most affordable, simple, fast and reliable. To get started you will need a bolt, a nut, some steel washers and a wrench.
Of course, it is unlikely that you will be able to use this method to connect wires in an apartment junction box, because now they are produced in miniature sizes, and the resulting electrical unit will be very bulky.
But if there are still Soviet-era boxes in your house or when you need to make a connection in a distribution panel, then this bolted method is best suited.
In general, it is considered an ideal option when it is necessary to connect completely incompatible conductors - with different cross-sections, made of different materials, multi-core with single-core.
It is important to know that using the bolt method you can connect more than two conductors (their number depends on how long the bolt is long enough).
You will need to do the following:
- Strip each connected wire or cable from the insulating layer by 2-2.5 cm.
- From the stripped ends, form rings according to the diameter of the bolt so that they can easily be put on it.
- Now take the bolt, put a washer on it, then a ring of copper conductor, again a washer, a ring of aluminum conductor, a washer and tighten everything securely with a nut.
- Insulate the connection using insulating tape.
The most important thing is not to forget to place an intermediate washer between the aluminum and copper wires. If you will connect several different conductors, then you do not need to place an intermediate washer between the cores of the same metal.
Another advantage of this connection is that it is detachable. At any time you can unwind it and, if necessary, connect additional wires.
How to properly bolt a wire connection is shown in detail in this video:
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:
Why can't you connect copper wire directly to aluminum?
To hang a chandelier or lay a new wire line in an old apartment, you often need to connect aluminum and copper wires. However, electricians categorically prohibit making such twists. Let's figure out why you can't twist copper and aluminum and how to connect conductors from different metals correctly.
Wiring difficulties
Modern rules for creating indoor wiring (PUE) require that all conductors in the apartment be copper. However, in Soviet times, in order to save money, in most houses the wiring was made of aluminum wires. Therefore, residents of old-built apartments often face the problem of connecting copper and aluminum conductors. There may be several reasons, for example:
- the need to build up a broken aluminum wire;
- installation of an additional outlet;
- replacing an old chandelier with a modern one.
Usually the wires are connected in the simplest way - twisting. However, electricians strictly prohibit twisting aluminum and copper. Such a connection is called fire hazardous and short-lived. However, not everyone is able to explain the reasons for the ban on the creation of such a connection.
What does physics say?
According to the laws of nature, when two metals join, a galvanic couple appears. Since each metal has its own electrochemical potential value, at the point of contact the pair members will begin to transport electrons. Such processes occur, for example, in a battery. If there is an electrolyte at the point of contact or the metals are under current, the rate of electron transfer from one metal to another will increase significantly.
Since the electrochemical potential of copper and aluminum differs significantly, galvanic processes at the junction occur quickly. This leads to several unpleasant consequences:
- The appearance of an oxide film on the surface of the aluminum wire. These metal destruction products conduct electricity poorly and significantly reduce the quality of contact.
- Gradual corrosion will destroy the conductors and create gaps between them. This will also lead to poor contact.
In addition to the ability to form a galvanic couple, aluminum and copper have a high difference in their ability to expand when heated. Due to temperature changes, conductors expand unevenly, which also leads to an increase in gaps and a decrease in the quality of contact.
A poor-quality contact begins to heat up when current passes through it. Therefore, the place where the copper and electrical wires are twisted will quickly turn into a source of heat. And it’s not far from the fire. Therefore, electricians categorically prohibit connecting copper and aluminum wires by twisting.
Some metals and alloys used in electrical engineering have slight differences in electrochemical potential and expansion coefficients. Such materials are called compatible. For aluminum, zinc, duralumin, and electrical steel are compatible. For copper – chrome, nickel, brass and bronze.
What if a connection is necessary?
Sometimes you still have to connect incompatible metals with each other. In such cases, special technological solutions are used that can improve the quality of contact. Let's look at some of them in more detail.
Connections using terminal blocks
Terminal blocks, or terminal blocks, are a consumable item for a modern electrician. This is a contact group placed in a plastic case, made of copper alloy and coated with a layer of nickel. They are quite simple to use:
- It is necessary to strip the connected wires.
- Insert the ends into the opposite sockets of the block.
- Securely secure by tightening the clamping screws.
If you press the aluminum core too hard, it may break off. Therefore, do not over-tighten the screws!
WAGO terminal blocks
A modern version of the terminal block, equipped with spring clips. It is enough to release the presser feet, insert the stripped wires into place and clamp them again. However, the accumulated experience in operating such pads has revealed a number of disadvantages:
- Over time, the retainer spring may weaken, causing poor contact and overheating.
- WAGO are more expensive than conventional terminal blocks.
Bolt connection
An ordinary steel bolt equipped with three washers can also help securely connect an aluminum conductor to a copper conductor. Rings are made at the ends of the wires, then they are put on the bolt. The order is as follows: washer - copper - washer - aluminum - washer. Then the contact is carefully pressed with a nut and insulated.
The disadvantage of this method is the large size of the connection. It is only suitable for large cross-section conductors.
Thus, although it is impossible to connect copper to aluminum by twisting due to the high fire hazard, there are safe connection methods for such wires. If you use one of them, you don’t have to worry about the stability of the contact and the protection of your home from fire.
Source: https://mschistota.ru/sovety/soedinenie-alyuminievogo-i-mednogo-provoda.html
Why can't you connect copper wire to aluminum? — Website about
06.12.2019
Connection of copper and aluminum conductors
There are many rumors about the connection of copper and aluminum wire. Some say that there is nothing wrong with this and give examples where such connections last for decades, while others say that they know from practice how quickly they break down. We will discuss who to believe and how to correctly connect such wires in our article.
Why you can’t connect copper and aluminum wire
First of all, let's figure out why you can't connect these wires together, and what you need to ensure that such a connection lasts for many years. To do this, we will have to dive a little into the theory and understand the structure of these metals.
How to connect copper and aluminum conductor
But you can connect a copper wire to an aluminum one. To do this, it is enough to place a third material between these two conductors or completely eliminate the possibility of moisture penetrating to the point of contact of the metals.
- Let's look at both of these options. Let's start with the simplest one - placing a third metal between the conductors. Usually, an inactive metal is also chosen for this, so that we again do not have the electrolysis process. And usually the instructions recommend using brass for this.
Connection of copper conductor and aluminum through a steel washer
The photo shows the same connection after heating the washer
- This is due to the fact that this material has fairly good electrical properties. It is chemically stable and interferes with the electrolysis process.
- Some suggest using regular steel or stainless steel for this. But you shouldn't do this. The fact is that these materials do not have very good conductivity. Therefore, when large currents pass through them, they will become very hot. As a result, we may get a fire again.
Note! If you still decide to go with a bolted connection, you can use a brass washer instead of a steel washer. If you have metal, you can cut it out yourself. The option with a steel washer can only be used in networks with a not very heavy load.
- The second possible option is to prevent water from entering the junction of metals. Sealing the connection will be too expensive and not always a reliable option. Therefore, in most cases, a special paste is used for this, as in the video.
Contact grease
- This paste not only prevents the penetration of moisture into the contact joint, but also oxygen. As a result, aluminum oxidizes very slightly, because it takes literally a few seconds to form an oxide film. And thanks to the absence of moisture at the junction, the most terrible process for such a connection – electrolysis – does not occur.
How to connect copper and aluminum wires correctly
Knowing the causes and possible solutions to the problem, you can begin to analyze the question of how to properly connect copper and aluminum wires. And here there are several quite logical answers, some of which we have already given in the section above.
Let's start with the question of lubrication. This can be technical petroleum jelly, lithol or any other lubricant that prevents metal oxidation and moisture penetration. But here the question arises with the subsequent isolation of such a connection. After all, electrical tape adheres very poorly to lubricant, and heat shrink can simply squeeze it out.
Note! In any case, twisted connections are prohibited. And for such different metals, twisting can be doubly destructive.
| Terminal blocks for connecting wires | You can connect copper and aluminum wires using a variety of terminals. These can be spring, screw or any other types, just keep in mind that aluminum and copper should not touch. |
| Brass wire lugs | If you are trying to connect solid aluminum and stranded copper wire with a screw terminal, it is advisable to use special brass lugs. Moreover, they should be used for both metals. |
| Crimp lugs for screw connections | This is due to the fact that when aluminum is screw clamped, it may lose part or even all of its cross-section. Aluminum is a fairly soft material and a well-tightened screw can completely crush it. |
| Ferrule for copper stranded wire | The situation is similar with stranded copper wires. But only in this case, when tightening the screw, it can break some of the wires in the conductor. Again - reducing the cross-section. Therefore, such tips can be an excellent panacea for such accidents. Moreover, the price of such products is mere pennies. |
| Wire crimping sleeves | One of the possible options for connecting a copper wire to an aluminum wire would be to use special crimp sleeves. Nowadays, sleeves made of brass are quite widely represented on the market. For a more visual demonstration, one edge is white and the other is copper. They are specially designed for crimping copper and aluminum wire. |
| Connecting wires by soldering | Aluminum and copper wires can also be connected by soldering. Only in this case you will need special solder for aluminum and high-quality tinning of the copper conductor. By the way, just tinning the copper conductor will be enough to prevent electrolysis. |
| Welding for such connections is usually not used due to the different melting temperatures of the metals. And this does not protect against the electrolysis process. Therefore, it is better to forget about welding wires. | |
| Screw terminals for large cross-section wires | Before connecting large cross-section aluminum and copper wires, it is better to put special lugs on them. They are pressed on and usually have a brass contact part. This allows them to be connected in the future using a regular screw connection without any problems. |
Conclusion
There is no clear answer to the question of how best to connect copper and aluminum wire. After all, everything here depends on local conditions and the supplies at hand. But in any case, there are quite a lot of such options. Only their direct twisting is not allowed, which in any case is prohibited by the rules of the PUE.
Source: https://kak-vse-ustroeno.ru/obshhestvo/pochemu-nelzya-soedinyat-mednyj-provod-s-alyuminievym.html
How to connect aluminum and copper wires correctly?
Connecting wires made of dissimilar metals (a particular and most common case is copper and aluminum) is most often necessary in cases where the home wiring is made of copper conductor, and the entry into the house is made of aluminum.
It happens the other way around. The main thing here is the contact of dissimilar metals. Copper and aluminum cannot be combined directly.
The reasons lie in the electrochemical properties of metals. Most metals, when combined with each other in the presence of an electrolyte (water is a universal electrolyte), form something like a regular battery. For different metals, the potential difference upon contact is different.
For copper and aluminum this difference is 0.65 mV. It is established by the standard that the maximum permissible difference should be no more than 0.6 mV.
If there is a higher potential, the conductor material begins to deteriorate and become covered with oxide films. The contact will soon lose reliability.
For example, the electrochemical potential difference of some other pairs of metals is:
- copper - lead-tin solder 25 mV;
- aluminum - lead-tin solder 40 mV;
- copper – steel 40 mV;
- aluminum – steel 20 mV;
- copper – zinc 85 mV;
Twisting wires
The simplest, but least reliable way to connect conductors. As mentioned above, you cannot directly twist copper and aluminum wires. The only possible contact option for such materials is tinning one of the conductors with lead-tin solder.
It is very difficult to tin the aluminum at home, but there will be no problems with copper. A powerful soldering iron, a piece of solder and a little rosin or other flux for soldering copper and copper alloys is enough. Tinned copper and pure aluminum conductors are tightly twisted together using pliers or pliers so that the wires wrap tightly and evenly around each other.
It is unacceptable for one conductor to be straight and the other to wrap around it. The number of turns must be at least 3-5. The thicker the conductors, the fewer the number of turns you can make. For reliability, the twisted area can be wrapped with a bandage made of thinner tinned copper wire and additionally soldered. The twisting area must be carefully insulated.
Threaded connection
The most reliable connection of wires is threaded (bolted). The conductors are pressed against each other using a bolt and nut. To make such a connection, it is necessary to make rings at the ends of the connected wires with an internal diameter equal to the diameter of the bolt.
Just like for twisting, the copper core must be tinned. Multicore wire must be serviced (even if wires of the same metal are connected).
The resulting compound looks like a sandwich:
- bolt head;
- washer (with an outer diameter no less than the diameter of the ring on the wire);
- one of the connected wires;
- second wire;
- washer similar to the first one;
- screw;
The copper core does not need to be tinned, but in this case a steel washer must be placed between the conductors.
A significant disadvantage of this method is its large dimensions and, as a consequence, difficulties with insulation.
Terminal blocks
The most technologically advanced way to connect wires is to use special terminal blocks.
Terminal blocks have a number of advantages over other connection methods:
- Ease of installation.
- Use of any combinations of conductor materials.
- Connecting conductors of different diameters.
- There is no need to manipulate the wire other than stripping its end of insulation.
- There is no need to insulate.
- Convenience of securing the block itself.
Clamping of the conductor in the terminal blocks can be done in 2 ways - directly with a screw, or using a metal clamping plate. The second option is preferable, since in the first case there is a risk of damaging the wire with the screw (aluminum is a very soft metal).
Permanent connection
riveter
This installation method is performed in the same way as using a bolt and nut, but using a special tool - a riveter. The operating principle of the riveter lies in the rivet design.
It is a hollow aluminum tube with a thickening at one end. A metal rod with a head is inserted into the rivet. When the rod is pulled through the rivet, it forms a bulge at the other end of the rivet, while simultaneously expanding the tube itself somewhat.
When a certain maximum force is reached, the rod breaks off, leaving a clean, formed rivet. If you do not take into account the cost of the tool, the price of an individual rivet makes this type of installation the cheapest after twisting. There is only one drawback - such a connection is disposable and permanent.
Another option for permanent connections is obtained by using special tinned copper connecting tubes. Such tubes are produced in several diameters to suit the most common diameters of the wires being connected.
The stripped ends of the wires are inserted into the opposite ends of the tube and the latter is crimped with a special device. Together with twisting, this is the most compact type of connection of conductors.
This method can be used only if the diameter of the wires is the same and exactly matches the diameter of the tube.
Alternative options
Wago clamps
The method of connecting dissimilar wires using special spring clamps has recently become quite widely used. The most famous clamps are from Wago.
There are 2 types of such clamps:
- Disposable , without the ability to pull out the wire.
- Lever , reusable.
The principle of operation is a special spring clamp made of a special alloy, which is enclosed in a plastic case. The design of the clamping edge allows it to cut into the metal body even if there is a thick oxide film on it.
Clamps are produced for almost all used conductor diameters and are designed for currents up to 34 A. However, experience in electromechanical work suggests that the maximum permissible current must be reduced several times, that is, clamps must be purchased with some current reserve.
Wiring using spring clamps is the fastest. One of the disadvantages is the fairly high cost of materials.
Features of the use of connections for external and internal work
nut clamp
All of the listed methods for connecting conductors of dissimilar metals are intended for the internal electrical network. For outdoor work, it is better to use a special plastic clamp “Nut”.
The plastic body of the clamp contains several metal plates. The clamp body is tightened with special screws and reliably protects the connection point from contact with the environment. As a rule, external electrical networks are not as critical of connection dimensions as they are indoors, so connections with the “Nut” clamp are a pretty good option.
It must be borne in mind that conductor connections, no matter what they are, are prohibited from being tightly sealed in walls, ceilings, etc., much less hidden under a layer of plaster. Only special distribution boxes should be used.
Blitz tips
And finally, a few tips that you should take into account in order to protect yourself in the future and not redo the work:
- To strip conductors, you should not use side cutters, pliers or any other tool with a similar operating principle. In order to cut the insulation without affecting the body of the wire, considerable experience is required and still in most cases the integrity of the wire will be compromised. Aluminum is a soft metal, but it does not tolerate bending very well, especially if the integrity of the surface is damaged. It is possible that the wire may break during installation. And it’s much worse if this happens a little later. It is necessary to remove the insulation with a sharp knife, moving it along the conductor, like stripping a pencil. Even if the tip of a knife removes some layer of metal, a scratch along the wire is not terrible.
- To tin copper conductors, under no circumstances should you use acid-containing fluxes (zinc chloride, etched hydrochloric acid, etc.). Even thorough cleaning of the connection will not save it from destruction for some time.
- Stranded conductors must be tinned before installation to obtain a monolithic conductor. The only exceptions are spring clamps and terminal blocks with clamping plates.
- Washers, nuts and bolts for detachable or permanent connections should not be made of galvanized metal. The potential difference between copper and zinc is 0.85 mV, which is significantly greater than the difference when copper and aluminum are directly connected.
- For the same reason, you should not purchase overly cheap terminal blocks from an unknown manufacturer. Practice shows that the metal elements in such pads are often zinc coated.
- You cannot use the advice to protect the direct connection of copper and aluminum conductors with various water-repellent coatings (grease, paraffin). Machine oil is difficult to remove from leather alone. The sun, air, and negative temperatures will destroy the protective coating much faster than we would like. In addition, some lubricants (especially grease oil) initially contain up to 3% water.
Source: https://housetronic.ru/electro/alyuminievyj-i-mednye-provoda.html
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.
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
Crimping
For this method you will need special crimping pliers and sleeves. The principle of connecting wires with a sleeve is very simple: an aluminum wire is inserted into the sleeve on one side, a copper wire on the other, and the sleeve is crimped on both sides with pliers. There are sleeves for wires with a large cross-section - from 16 mm2 to 300 mm2, but in this case a special hydraulic press will be required. The only drawback of crimping is the high cost of the tool.
Special sleeve for connecting aluminum and copper
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
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.
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
