When repairing electrical wiring in old houses, you may be faced with a situation where large sections of wiring have to be changed. However, in most cases, the old wiring is made of aluminum, and you only have copper wire for replacement. In general, it is strictly forbidden to connect conductors made of such different materials, but it happens that there is simply no other way out. Let's consider how, nevertheless, to connect the aluminum and copper wire so that there is no short circuit or fire.
To do this, you should strain your memory and remember the school course in chemistry and physics.
First, let's remember what it is galvanic cell... Simply put, an electrochemical cell is a simple battery that generates an electrical current. The principle of its appearance is based on the interaction of two metals in the electrolyte. So, the twist between the copper and aluminum wire will be the same battery.
Galvanic currents quickly destroy the material. True, in dry air, their appearance is excluded. And if you twist to the outlet, then it will not fall apart in a few hours. However, later on, such wiring is in trouble.
Over time, the materials from which the wires are made deteriorate, along with this constantly resistance increases... If a powerful consumer of current is connected to the outlet, the twist will begin to heat up. With regular use of such an outlet, the threat of fire increases.
Therefore, it is strictly forbidden to connect an aluminum conductor to a copper one. However, emergency situations arise when it is simply necessary to make such a connection.
Let's consider several ways how to connect aluminum and copper wire. These methods will help you successfully cope with a difficult task.
Of course, this will not happen within a year, but if the connection is to function for a long time, then it is worth thinking about other methods of fastening.
The very principle of fastening using the twisting method is that both conductors wrapped around each other... For a better connection, the copper cable is tinned with solder. Stranded copper wire will have to be tinned without fail.
To combine copper and aluminum in this way, you need a pair of simple washers, one lock washer, screw and nut. This method is very reliable - the contact between the conductors will be provided for many years. For this fastening, neither the cross section of the wire, nor its type - stranded or single-core is important.
The insulation is removed from the end of the wire. A spring washer is put on the screw, then a regular washer is put on, then a ring of aluminum wire. It is supported by a simple washer. After that, a copper conductor is put on, and then a nut is screwed onto the screw. It grips the entire joint tightly.
A stranded cable must be soldered before connecting.
This is a modern method of wiring. Although it loses a little in reliability to the threaded connection method , the method has its advantages:
Let us explain the latter, it happens that a small piece of cable sticks out of the wall or ceiling. It is impossible to twist - there are very few wires. And the twist made on the ceiling will not last long, after some time the wires will simply break off. And the terminal block will hold both conductors with screws for a long time. Then the block completely eliminates the contact of the two stripped conductors.
Installation is carried out as follows: the end of the wire stripped from insulation (about 5 mm.) Is inserted into the terminal hole of the block, after which the locking screw is tightened.
The terminal block cannot be hidden in plaster or wall without a junction box.
This method appeared not so long ago. There are two types of such a connection: disposable and reusable... There is a special lever for the last connection in the terminal block. Thanks to it, the wire can be inserted and removed several times. Terminal blocks of this type can successfully connect copper and aluminum stranded wires of various types.
They are widely used for installing chandeliers and connecting wires in junction boxes. Some force is required to insert the wire into the hole in the terminal block. It will take even more effort to pull the conductor out. For practical use, it is better to use reusable models. In the event of an error, the connection can be quickly redone.
It is very easy to perform such an installation. First with the cable insulation is removed(about 10 mm.). Then, on the reusable terminal block, you need to raise the lever, insert the wire, and then return the lever to its original position. It's that simple!
In terms of reliability, it is not inferior to a threaded connection and has its own Advantages and disadvantages:
Installation is carried out using a special tool - a rivet. An aluminum wire is put on the rivet, then a spring nut, then a copper wire and a flat washer. Then the riveter comes into play and the connection is ready.
It is worth mentioning that the connection section must be insulated.
Is it possible to solder conductors made of various materials? It is quite possible if meet certain conditions.
There will be no problems with brazing copper, unlike aluminum. An amalgam forms on the surface of this metal, exhibiting surprising chemical resistance. That is, the solder cannot stick to it. This phenomenon is often surprising to novice electricians.
To solder two different conductors, you should stock up on a solution of copper sulfate, a Krona battery and a piece of copper wire. On the aluminum wire, the future soldering point is carefully cleaned. Then drip on this place copper sulfate solution.
The copper wire is connected to the positive pole of the Krona battery and dipped into copper sulfate. An aluminum conductor is connected to the negative pole of the battery. After a while, a layer of copper will settle on the aluminum, on which you can solder the required wire without any problems.
Once again, it is worth noting that any wire connection must be insulated.
Can place connections in special junction boxes .
If you plan to make a connection with my own hands, then you should not resort to the soldering method. It requires certain experience and qualifications. It is better to use another of the above methods of connecting the aluminum and copper conductors.
The most accessible and common methods were discussed in the article. However, in the absence of experience in carrying out such work, it is better to turn to professionals.
Reading time ≈ 3 minutes
Wiring is never complete without wiring. The higher the electricity consumption in everyday life grows, the more important is the correct connection of the wiring wires, which would ensure the requirements for electrical and fire safety. Correct wire connection is the level of contact density, as well as the electrochemical compatibility of the metals of the wires being connected.
Nowadays, many apartments still have aluminum wiring. As soon as in such an apartment a simple task arises of replacing a chandelier or an outlet, a problem may arise. connections of aluminum and copper wires.
It is known that direct connection of these metals is strictly prohibited and is a flagrant violation. Direct contact of copper and aluminum is unacceptable due to the incompatibility of these metals. Under the influence of moisture, such a connection becomes unsafe: it can cause a fire.
Dry contact, although a little more reliable, is also unsafe: it will just break down more slowly. If moisture suddenly gets on such a contact, an accident may occur even with a small current.
There are several ways, here are the main ones according to the PUE:
Perhaps the easiest way is to use a layer of neutral material. The neutral metal is lead-tin solder.
The method is good in that it does not require clamps, or if the bolted connection does not fit into the box.
Despite the fact that the method is simple and quick, nevertheless, if the cumbersomeness of the connection is not a problem, it is better to use a threaded connection, it will be more reliable. Threaded connection of copper and aluminum wires is also quite simple. For this type of connection, you need to prepare a spring washer, three simple washers and a nut. If the conductors have a core diameter of up to 2 mm, choose the M4 screw.
If the copper wire is stranded, you must first wire it. Do not forget that such connections must be checked periodically: the optimal frequency is once a year.
When partially replacing electrical wiring, lengthening the conductor or replacing a burned-out area, a wire is used. It happens that they do not coincide in their material. Then it becomes necessary to connect aluminum wires with copper ones. There are five ways to do this, and each has its own advantages and disadvantages. Some of them require preliminary preparation of the guide.
The industry produces two types of wires for household purposes, copper and aluminum. The former have less resistance, which allows using a smaller cross-section with the same load. They are more resistant to mechanical stress, this makes it possible to twist repeatedly, not to be afraid that they will break at the place of the cut. The latter have one advantage - comparative cheapness. But she sometimes plays a key role. What can happen if the connection is of poor quality?
Copper and aluminum have different characteristics, for example, different coefficient of expansion when heated. When a large current passes through an aluminum conductor, it begins to "flow". If the cores move relative to each other during heating or cooling, this will lead to a gap between them. The gap, in turn, will lead to discharge (sparking). Sparks can cause fire. Along with this, copper and aluminum begin to oxidize, the resistance between them increases, the voltage due to this drops or may completely disappear. Power surges can have a detrimental effect on connected devices.
There are several ways to connect. They all have their pros and cons. Some require special equipment and skills, while others are easy to use. Here are a few of them:
After the twisting has been made, it must be protected from the environment by coating with any waterproof varnish. This is to reduce further excessive oxidation. Then it is insulated with electrical tape or special caps, which are sold in the store, and hidden in an insulating case. But even all this does not guarantee that the twisting will work flawlessly.
More laborious than twisting connection. Requires a tool and some skill. Has greater mechanical strength. On the electrical side, it is better than twisting. Allows you to immediately connect a large number of wires, and of different cross-sections. You can connect both single-core and multi-core.
A bolt is used for the connection, on which the conductors are put in turn... They are pre-stripped and wrapped in rings. Each core, if made of different material, is laid with a washer. A washer and a spring washer are applied to the last conductor. The entire package is tightened with a nut until the spring washer is straightened. Further squeezing may break the conductor.
To prevent the washer from cutting the wires, they must be put on in a checkerboard pattern (so that they do not lie on top of each other). If the copper wire is irradiated, no washers are needed. A stranded copper wire also needs to be soldered, then it will not disintegrate when compressed.
After assembly, it is necessary to take measures to prevent short circuiting with adjacent packages. Over time, it is necessary to check the condition of the spring washer, if it is loose, tighten the nut. Such a connection prevents sparking, allows the wires to be removed along different directions... If necessary, it can be easily disassembled and assembled without damaging the conductor.
The terminal connection is manufactured in the factories. Has an extensive assortment. Two groups can be distinguished:
Pads have different shapes and designs. The bottom line is to attach several wires to one conductor (plate, square, etc.), which are inserted into special connectors and pressed with a screw. As a rule, the pads themselves are attached to the base, creating the rigidity of the structure.
The advantage of the pads is that no preliminary steps are needed, with the exception of stripping the veins. The connection is fast and requires no skills. They are irreplaceable if the conductor is short (connecting a chandelier, restoring a broken wire). If they are located in distribution boards, metering boards, they do not require isolation. Since each wire is connected separately, both copper and aluminum wires can be used.
The disadvantages include the following:
Terminal blocks have recently found widespread use. According to their purpose, they are of two types:
Reusable the terminal strip is a fully insulated block. Instead of screws, a spring plate is used, which is squeezed out using a plastic lever. Then a wire is inserted into the opening. In some embodiments, the plate is serrated to allow the use of bare wires. To remove the wire, you must lift the lever again.
One-time have the same principle, but do not have a lever. Designed for single use. If the wire is pulled out and reinserted, the connection quality will be poor.
Advantages:
Disadvantages:
Perhaps the most time consuming method. Requires special knowledge and skills. Special tools and fixtures are required. This method includes:
Riveting very similar to a threaded connection, with the only difference that a rivet is used instead of a bolt. The ends of the wires are cleaned of insulation and cleaned with sandpaper. With a combination of aluminum and copper wires, the latter is tinned. This also applies to copper stranded wire. After that, rings are made of a slightly larger diameter than the rivet. Finally, when the entire structure is assembled (without intermediate washers), a washer is put on top. All this is squeezed by the terminal block. Insulated in the same way as threaded.
Soldering used where high reliability and low resistance are required. It looks like a twist, but the wires are soldered. This cannot be achieved in the usual way for aluminum, therefore the wires must be prepared.
To do this, you need a solution of copper sulfate, a small non-metallic container, a constant voltage source of 9-24 V. Pour a solution of copper sulfate into the container and lower the previously cleaned conductors to the length of the twist. We connect the copper wire to "+" so that the electrons go from it, and the aluminum wire to "-". We turn on the power supply.
The voltage, of course, can be increased, the main thing is that the solution does not boil or there is no overload in the electrical circuit. You can also reduce the stress, then the process will proceed more slowly. All this works until the aluminum wire is covered with a copper film.
Then both wires are covered with a layer of tin. Twisting is done in 3 turns for a thick wire and 5 for a thin one (less than 1 mm). All this is carefully soldered. It remains to cover them with waterproof varnish, insulate - and the connection is ready.
Advantages:
Disadvantages:
Now, knowing all the ways to connect copper and aluminum wires without soldering, you should be able to fix this problem when it appears.
When installing electrical wiring, the question sometimes arises of connecting copper and aluminum wires. This issue is especially relevant for electrical work in the old housing stock, where the bulk of the power grids is made of aluminum wire. How to connect aluminum and copper wires to avoid wiring problems will be discussed later in this review.
As you know, the cause of the problems of direct connection of copper and aluminum is electrocorrosive processes. In a dry environment, nothing will happen with direct contact, but with increased humidity at the junction, a short-circuited galvanic cell is formed, in which metals begin to play the role of a battery with "plus" and "minus". The metal itself practically melts, as a result of which there is a break in the network with a possible short circuit and ignition of the insulation. Which in turn can lead to a fire.
In order to avoid this, various types of contact devices are used for the indirect connection of copper and aluminum wiring.
All connection methods can be divided into 2 groups according to the presence of a wire contact:
Important! To connect aluminum and copper wires, it is recommended to use methods from the second group. It is allowed to use connections from the 1st group, provided that the copper wire is processed. For example, it can be tinned with solder.
The main method of connecting wires in a domestic environment, 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 with extreme caution, observing the following conditions:
There are three main types of twisting: plain, band and groove. It should be noted that bandage twisting will give the best results. When performing twisting, it should be borne in mind 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 cross-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 long enough, but only the use of an indirect connection can give a sure guarantee.
First you need to prepare the ends of the veins. 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 shrinkable tube is put on one of the wires, before twisting, upon completion of all operations, the tube is shifted by open space and is fixed on it. After cleaning the ends, you need to twist the wires according to the proposed scheme. In this case, it is necessary to ensure that the cores are twisted mutually, and that one cable core does not overlap on another.
For the convenience of twisting a stranded copper cable, its conductors can and should be irradiated. It should also be noted that tinning copper in any case increases the reliability of the twist connection. After twisting, the connection point must be covered with a moisture-resistant varnish. Electrical insulation can be done using heat shrink tubing or soft-grip caps or cone spring caps.
Insulation of wire ends with cone spring caps
Important! Unless absolutely necessary, it is not recommended to use a twist to connect copper and aluminum cables. Nowadays, there are many safer and more reliable ways to combine copper and aluminum into one network.
In this case, a metal or plastic sleeve or tip is put on the twist connection, which is fixed on 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 made of PVC insulated metal tube. The nozzles are usually plastic caps into which the connection is inserted, after which the cap is crimped with pressing tongs.
Separately, it should be noted the connection using nozzles-caps with a clamping ring or a cone spring. In this case, after twisting the cores, a cap is put on the twist, after which rotational movements is screwed onto the connection, after which it is simply squeezed with pliers. In this case, a soft metal ring inside the cap tightly compresses the joint. This crimping option is quite affordable for domestic use.
A reliable, albeit 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 bare ends of the conductors.
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, in addition, it is very inconvenient to isolate it. But, at the same time, this type of connection requires only a bolt and a nut.
The first step is to prepare the ends of the wire. 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 rivets are made from the bare cores. With these rings, the wire is put on the rivet or the threaded part of the bolt. A spring washer is laid between the aluminum and copper cables, this is necessary so that there is no direct contact between these metals. Then the connection is fixed by tightening the nut or rivet.
It is worth noting that this option is suitable for splicing wires of sufficient length, while 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.
In this case, the wires are clamped by a riveted rivet, consisting of a tube and a core, fixed with a rivet. For connection, the prepared cores with wound rings are put on a rivet tube with a gasket - a steel washer. After that, the rivet is crimped with a rivet, the core wedges the rivet tube, thereby squeezing the metal of the veins together, thereby fixing the cable veins.
In this case, the contact turns out to be one-piece, but at the same time strong and reliable. For this type of connection, a special tool is required - a riveter, and the skills to work with it. This method is used mainly for working with wire breaks, splicing wire ends in hard-to-reach places.
It is possible to connect copper and aluminum wires in such a tricky way, which also requires preliminary tinning of the copper wire: clamp the wires with two steel strips, with bolts along the edges. Advantages of the method: the ability to connect several branches of the wiring at once, without increasing the length of the bolt. In this case, the bare ends of the veins are placed between the strips. 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 the preparation of the copper wire by tinning.
Convenient and reliable connection method. The terminal block is a strip of insulating material that houses the wire slots. The fixing of the wire in the sockets is carried out with clamping bolts. An important feature in our case is the absence of wire contacts between themselves. To connect copper and aluminum wires, just a screwdriver is enough.
The terminal box is a system of several separately placed terminal blocks, combined into one structure and having several leads.
The advantages of this connection method are:
At the same time, for the installation of hidden wiring in the wall, the terminal block requires the installation of a junction box. Concealed wiring is not permitted without a junction box. In this case, however, a flush-mounted terminal box can be used.
When working with the terminal box, it is important to carefully fix the wire ends in the socket, especially when it comes to aluminum wires... This is especially important when installing the box outdoors or indoors, where temperature fluctuations are possible.
Currently released as terminal blocks and terminal blocks of reusable and single use.
Both reusable and single-use terminal blocks are produced in a wide range, including with a different number of plug-in branch lines, designed to fix wires with a cross-section of 0.08 mm² to 6 mm². Also 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.
Sectional view of the spring terminal block and placement of the connection in the junction box
Terminal boxes with spring clips were first released by the German company Wago, from which they got their name, but now there are a large number of analogues, including counterfeit ones. For this reason, it is necessary to purchase spring terminal boxes only from electrical shops. When purchasing terminal boxes on the market, there is a high probability of purchasing low-quality products that do not meet the stated requirements.
To fix the wire 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 by means of a spring clip or a screw. It should be noted that mounting in a terminal box usually does not require additional insulation, but at the same time, when placed in a wall, a junction box is required. Thus, spring terminal blocks have a number of advantages over other types of connections due to the convenience of connection.
Thus, it is quite possible to connect copper and aluminum wires, but it is necessary to take into account the location of the cable, the environment. By twisting, copper and aluminum can only be bonded in a dry room. If the humidity in the room rises, this connection may become unusable and, moreover, cause a fire. The most optimal today is the method of connecting electrical wiring by means of spring terminal blocks.
The main advantage of this method is stable fixation in any environment. With all the advantages of a screw terminal block, threaded or riveted connection, when operating under conditions of sharp temperature changes, the contact under the screw may weaken. Due to the difference in thermal expansion of the metals of the wires. Loss of contact or short circuit is possible as a result of these changes. Thus, with all the variety of methods for connecting copper and aluminum wiring, the safest method for currently, is the use of self-clamping terminal blocks.
Greetings! Today I will tell you how to connect copper and aluminum wires to each other, so that they do not oxidize, and the connection is as reliable as possible.
In general, in theory, it was always explained to us that the connection of conductors with different resistivity, in this case copper and aluminum, is strictly prohibited, but no one said that this prohibition could be bypassed without violating any rules.
Although the theory tells us about the categorical exclusion of such crafts, even in everyday practice we more and more often have to build up (lengthen) aluminum with a copper wire. For example, when, when replacing an outlet, the wiring breaks off at your root. This happens everywhere, since the shelf life of aluminum wiring has long been out, and it is becoming more and more difficult to find aluminum wires on the market of electrical goods.
Now let's consider several options for connecting copper with aluminum:
The first option there will be a connection using bolted terminals, this is one of the simplest and safe ways connections. And it is simple because you just need to insert the strands cleaned of insulation into the sleeve of the terminal block, and tighten them tightly with bolts. For two veins with cross section 2 * 2.5 mm, 16 Amp terminal blocks will do.
After the work done, everything looks pretty neat and reliable.
This method of connection has been practiced for a long time and did not cause any particular complaints. But nevertheless, there are disadvantages here:
Second option we are associated with a certain innovation called Wago. These are self-clamping terminal blocks designed for switching wires in junction boxes, and also for extending wires, including aluminum and copper ones. The variety of such terminal blocks is large.
But to build up an aluminum wire with copper, this type of Wago is most suitable
All we need to do is just pull the clamp up, at a right angle, and insert the wires we need into the open contacts, then snap the clamps back. A tight connection is provided to us. Today this is the most popular connection due to its speed and reliability. But unfortunately, if the break is in an inconvenient place, you again will not be able to use this terminal block.
If the situation is a little more serious,
than a broken wire in an outlet ... For example, if you have a fire in your control room, and you need to build high-quality input (supply wires) wires, then we need special connecting clamps
The clamps will provide a tight connection and make it possible to withstand heavy loads. But if it is not possible to buy clamps, then for such loads, the correct bolted connection is quite suitable.
To increase the contact area, both wires must be bent into rings. The veins on all sides must be overlaid with washers so that during the pulling of the wires, they are not forced out. At the end, be sure to lock it so that over time the screw does not loosen.
