Is it possible to combine copper with aluminum?

Copper to aluminum connection - electrician's advice - Electro Genius

09.06.2019

For electrical wiring in apartments, the widespread use of copper wires currently prevails. Today you can find aluminum electrical wiring only in places where there is no choice of cable products or in conditions of budget deficit.

After all, just 10-15 years ago, all new houses were sold with aluminum wires and copper was used only by pragmatic wealthy people and, perhaps, aesthetes.

When renovating an apartment yourself, in an old residential building, you may be faced with the task of correctly connecting copper and aluminum wires .

What is special about connecting copper and aluminum conductors to each other? And what pitfalls can you encounter along the way? It would seem, what kind of problem is this? Connect as usual and don’t bother yourself. However, with such connections everything is not so simple. All rules strictly PROHIBIT direct contact between copper and aluminum wires.

Why is it impossible to connect copper and aluminum in the usual way?

The problem lies in the properties of these metals. Aluminum is a more active metal than copper. As a result, an oxide film quickly forms on the surface of aluminum under normal conditions.

This film has worse electrical conductivity properties in contrast to pure aluminum. In this regard, the electrical contact becomes worse compared to copper, the oxide film on which has virtually no effect on the quality of the contact.

The phenomenon of electrochemical incompatibility of metals appears.

It turns out that when copper and aluminum wires are connected, electrical contact occurs between their oxide films. The contact is of poor quality, which will heat up with all the ensuing consequences.

When moisture enters, an electrolysis process begins, which destroys the contact and turns the connection into a potential source of fire.

With such contact, aluminum is the first to be destroyed, with daily heating and cooling, cracks and cavities appear, under the influence of moisture, the connection becomes covered with oxides and salts, the insulation also begins to deteriorate, conductive soot is formed, and over time the contact is broken or leads to a fire. A dry contact will deteriorate slowly over years, and if moisture gets in, an accident can occur in a matter of weeks even with low currents.

There have been precedents in history when copper-aluminum connections have quietly served their purpose, but such examples are the exception rather than the rule. This is possible under greenhouse operating conditions and low currents.

How to properly connect copper and aluminum conductors

What to do when you really need to connect dissimilar metals? There are only two ways left: to connect through another metal or to eliminate the formation of a destructive oxide film.

In the first case, a variety of connectors are used:

• terminal blocks without direct contact of dissimilar conductors,
• protective layer of third metal
• washers
• special tips.

To connect copper and aluminum, special pastes are used, which protect the contact from oxidation and moisture, and prevent subsequent destruction of the contact.

If for the friendship of these two metals a third is needed, then one of them can be tinned. For example, a tinned copper stranded wire will perfectly perform the task when connected to a single-core aluminum wire.

For the specific task of connecting to an aluminum riser, branch clamps (clamps) with or without punctures, the so-called “nuts,” are used in the access panel. They have an intermediate plate that prevents direct contact. There are specimens both with and without paste.

For more everyday tasks, you can use terminal blocks with partitions or different sockets for copper and aluminum conductors.

You can even use a regular bolted connection, the main thing is not to forget to place a washer, galvanized or stainless steel, between the copper and aluminum wires.

Wago terminals successfully combine the properties we need. They have separate clamps for each wire and special pastes for connecting to aluminum wires. These Wago terminals differ from pure copper terminals in color - they are gray-black. For use at home, when repairing old electrical wiring, we recommend that you take a closer look at them.

Connecting aluminum and copper wires when installing new or repairing old electrical wiring is a troublesome and very responsible task. By following simple rules, you can brilliantly solve the problem.

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Good socket design

Source: https://orenburgelectro.ru/podklyuchenie/med-s-alyuminiem-soedinenie-sovety-elektrika.html

Is it possible to solder aluminum and copper - Metalist's Handbook

Despite the fact that in modern construction, during electrical work, aluminum cables are increasingly being replaced by copper cables, aluminum remains an indispensable material in the manufacture of large-section wires and cables.

The reasons for this lie on the surface - the electrical resistivity of aluminum is approximately one and a half times greater than that of copper, and the volumetric weight is three times less.

With a large conductor cross-section, when weight is more important than strength, the choice in favor of aluminum is obvious. The cross-sectional area of ​​an aluminum conductor will be one and a half times greater than that of a copper conductor, and at the same time, aluminum will still be two times lighter than copper. Soldering, among other methods, is used to connect wires.

Soldering methods

The problem with using aluminum conductors is their rapid oxidation. The oxide film significantly impedes the passage of electric current during connections. To do this, twisted aluminum wires are soldered.

You can solder aluminum wires in a junction box using a soldering iron or a gas torch. It is more difficult to use a soldering iron due to the inability to accurately heat to the required temperature. And for aluminum, overheating is just as unacceptable as underheating.

Metal has high thermal conductivity, and the insulation over a large area from the soldering point can simply melt.

It is easier to regulate the heating temperature with a gas burner, but it takes a long time to prepare the surface. However, it is the torch that will need to be used if it is necessary to solder any massive parts to each other. In any case, when soldering aluminum wires, they need to be prepared.

Preliminary processing

The difficulty with soldering is that aluminum itself is a very low-melting material (660 ℃) and if heated carelessly it can melt.

Another factor that makes soldering aluminum wires difficult is rapid oxidation in air.

The oxide film on the surface of the material reliably protects aluminum from the effects of all kinds of external factors, but it also prevents the adhesion of solder to the material and must be removed.

It is almost impossible to mechanically remove the oxide film under normal conditions. The material is instantly oxidized and covered with a new film. You can mechanically remove the oxide film under the oil layer.

But before this, the oil must be heated to 200 ℃ in order to remove any active oxygen that may be present there. This method is very inconvenient at home and labor-intensive.

Therefore, the ends of aluminum conductors must be tinned before soldering. Using rosin or most other fluxes will not work due to the high chemical resistance of the oxide film. It does not dissolve even with organic acids.

To tin the wires, you must use both a special flux and a mechanical method.

Of course, this must be done before the wires are twisted, otherwise it will not be possible to mechanically clean the entire surface of the wire. Only the tinned ends can be twisted together and soldered.

Working with a soldering iron

In order to solder aluminum with a soldering iron, there are several methods, the essence of which is to clean immediately under the flux layer in direct contact with the molten solder.

The first method is that aluminum conductors, before soldering, are cleaned with a hot tinned soldering iron using a mixture of rosin and steel filings.

The second method involves stripping the aluminum wire on medium-grit sandpaper directly under the influence of a hot soldering iron with solder and flux.

Gas burner

Processing with a gas burner is carried out when the parts are in the position relative to each other in which they will be used. The processing smoothly transitions into the soldering process itself.

This happens as follows:

• the burner heats the surfaces of aluminum parts;
• upon reaching the temperature at which the metal is reduced from the oxide, the film is mechanically peeled off;
• under the influence of a flame, the parts are coated with flux, and solder is introduced into the soldering area.

If the parts are thick, then their edges must be cut at an angle of 45°. Typically, heating occurs to the melting point of tin, when the solder spreads and fills the twist groove.

Differences in technology when using flux

Thanks to the achievements of modern science and technology, flux compositions for aluminum have been obtained that actively dissolve the oxide film and protect the material from further oxidation.

Examples of such drugs are formulations labeled F-59A and F-61A. The letter A means that these compounds are intended for soldering aluminum.

When using these fluxes, soldering aluminum wires is greatly facilitated. It is enough to simply treat the finished twist with flux, without even heating it, and then, after heating it with a soldering iron or torch, apply solder.

It will spread over the entire surface of the wires and adhere well, providing a strong and electrically conductive solder joint.

Features of soldering stranded wires

Stranded wires must be soldered only using a special flux, since their mechanical processing is almost impossible. Soldering technology differs in that each wire must first be well treated with flux.

To do this, the bundle will have to be untwisted and fluffed. After processing, each thin wire conductor is covered with solder and the bundle is twisted. After this, twist the two ends and solder it.

Can it be connected to copper?

Situations often arise when it is necessary to connect an aluminum wire to a copper wire. This is perhaps the only case where soldering cannot be used.

It's all about the aluminum itself. It cannot be soldered to other metals at all due to its physical and chemical properties. When connecting directly to copper, galvanic corrosion will occur between the two active metals and will quickly destroy the connection.

And if they are soldered using solder that is neutral to both materials, then the different coefficients of thermal expansion of the metals will quickly destroy the soldered contact. After all, when current passes through a conductor, it will certainly heat up, and after switching off, it will cool down.

Safety precautions

Safety precautions when soldering aluminum wires boil down to observing general precautions when working with electric heating devices, open flames and aggressive liquids, such as fluxes.

It is unacceptable to use faulty soldering irons with damaged insulation and with more power than necessary.

Do not use burners near flammable objects. When working indoors, forced ventilation must be properly organized.

Difficulties in soldering aluminum wires

The main difficulty when soldering aluminum wires, as indicated above, is the presence of an oxide film on the surface of the metal. Fighting it greatly slows down the soldering process.

And if you consider that aluminum wires are now used mainly for laying external power wiring, it becomes obvious that a regular soldering iron and sandpaper will not be enough in this case. Welding is increasingly being used to connect such wires.

Source: https://ssk2121.com/mozhno-li-payat-alyuminiy-s-medyu/

Methods for soldering aluminum wires

Despite the fact that in modern construction, during electrical work, aluminum cables are increasingly being replaced by copper cables, aluminum remains an indispensable material in the manufacture of large-section wires and cables.

The reasons for this lie on the surface - the electrical resistivity of aluminum is approximately one and a half times greater than that of copper, and the volumetric weight is three times less.

With a large conductor cross-section, when weight is more important than strength, the choice in favor of aluminum is obvious. The cross-sectional area of ​​an aluminum conductor will be one and a half times greater than that of a copper conductor, and at the same time, aluminum will still be two times lighter than copper. Soldering, among other methods, is used to connect wires.

Connection of copper and aluminum PUE

Cable and wire products include a variety of types of wires that are designed to solve electrical problems. Moreover, when performing household electrical installation work, it is customary to use either aluminum or copper wire. Other materials are not popular.

If there are no restrictions on weight and cost, then it is better to use copper products. But copper has a significant drawback - it oxidizes in the open air, which often leads to deterioration of contact.

As a result, the junction begins to conduct electric current less and less well, a voltage drop occurs, the connection heats up more and more, and over time the electrical wiring may catch fire.

Therefore, to prevent short circuits and ensure a safe connection, it is better to use aluminum wiring.

Of course, aluminum also has its drawbacks. Its conductivity is 1.5 times lower than that of copper.

Why aluminum

Although aluminum conductors do not have high performance characteristics, they do:

• cheap compared to copper;
• are light in weight. Thus, aluminum wire is 3 times lighter than copper;
• universal in use - the operating temperature range is quite wide from –50 ⁰С to +50 ⁰С;
• resistant to high humidity - up to 98%;
• resistant to corrosion damage. Although there are nuances here too: the surface of any aluminum product in air is instantly susceptible to oxidation and is immediately covered with a film that protects the wire from further oxidation.

It would seem that it is more profitable to use aluminum products than copper ones. But she also has a number of negative qualities. Thus, the disadvantages of aluminum conductors are the low mechanical strength of the material, and the connection of such wires causes problems in the passage of current through them. Besides:

• the conductivity of aluminum is not high enough - 0.0271 Ohm×mm²/m;
• aluminum is susceptible to oxidation, and its film, which appears after it, does not conduct electricity well. But here, too, there is a catch: this film consists of particles of the upper layer of the conductor itself, which separates from the overall structure and thereby reduces its diameter. As a result, the initial resistance characteristic of aluminum wire increases;
• Due to the increased resistance of the film on aluminum wiring in the places where its individual parts are connected, the contact resistance increases, which causes the wiring to heat up. Therefore, if the service life of the aluminum wires used is exceeded, this may lead to a fire;
• Aluminum is not elastic and very brittle. Moreover, fragility increases after overheating.

Whether to use aluminum or copper wires depends on the tasks and priorities.

Application of aluminum wires

The most popular brands of aluminum wires are SIP and AVVG.

The AVVG universal power cable can be used under any conditions, sudden temperature changes and high humidity levels - up to 98%. This is a cable with aluminum conductors and polyvinyl chloride insulation that is quite tensile strength and resistant to aggressive environments.

Such wires are intended for stationary single electrical wiring installations that will not be subject to significant mechanical loads, for example:

• in open areas where the impact of climatic factors is maximum;
• in voids that are located in building structures;
• in basements and rooms that are subject to flooding;
• rarely underground.

Such wires can be used for operation in systems where the voltage passes no more than 660 V, and for conductors with a core cross-section of more than 50 mm, use in networks that carry a voltage of 1000 V is permissible.

The marking of aluminum SIP wires means that they are intended to provide and distribute electricity in overhead power lines and in lighting electrical networks with voltages up to 35 kV. They can be used as an alternative to traditional bare wires because they have an insulating layer of polyethylene. The advantages of SIP include the following properties:

• prevent the risk of overlapping and twisting of wires, which is typical for uninsulated lines;
• help reduce the width of the clearing, and when laying electrical lines in the city, they do not require the allocation of a large right-of-way of land;
• reduce operating costs by up to 80%;
• eliminate the risks of illegal connection and theft of electricity.

Rules for using aluminum wires

Based on the above, aluminum conductors are not considered the most optimal for laying wiring in residential buildings. But their use is possible subject to the following rules:

1. if it is necessary to connect aluminum wires, then it is necessary to use exclusively a mechanical method, clamping contacts and a lubricant specially designed for this, which will reduce the likelihood of contact oxidation;
2. do not connect aluminum wiring directly to copper wiring;
3. periodically tighten the screw connections - during operation, aluminum begins to “leak” from under the clamping point, and this can lead to a decrease in the contact area and burning of the places where the wires are connected;
4. monitor service life.

If you plan to change the copper electrical wiring in the house and install aluminum, but not in all rooms, but partially, then know that this can be done, but subject to some nuances:

• PUE prohibits the use of aluminum wire with a diameter of less than 16 mm² during installation;
• Welding of aluminum wires is not permitted.

How to properly connect aluminum wires

Taking into account the advantages and disadvantages of this type of conductor products, it is customary to use screw or spring clamps when connecting them.

Before connecting aluminum wires using screw terminals, it is recommended:

• clear their ends from the insulating coating by 2 cm;
• clean them with fine-grained sandpaper;
• twist the bare ends into a ring with a diameter slightly larger than the diameter of the clamping screw;
• put the resulting loop on the clamping screw and screw it in as far as it will go.

The disadvantage of this connection method is that due to the leaking property of aluminum, the screws will have to be constantly tightened, so they must be easily accessible.

In the case of using the spring connection method, it is necessary to insert the pre-stripped cores into special terminal blocks. This will avoid re-tightening the contacts, since they will be securely fixed by the spring located inside the terminal block.

Twisting of aluminum wires is not allowed by the rules of electrical installations (PUE).

Connecting aluminum and copper wires: what are the risks?

Sometimes it happens that when laying aluminum wires it is not possible to avoid connecting with copper wires. But, as you know, direct contact connection of copper and aluminum in electrical wiring is not recommended and even dangerous. What to do?

It is impossible to twist wires made of two different metals together, because aluminum and copper differ in their properties, chemical structure, and current conductivity, and the resistivity of an aluminum wire differs from that of a copper wire.

This also applies to the protective film that forms after oxidation: on copper products it conducts electric current, but on aluminum the film has such a strong resistance that it practically does not allow current to pass through and, accordingly, is practically resistant to heating. And after heating and cooling occurs several times in a row at the junction of copper and aluminum wires, they are greatly weakened, which can lead to overheating, sparking and even fire.

Also, in places where copper and aluminum wiring are connected, a galvanic couple can occur. It causes dissociation of the oxides of electrical conductors, contributes to the destruction of the metal structure and the formation of voids and cavities in it, which in turn contribute to a reduction in their cross-section and a deterioration in their ability to pass electric current.

  Why do you need a star and delta connection?

In a word, the connection of aluminum conductors with copper leads to electrocorrosion of the metal and its destruction.

But if you need to connect different wires, then in this case you should not use soldering of aluminum and copper wires, but bolted connections and terminals. Thanks to this, higher security can be achieved than using the conventional twisting method.

Aluminum wire extension: what is it and when is it used?

When carrying out electrical installation work, incidents and difficulties occur: the wire may break on its own due to “old age,” the wall was accidentally cut while drilling, the length was not calculated, and so on. What to do in such situations? The solution to these problems is to build or extend the wire.

How to extend aluminum wire correctly? To do this, there are several ways to lengthen a rather fragile aluminum wire:

• the use of a special heat-shrinkable tube, which is placed on the ends of the wires;
• extension using a block;
• connecting aluminum wires to each other using an aluminum spiral followed by insulation.

If you are using aluminum electrical wiring that is 20–30 years old, using the method of lengthening it becomes unsafe, because in the age of using powerful electrical appliances, the risk of fire increases.

on this topic

Source: https://1000eletric.com/soedinenie-medi-i-alyuminiya-pue/

How to connect aluminum wires to copper wires correctly?

Depending on the type of connection you choose, you will need different materials and tools.

For mechanical connections:

• pliers;
• knife or device for removing insulation;
• PPE caps;
• terminal blocks;
• self-clamping terminals;
• sleeves;
• screw terminals;

When crimping, you will need presses (hydraulic, mechanical, manual of various types, press pliers, etc.).

For welding you will need the following:

• argon-arc welding machine;
• oscillator;
• rubber boots;
• welding mask;
• burner;

For soldering;

• knife or device for removing insulation;
• soldering iron (for small sections of aluminum wires – 60-100 W; for sections larger than 2 mm – 100-200 W);
• solder (POS40, POS60 solders are ideal for home use);
• steel brush;
• sandpaper;

The choice of fluxes deserves special attention, since the better the flux, the easier it will be to solder aluminum. Today, despite the large selection of fluxes, the most preferred ones for soldering aluminum at home are FIM, F-64, FTBf.

Connection methods

The need to connect aluminum products with copper, aluminum or aluminium-copper especially often arises in Soviet-built apartments - this occurs due to the failure of individual sections of aluminum electrical wiring, or due to its complete replacement.

Few people know that the joints must be as strong as possible to prevent heating. If the work done is done poorly, the resistance will increase, causing them to heat up, which will result in a short circuit.

The following methods exist:

1. Soldering.
2. Welding.
3. Mechanical connections:
   • twist;
   • use of terminal blocks;
   • use of contact clamps (self-clamping terminals);
   • connection using bolts;
   • crimping method (crimping);
   • spring devices;

Each of the listed methods has characteristic features.

Twist

It is considered the most short-lived method , especially when the connection occurs with cables made of other metals. However, there are also rules for twisting, compliance with which will significantly improve the quality of work, increase service life and safety.

types of twists

Types of twists:

1. Bandage twist. Bandage twisting is used to connect cables of large diameters. To strengthen the bandage twist, soldering is used - exclusively after tinning the copper wire.
2. Twisting with a groove. The strongest twist.
3. Simple twist . Simple twisting is used exclusively in domestic conditions; this method is most often used to connect current-carrying conductors in junction boxes.

It is not recommended to use twisting for conductors with a cross section exceeding 10 mm2. (for comparison, the average thickness in distribution boxes is 1.5-2 mm2).

Particular care must be taken when connecting multi-core wires (cables):

1. The twisted areas must be cleaned.
2. To strengthen the contacts obtained, it is recommended to use PPE caps.

Welding

Welding aluminum wires at home is a labor-intensive process that requires experience and special knowledge. The main feature is that the seams resulting from welding must form an exclusively integral whole with the original product - only if this condition is met, the current can flow unhindered.

Obtaining a positive result is complicated by the fact that when welding in air, the aluminum surface is covered with a refractory oxide film, so argon-arc welding or fluxes are used.

Welding has a number of specific features:

1. The additive must be applied in short reciprocating movements.
2. The filler wire together with a special electrode must be at an angle of 90° during welding.
3. It is necessary to adhere to one selected arc length (most often 1.5-2.5 mm).
4. The electrode should be 1-1.5 mm away from the burner tip.
5. Welding must be done exclusively from right to left.

Spike

The safest method is soldering - with certain skills you can perform soldering at home:

1. Before soldering, the ends of the wires must be tinned: the part that will be connected is thickly coated with rosin and placed on a grinding surface (wheel or sandpaper).
2. Next, the wire is pressed to the surface with a soldering iron, constantly adding rosin until the required thickness of the wire is achieved.
3. After which the soldering is carried out in the usual way.
4. The most important thing in the soldering process is to prevent the aluminum surface from coming into contact with oxygen - otherwise, a heat-resistant oxide film will form. To do this, the cable to be stripped is generously lubricated, or filled with flux, and in some cases, heated.
5. In the case of soldering wires with a cross-section of up to 4 mm2 , they can be cleaned directly in the solution.
6. If the cross-section of the aluminum wire is 4-10 mm2, it is necessary to remove the insulation, clean it to a shine and twist it.
7. When soft solders are used , AF-44 flux is optimal.
8. The resulting connection should be cleaned of flux residue, wiped with gasoline, coated with moisture-resistant varnish, then with electrical tape, then with varnish again.

Crimping (crimping method using sleeves)

For cases when it is necessary to connect a multi-core cable, or more than 2 single-core wires into one connector, it is best to use crimp sleeves:

1. into such a sleeve .
2. After which the sleeve is compressed using a press or special pliers, a reliable, permanent contact.

This method is most widespread when connecting powerful consumers.

Instead of sleeves, NKI tips are widely used, at one end of which there is a small crimp sleeve - cable cores are inserted into it. At the other end there is a slip ring, thanks to which you can get a high-quality connection with screw terminal blocks.

Using Terminal Terminals

The easiest way to combine aluminum cables into a single current-carrying core is to use contact clamps.

Their types:

• polyethylene clips;
• self-clamping terminals (terminal blocks);
• screw;
• spring (PPE caps);

Advantages of contact clamps:

1. They do not require additional insulation ; to connect, it is enough to strip the aluminum cables, assemble them into a bundle, and then screw the clamp onto the bundle until it stops (insert it into the terminal, or clamp it with a screw, etc.);
2. The resulting contacts have much greater mechanical strength than when twisted;
3. The resulting contacts do not heat up, which minimizes the possibility of short circuits and fires.

Screw connection

Screw (bolt) connection is the most common contact connection of aluminum wires and cables to electrical appliances, instruments, and machines. However, the properties of this metal to spread under excess pressure, along with the difference in coefficient. Thermal expansion of aluminum and the metal of the screw (bolt) can lead to mixing of the screw contact of the wire.

Subsequently, the ring gradually creeps out from under flat washers, most often used for screw (bolt) contacts.

To prevent the described violation (which can lead to short circuits), cable clamps must have the following devices:

1. Limiting the unwinding of the cable ring (limiting star washers).
2. Preventing contact pressure from weakening after yielding (standard spring washers).

Spring connection (PPE caps)

These are caps made of non-flammable plastic, with metal springs located inside. After screwing the PPE onto the wires (twisting), the springs move apart, compressing the cable cores and ensuring tight and reliable contact, and also removes the layer of oxides from the wires.

At the same time, plastic serves as electrical insulating, fire and mechanical protection for the entire connection. For high-quality contact, the size of the PPE caps must be selected correctly - they must be screwed onto the cables with force.

Adviсe

1. When using a bolted connection, it is necessary to remember about the fluidity of aluminum - the clamping bolt must be periodically tightened so that the aluminum does not leak out over time. At the same time, the mechanical pressure on the cable without tension should not exceed 150 kg/cm2. When the tip is clad with copper, the pressure should not exceed 100kg/cm2. When heating live wires, the maximum pressure is no more than 200 kg/cm2.

   If these values ​​are exceeded, the aluminum cable will “leak” under voltage.

2. If you have no other choiceIn addition to using simple twisting, you must remember that the contact will be more reliable when using certified PPE caps. Remember that any cable contacts covered only with electrical tape are not recommended.

3. For quick and high-quality soldering of aluminum cables, it is necessary to replace rosin with high-quality mineral oil (for sewing machines) or gun oil.
4. When choosing self-clamping terminals , we recommend reading the markings, which display the number and cross-sectional area of ​​the cable for which the device is designed.
5. Any mechanical connection of an aluminum wire with a copper wire is possible only when the latter is coated with tin-lead solder.

Source: https://slarkenergy.ru/provodka/cable/kak-soedinit-alyuminievye.html

Can copper be combined with aluminum?

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 clamps for joining aluminum and copper are very popular, as they are very convenient to use:

1. Click the pressure plates to the side.
2. Insert wires into holes.
3. Place the plates in their places and clamp them.

WAGO terminals for connecting copper wire to aluminum are an excellent solution

But now WAGO is casting doubt on its reputation. According to numerous reviews, the spring contact weakens, which leads to burning of the terminal block and its rapid replacement.

Twisting wires

Twisting aluminum and copper wires was previously mentioned as a very unreliable connection method, but sometimes this is the only way to quickly restore power supply.

A couple of tips before twisting:

• Before twisting, the copper wire should be well tinned.
• The amount of twist must be at least 5 turns.
• After work, the joint must be protected with several layers of insulating tape or heat shrink tubing.

Soldering copper to the terminal block

You can solder copper and aluminum together. If everything is clear with copper, then for soldering aluminum you need a special flux. Some electricians simply solder copper wire to the terminal block.

Flux for aluminum

Terminal blocks

The list of electrician tools and consumables includes terminal blocks. Terminal blocks are copper or brass coated with a layer of nickel, designed for wires of a certain cross-section and covered with a layer of insulating plastic. The wires are secured with 2 small screws.

When connecting copper and aluminum terminal blocks, the locking screws must be properly tightened. If you tighten them, you can damage the aluminum conductors, which will not have a very good effect on the further operation of the electrical wiring. Therefore, it is necessary to find a middle ground: not tighten too tightly, but achieve high-quality contact.

Bolted connection

If you don’t have a terminal block, soldering iron or WAGO at hand, and the cross-section of the wires is large enough, then you can achieve high quality with an ordinary bolt.

To connect two wires you will need: a bolt, a nut, 3 washers. Sequencing:

1. Make rings at the ends of the wires, the same diameter as the bolt. For convenience, it is better to use round nose pliers.
2. Place the rings on the bolt in such an order that they are between the three washers.
3. Tighten the nut and check the quality of the connection.
4. Apply several layers of insulating tape.

Source: https://crast.ru/instrumenty/mozhno-li-med-soedinjat-s-aljuminiem

Aluminum and copper wires - how to connect? Terminal blocks for connecting wires

When making repairs (even cosmetic ones), we are often faced with the need to put the electrical wiring in order. In old houses, it happens that the wires are almost the same age as the owners of the apartment, and therefore it is simply necessary to replace entire sections of the wiring.

But this is where the main problem lies: very often the old wires are made of aluminum, and you only have a piece of copper wire to replace. Let’s make a reservation right away that according to all the rules, joining them is strictly prohibited, but there are all sorts of situations.

So in this article we will discuss aluminum and copper wires. How to connect them so as not to become the culprit of a short circuit and fire?

Why can't you do this?

In order for you to fully understand the danger of such actions, you should talk about why you should not twist copper and aluminum wires. We have to remember physics and chemistry.

Do you remember what a galvanic cell is? Roughly speaking, this can be called a battery in which the current arises as a result of the interaction between two metals in the electrolyte. Accordingly, the twist between aluminum and copper is such a battery.

Of course, in dry air the formation of galvanic currents, which quickly destroy the material, is practically impossible. Yes, even the twist to the socket, which is constantly used to connect a kettle or other powerful appliance, will not fall apart after a couple of hours, but troubles await you for sure.

Judge for yourself: over time, the wire materials gradually deteriorate, and the resistance constantly increases. Accordingly, the twisting area begins to heat up very much when a powerful current consumer is connected to the outlet. If this happens regularly, then the likelihood of a fire becomes extremely high.

That is why it is not recommended to join aluminum and copper wires for a long time. How to connect them if an emergency arises? Agree, in the countryside it is not always possible to visit an electrical goods store!

Recommended method

Let us repeat once again that it is not always possible to do everything “according to science,” but we still strongly recommend using terminal blocks to connect wires. This is the easiest, fastest and safest way in which even the most inexperienced electrician can connect wires. Let's look at the most common structural types.

"Nuts"

The oldest and most proven method is terminal blocks for connecting wires, called nuts. As you can understand, they received the nickname because of their specific shape. Structurally, they consist of three plates, between which the wires are fixed.

A special advantage of this method is the fact that it is not at all necessary to cut the central line to insert the second wire. To do this, you just need to peel off the insulation in the right place, and then clamp this area between two “nut” plates. A branch wire is inserted between them, after which the plates are securely twisted together.

WAGO

No less common are the methods of connecting wires, which are united under one abbreviation WAGO. These are very simple and reliable devices with which you can dock everything in a couple of seconds. This is done as simply as possible: the ends of the wires are stripped of insulation, after which they are inserted into the connectors.

The trick here is that the internal space of this connection is filled with a special lubricant, which prevents oxidation and galvanic reaction between different types of metals. But! We could recommend the use of this kind of devices only in those networks to which powerful devices will not be connected.

The fact is that under heavy load, connections of this type will become very hot, as a result of which the terminal materials will begin to deteriorate. It is not surprising that WAGO is most often used when working with lighting fixtures.

Terminal blocks

They are also quite common and popular. They look most like a small strip with terminals. As in the case described above, to use them you need to strip one end of the wire, then insert it into the adapter hole and tighten the bolts. On the other hand, everything is done exactly the same.

Here again lies the rub. How will aluminum and copper wires behave in this case? How to connect them if you need to connect really powerful devices to the network?

Fortunately, pads are quite suitable for this purpose. If the thickness of the insulating plate is normal, then it will withstand even very high loads without problems. But remember that it is highly not recommended to install terminal blocks in a room with high humidity. There is no insulating lubricant in them, so the formation of a galvanic couple cannot be ruled out.

What other ways to connect wires are there? Let's figure it out.

Bolt-on mounting

This installation method is also great when you need to join copper and aluminum. The wires are clamped with a bolt, and between the two metals it is necessary to place a washer made of high-quality anodized steel. Remember that this type of connection must be checked for strength at least twice a year. If such a joint is used in a network that experiences high loads, then this needs to be done even more often!

Soldering iron

Is it possible to solder wires that are made of different metals? Yes, this is quite possible, but some important conditions will need to be met.

We won’t talk about copper for a long time, since there shouldn’t be any difficulties in this matter. But there will be problems with aluminum. Their cause is amalgam, which instantly forms on the surface of this metal when it enters an oxygen environment. It is surprisingly chemically resistant, and therefore solder does not stick to it at all.

This is something that novice electricians constantly encounter, for whom any soldering of aluminum wires is a novelty.

How to remove this annoying film? First you will have to prepare a saturated solution of copper sulfate, a Krona battery and a piece of normal copper wire (not Chinese).

On the aluminum wire, you need to carefully clean the place of future soldering, and then drop a couple of drops of copper sulfate solution onto it.

Attach aluminum to the negative terminal of the battery, and a piece of copper wire to the positive terminal. Dip its end into copper sulfate. After some time, a fairly decent layer of copper will settle on the aluminum, onto which you can solder the wire you need without any problems.

As you can see, soldering wires, even in this case, can provide a reliable and high-quality connection.

Important!

In almost all the cases that we have discussed above, rigid fixation of wires stripped of insulation is used. Somewhere terminals are used for this, somewhere bolts. But few people take into account one important point when twisting aluminum and copper wires. We already know how to connect them, but it’s also worth talking about the safety of this process.

The fact is that aluminum under load becomes quite plastic and begins to “flow”. All (!) connections of this kind must be checked regularly and the bolts must be tightened. Otherwise, the day will come when a terminal that is kept on its word of honor will simply burst into flames, unable to withstand the strong heat.

Other tips

• Stranded copper wires should never be clamped. The fact is that when clamping, a whole range of conditions are formed that this wire really does not like. So, part of the veins may well come out of the connection. The remaining part of the wire will be subject to a very high load, which may result in a fire.
• It is very important to select the terminal exactly for the cross-section of the wire you are using. From a channel that is too narrow or wide, the wire will simply fall out, and this is fraught with unpleasant consequences.
• Don't overdo it! In most cases, brass is used in terminals and sleeves, and this material is characterized by increased fragility.
• Look carefully at the markings, which indicate the maximum permissible current. As a rule, it is exaggerated: it is better to divide the indicated value by two.

We strongly advise against buying the so-called NoName from China.

You won't go broke by spending a couple of rubles more, but buy a really high-quality terminal from a normal manufacturer! Manufacturers Tridonik, ABB, and Verit have proven themselves to be excellent.

What about the multi-core option?

If you have carefully read the article, then you already know very well that stranded wires should not be clamped. But what to do in the case when you need to connect them to a thick aluminum outlet, but you don’t have a soldering iron, copper sulfate and batteries, and you don’t want to bother with them?

It's time to tell you that there are special types of wire connections that are specifically designed to solve this kind of problem.

Sleeve connections

In specialized stores for electricians, you can easily find sleeves specially designed for normal connections. They look like miniature tournament spears of knights: behind a protective plastic cap there is a hollow metal tip.

How to work with them? It's simple: carefully remove the insulation from the end of the wire, twist the strands into one “pigtail”, and then insert it into the hollow tip. After this, the sleeve is crimped (you can use the most ordinary pliers). The resulting tip is inserted into the terminal.

This way you can easily connect the wires without soldering. Of course, no one forbids the above-mentioned “pigtail”, provided that you have a soldering iron, to tin it with solder and weld it with aluminum in the way that we described above.

Is it possible to connect aluminum wire to copper

Question “Is it possible to connect aluminum wires with copper?” home craftsmen do not ask questions out of idle curiosity. The safety of their operation depends on how accurately all the standards and requirements for work with electrical networks are met.

When performing repair work related to electrical wiring, very often it becomes necessary to connect conductors made of different materials. In this case, you can use several methods that are easy to use and allow you to get a secure connection.

Terminal connection

The second option is cable clamping. Using standard terminals, it is possible to obtain the fastest, simplest and highest quality connection without forming rings and isolating areas where different materials are combined. Thanks to the special design of the terminal block, the risk of contact between exposed cables is completely eliminated.

Using a simple terminal you can connect only two conductors directly

Permanent twist

The third option is to rivet the cores using a sleeve. This method is simple and quite accessible, but involves the use of a special riveting machine and heat-shrinkable tube, which allows for reliable and safe insulation of twisted areas. Thanks to the wide range of rivets, differing in length and diameter, you can independently quickly connect conductors with almost any cross-section.

Riveting wires using a metal sleeve requires the use of a special tool - a crimper or press pliers

When copper and aluminum wires with different linear expansions are directly connected, they come into contact with oxide films, which negatively affects the quality of electrical wiring and its durability. To obtain the most reliable connection of such cables, it is necessary to use special insulating materials or use one of the methods listed above.

Source: https://aqua-rmnt.com/ehlektrosnabzhenie/mozhno-li-soedinyat-alyuminievyie-provoda-s-mednyimi.html