Aluminum and copper wire: is it possible to connect the wires together and how to do it correctly

Any cable consists of aluminum or copper conductors. By the rules of electrical installations, the usual twisting of such wires is strictly prohibited. But there are situations during installation when there are no options other than how to connect the aluminum and copper wires. There are many such opportunities. All that remains is to choose an affordable and safe one.

Electrochemical destruction of metals

The opinion that it is impossible to combine aluminum and copper is often mentioned. This is true from the analysis of the chemical compatibility of metals. In the world of modern technology, you can find dozens of conjugations of metal pairs.

There is a concept of electrochemical potential difference, the indicators of which are summarized in a special look-up table.

From it, if necessary, take indicators and are determined with compatibility:

• Copper - lead-tin solder 25 mV.
• Aluminum - 40 mV lead-tin solder.
• Copper - steel 40 mV.
• Aluminum - steel 20 mV.
• Copper - zinc 85 mV.

To understand what is happening, it is necessary to understand the reactions that the electrodes of different metals enter upon contact.

In the absence of moisture, the reliability of the contact is undeniable. But there is no ideal setting. The humidity of the atmosphere always negatively affects the quality of the compounds. Any conductor has a certain electrochemical potential. This property is used in practice in the operation of storage batteries.

Getting on the contacting planes from various compounds, water creates a short-circuited galvanized medium. One electrical conductor begins to deform. The material from which it is made is also subject to destruction.

Methods for connecting wires from different metals

Technological rules allow direct connection of different metal conductors with an electrochemical potential coefficient of more than 0.6 millivolts. According to tabular data, for a binder of aluminum and copper, it equals 0.65 mV, which makes such a combination unacceptable. However, there are ways to correctly interconnect differing wires.

Twisting cable connection

Most famous, but an unreliable technique is called twisting. This method does not require special skills and is easy to manufacture. For these reasons, it is used quite often. Before connecting the aluminum wire with copper, you need to imagine what is happening in a similar combination with temperature drops and precipitation:

• There is a gap in the connection.
• Increased resistance at the ligament point.
• Heat.
• Oxidation of cables, destruction of contact.

This method will not work for secure communication. Although, if you perform certain operations, in some cases you can use twisting to connect aluminum and copper wires:

• The veins should be tightly wound on top of each other.
• The twist should be coated with a waterproof mastic to provide additional insulation.
• To reduce the tension, the ends of the cables must be tinned with lead solder.
• The number of revolutions in such a bundle is not less than three for veins of large cross-section, more than five if the cross-section is less than one square.

Threaded wire connection

A similar method is accomplished by clamping the ends of the cable into a bolt connection. This is the most reliable connection between aluminum and copper wires between each other. It guarantees tight contact for the entire period of use of the twist. Replacing bolts of different lengths makes it possible to combine an unlimited number of cables:

• Different sections.
• Multi-wire and monolithic.
• With washers to prevent direct contact with copper and aluminum conductors.

Procedure:

1. Cut the insulating cover to the required length for fastening.
2. Sand and degrease the cleaned areas. Insulate multi-wire cable. Connect the cores with a thread through steel washers.
3. Tighten the nut tightly.
4. Shock absorbers are placed in front of the outer washers to prevent pinching and breaking of the wire. When crimped, it will straighten and the connection will be fixed.

Connecting different cables with a terminal block

Splicing cables through terminal connections has become widespread in recent times. Although the quality of contact it is inferior to bolt, there are also undeniable advantages:

• The wires are connected in random order.
• There is no need to make connecting rings and donning ferrules.
• The design features of the terminal blocks do not allow shorting the wires.
• Insulation of the contact point is not required.
• The work of connecting the terminal contacts is simple.

The ends of the wires are stripped about five millimeters, inserted into the clamp and pulled. This method is irreplaceable when connecting aluminum cables, the cores of which break from multiple bends.

Repair of damaged cables using terminal blocks is also the only permissible due to the short length of the wires. After splicing, the junction box is mounted.

Of the many connecting devices not the last place are occupied by the German spring terminal blocks of the Vago company of the same name. They are both disposable and with a clip for repeatedly splicing the wire. Such terminal blocks are used when working with single-wire wires with a cross section of one and a half to two and a half squares made of any metals in insulating boxes. According to the passport, they are designed for twenty-four amperes in load. The contacts are treated with a special compound to prevent oxidation.

These are the easiest devices to use. The wire is stripped and forcefully inserted into the block. The fixation is reliable. It is possible to get the wire with a well applied force. In this case, the spring block is destroyed and re-use is impossible, which is the biggest disadvantage of this product.

Reusable terminal blocks Wago with an orange lever are designed for the use of wires of any type with a cross-sectional area of ​​up to four square millimeters and currents up to thirty-four amperes. Apply repeatedly until complete wear and tear.

The method of application is available to anyone. The insulation is stripped to a distance of about ten millimeters, the lever rises, the wire is placed in the channel and the lever slams. The connection is fixed.

Vago terminal blocks are effective devices for installing electrical networks. They do not require the use of special tools, but they are quite expensive.

Monolithic connection method

The technique for making such a connection is similar to a threaded one. A rivet and a special device, a rivet, are used as a fastening element. The rivet is a hollow aluminum rod, thickened on one side. A wire pin with a hat is placed in it. When passing through the cavity, it creates a thickening on one side. Then the hairpin breaks offforming a rivet.

If you do not take into account the price of the rivet, this method of contact becomes the most accessible, apart from twisting. The disadvantage of such a contact is one-time use and the impossibility of disconnecting in the event of an erroneous performance of work.

The use of special copper sleeves will be another way of permanently connecting conductors. They are produced in various sizes, for each cable section its own. Bare ends of wires are threaded through them and crimped with special pliers. This method is the most compact on a par with twisting.

Soldering wire connection

If desired, dissimilar wires can be soldered. This method must take into account certain technological features. Before properly connecting the wires, the aluminum and copper must be prepared for soldering. Copper does not require any special tweaks. Aluminum wire is another matter. On its surface, under the influence of ambient air, an oxide film is formed - amalgam. It resists chemical attack and does not adhere to solder.

To neutralize it, you will have to make a simple device. The tip of the aluminum wire is cleaned and processed with a solution of copper sulfate. A battery is taken and this conductor is attached to it minus. The copper wire is fixed on the plus with one end, and with the other it is dipped in the same solution. After a certain period of time, the aluminum will be covered with a copper coating and will become available for soldering.

Specificity of connections for outdoor installation

Outdoor electrical connections are subject to various weather conditions. Insulation requirements are more stringent. In order to prevent short circuits, a nut clamping set is used.

Its plastic sheath contains metal clamps, in which the wires are connected by tightening the screws. The body halves are tightly compressed with screws or snap rings. Such a cocoon guarantees protection from external weather fluctuations. This is a fairly large-sized connection, but in outdoor conditions this is not critical.