How to twist aluminum wires correctly

How to twist wires correctly

When laying wiring in the house, you cannot do without connecting the wires. After all, a network with branches is laid around the house to power certain electrical appliances.

The need for wiring connections

Distribution boxes are used to branch the electrical network. But they are intended only to hide the connections of power network branches.

The need for wiring connections is found everywhere. They connect wiring in different ways in the house, electrical appliances, cars, in general, wherever there are wires.

Nowadays, several methods of connecting wiring are used. Each of them has its own positive and negative qualities.

The most common ways are:

1. Twisting;
2. Soldering;
3. Welding;
4. Use of terminal blocks, blocks;
5. Use of self-clamping terminal blocks;
6. Use of connecting insulating clips (PPE caps).

Twist

The simplest and most common way to connect wires is ordinary twisting.

For this type of connection, all the equipment required is a knife for stripping the insulation and pliers to ensure a reliable connection. However, at the end, the place of twisting will need to be insulated.

Twisting is done in several ways.

The simplest is mutual twisting of the stripped ends of the wiring.

For reliability, it is advisable to expose the wires by at least 5 cm. Next, the exposed ends are crossed so that the edges of the insulation touch, and then the crosshairs of the wires are grabbed with the jaws of pliers and twisted with a rotational motion.

After twisting, the connection is bent to one side so that the twist lies parallel to the wire. The connection is then isolated.

The second method is also effective and simple twisting.

The stripped ends of the wires are slightly bent in the middle, and at the bend the wires engage with each other.

After the end of one wire is wrapped around the second, the same is done with the other end of the wiring.

For reliability, the made windings can be slightly tightened with pliers. Then everything is isolated.

The next method is a bandage connection. For such twisting you will need a piece of stripped wire.

The two wires to be connected are placed parallel to each other so that the stripped ends touch along the entire length.

Then they are wrapped with the available piece, creating a kind of bandage.

The last of the used twisting methods that you can find is groove twisting.

To do this, small hooks are made from the ends of the wires, which are interconnected, and then one edge of the wire is wound around the other.

More complex types of wire connections are presented below.

Now about ways to isolate twists.

Often, different types of electrical tape are used for insulation. When using it, you need to wrap not only the place of twisting, it should extend at least 2-3 cm onto the wire insulation.

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This will ensure complete insulation, including from moisture.

In addition to electrical tape, it is possible to use thermal tubes.

Such a tube of the required length is placed on one of the wires before twisting.

After twisting, the tube is pushed onto the joint. In order for it to tightly grip the wiring, it needs to be heated a little, for example, with a lighter.

The temperature will cause the tube to shrink, creating a tight fit.

The positive qualities of twists include ease of implementation with minimal equipment, while they are considered quite reliable.

If good insulation is provided, the twist can last a long time. Also, the twist itself is a detachable connection; you can twist it at any time.

It is considered more preferable in networks that are not fixed and can sag, which is especially important for cars where the wiring is constantly exposed to vibration.

One of the disadvantages is the impossibility of connecting wires of different sections; the resistance in such twisting can be very high, which will lead to heating and melting of the insulating layer.

It is difficult to combine multi-core cables by twisting. They are too soft, so the connection may break when stretched.

If multiple insulated strands are used in the wiring, then after each strand is insulated, the total thickness at the junction can be very large.

It is also not recommended to use twisting to connect cables made of different metals, for example, aluminum and copper.

This will affect both reliability and increased resistance at the junction of the wires.

Soldering

The next method of connecting wires that is often used is soldering.

It is noteworthy that soldering is only an improvement in twisting. That is, the wires must be twisted before soldering and then soldered.

To perform soldering, a soldering iron and solder are used. Thanks to this connection, the twisting strength of a multi-core cable can be significantly increased.

The advantages of soldering include increased strength, especially for stranded wires.

After soldering, the resistance at the connection point will be significantly lower, which means the twist will not heat up.

However, soldering is only used on copper stranded wiring; aluminum wires cannot be soldered.

However, soldering is very fragile, and if done incorrectly, the connection will be unreliable.

Welding

Another way to improve twisting is welding. Again, welding is just a method of increasing the reliability of twisting.

It is not applicable for aluminum wires; welding is used only on large-section copper cables.

Reliability when welding is much higher than when soldering. It is a good way to improve connections in a junction box, but welding is still not very practical.

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In addition, it will require special equipment, a welding inverter.

Welding is not used on aluminum wiring; an additional disadvantage is the possibility of weakening the twist, since when the wires are very heated, which will be necessary during the welding process, the twist itself may weaken due to a change in the physical properties of the metal.

Soldering and welding cannot be considered separate connection methods; they only provide additional reliability.

Also, after using a soldering iron or welding machine, the connection point will still have to be insulated.

Terminal blocks and blocks

But the use of terminal blocks and blocks is a completely separate way of connecting wires.

The terminal block and block are a small metal plate with contacts on the edges.

This plate is encased in insulating plastic. Bolts are often used to clamp wires.

The difference between a terminal block and a block comes down to the fact that the terminal block allows you to connect only two wires, while the block is designed for several connections.

Simply put, a block is several terminal strips connected together to provide several separate connections.

To connect two wires, it is enough to clean their ends of insulation, and you don’t need to clean much, 0.5 cm is enough, it is only important that the cleaned end reaches the contact.

In this case, the bare wire should not protrude beyond the edges of the terminal block, in order to avoid accidental contact with it.

Next, the bolt is clamped with a screwdriver, ensuring reliable contact of the wire with the plate.

On the other side of the terminal block, the other end of the wire is fixed. The metal plate will act as a bridge between them.

When using a terminal block, they connect only two wires; for subsequent ones, another terminal block is used.

The block allows you to provide several connections, which, with a large number of wires, will result in more compact dimensions.

Terminal blocks and blocks are good because they allow you to connect together wiring made of different metals and differing in cross-section.

In addition, they are detachable, so you can disconnect the desired wire at any time. They are good for both single-core and stranded wires.

Their disadvantages include the increased dimensions of the connection, especially for the pads.

Hiding terminal blocks and strips can be very difficult. In addition, ordinary terminal blocks will not allow insertion into the wiring; twisting allows this. But about the sidebar - a little lower.

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Self-clamping terminal blocks

Self-clamping terminal blocks are a type of conventional terminal blocks. They provide an even faster connection because you don't even need to use a screwdriver.

The contacts in them are spring-loaded, so to connect the cables it is enough to insert the ends of the wires into the holes with the contacts.

During installation, you need to overcome the force of the spring, after which it will press the contact to the wire. It is noted that this method is very convenient for multi-core wires.

Among the disadvantages of such a connection is that the connection is not particularly reliable; it will not be difficult to pull out the wiring from the terminal block. This is especially true for single-core wires with a large cross-section.

A common disadvantage of terminal blocks is the possibility of moisture getting on the contacts, which can lead to their oxidation and disruption of the connection.

PPE caps

PPE caps are a simple and convenient way to connect. They are produced in three types - without contacts, as well as with clamping and spring-loaded contacts.

Caps without contacts are made only of insulating material. They are intended for insulating twists.

They are placed on top of the twist, protecting it from moisture.

Caps provide easy access to the junction of wires and are often used in junction boxes.

In caps with a clamping contact, a ring of soft metal is installed inside. Such a cap is put on the twist, and for a better connection, the installed ring is compressed with pliers.

This cap can also be used as a separate connection, without preliminary twisting.

The wires, stripped of insulation, are inserted into the cap ring, after which it is clamped with pliers. These caps provide a virtually permanent connection.

Caps with a spring contact work identically to those described, but they do not need to be clamped; the spring inside will ensure secure fastening. This cap has a detachable connection.

Wire insertion

At the end, a few words about the sidebar. Most often, twisting is used for such a connection.

On the wire to which you want to connect another wire, a small area is cleared of insulation. The stripped end of the connected wire is wound onto the cleaned area, after which everything is insulated with electrical tape.

It is possible to use a special terminal block for insertion. It is T-shaped and consists of two halves with a plate inserted in them.

Such a terminal block in two halves encloses the cleaned area to which the insertion will be made. And the wire that needs to be powered is connected to the side tap of this terminal block.

All types of electrical network connections used were discussed here.

And although the electrical network has been used for a long time, the best connection of two wires is still ordinary twisting, perhaps in addition reinforced by soldering or welding.

Source: https://ElektrikExpert.ru/kak-pravilno-skruchivat-provoda.html

The easiest way to connect wires: how to twist them together correctly?

When installing a branch in a junction box, and also when it is not possible to lay the line with a single piece of cable, the wires have to be connected.

There are different ways to do this and one of them is twisting. Can it be used, in what form and how to twist the wires correctly.

Twisting wires together according to the PUE

Twisting in its pure form, that is, when the wires wrap around each other without additional fixation, is prohibited according to the PUE. The reason is that, due to the elasticity of the metal and due to repeated heating-cooling cycles, the contact gradually weakens, which means the contact resistance increases.

In the old days, when the list of electrical receivers in an apartment was limited to a TV, lighting and a low-power iron, this was not a threat, so twisting was used everywhere.

With the advent of water heaters, multicookers and other powerful equipment in everyday use, the strength of the current flowing in home wiring has increased significantly, and under such conditions, an area with even low resistance quickly heats up to the point where the insulation melts or ignites.

Nevertheless, every electrician must be able to twist correctly, since for high-quality welding or soldering of wires they must first be twisted. In addition, twisting can be useful as a temporary method if you do not have a terminal block or other clamp at hand.

Twisting methods

There are such types of twists: parallel, sequential, bandage. There are also varieties for connecting stranded conductors.

Types of twisted wire connections

How to twist it with your own hands?

Usually in everyday life, when reorganizing the wiring, the home handyman is faced with the question of how to properly twist the wires in the junction box. In this regard, each of the listed methods is worth considering in detail.

Parallel

They operate in this order:

1. at a distance of 7-8 cm from the end of each core, cut the insulation and remove it. It is important not to damage the core itself, otherwise it will break off when twisted. If a regular knife is used, the cut is made obliquely, directing the blade almost along the conductor. The latter is rolled with a finger on the table. It is more correct to use a special tool - a stripper or an electrician's knife with a heel. Such a tool is physically unable to make a deep cut in the insulation, so that the core is guaranteed to remain undamaged;
2. clean the wires to a metallic shine with sandpaper;
3. fold the wires crosswise where the insulation ends;
4. holding the wires at the intersection point with some pliers, twist them into a tight bundle with the other. To avoid damaging the insulation with the tool, they are wrapped with electrical tape;
5. with pliers they cut off the ends of the veins sticking out to the sides, making the same twisting movement;
6. isolate the connection (insulation methods are described below).

The recommended twist length is 15 core diameters. The minimum permissible length is 10 diameters.

It is inconvenient to grab thin wires with pliers; they are twisted by hand. To do this, they are folded in parallel, and the ends are bent so that you can grasp them with your fingers.

Sequential

Consecutive twisting exceeds the previous one in strength, order of execution:

1. the bare and stripped veins are folded crosswise, so that the intersection point falls in the middle of the bare area;
2. The 1st wire is wound onto the 2nd, moving from the intersection point to the insulation;
3. The 2nd wire is wound on the 1st according to the same scheme.

This method can withstand tensile forces better than the parallel method. This option is also more preferable for circuits subject to vibration, for example in a car.

Twisting in automotive wiring is used only as a short-term temporary option. Permanent connections here are made using crimp sleeves.

Bandage

The bandage method is implemented like this:

1. the connected conductors are applied one to the other in parallel;
2. tightly wrap a piece of wire around them (you must use a fairly flexible one);
3. isolate the connection.

Before insulating the twist, it is recommended to check it. Having connected the load, use the line for several hours, and then, making sure to de-energize it through the circuit breaker, check the twisting temperature. If it is hot, the contact is bad, the connection is redone. In this case, the ends of the strands are bitten off - they cannot be twisted again.

Safety precautions: before touching bare wires with your hands, you should always check the absence of voltage with a phase indicator.

How much can you twist into one twist?

Up to 6 wires are combined using the twisting method. More than 2 cores are connected by parallel or bandage twisting, while serial twisting is only applicable for 2 cores.

Parallel twisting of several cores (more than 2) is done as follows:

1. the stripped wires are straightened and folded together parallel and in the same plane;
2. holding the place where the insulation ends with some pliers, with the other they bite the ends of the wires and twist them as tightly as possible;
3. bite the ends of the veins with wire cutters, making a twisting motion;
4. isolate.

If it is necessary to make a large number of twists, use a screwdriver: clamp the ends of the cores in the chuck and activate the tool. In order not to hold a bundle of wires in your hands, it is useful to make a simple device in the form of a washer welded to the rod.

Stranding of stranded conductors

Stranded strand (sometimes mistakenly called stranded) is made up of several thin wires, which gives it flexibility. These wires are used to make power cords, portable sockets and extension cords.

They are also used in distribution boards, where, due to the close proximity of devices and tight spaces, the cable has to be bent strongly. Due to their flexibility, twisting stranded wires using any of the methods described above does not provide high-quality and durable contact.

Twisting of stranded wires

The following method is used:

1. each core is dissolved into two or more bundles (depending on the number of wires);
2. apply the wires one to the other and twist bundles from different wires in pairs;
3. the resulting bundles are twisted into one.

All that remains is to isolate the connection, as usual.

Is it possible to twist copper and aluminum?

To the question of whether it is possible to twist a copper wire with an aluminum one, the answer is clearly negative, for two reasons:

1. corrosion . Different metals in the contact zone are always destroyed due to corrosion, electrolytic or atmospheric. The rate of destruction for each combination is different and in some cases it is relatively low. But there are pairs of metals, upon contact of which corrosion occurs especially intensely. The combination “aluminum - copper” belongs to this group. As a result of chemical changes, the conductivity of metals drops sharply and the connection heats up;
2. difference in coefficient of thermal expansion . Because of it, heating-cooling cycles will lead to weakening of the twist and, as a result, deterioration of the contact.

There must be an intermediary between aluminum and copper - brass or galvanized steel; to connect such conductors the following is used:

1. terminal blocks: wires are inserted into different terminals;
2. sleeves for crimping of the GAM brand (half is made of aluminum, the other is copper);
3. soldering using special solder and flux;
4. bolt clamp with a galvanized washer between the aluminum and copper conductors.

Sequence of actions when using bolt clamps:

• put a washer on a small diameter bolt or screw;
• twist the end of one strand into a ring and put it on next;
• put on a galvanized washer;
• twist the second core into a ring and also put it on;
• use another washer and tighten the connection with a nut.

Contact of aluminum with tinned copper is also allowed.

In air, aluminum quickly becomes covered with an oxide film with high resistivity, to avoid which the ends of the cores of this metal are lubricated with quartz-vaseline paste before making the connection. This paste is added to terminals and connecting insulating clips (PIC) for aluminum wires at the production stage.

If the wires are of different sections

If there is a large difference in the cross-section of the wires being connected, the following method is used:

1. strip the end of the thicker core to a length of 8 cm;
2. a thinner wire, also previously stripped, is tightly wound into the middle of the bare area (so that the winding length is 2.5 cm);
3. bend the exposed sections of the thick wire on both sides of the winding in a U-shape and crimp with pliers so that they fix the turns of the thin wire;
4. isolate the connection.

In the same way, you can connect a single-wire core to a multi-wire one: the second is wound on the first and further in the text.

Insulation methods

The twist is insulated with electrical tape, heat-shrink tubing, and special PPE elements.

Insulating tape

Insulating material for use in dry rooms.

It is a tape with an adhesive layer made from the following materials:

• PVC;
• paper and acetate fabric;
• epoxy and polyester films;
• fiberglass and mica.

PVC tape is best suited for household use. The highest quality variety, recommended for use, is made from class A PVC film and coated with rubber-based glue.

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The end of the tape is glued to the insulation near the beginning of the bare area and then wound, moving towards the end of the twist and partially overlapping the previous one with each subsequent turn. Having gone around the end of the twist (it should not just be wrapped, but covered with tape), move in the opposite direction. The electrical tape is wound in at least two, and preferably three, layers.

Heat-shrink tubing

A more reliable insulator, suitable for use in rooms with high humidity and even outdoors. The tube is made of a special polymer that shrinks in size when heated.

The product is installed as follows:

• a heat-shrinkable tube is placed on one of the wires to be connected;
• perform twisting;
• slide the tube onto the twist;
• warm up the insulator with a hair dryer or, in the absence of one, with a lighter. As a result, the tube will shrink and tightly wrap around the twist.

Heat-shrinkable tubes are available in different diameters for wires with different cross-sections.

For reliability, it is recommended to insulate the twist with two heat-shrinkable tubes.

Connecting insulating clamps (PPE)

The product not only isolates the twist, but securely fixes it, and such a connection no longer contradicts the PUE and other regulatory documents. PPE (also called insulating caps) is a polymer tube, capped at one end and equipped inside with a steel conical spring made of square wire .

When screwing the connector onto a twist, the spring, especially its narrow part, tightly presses the wires one against the other. PPE differs in size and it is extremely important to choose a product that matches the cross-section of the cores and their number . There are caps for connecting 2 wires with a cross-section of 1.5 mm2, 4 with a cross-section of 2.5 mm2, etc.

It is customary to paint them in different colors, but there is no standardized system - each manufacturer adheres to its own colors. If you choose the wrong PPE, then either the spring will not crimp the wires with sufficient force (the cap is too large), or they will not fit into the narrow part of the spring (the cap is small). Connectors for aluminum wires contain quartz-vaseline paste.

Source: https://proprovoda.ru/provodka/provoda-i-kabelya/kak-pravilno-skruchivat.html