Electrician for beginners: how to use terminals correctly to connect wires

Grandfather's methods of primitive twisting of wires with obligatory insulation with the notorious blue tape are long gone. Modern wiring requires a professional approach, which means it is necessary to use materials and devices that meet not only the highest safety requirements, but also simplicity, reliability and attractive appearance. One of these devices is terminals for connecting wires. Today we will talk about how to choose and use them correctly.

Small terminal - the solution to many problems in electrical wiring

How can the wiring be connected

The way the two wires are connected depends on many factors. Consider the metal of the conductor, the thickness of the wiring, the number of cores and the type of insulating material. An important factor is the conditions in which the connection will be operated.

There are several main types of connections:

Each specific connection uses its own terminal

Let's consider in detail the main characteristics of all these compounds.

Features of professional twisting

Twisting is the simplest method of connecting wiring. No special tools are required for work, a knife and pliers are enough. To make the connection strong, experts recommend stripping the cores by at least 5 cm. To make the contact tight, the wires are clamped with pliers and twisted with a rotational motion. After the resulting connection is wrapped in one direction and tightly wrapped with electrical tape. This is the simplest version of such a connection.

Professional electricians have other ways to twist wires together:

Twisting options

Instead of electrical tape, you can use modern material - heat shrink tubing. Before connecting the conductors, the heat shrinkage of the required length is put on one of the wires and then pulled over the twist. It remains only for a moment to bring a match or lighter to the tube, it will shrink and tightly fix and insulate the veins.

Heat shrink material shrinks under temperature

With reliable insulation, such a connection will last long enough. Its advantage is good vibration resistance, which is good for moving machinery. Electricians do not recommend using this method when connecting wires of different sizes. During operation, excessive resistance heats up the contact point so that the insulating layer can melt. Professionals do not advise twisting wires with conductors of different metals and cables with a large number of conductors.

Soldering for perfect conductivity

Not only the perfect operation of the mechanism, but also the safety of its user depends on the reliability and strength of the conductor connection. Soldering is one of the most reliable types of connection.

Soldering iron is available in almost every home, and the procedure itself does not take much time

Rosin is used for tinning, and tin or other fluxes are used as solder. Copper wires are recommended to be soldered with tin or lead, aluminum - with zinc-tin, aluminum or copper compounds. Before soldering, the wires are stripped and twisted using one of the above methods. After that, rosin and flux are applied to the twisting place with a soldering iron.

After soldering, the connection is insulated with tape or heat shrink. The hardest part is soldering aluminum wires. It oxidizes rapidly at high temperatures and does not form a strong bond with the solder material. For a strong connection, you need to use tinning.

If soldering is done correctly, the contact should be good. The only drawback is the fragility of the connection, it will not last long under vibration and mechanical loads.

For professionals: welding

Welding allows the metal of the conductors to fuse and provide optimum resistance. This contact is strong and durable.

The only drawback of the connection is the need to use special equipment - a welding machine

Arc, spot, torsion, plasma, ultrasonic and beam welding can be used.

Such work requires experience and dexterity, so the welding method is a tool for professional electricians. They use graphite and carbon electrodes, work stationary and use high-precision inverters with voltage regulation... This technique is not suitable for domestic conditions, only experienced welders know how to correctly connect the wires to each other in such a complex way.

After welding, the contact point is also insulated with tape or heat shrinkage.

Crimping with sleeves

Returning to the ways of connecting wiring more accessible for domestic use, it should be noted that crimping is a simple and affordable method that can be used without special skills.

Sleeve connection is characterized by high strength and resistance to mechanical stress

The technique is very simple - wire strands are inserted into a metal sleeve and then the soft metal is crimped with pliers or a vice. It is best to use special pliers for this purpose. They can manually crimp sleeves up to 120 mm². If a larger liner is required, use hydraulics. The disadvantage of a sleeve connection is that it is final, and, if necessary, it will not work to correct the contact without cutting the wire.

The use of terminal blocks for connecting wires

The easiest to use and at the same time reliable is installation using terminal blocks.

These simple yet reliable devices are confidently replacing other switching methods.

Terminal clamps for wires can be used when mounting conductors from different metals. At the same time, the design of the terminals avoids direct contact between aluminum and copper and the formation of corrosion inevitable for such a connection.

Terminal blocks are divided into three main types: knife, screw and spring. As a rule, a brass alloy is used as the base material. Some models are filled with a gel that protects the contacts from corrosion.

Standard requirements for terminal strips

Like any electrical component, the terminal block has developed standards of reliability and quality:

Pros and cons of terminal switching

As with any device, terminal connections have their advantages and disadvantages. First about the benefits:

Small devices fit neatly in a junction box

Disadvantages of clamp connections:

How to choose terminals for connecting wires

To choose the right terminal, first of all, you should study the cable that you plan to connect. You need to find out the size of the section, it is usually indicated in the marking of the wire.

The second selection criterion is high-quality terminal material. It must be rigid enough and have reliable insulation. It is better if the screw and bracket of the device are made of steel. The terminals must be compact. It is possible that you will have to place the contact group in a limited space, so the size of the connections will matter.

If the terminals will "nest" on the rail, devices of appropriate dimensions are selected

Another criterion for the right choice is ease of installation and maintenance. The terminals with a guide cone and a flag marking the conductor entry point are especially convenient in operation.

Convenient if the terminal surface is suitable for marking. Sometimes it is necessary for the further operation of the connection.

These simple yet reliable devices are confidently replacing other switching methods.

Types of terminal contacts

Modern manufacturers offer a wide range of switches for performing connections of different purposes. Each model meets certain tasks and requirements, we will consider them in more detail.

Screw switches

These simple and reliable devices are perfect for installation in wall outlets and similar locations. The cores are fixed in the terminal with screws.

Screw terminal block

Screw terminal blocks are not used for aluminum wiring. This is due to the fact that the aluminum conductor collapses under the pressure of the screw fastener. If the switch has ground contact, the screw head is marked with green paint.

Terminal clamps for wires

The design of such switches involves the use of a small spring that fixes the core in the desired position.

Terminal clamp

These terminal blocks are installed in an instant: the stripped wiring is simply inserted and fixation is carried out in one click.

Junction Box Switches

Such terminals are used to connect wires in junction boxes. The switch body is made of polycarbonate and the contact point is made of copper. Springs are used to fix the cores.

Many switch boxes come with pre-assembled switches

For reliability, the terminals are treated with a special paste that protects the contacts from overheating.

Video on how to properly connect wires in a junction box using terminals

Fuse Terminals

A separate type of switches is with a built-in fuse.Such contact groups additionally protect the wiring from short circuits.

Fuse contact device

Such wagons for connecting wires take up more space than conventional terminal blocks and are used in cases where electrical appliances do not have built-in fuses in their design.

Connecting pads

Pads are a handy gadget for connecting multiple wires. Brass tubes with threaded holes are placed in the body of such a device. With the help of such small devices, it is possible to connect copper and aluminum wires to each other, as well as conductors of different cross-sections.

Terminal blocks

Switching in the block occurs in such a way that the conductors do not contact directly. The only thing you should pay attention to is the indicator of the rated current on the block itself.

Blade terminals

These switches are also called wire crimp terminals. They are used for power conductors with a small cross-section up to 2.5 mm. The maximum voltage for such a connection is 5 kV. Such a connection will not withstand a more powerful current, so knife terminal blocks are not used in large power plants.

Knife switches can connect from 2 to 8 cores

Which terminal blocks are better

In fact, choosing the right terminal should be taken very seriously. Especially if there is a need to connect wires with conductors of different metals. During operation, such contacts get very hot and deformed. This can lead to a complete loss of circuit integrity and even a short circuit. It is worth remembering that spring and screw terminal blocks are not suitable for fastening aluminum and copper wiring.

A few words about switch manufacturers

Products of European, Chinese and domestic manufacturers are presented on the shelves of electrical goods stores. As a rule, few ordinary buyers are puzzled by the origin of switches. And in vain. These tiny, finger-sized devices can help keep your property safe. You should not blindly trust Chinese consumer goods. In most cases, China's products do not meet the requirements of domestic standards.

Such terminal blocks melt at the first voltage drop.

Domestic products are more reliable, but less aesthetic and technological. European goods are more expensive, but I bought such a terminal and forgot. Manufacturers guarantee long-term and reliable performance of their products. Here is some of them:

LEGRAND

Screw switches from this manufacturer are the most popular product in this category. Brass products are nickel plated and can reliably withstand extreme temperature changes. Such terminals are distinguished by their high strength and a wide range of sizes.

To make it convenient to distinguish between wires during installation and operation, the terminals are made in different colors

WAGO

The products of the French company guarantee a strong connection of wiring of different types and cross-sections. The devices perfectly resist possible vibration and stretching and are installed without special tools. The main material of French terminal blocks is tin-plated copper, giving good contact with low resistance. Some models are filled with anti-corrosion gel.

The WAGO product range allows you to choose a product for any task

PHOENIX CONTACT

The German manufacturer is distinguished by excellent product quality. It offers over 200 kinds of different switches for different types of connections. Among the models presented there are those resistant to high humidity and explosion hazard.

PHOENIX CONTACT terminal blocks are particularly robust

WIEDMULLER

Another European brand offers one and a half hundred terminal models. The assortment is based on screw connections made according to DIN technology.

WIEDMULLER terminals

Common problem: how to connect aluminum and copper wire

Residents of Soviet-built houses often face such a task. At that time, almost all wiring was done with aluminum conductors. Modern electricians mostly use copper wire. How to connect aluminum to copper wire? There are skeptics who argue that such a connection is impossible. You shouldn't believe them. If you correctly use the techniques that we will give below, the switching will be reliable and durable.

As already mentioned, ordinary twisting will not work for such a connection. The contact between copper and aluminum is very hot and can damage the insulation layer.

Option 1 - bolted

This is a simple and affordable method using a steel nut, bolt and washer. Due to the impressive dimensions of such fasteners, it is unlikely that it will be possible to place it in a modern small junction box. But on the other hand, such switching allows you to combine wiring not only from different metals, but also with different sections. These connections are easy to disassemble and assemble when needed.

Video recommendations for bolting:

Option 2 - nut connection

The name of such a connection was invented by electricians because of the external similarity. For fasteners, a special crimp is used, which is sold in electrical stores. The device consists of two dies with grooves for conductors. After fixing the veins, the dies are wrapped with electrical tape.

In practice, it looks like this:

Option 3 - terminal switch

Easy to install and reliable connection option. The block is selected in accordance with the cross-section of the wires. Serrated fasteners provide a secure fixation of the conductors. It must be remembered that aluminum does not like screw connections, so you will have to periodically check the contact without waiting for it to loosen.

Switch installation guidelines:

A small master class on connecting wires using terminals

Illustration	Description of work
	To connect with terminal blocks from the 2273 series, strip the wires to a length of 10 millimeters. After stripping, the ends of the wiring are inserted with little effort into the terminal holes. Removing them is easy - you just need to pull the wire using light rotational movements. Such devices are suitable for junction boxes.
	To install the 22 series terminal blocks, bend the levers. After that, the stripped cores are inserted into the holes and the levers are returned to their place. Such switches are very convenient as a temporary measure, they are easily disconnected.
	Series 224 is best used for connecting ceiling and wall luminaires. It will reliably connect solid and stranded wires. The conductors are stripped as usual, but the stranded conductors must be twisted before installation so that none of the thin wires are bent or broken. The single strand wire is inserted into the hole with grease. The connection is easy to disassemble by pressing the lever.
	To fasten the wiring with PPE, you should strip the ends of the wires to a length slightly less than the length of the cap. After that, the cap is simply screwed onto the conductors. If you remove the cap, you will find a spring holding the twist together.
	The screw terminal blocks require periodic maintenance. The solid wire is simply stripped, inserted into the hole and tightened with a screw. The stranded wire must be tinned or crimped with a tip and only then inserted into the groove of the terminal. This way the protected end will not be torn apart by the screw.

At what price can you buy terminals

Terminals and terminal blocks are sold in specialized electrical stores. Many online stores also offer such a product. The average cost of one device is 8 ÷ 15 rubles. You should not buy too cheap products, most likely, they are made of low-quality material. Trust trusted manufacturers, and let there be light in your home!

If you have experience using switches from manufacturers that we did not mention - share your impressions!

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