Wiring connection. Methods for connecting wires in junction boxes. Benefits of using these products

All work carried out in the field of electrical engineering requires a careful and balanced approach. Each operation must be carried out in strict accordance with technology. Therefore, quite often, novice electricians have the question of how to connect the wires in the junction box.

Purpose and types of distribution boxes

In an apartment or private house, the distribution of electrical networks begins with a panel installed at the entrance. However, as practice shows, each room requires additional distribution of wires due to the presence of several connection points, mainly switches and sockets. All lines drawn to these points are connected in junction boxes. Thus, in addition to a reliable connection, free access to wires and cables is provided for performing various operations.

Depending on the type of installation, distribution boxes can be external or internal, designed for hidden installation. In the second case, a hole is prepared in the wall to the size of the distribution box. After installation, the box cover will be in the same plane with the wall surface. The outer box is fixed to the wall surface and covered with finishing materials, for example, plasterboard.

Junction boxes are usually round or rectangular in shape. They are equipped with four pins, and in some designs there may be more. Each terminal has a thread or fitting for more convenient or plastic pipes where the wires are laid. In the future, this greatly simplifies the replacement of a damaged cable. It is easily disconnected in the box, and then from the switch or outlet and pulled through the pipe. In the same way, a new wire is laid in its place.

Wire connection diagram in junction box

Methods for connecting wires in junction boxes

The connection of cables and wires in junction boxes can be done in different ways. The simplest method, although not entirely reliable, is considered to be ordinary twisting. Due to weak and unreliable contact, overheating and short circuit of the wires may occur. This method is recommended to be used temporarily, for example, to check how the assembled circuit works. However, even with temporary use, it is recommended to follow certain twisting rules.

For stranded wires, the insulation is stripped to approximately 4 cm. The wires are separated from each other by a distance of about 2 cm. The connection is made to the junction of the undivided wires. The conductors are first twisted with fingers, and then the twist should be tightened securely with pliers and insulated with tape or heat shrink tubing. Connecting single-core wires is much easier. They are twisted together over the entire length of the area cleared of insulation.

Special mounting caps are often used for twisting. They provide a more reliable connection, high-quality contact and insulation. Each cap consists of two parts: an outer one - plastic and an inner one, with a metal part in the form of a cone, inside of which there is a thread. This connection allows you to increase the contact area and is excellent for two or more wires. The twisting process itself is very simple. You need to remove the insulation by about 2 cm and lightly twist the connecting ends. Then you need to put a cap on the twist and turn it with force several times so that the wires get inside. The dimensions of the caps are selected in accordance with the cross-section and number of connected conductors.

Soldering is considered one of the most reliable methods. Before connecting the wires, it is necessary to tin them with rosin or a special soldering flux. Then the conductors are twisted, the tin is taken onto a heated soldering iron and the twisting is heated until the molten metal flows between the turns. The connection is completely enveloped, thereby establishing high-quality contact.

If available, the wires can be connected by welding over the entire twisted area. If the cross-section of the core is 1.5 mm2, a current of 30A is required, with a cross-section of 2.5 mm2 - 50A. Welding of copper conductors is performed with graphite electrodes. The ground is carefully connected to the top of the twist, and an electrode is brought to the bottom. After a short touch, an arc appears, producing instant welding. The connection point must cool down, after which it must be insulated.

When connecting wires in a junction box, you must not forget about the terminal blocks. They can be screw or with clamps. The required number of conductors is inserted into a certain place, after which they are securely connected using screws.

Junction box installation

No electrical wiring diagram can do without some kind of connections, branching wires or cables. There is a special box for this purpose. It is located under the ceiling and is a round or square box made of polymer material.

In this material we will tell you how to make connections correctly, demonstrate diagrams, photos and video instructions.

Why use a junction box

There are cases when, when installing electrical wiring, they neglect the installation of such distributors, considering that this is just a waste of time, since the box must first be installed, then the connections to it must be made, which will lead to additional difficulties. It’s easier to simply twist, insulate and simply plaster the wall. But here you need to think a little ahead, since in this case important points are missed:

• No free access to wires. For example, if the socket in your room does not work or the light has gone out, and after checking it turns out that the problem is a lack of voltage. How to check? Completely remove the trim? Tearing off wallpaper and plaster to get to the twist? This will ruin your renovation.
• If you want to install an additional outlet. It is not always convenient to connect it by laying wires from a previously installed outlet. Thanks to the distribution box, you can easily make new connections.
• The regulatory document PUE states that “places of connections and branches must be accessible for inspection and repair,” therefore the installation of such a distributor cannot be neglected.
• The absence of such distributors is contrary to fire safety standards.

As you can see, the distribution box plays an important role. But installing it is just the beginning. All that remains is to connect all the wires in it. What's the best way to do this? Let's look at some ways.

Types of connections

What is the task when connecting wires? Ensure good contact between the cores so that the chain does not break and there is no risk of a short circuit. In order to ensure this, you can act in several ways:

1. Twisting.
2. Crimping.
3. Welding.
4. Soldering with a soldering iron.
5. Use of screw terminals.
6. Bolted connections.

These are time-tested methods that you can use to ensure reliable contact. Let's take a closer look at each of them. You will learn how to properly connect wires using any of these options.

Twist

Such twists in the junction box are officially prohibited. The seventh edition of the regulatory document PUE, chapter 2, paragraph 2.1/21 lists all types of permissible connections, but there is no twisting in them. And this is not surprising, since such a contact is sensitive to pulse current and has a high transition resistance. Over time, the contact will deteriorate and simply burn out. Due to the fact that the contact area is small, heating occurs under heavy loads and the contact is weakened even more.

This option is chosen because of its simplicity. It is enough just to strip 10–20 mm of insulation and twist the wires together using pliers. This is what our fathers and great-grandfathers did. But such a connection is often unreliable, especially if an aluminum core is used.

Crimping with a connecting sleeve

A fairly reliable method that will require the purchase of a connecting sleeve. You need to select it based on the diameter of the bundle being connected. Depending on the wires you connect, the material of the sleeve itself is selected. For copper wires the sleeve must be copper, for aluminum wires - aluminum. To ensure a reliable connection, the sleeve is crimped with a special tool called press pliers. This technology is quite effective and is included, along with other methods, in regulatory documents.

To connect this way you need:

1. Remove the insulation, taking into account the length of your sleeve.
2. Twist the wires into a bundle and insert them into the sleeve.
3. Compress the sleeve using press pliers.
4. Insulate the twisting area with heat shrink or insulating tape.

It is not recommended to use pliers in such work, since the connection will not be reliable enough. It is much better to buy press pliers or borrow them from good neighbors.

Welding

This method can be called the most reliable and safe, because the wires are connected using fusion and become one. Due to the fact that the welding will not oxidize, such contact will not weaken over time. But to carry out such work you will need skills in working with welding equipment.

In addition to skills, you must prepare:

• 24 volt welding machine with a power of more than 1 kW;
• welding gloves for skin protection;
• welding glasses or mask;
• sandpaper for stripping wires;
• stationery knife for removing insulation;
• carbon electrode;
• flux, thanks to which the melt will be protected from exposure to air.

After all the tools and materials are ready, all that remains is to do the welding, which will not be difficult. The work can be divided into several steps:

1. Remove 60–80 mm of insulation and clean them using sandpaper. The veins should shine.
2. Connect the wires using the twisting method, twisting one onto the other so that the ends are level with each other. It is recommended to make the length at least 50 mm.
3. Pour flux into the recess of your electrode.
4. Place the ground of the device on the bare wire, turn on the welding machine and press the electrode to the top of the twist.
5. Hold the electrode until a ball called a contact point forms. This usually takes 1–3 seconds.
6. All that remains is to clear the point of flux and insulate the welding site with heat-shrinkable tubing or electrical tape.

This type of connection will last a long time. In some old Khrushchev buildings, such welding lasted 50 years and consistently performed its function.

Soldering with a soldering iron

The method is very similar to welding, only in this case the wires are connected using solder. For these works you will need a soldering iron. To work you will need:

• soldering iron;
• fine sandpaper;
• rosin (flux);
• brush for applying rosin;
• tin-lead solder.

The operating procedure is the same as for welding:

1. Removing insulation and cleaning with sandpaper.
2. Twisting.
3. Application of flux.
4. Direct soldering. The soldering iron melts the solder, which should flow into the twist itself, reliably connecting the wires to each other.

Often copper wires are soldered using this method, but if you purchase special solder for soldering aluminum, you can also solder copper from aluminum.

Using screw terminals

This method is fast, simple and effective. And most importantly, such clamps can combine dissimilar metals. For example, if you need to connect aluminum and copper conductors, which in itself, as you know, is contraindicated. These clamps are very simple and compact, and their cost may pleasantly surprise you.

To connect wires with clamps you only need to complete 2 steps:

1. Remove 5 mm of insulation.
2. Insert into the clamps and tighten the screw.

That's all, as you can see, everything is very simple and fast. It is only important to control the force with which you clamp. If you tighten the screw too tightly, you may damage the wires. You need to be especially careful when working with aluminum wires.

The only disadvantage of a screw connection is that when working with a multi-core cable, it must be crimped with a special nozzle to ensure normal contact and integrity of the wire.

Bolted connections

This connection is quite reliable, but cumbersome. It is not suitable for modern distribution boxes due to its dimensions, but for large old-style boxes it is just right. This method can be used to connect both homogeneous and dissimilar metals. The work is carried out as follows:

1. A steel washer is placed on the bolt.
2. The insulation is removed from the conductors and they are formed into a ring.
3. The first ring is put on the bolt.
4. Then comes another steel washer, which is placed on the bolt after the first.
5. The second connecting wire is put on top.
6. This entire “sandwich” is clamped with a nut.
7. In the end, everything needs to be insulated.

It is this design that makes the contact bulky. If you need to connect several pairs of wires, then this option will not be the best.

This method can be called the most modern, popular and easy to use. All you need is to buy special terminals at the store. Inside these terminals there is a special paste that prevents metals from oxidizing. Thanks to this, various metals can be inserted into such joints.

The work is as follows:

1. 10 mm of insulation is removed from each wire.
2. The lever, which is located on the clip, rises up.
3. The conductors are inserted into the connector.
4. The lever lowers to its original position.

If your clamps do not have levers, they must be inserted until the terminal snaps into place.

We have looked at the most reliable methods by which you can combine wires in a junction box. This is a very important stage of electrical installation work, since 70% of errors during the work consist precisely in incorrect connection of conductors. But if you, even without experience in such work, use the methods given in this article, you can easily do everything in accordance with the requirements of the regulations. But which of these methods to choose depends on your capabilities and desires.

Video

This video shows how to connect wires in a junction box:

You will learn everything about sleeving wires or crimping lugs from the material provided in this video:

Scheme

Let's assume that you are a bit of an electrician and decide to install or replace the wiring in your own house or apartment yourself. But if you don’t know any other way than to connect the wires in the junction box using simple twisting, we recommend that you familiarize yourself with this material. After all, there are many methods for reliable joining of contacts: welding, soldering, crimping, as well as the use of electrical connectors. Each of the options must be applied correctly and in the right place.

Soldering and welding of wires

Modern requirements set out in regulatory documents (PUE) prohibit splicing electrical wiring by conventional twisting, regardless of the insulation method. But if the twisted wires are soldered or welded, the contact will be reliable and will comply with all the rules.

Let's look at how to connect current-carrying parts of cables in a junction box using desoldering:

1. Remove the insulation from the wires at a distance of about 3 cm and sand them with fine sandpaper.
2. Twist the strands tightly together using pliers.
3. Using rosin and solder (POS 61 brand is suitable), carefully tin the connection so that molten tin flows into the space between the wires.
4. Insulate the joint with heat shrink tubing or wrap it with adhesive tape.

Note. Soldering copper is not difficult, but oxidized aluminum sometimes has to be treated with acid.

Connecting wires by welding is performed in the same manner, only instead of a soldering iron, a device with a carbon electrode is used. A special recess is made in it, into which flux is poured, after which the device is plugged into the network, and the electrode is pressed against the twist until an influx is formed in the form of a small ball.

The advantage of this method is the durability of the joint and the ability to connect wires of different sections, including multi-core ones, in the junction box. Due to its reliability, the connection is successfully used in power lines with various loads, but it has some disadvantages:

• Do not solder or weld copper conductors with aluminum ones;
• This connection is permanent and in case of alteration according to a new scheme, the contacting areas have to be bitten off.

Reference. Soldering contacts is often used when installing low-current networks, for example, telephone cables and radio points.

Disconnection by crimping method

In this case, the reliability of the connection of the wires in the junction box is ensured using sleeves made of the same metal as the conductors - aluminum or copper. To complete the job, you will also need special press pliers, shown in the photo.

Note. Some would-be electricians practice crimping sleeves with ordinary pliers, which is unacceptable. Correct fixation of contacts is carried out only with pliers.

Now about how to connect electrical wires in a box in this way:

1. Perform termination and twisting of wires as described above.
2. Place a sleeve over the twisted ends (it should be matched to the diameter and fit tightly).
3. Crimp the sleeve with pliers in two places.
4. If the distribution boxes are installed outdoors, the connection is insulated with heat shrink, ensuring tightness. PVC insulating tape can be used indoors.

This joining option has the same pros and cons as welding: you can connect wiring of different sections and numbers of wires, but you cannot connect contacts made of dissimilar metals.

Application of connecting terminal blocks

Terminals for quick connection of wires are of 2 types:

• screw clamps in the form of blocks;
• Wago type self-clamping connectors

The technology for splicing electrical cables using terminal devices is quite simple. The wires need to be exposed only 1 cm and inserted into the clamps. In the first case, the cores are fixed with screws, in the second - with levers or automatic latches. By the way, terminals with latches are disposable, while terminals with levers are used repeatedly.

We list the advantages of screw terminal blocks:

1. Fast and reliable docking.
2. Ability to connect copper wiring to aluminum.
3. Provides a detachable connection.
4. Does not require additional insulation.

One of the disadvantages of the pads is their size. It happens that when there is a large accumulation of wires coming from several switches or sockets, the screw connector does not fit inside the junction box. Point two: single-core wires are fixed without problems, but multi-core wires are flattened with screws, which is not good. Therefore, it is better to pre-tin such ends.

Wago clamps, which allow you to connect up to 4 wires of the same cross-section, have the same advantages as screw terminals, but take up less space. In this case, the operation of disconnecting the entire junction box will take about 5 minutes, which is very convenient for installing electrical wiring. Judge for yourself: the bare end needs to be inserted into the clamp with pliers until it stops and that’s all.

Reference. Similar devices are often used for laying Internet cables and other low-current networks.

Since there are cheap products on the market from various Chinese manufacturers, self-clamping terminal blocks have acquired a dubious reputation. The fact is that in low-quality connectors, the contact weakens over time, causing them to overheat and melt. If you purchased original Wago products, then there will be no problems; in other cases, it is better not to take risks and connect only lighting wires with clamps (power supply to switches, chandeliers, and so on). Wire the sockets using a different method.

The master will tell you how to use self-clamping terminals correctly in his video:

Plastic PPE caps

The abbreviation SIZ stands for connecting insulating clamp. It is a cone-shaped cap made of plastic, which contains a steel spring with an anodized coating.

The technology for using the product is as follows:

1. Remove the insulation from the wires to be connected to a distance of 2-3 cm.
2. Gather the wires into one bundle and insert them into the cap until it stops.
3. Applying force from the blind part, turn the cap by hand 2-3 turns. A traditional twist is formed inside, secured with a spring.

Such clamps are quick-release and reusable, provided that the spring was not damaged during dismantling. With their help, the connection in the box is made quite quickly, does not require insulation and does not take up much space.

Important point. In order for the PPE cap to provide reliable and durable contact, it must be selected according to the diameter corresponding to the total cross-section of the wires being connected. For the correct selection, use the table:

Details on how to connect wires in a junction box in various ways, including using caps, are described in the video:

Conclusion

Now, knowing the features of all methods of connecting contacts in a junction box, you can choose the best option and successfully apply it. Finally, let us mention another old method of connecting conductors - bolted, when the conductors are bent around the thread to the right side and pressed with a nut. But this option is practically not used due to the inconvenience and cumbersomeness of the connection, although it is considered reliable and complies with the PUE.

Design engineer with more than 8 years of experience in construction.
Graduated from the East Ukrainian National University. Vladimir Dal with a degree in Electronics Industry Equipment in 2011.

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In order to provide every corner of an apartment or office with electricity, you cannot do without a distribution box. Modern distribution boxes are very diverse both in shape and in the materials from which they are made. They come in overhead and internal installations.

The purpose of such devices is to route wires in the desired direction to points of consumption or disconnection - these can be switches, sockets or lighting fixtures. Routing the wires in a junction box will not be a hassle for a professional electrician, but for a novice electrician it can be a real science. Today, WAGO universal terminals are increasingly used for contact connections in the distribution box.

We follow the colors of the wires in the junction box

In order to cope with the installation, you need to use your imagination: the wires are “pipes”, and the electric current is “water”. The “water supply” flows through the phase wires, but the “return” flows through the neutral conductor, while the protective conductor serves just in case of an emergency: if “water” leaks somewhere, it will certainly be “drained” into the ground. It is very convenient that they are modern. The most common colors look like this: white – phase (L), blue – zero (N), yellow-green – ground (PE).

During electrical installation, it is very important to maintain consistency in the colors of the wires, which will greatly facilitate their routing in the junction box. Before starting electrical installation work, you need to clearly decide on the installation of lighting points, sockets and switches, i.e. draw up a diagram to install distribution boxes in convenient places, and in the future preventive and repair work could be carried out.

Be sure to read detailed articles about connecting wires:

Installation procedure for distribution box

Many people make repairs using suspended or suspended ceilings, so the electrical wiring must be laid so that it does not end up in the drilling area when the guides are installed, and care must also be taken to ensure that the distribution boxes remain within the access area. If the junction box remains behind the false ceiling, you can install a small hatch.

The last word in electrical engineering says this: from the distribution board you need to lay a wire for lighting - 3x1.5, for sockets a wire - 3x2.5. Therefore, in the junction box there may be a fairly large number of wires for connection. To avoid confusion, they must be labeled.

Scheme in a junction box, two lamps

Scheme in a junction box, two lamps and a group of sockets

Knowledge of modern technologies and methods of working with electrical fittings, is it really necessary? Yes, you need to know how to connect electrical wires correctly.

This can be useful during installation and installation of any power supply systems. Is the wiring burned out, does the lighting fixture need to be replaced, or new equipment needs to be installed. Such knowledge may not be necessary, but it would be better to know all the common methods of connecting electrical wires

Application in terminal block circuits

Terminal blocks are electrical products made of non-conducting material, inside of which a conductive sleeve is inserted, which has a pair of screws at opposite ends. They serve to secure the wire. An excellent choice for implementing a modern way of connecting wires.

When choosing a reliable connection of wires, it is important to remember: terminal blocks are produced with different holes for many cross-sections.

This method is almost always used for connections in junction boxes of any type, during installation, installation of wall and other lamps. It is suitable for. It is easy to mount a network using such fittings; you just need to insert the bare ends into the holes and, using moderate force, securely tighten the screws. The wire itself should not be crushed. Having figured out how to properly connect electrical wires using terminals, it is worth exploring other equally reliable methods.

Terminal method rating: Excellent fastening quality. Their prices are reasonable. Quite quick and easy installation. A good opportunity to connect different conductors, for example, aluminum and copper.

It is not recommended to connect aluminum and stranded circuits with blocks. This is due to the high fragility of aluminum wires and the great flexibility of the stranded wire conductors themselves. But overall a decent method.

Spring terminals

Quick installation of electrical networks is sometimes simply necessary. For example, install temporary lighting on a balcony, terrace, gazebo. Wago spring terminals are an excellent product for such work. A modern and of course reliable way to connect wires. Although they are new to the electrical accessories market, installation using spring terminals is quick and, importantly, convenient.

The main difference between the use of the Vago terminal blocks themselves: they are more convenient to connect any wires in electrical boxes than with twisting. Here, for high-quality installation, a unique clamping mechanism is used, rather than a simple screw. Manufacturers produce both disposable and reusable vagon systems.

1. In the usual version, this product is used for one-time use; during repair work in the future it cannot be restored. It is removed and a new one is installed in its place.
2. Wago reusable terminals are a little more expensive, but with their help you can disconnect the assembled contacts several times, rewiring the circuit to suit your needs. This speeds up the process of repairing or installing permanent and temporary networks. A simple lever-type mechanism provides the advantage that it is possible to carefully but efficiently fix any wire without damaging or squeezing it.

With the help of a vault, it’s easy to do the fastening yourself; you just need to strip the insulation and insert the required wires into the mounting hole. Press the lever. It's important to get it right.

Wago Clamp System Rating: A unique opportunity to combine any aluminum, copper and other conductors. There is an option for connecting multi-core cables simultaneously (two or more).

Wago universal clamps allow you to fix any thin stranded conductor without damaging it. Another plus is the compact size of the pads.

Excellent quality and durability. The Vago type block has a technological hole that provides access for a screwdriver with a voltage indicator. The operation of any power line can be checked at any time. Perhaps one drawback is the considerable cost of the terminals themselves. But this type of wire connection is the most modern and fastest.

Isolation with PPE caps

Deciphering the product is not difficult, connecting insulating clips (PPE). They are ordinary nylon or plastic caps with an internal lock.

The simplest type of connection of wires, it is carried out after twisting the conductors themselves, the cores. Caps are often used to connect wires in junction boxes and to mark connections with the desired color.

Evaluation of the use of such products: Quite low cost of PPE. The use of safe material prevents ignition of electrical wiring. Easy installation, put it on a twist of wires and you're done. These caps have a wide range of colors, which is convenient. Of course, if the wires are not color coded, colored PPE has the ability to determine or simply mark zero, phase and other necessary electrical routes.

There are also disadvantages: Insufficient level of fixation. Multicore wires can be installed only after soldering.

Installation of networks using sleeves

This option claims to be the most reliable connection method. Any load and quality of wires.

The conductive wires are inserted into a special tube - a sleeve, and crimped with a certain force. There is one thing, but. The cross-section of the wires should not exceed the cross-section of the mounted sleeves. Having inserted and crimped the clip, the sleeve is carefully insulated with heat-shrinkable tubing or other insulating materials.

Overall rating. A great way to securely connect wires. The direction of the conductors can be on different sides of the tube or on one side. The sleeves are quite inexpensive. A good way to reliably connect wires to each other.

There are also disadvantages. Disposable use of sleeves, they are not dismountable. To carry out such work you will need a tool: pressing pliers, which are also used as a special tool. They remove the insulation. They have a crimping device in their arsenal, and electrical installation work takes a little longer.

Soldering or welding wires

This method is reliable. Typically, this method of connection in a junction box involves first stripping and twisting the ends, after which they are dipped into heated solder. It is advisable to connect aluminum to aluminum wires by soldering. They are then insulated using a heat pipe or insulating tape.

Evaluation of the soldering method. It gives strong chain contacts and excellent quality, not expensive, it is the most reliable method of connecting electrical wires in a soldered box.

Technological disadvantage. You can't do this without a soldering iron. The speed of work is not high. The connection is naturally not detachable. It follows from this that soldering is done in extreme cases, using more modern connection methods. It has not been popular among masters for a long time because it takes more time.

There is also a less common method for connecting electrical wires, welding. The process is similar, but requires the use of a special welding machine, of course, and certain skills.

Contact twisting method

Not a new, one might say “old-fashioned” method, it consists of spiral twisting of the cores among themselves. The essence of all work is to twist the stripped conductors using pliers, and cover the twisted area with insulation. These are, perhaps, all the ways to twist wires.

Evaluation of this connection method. High speed of all installation work. The cost part is minimal.

Flaw. It is prohibited to connect together strands of different compositions, copper and aluminum wires., oxidation is inevitable. According to the regulatory framework, fastening wires with twists in a junction box is not recommended for use in rooms with flammable materials, high humidity, basements, or in any house built of wood. More details about the twisting method. I definitely recommend watching a video about which is better: twisting or Vago terminal blocks.

Wire clamp "walnut"

Such a device is simply a cable clamp that has two plates inside and several screws for tightening, usually in the corners. It is enough to screw the wires to the plate itself. Then put a carbolite shell on top.

Grade. An excellent option for connecting any electrical wires in a large and medium-sized junction box. Definitely, these types of products are quite convenient and have a high degree of protection. Makes it possible to quickly connect a wire to a thick gauge track without tearing it.

Flaws. Dimensions allow installation only in spacious distribution boxes and switchboards. Over time, the screws loosen.

Tip: When choosing fittings and method, remember the following:

• It is necessary to work only with isolated tools and use protective equipment.
• Be sure to post a “do not turn on” warning sign on the shutdown panel or meter.
• Connect electrical appliances according to the attached instructions.

Having considered the main types of wire connections, you can easily select the right option. And having a simple tool and a diagram at hand, you can mount it yourself. In details