Connecting wires in a junction box: learning how to connect wires. Junction box: installation instructions

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One of the important stages of electrical wiring installation is the connection of wires in the electrical junction box, which follows immediately after laying the cable. At first glance, some may think that using a junction box to connect wires is essentially a waste of time, but this assumption is wrong for several reasons.

Wire connection diagram in the junction box

During operation of the electrical wiring, malfunctions may occur - for example, a circuit break has occurred. If during electrical installation the workers did without distribution boxes, and the joints were simply rolled up with a finishing material such as plaster, then in order to get to the connections again, they will have to disturb the external finish - tear off the wallpaper, break a layer of plaster, etc. It is unlikely that anyone will be satisfied with such prospects. If in the future you need to install additional sockets, then in such cases it is not always convenient to pull wires from previously installed sockets; it is easier to organize the connection directly to the box.

If the wires are connected using terminal blocks, then you will have to drill a fairly deep channel into the wall, which is much more labor-intensive than simply connecting the wires in a junction box.

Finally, from a fire safety point of view, the advantage of using junction boxes is undeniable. For the correct organization of electrical installation work, there are special Rules for the Construction of Electrical Installations (PUE), which also regulate the procedure for connecting electrical wires.

Methods for connecting wires in a junction box

According to these rules (PUE), there are the following methods for connecting wires in a junction box:

• Connection using terminal blocks is the most preferred method: the terminal blocks are small in size and easily fit into the distribution box, and it is not difficult to buy them. All that remains is to cut the wires to a certain length, connect the corresponding wires and place the resulting assembly in the box.
• Connecting wires in a junction box soldering method- a method more suitable for professionals who have sufficient experience in carrying out such a procedure. Without experience, a person will spend a lot of time on soldering, and it is not a fact that the result will be a high-quality connection.
• Connecting wires in the distribution box crimping method can be considered the most reliable permanent connection. However, this is quite labor-intensive work that requires skills, special devices and materials - these are press jaws, copper or aluminum sleeves and heat-shrinkable tubing. Pre-stripped cores should be inserted at both ends of the sleeve until they stop and the connection should be crimped. Immediately before crimping, a heat-shrink tube should be put on one of the switched wires, and after crimping, slide the tube onto the sleeve and heat it to the shrinkage temperature.

The twisting method is the simplest connection option. However, if we talk about whether such a connection of wires in a junction box is reliable, PUEs allow such a method only as a temporary one and prohibit twisting without subsequent full modification of the connection.

For those who are faced with such a task as connecting wires in a junction box for the first time, the photos and videos presented in the article will help to visualize as clearly as possible how this procedure is carried out in all the ways listed above.

The main wiring elements switched in the box are lamps and sockets, and the connection diagram of the wires in the distribution box will be different for them. The socket will require a simple connection of wires by color. There will be three colors in total: phase (gray, brown or black), neutral (blue or cyan), ground (yellow with a green stripe). There are also wires without grounding, then the cable will be two-core, and instead of three colors there will be two. For a lamp with a single-key switch, only 2 wires will need to be connected in the box: the zero will be connected to the wire going directly to the lamp, and the phase will pass to the lamp through the switch. For a chandelier with a 2-key switch, the only difference will be that in this case, 2 wires will go to the chandelier from the switch, responsible for different groups of light bulbs, and the zero will remain common.

Video of connecting wires in a junction box

Junction boxes perform a very important function. They ensure the distribution of electrical wires between points of consumption, i.e. switches, lighting fixtures and sockets.

Have you decided to install the devices listed above yourself? Then you need to thoroughly understand the features and order of connecting cables, as well as the basic methods of connecting them.

For a better understanding of the process, this event will be considered in several stages: from preparing the necessary materials to connecting electrical appliances using the example of an outlet, a two-key switch and light bulbs. First, you will learn about the basic methods of connecting cables and wiring features

There are several methods for connecting electrical wires. You can choose the most convenient and suitable option for your case.

The first stage - getting ready for work

First of all, we prepare everything that is needed to connect electrical appliances to the box. Set includes:

• cables 3x2.5, VVG;
• cables 2x2.5, AVVG;
• switch with 2 keys;
• fastenings;
• lighting fixtures;
• socket;
• round nose pliers;
• roulette;
• wire cutters;
• pliers;
• flat screwdriver;
• hammer.

Second stage - make the markings

At this stage, we mark the installation locations of electrical appliances and the routes for the wires. This way we can calculate the required amount of materials for installing the system.

The third stage - we begin installation

First turn off the electricity supply.

We connect the wires to the junction box. As a rule, cables are laid in grooves. Small nails or special plastic staples are used to secure the cables. If the work is carried out in a wooden house, the wires will be supplied through special mounting boxes.

Important note! You should try to lay the wiring so that the cables do not intersect. If intersections are unavoidable, such places must be isolated especially carefully.

The fourth stage - we connect electrical appliances and connect the wires

We insert approximately 10 cm of wire into a distribution box pre-built into the wall or fixed to the base (depending on the model). We remove the general sheath from the cables. Then we remove approximately 0.5 cm of insulation from each core. At this point, we focus on the situation - we remove enough insulation so that the cores can be connected in the chosen way.

The diagram shows an example of connecting electrical wires using terminal blocks.

In the example under consideration, the connection is made using a two-wire wire, in which one wire is a zero, the second is a phase. We connect the socket to zero and. We connect the phase supply wire to the socket and one core of the switch cable.

In our example, the switch is two-key. Each key is responsible for controlling a separate group of lighting fixtures. We connect the second wire of the switch cable to the first button, the third wire is connected to the second button.

The distribution box contains the neutral wires from the socket and light bulb sockets. The power cable is connected: zero is marked in blue, phase is marked in red. Wires are connected to connect each switch button to the light sockets.

Fifth stage – checking the system’s functionality

We turn on the power supply and check the operation of our outlet and. Everything works fine. We did a great job.

Now you know the order of connecting the wires in the junction box and the connection features of each main electrical appliance. Using the information received, you will be able to independently cope with all planned activities.

Good luck!

Video - Connecting wires in a junction box

In order to ensure reliable and uniform distribution of electrical energy in urban and private homes, electrical wiring is divided into several groups, for which a separate supply wire is laid in each room, to which all consuming wires of the premises are connected, such as: lighting, switches, plug sockets and others. One of the common methods of switching branches is the use of a distribution (branching) box. It is a housing made of plastic or metal, with holes for cable entry, in which the wires are connected to each other and converge at one point according to a given room wiring diagram. From the outside, the branching box is closed with a lid. The lid may have a rubber ring that ensures a tight connection with the body, be attached with screws, or snap into the grooves of the box body.

Types

Depending on the method of laying the electrical wiring of the room, distribution boxes are divided into:

• internal (with hidden electrical wiring of the room);
• external (with open electrical wiring of the room).

In urban environments, internal distribution boxes are most suitable. They are round in shape, 40mm deep and 80mm in diameter, and can accommodate up to 9 uncoupled cable ends. In country houses with open electrical wiring, external distribution boxes are most often used in a square or rectangular shape. In wooden buildings, the box body must be made of flame retardant material (fireproof plastic, metal).

Installation of distribution box

Internal distribution boxes

Installation of the distribution box should be carried out in the following order:

• gating of walls for supplying wires to the box;
• creating a seat: a recess is knocked out in the wall (block, concrete or brick) using a crown that strictly matches the diameter of the transfer case;
• the niche must be moistened with water and filled with a solution of gypsum plaster or alabaster;
• After this, the box is pressed into the solution to the level of the wall. Excess mortar released around the edges should be removed with a spatula. It is important to hold the box until the solution hardens, otherwise it will protrude from the recess in the wall. The position of the box is fixed using a building level, the lowering of switches and sockets must be strictly vertical; for horizontal laying of wires, it is permissible to use the natural gaps of the room between the floor slab and the wall;
• connect the wires;
• close the lid and apply a thin layer of finishing plaster or wallpaper on it.

Installation of the inner box is greatly simplified in rooms with walls decorated with plasterboard or other material. The hole for the seat can be cut with a hacksaw blade or a knife, the box is attached to the wall with two self-tapping screws: on the outside the box is attached to the wall with a border, on the inside it is pressed with a “claw”, so the error in the diameter of the cut hole is unacceptable. The cable is secured to the plasterboard or panels that cover the ceiling or walls, which facilitates the installation of a hidden junction box since there is no need to chisel the walls.

External distribution boxes

External distribution boxes most often have a square or rectangular shape, so it is necessary to fix them strictly at the level of the wall. The box body is attached to the wall using two dowels and self-tapping screws; the electrical cable is inserted through special seals in which holes are cut that are slightly smaller than the diameter of the cable.

Connecting wires

The junction box allows all possible ways of connecting wires:

• twist;
• connection using terminals built into the junction box;
• self-insulating clips (PPE);
• crimping (twisted wires are placed inside a copper sleeve, crimped with a special press);
• welding or soldering.

During electrical installation work, you should not abuse wire connections, since no crimping or welding can be more reliable than an intact cable. A large number of switching nodes increases the likelihood of electrical wiring malfunctions; in addition, distribution boxes must be in the public domain to be able to repair them, which is difficult when there are a large number of them, so boxes should be installed where they are really needed. At the same time, the desire to reduce the number of distribution boxes leads to significant cable consumption, so when planning work, a balance should be found between these factors.

An example of the optimal location of distribution boxes is shown in the picture below

Installation safety rules

The connection of wires inside the box must be made in strict accordance with the electrical diagram of the room, otherwise accidents in the electrical network are inevitable. To avoid errors when connecting wires, it is recommended to label each end of the wire coming out of the junction box. Each group of wires connected in a junction box should be labeled separately. When using boxes with a metal body, it must be grounded.

The picture above shows the layout of distribution boxes in a three-room apartment with a recording studio equipped in it. In the hallway there is an input distribution box 1. In room 3 there are two distribution boxes 5 and 6, located one behind the other. Box 6 connects the wires of switches and sockets in the area of ​​the room reserved for the recording studio.

Electrical wiring installation in a house, apartment, garage, office, etc. is always performed with the installation of distribution (branch) boxes. At least one is always installed in each room.

Electrical cables or wires extend from branch boxes to lamps, switches and sockets. They consist of a plastic case with a lid; they can be built-in for hidden electrical wiring (in Figures 3 and 4) and overhead for external wiring (in Figures 1 and 2).

Metal distribution boxes are subject to mandatory grounding and are installed only when laying electrical cables in metal pipes. For example, in wooden houses and buildings in accordance with the rules and requirements.

Branch boxes vary in size and shape. Large boxes should be used in places where there will be a large number of cables or wires. It is better to take round ones in shape than square or rectangular ones, because you won’t need to level them. And you can use a hole saw to drill a hole in drywall, block, brick, etc.

Before you start installing the box it is necessary to make grooves and secure cables in them from the installation site to sockets, switches and lamps. Or secure the cables behind the drywall or panels that line the walls or ceiling.

With open wiring the overhead box is attached to the ceiling or wall with 2 screws or dowels, just route the electrical cables through special seals. It is necessary to cut a hole in the seals slightly smaller than the diameter of the cable. The illustration shows an option with dust seals. There are waterproof options with rubber seals and threaded plugs.

For installation of a built-in box it is necessary to knock out or drill a recess into which the box must then be pressed flush. It is much easier to place the box in drywall.

Installing a distribution box in drywall.

After this, we strip the wires and connect them along this line.

How to install a distribution box for hidden electrical wiring.

All electrical wiring in houses and apartments is hidden under plaster or in the channels of panel houses, so the distribution box is hidden flush with the wall. For her installation required:

Not round when applied the box must be ensured that it is fixed exactly level. This is especially true for rectangular options. Square boxes, even if crooked, in most cases allow you to straighten the lid.