Junction box for electrical wiring: diagrams, step-by-step instructions

The main difficulty that you may encounter when laying electrical wiring in a private house, apartment or specific room is the need to switch them inside the junction box.

There are several common mistakes associated with this process, and if you want to avoid them, there are a number of important points to consider. Laying out the wires into grooves or cable channels is not difficult. The distribution box is another matter: when working with it, you need to follow certain rules and recommendations.

Purpose of distribution boxes

Electrical wiring must be divided into groups depending on the energy consumer. For this purpose, similar structures are installed that perform important tasks:

• ensuring fire safety;
• aesthetics.

Under the body of the box there are conductors, which are thus protected from various damages. This allows you to increase the service life of electrical wiring.

Junction box with conductors

The main task of the distribution box

With this design, you can reduce the budget for organizing electrical wiring. After all, in the absence of a distribution box, a cable would have to be connected to each electrical appliance, which would create too many channels that would have to be hidden in the ceiling. In addition, all this does not look aesthetically pleasing.

At the same time, the correct distribution of conductors inside the box increases the level of fire safety in any type of room. This is due to the insulation of connections and flammable materials that are located in the wall. In addition, this design is convenient for repair work.

However, the main function of the distribution box is to distribute electricity between consumers that are installed in a specific room. In addition, the design of the product allows for expansion by adding additional branches (when it is necessary to install a new switch or socket).

You can add a branch to the distribution box for a new energy consumer

Why does the box have different names?

This piece of electrical equipment goes by several names, including: distribution box, branch box, junction box. Only their operating principle is the same: the box is a center where electricity is supplied from the power source, and then it is distributed through separate channels that go to switches, sockets and other devices. Therefore, such a design is usually called “distribution”. Otherwise, the box is also called a “branch”, this is due to the fact that only one cable goes into it, but several channels come out.

Note! The boxes are also called soldered boxes, which is due to the way the wires are connected inside. So, the wires must be soldered after twisting. We will talk more about this and other connection methods below.

Among some electricians, you can find another name for this box – “disconnection box”. This word is formed from two definitions: distribution and connection. After all, first you have to distribute the wires and then connect them to consumers.

Distribution boxes installed in the wall

Accordingly, if a store consultant calls the box differently, you shouldn’t be surprised, because it’s the same product. Rather, you should pay attention to the dimensions of the box, because you will have to make a recess in the ceiling for it. As a rule, standard products are produced in the form of a rectangle measuring 10x10x5 centimeters.

Prices for distribution boxes

Junction box

Main features and specifications of Meet MS-158M

Appearance of Meet MS-158M
A device with a large number of functions and good characteristics:

Tip #1. Some amateurs suggest assembling a metal detector using improvised means, CDs , DVDs , a calculator and a battery. Don't waste your time, this is complete nonsense, verified.

To detect a box or wiring in a wall, a winding, an electronic circuit and a power source are required; the assembly and joining of all components requires certain knowledge and practical skills. For one-time use, this is not worth doing; it is easier to use other methods.

Will it be possible to do without junction boxes during the installation of electrical wiring?

Of course, it is possible to install wiring in an apartment without junction boxes, but this is impractical - then you have to pull many cables from the main panel to the power consumers, which is why deep grooves are made in the wall, which will have to be puttied. In addition, this involves spending money on the purchase of cables, so the only rational solution is to purchase distribution boxes for premises.

Corrugated pipes for electrical wiring

However, some users mistakenly believe that the connection point, which is located inside the box, is less secure than the whole cable. In fact, with proper installation, there are no problems with the junction box and wiring connections.

In addition, if you imagine that the box is missing and a malfunction has occurred, you will have to remove the wallpaper and chisel the wall to find the damage. If there is a design, it will be enough to remove the cover and inspect the condition of the electrical wiring.

Types of distribution boxes

You can find a large number of varieties of these designs on sale. Therefore, to choose one of them, you need to familiarize yourself with these types in more detail.

Designs have different appearances

Table No. 1. Types of junction boxes according to installation method

Table No. 2. Materials for making the case

Table No. 3. Types of distribution box configurations

"Empty" junction box

Products also differ in the number of inputs. At a minimum, the design is designed for two inputs (to connect two cables), and a maximum of sixteen inputs. It is necessary to choose one type or another based on the electrical wiring diagram of the room.

The designs also differ from each other in the degree of protection, so this criterion should also be paid attention to when choosing a box. This is important when installation needs to be done in a room with high humidity or high air temperature.

What do junction boxes protect against:

1. The standard product assumes the presence of sealing rubber. As a rule, this is enough for most areas of the apartment.
2. From dust particles. This is relevant at production facilities.
3. From the water. Such boxes are installed in the bathroom, toilet, room with a swimming pool.
4. From mechanical shocks. This is true if the box is installed outdoors.
5. From exposure to high temperatures. Such products are purchased if there is a log house or if the walls are decorated with flammable materials.

In shape, the boxes are square, round and rectangular - the latter are used when there are many cables. Round designs are used when there is a small number of cables. In addition, they are often chosen for concrete floors.

General description of products

Engineering communications are a network of a central channel, branches, and end points. For the system to function properly, it is necessary to form reliable nodal connections of individual elements. In the case of electrical wiring, the event is carried out using electrical junction boxes.

In fact, the device is represented by a box with a lid. Install it at each node branch. The main goal here is to isolate contact connections from possible environmental influences and unauthorized mechanical influence. It also protects the premises from fires during a short circuit and protects people from electric shock. Additionally, two problems are solved: access to contact nodes for various purposes, and a decorative component.

Where is the distribution box installed?

Most often, they prefer to install the junction box under the ceiling at a distance of approximately 25 centimeters from it. This is associated with the safety of using electrical wiring, because the possibility of the protective cover falling off cannot be ruled out, which will cause electric shock to a person.

Junction boxes are fixed at height

Note! Another reason for accurately calculating the location of the box is the cable consumption for network wiring. Therefore, the closer you can bring the conductor to the consumer, the shorter the branch from the box to this point will be.

Prices for popular models of wall chasers

Wall chaser

Installation of a distribution box in a residential area

In this case, you will need to prepare the following devices and materials:

1. A jigsaw with a special disk for creating grooves where the wires will be placed.
2. A hammer drill is needed when you plan to “sink” the box into the wall, so you will need to prepare a hole.
3. Hammer for additional cutting of openings after using a core drill.
4. Wire cutters - for cutting wires to the required length.
5. Wiring stripping tool.
6. Additional devices for connecting cores.
7. Tester.

Electricity supply diagram

Approximate power supply diagram for an apartment

In the diagram you can see where the distributors are installed. So, if there are few sockets and switches in the room, then here you can determine where to install additional channels.

Installation of a distribution box: step-by-step instructions

Step 1. First you need to display on the wall the lines where the grooves will go, according to the diagram.

Grilling is performed along these lines

Step 2. Next, in the designated places you need to make recesses for installing the boxes.

It is necessary to secure the box to the wall with self-tapping screws or plaster

Step 3 . Wiring is inserted into the box and connected to each other.

After connecting, check that the wiring is working properly

Step 4. Now all that remains is to close the box with the lid.

Putty is not applied to the decorative cover

Note! They try to secure the cover in such a way that when removing it the surface of the wall is not damaged.

Video - Installation of distribution box

Simple industrial devices for detecting wiring

Many manufacturers make wiring detection indicators with various additional functions; let’s consider the simplest and most accessible for the average consumer working at the household level:

• Indicator screwdriver with autonomous power supply on button-type batteries and LED as an indication. To determine the route of the wires, just take a screwdriver by the metal end of the pen and move the handle along the wall; when guidance appears, the LED will light up.

Searching for hidden wiring with a self-powered indicator screwdriver.
The brightness of the glow depends on the proximity to the wire; the calculation of the box is also done by searching for places where the lines converge and tapping. The accuracy of detecting wires under plaster is up to 3 - 5 cm. Such a screwdriver costs up to 100 rubles.

• The universal screwdriver has three operating modes, “O” - determining the phase in the circuit by simply touching the bare end of the conductor with a pen. In “L” mode, the indicator non-contactly indicates the presence of a live wire at a distance of 1.5 cm.

Elements of the universal indicator screwdriver
Mode “H” reacts with increased sensitivity to the magnetic field of the conductor of hidden wiring at a depth of up to 3 cm. The cost of universal indicator models depends on the number of options and manufacturer: 200 - 300 rubles.

• domestically produced hidden wiring indicator “Woodpecker”

Sensitivity interval from antenna to live wire in mm

The first is low, the most accurate detects a hidden wire at a distance of 1 - 1.5 cm, in the fourth mode the detection accuracy is up to 3-4 cm.

Appearance of controls and indications of the Woodpecker detector

The presence of an electric field in the conductor is indicated by an indicator LED and an audible buzzer. To test, press and hold the corresponding mode button while moving the tip of the antenna along the surface of the wall. The simplest Woodpecker model costs about 800 rubles.

To detect a junction box, when using any device, the intersections of lines are identified.

Methods for connecting wires in a junction box

There are several basic ways to connect the wiring in a junction box. In order to choose one of them, you need to consider the options in more detail.

Stranding and insulation

This is an old, but proven method of connecting wiring over the years. The bottom line is that the ends of the conductors are first stripped of the insulation layer and then twisted together with pliers. After which this place is wrapped with electrical tape.

Twisting conductor strands

This method has advantages:

• ease of installation;
• no need for additional expenses.

However, there are some disadvantages:

• poor-quality connection of cores;
• inability to connect copper and aluminum wires.

It is worth noting that conductors are often connected in this way during temporary installation of electrical wiring. According to safety regulations, the connection method is not suitable for rooms with high humidity levels.

Soldering or welding

It is in these ways that you can make a durable connection of wiring cores. First, their ends are carefully stripped of the insulating layer, then twisted, but without effort. Next, you will need to solder the wires using solder and a soldering iron so that they turn out monolithic. Then you need to wait until they cool naturally, and only then wrap them with electrical tape.

Soldering wire cores

In cases of soldering thick wires, you will need to use a soldering iron with a dense copper tip.

Note! Some would-be craftsmen do not want to wait for the veins to cool naturally, so they cool them under running water. However, this should not be done - microcracks will appear on the surface.

The advantage of soldering is the reliability of the connections, but this method also has some disadvantages:

• the need to purchase a soldering iron;
• this is a labor-intensive process that not every beginner can handle;
• the connection is permanent;
• Over time, the level of resistance in the soldering increases, which leads to voltage leakage.

Often, instead of soldering, the cores are connected by welding. The process has a similar principle, only here a welding machine is already used, so the master must have the appropriate skills.

Video - Soldering twists

Crimping with sleeves

This is also one of the most reliable methods of fixing conductor cores. Here they are placed in a special sleeve and clamped with a crimping tool on both sides. After which this sleeve is wrapped with electrical tape or a cambric is attached to it.

Crimping of conductor cores

It is worth noting that the cores are placed in the sleeve either from different sides or from one. In the case of the first option, they will be connected in the central part of the tube. When choosing the second option, it is necessary to take into account that the diameter of the cores should not exceed the volume of the sleeve.

The advantages of such a connection should be noted:

• reliability;
• affordable cost of sleeves.

Disadvantages of the method:

1. The sleeve is used only once. This means that in case of repair, it is torn down and a new one is fixed.
2. You will need to use a special tool for high-quality crimping on all sides.
3. Wires made of aluminum and copper are crimped only with special tubes, which are difficult to find in stores.
4. Electrical installation will take time.

Terminal connection

If the wiring is made of different materials, it is recommended to use special clamps with springs or screws. Connecting the conductors using this method is not difficult; all you need is a screwdriver. The main thing is not to overtighten the bolts.

Connecting wires with clamps

Using smartphones and special applications

Many smartphones include magnetic sensors and special software applications that allow the phone to be used as a compass metal detector or a magnetic field indicator to detect hidden wiring. Installing applications, their capabilities and configuration require detailed consideration in a separate article. Before installing applications, you need to make sure that you have the appropriate sensor on your phone.

Tip #2. For about the last 10 years, when building a house or renovating an apartment, wise property owners have been photographing or filming the process of installing electrical wiring during the construction phase. The installation locations of the boxes are recorded and landmarks are marked.

Photos and videos are stored on digital media; for reliability, as a backup option, they can be placed on terminal resources on the Internet “Cloud” or in separate folders on other email portals and social networks. In this situation, it is almost impossible to lose information.

Wiring diagrams

It is necessary to become more familiar with the features of connecting the wiring from the junction box to consumers.

Prices for various types of voltage indicators

Voltage indicator

Connecting sockets

Often sockets are connected in groups on one line. So, 3 cables with several conductors are placed inside the box. Brown indicates the phase conductor, blue indicates neutral, and green or yellow indicates ground. Of course, some manufacturers use other colors.

Connecting sockets

The wires are laid out on a flat surface, and then cut to a certain length, but with a margin (so that it can be separated again). Next, it remains to fix them according to the diagram.

Connecting a switch with one button

This is where installation becomes more complicated. After all, there are three groups of electrical wiring with different connections. One conductor is responsible for supplying voltage from another box or panel, the second comes from the lighting fixture, and the third from the switch.

The phase conductor is fed to a switch, which is connected to the lamp. Here you should make sure that the voltage supply occurs precisely when the switch is closed. The neutral and grounding conductors from the lamp are connected to the shield.

The principle of connecting a switch with one button

Connecting a switch with two buttons

A three-core cable is connected to this type of switch (without a grounding conductor, because it is connected directly to the panel). The first conductor goes to the common contact of the switch, the second to the first button, and the third to the second button.

Note! The phase conductor is connected to the common contact, the zero is fixed directly from the board and lamps. The phase wires from the lighting fixtures are fixed with the cores on the buttons.

Connecting a switch with two buttons

A simple indicator of hidden wiring on one transistor

Even a person far from radio engineering can assemble an indicator on one transistor on his own. The circuit is simple, the main element is the field-effect transistor KP103 or KP 303.

Hidden wiring detector circuit using one transistor

The source of the transistor is connected to the “+” of the power supply, the drain to the “minus”, through a 1.6 kOhm microphone capsule from an old phone and a switch. The gate of the transistor is used as an antenna; a copper wire of 8-10 cm with a cross-section of 1-2.5 mm2 is soldered to it.

Appearance of field effect transistor KP 103

The accuracy of detecting a hidden wire with such a device is 3-5 cm; the work is based on the change in resistance between the drain and the source when exposed to an electric field. You can connect a multimeter in the 200 kOhm measurement mode to the circuit between the drain and source to monitor the maximum resistance value as the antenna approaches the wire.

A similar circuit can be assembled using 561 series microcircuits, its operating principle is the same.

Hidden wiring detection detector on K561 chip