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 channels panel houses, so the junction 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.
In the premises of buildings on structures for various purposes, wiring is laid from the input distribution board in most cases along the walls through distribution boxes. In some cases, installation is carried out on the ceiling or floor. IN classic version of a private house or apartment, three groups of lines are allocated from the distribution board:
- Lighting;
- Rosette;
- Lines for individual high-power heating devices.
A circuit breaker is installed for each group in the control panel. Heating devices, electric stoves are usually connected via a separate line, bypassing distribution boxes with an individual safety switch.
Lighting and socket lines are laid through boxes in which a circuit break is made to connect branches to sockets, switches, chandeliers, lampshades and other lighting fixtures.
The wires of the main line are selected with a larger cross-section than the branches, this is due to the fact that on a separate outlet or lighting fixture, the load currents are limited by the power of one device. On the main line, the current strength is the total from the load from all outlets.
Basic requirements for installation locations of distribution boxes
One of the main requirements of the PUE is quick access to the distribution box; it should not be filled with furniture, household equipment, walled up with a thick layer of plaster or covered with bricks. In case of wiring repairs or modifications, the box cover should open easily. It is not recommended to install distribution boxes in walls at the level of hanging cabinets; a dowel or self-tapping screw may fall into the box when drilling.
This technique allows you to navigate when drilling walls so as not to damage hidden wires. During installation suspended ceilings hatches are made to provide access to the boxes. In old premises, wiring and boxes can be moved outside under the frame suspended ceiling, in new buildings this is taken into account and done immediately.
Types of distribution boxes
Distribution boxes are divided according to two characteristics: material of manufacture and design.
Materials:
- Metal;
- Plastic.
Old-style metal boxes are in most cases used for installation in wooden walls in order to ensure fire safety. Modern models are made of plastic.
Table 1 JBR distribution boxes
Depending on the method of laying the wiring and the material of the walls in the boxes, there are design differences:
- Overlay boxes for open wiring;
- Inner boxes for hidden wiring;
- Products can be square or round cylindrical in shape with varying depths;
- For installation in brick and concrete walls;
- For mounting in walls with hollow spaces, in decorative finishing, drywall, plywood, chipboard or other materials.
Depending on the installation conditions, the design of the distribution boxes and the appropriate installation method are selected.
Features of installation methods for distribution boxes of various designs
The simplest process when installing overhead boxes for exposed wiring. They are simply screwed to the wall surface with self-tapping screws or nailed with dowels. In the case of boxes for hidden wiring in the walls, you have to drill holes of the appropriate diameter and depth. The dimensions of the boxes are selected based on the number of wires that go into it; the more wires, the larger the diameter and depth of the box should be.
Installation of distribution boxes in brick and concrete walls
In extreme cases, holes in brick and concrete walls can be drilled with a hammer and chisel, but this requires a lot of effort and time. In modern conditions, a hammer drill is used with special crowns of various diameters, which have pobedit, tungsten or diamond teeth around the circumference. A drill with a tip made of the listed materials is installed in the center of the crown; this stabilizes the crown during drilling.
Size table various models crowns for concrete
Before installation, the ends of the wires are inserted into the technological holes of the box. A gypsum mortar is applied around the perimeter of the hole and a glass is inserted to its full depth; the upper edges of the glass of the box body should be level with the wall surface. After the solution has hardened, you can begin cutting and connecting the wires.
Tip No. 1 In order for the top edge of the box to coincide with the level of the plane of the wall surface, it must be installed after laying the wires and plastering the walls.
Installation of distribution boxes in hollow walls (plasterboard, plywood, other decorative materials)
A hole can be drilled in drywall using a concrete drill bit. wood slabs drilled with special crowns with several toothed plates. The boxes in these cases have clamping strips in their design, which, after installation, are pressed against the back side of the drywall sheet by rotating the bolts. Before installation, the ends of the wires are inserted through the holes into the box. You can drill holes a regular drill using the appropriate attachment.
Tip No. 2 A typical mistake: before drilling a crown with a hammer drill with a crown for concrete, do not forget to switch it from the perforation mode to the normal drilling mode. Otherwise, the gypsum board may simply break, crack, or form a shapeless hole.
Cutting and connecting wires in the box
The wires are inserted into the box at 15 - 20 cm, from cables such as PUNP, VVG and other similar types, the outer layer of insulation is removed almost completely, leaving 2 - 3 cm in front of the technological hole. The insulation from the current-carrying conductors is removed by 7 - 8 cm, the connected ends of the wires are folded into one bundle, and clamped with pliers at the level of the insulation cut.
The ends of the exposed wires are clamped with the second pliers, the first pliers are held in place, the second ones are rotated clockwise, thus twisting is done.
A typical mistake when twisting wires is twisting; the wires must be pulled tightly, but the force must be calculated so that the wires do not burst due to overtightening.
Unevenly protruding strands at the end of the twist are cut off evenly with pliers; according to the requirements of the PUE, the ends of the twist must be welded or soldered. For welding, you can use a 220/36V step-down transformer; a graphite rod is used as an electrode. In practice, most electricians ignore these requirements; correctly made twisting ensures reliable contact.
After twisting, the bare ends are insulated; this can be done in various ways:
- Regular PVC electrical tape;
- Heat shrink tubes;
- Plastic caps.
Recently, boxes with contact strips have appeared, where switching is carried out on terminals with bolt clamps.
Having finished the insulation, the wires are laid inside the box so that the twists do not touch each other, then the lid is closed. To make the lid harmonize with the interior, it is painted in the appropriate color and sealed with a circle of appropriate wallpaper or other material.
Wire connection diagrams may be different, depending on the connected wiring elements. But there are general rules:
- All ground wires are twisted into one twist;
- All neutral wires are twisted into a separate twist;
- Phase wires are also twisted into one separate twist;
- The wires from the outlet in a three-wire circuit are connected directly to the main line, one wire to the phase twist, the second to the neutral and the third to ground.
- Lighting devices are connected in phase through a switch, the neutral wire from the base contact goes into the box for neutral twisting, grounding from the lighting fixture body to the grounding twist.
- Blue is used as the neutral wire;
- Red, white, brown and others as phase;
- A conductor with yellow-green insulation serves as grounding.
FAQ
- The holes in the box are made at the very bottom, the wires go higher and interfere with installing the box in the hole in the wall, what should you do in this case, maybe remove the outer shell and lead the wires to the hole between the box body and the concrete?
No, the wires must fit into the holes freely and not be pinched by the box body. In front of the technological hole in the wall, a short groove is made to the insertion depth, then it is covered with gypsum mortar.
- There are boxes with lids that don’t close well, is it better to buy one with a lid that is screwed on?
Manufacturers usually make high-quality boxes with tight-fitting lids. If the box was closed before installation, then it will be closed after. In this case, a characteristic mistake is made when pressing the box into the hole in the wall; the body goes very deep, the upper edges are below the level of the wall surface. The second option, when the box is fixed with gypsum mortar, the body is deformed and the upper part takes the shape of an ellipse. In these cases round lid or does not fit tightly, or does not close at all, be careful when installing.
Today we will talk about how to install a junction box in concrete. An electrical junction box is a small container made of plastic or metal in which all groups of conductors in a certain room are connected.
Appointments of this product the following:
- Providing the opportunity to repair and maintain the home electrical network. For example, if the connection of the input wires to a room with an outlet group fails, you can easily repair the problem area.
- Possibility of connecting new lines to the room electrical wiring. If you decide, you will not need to pull another cable from the main panel, but just create a new route from the distribution box.
- Ensuring uniform distribution of electrical energy throughout the room by creating several main power lines connecting into a single whole.
As you can see, this product plays an important role in any other room.
Design
The design is quite simple and consists of a container with a lid, as well as inlet openings - seals (if the container is of an external installation type). The photo shows in detail the components of the electrical distribution box, hidden and external:
As you can see, the products are different from each other, but still perform the same function.
Please note that the distribution box for hidden wiring may have claws with springs installed on the sides. Their purpose is additional fixation if installation is carried out in a plasterboard wall.
Varieties
As you already understood, today there are several types of electrical distribution boxes. As a rule, the division occurs according to the following characteristics:
- material of manufacture (metal or plastic);
- installation method (open or hidden);
- product shape (rectangular, round, square);
- size.
Metal and plastic
Metal junction boxes have been used since the last century, when the plastic version had not yet been invented.
Not rare metal version products are still in use today. Most often, the installation of metal distribution boxes is carried out with either wooden house. This is because the metal, when the cable ignites spontaneously, will prevent the flame from spreading.
The plastic version is more modern. There are products of both external and hidden types. Their advantage is low price, convenient design and attractive appearance. By the way, there are fireproof junction boxes made of self-extinguishing plastic.
External and hidden
If the wires in the room are connected open method, an external junction box is used. When installing under plaster, a hidden type product is used.
For hidden installation For outdoor installation
Both options do their job quite well, but it is still easier to repair and operate a wall-mounted object.
In addition, there are distribution boxes with terminals that allow you to efficiently connect the wires to each other. Such products are usually made for outdoor use.
Rectangular, square, round
Distribution boxes are also available in various geometric shapes. The reason for this is various purposes. If only a few wires will be supplied, a round shape will be enough. If there are a large number of cores, it is necessary to use rectangular or even square containers, because they have a large capacity.
Please note that installing a round junction box in concrete takes less time, because... There is no need to level the product! At the same time, for open electrical wiring, a square-shaped product will look more beautiful.
As for the sizes, they can be different, depending on what cable section you have chosen. We immediately recommend that you read the article: for electrical installation work.
Connection instructions
As we said earlier, the installation of the distribution box can be carried out open and in a hidden way. Let's consider the main stages of each method.
Outdoor installation
This type of installation is simpler and does not take much time.
Everything for your attention step-by-step instruction, which will help you install the distribution box in the wall yourself:
- Turn off the power in the house and check for power using an indicator screwdriver. We talked about this in the corresponding article.
- Mark the attachment points with a simple pencil.
- Secure the box in concrete wall using dowels. The design of the product includes 2 holes for self-tapping screws.
- Cut off the ends of the seals to enter all groups of wires. The cuts should have a diameter slightly smaller than the cable cross-section to protect the wiring from dust and moisture.
- Connect the wires together. To do this, we recommend that you read. All you need is to correctly connect phase to phase, zero to zero and ground to ground (for the socket group). To connect the input group with a group of switches and lighting, read the article:.
- Insulate joints with PVC insulation if necessary.
- Close the lid.
That's the whole technology for installing a distribution box in concrete with your own hands. I would also like to immediately note that the most reliable
The main difficulty you may encounter during the installation process electrical wiring in a private house, apartment or specific room - 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 things to consider: important points. 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 branching boxes
Electrical wiring should be divided into separate groups depending on the electricity consumer. For these purposes, special electrical products are used that perform important functions:
- increasing the level of fire safety;
- aesthetics.
Cables are hidden under the box body, which ensures reliable protection from mechanical damage and significantly extends the service life of the wiring as a whole. If we consider the installation principle, then devices are divided into built-in and external, suitable for open wiring. The first are placed inside pre-prepared niches, the second are attached to the surface of any wall. There is also a special outdoor box.
Main function of distribution box
Using this electrical product, you can significantly reduce the cost of organizing electrical wiring. Without this element, it would be necessary to connect each electrical appliance with a separate cable, which would lead to an increase in the number of channels required for installation and spoil appearance.
Proper distribution of the cable inside the box will increase the safety of residential and non-residential rooms. This is due to the insulation of connecting points with flammable materials contained in the wall. The design of the equipment is thought out to the smallest detail, therefore it guarantees ease of repair work.
But the main function of the box is related to the uniform distribution of electrical energy between all consumers installed in the room. In addition, the product structure takes into account potential expansion due to the addition of new branches of the electrical circuit.
Why are they called differently?
This electrical equipment is called differently, from distribution to branch or junction box. The principle of operation is always identical: the box is the head center into which the Electric Energy from the source, after which it is distributed among different branches, supplying voltage to sockets, switches and lighting fixtures. That is why it got its name – “distribution”. The alternative name “branch” appeared due to the fact that one wire enters the box and several cables exit.
Soldering products are so called because of the method used for switching wires inside the case: after twisting, they must be soldered. Despite the huge variety modern methods switching cables in boxes (terminal blocks, sleeves, clamps, welding), they are still called soldering boxes.
Another synonym for the device was the word “exclusive”. You can hear it only among people involved in the electrical installation industry. In fact, the word is derived from two other terms - distribution and connection: first the wires are distributed into branches, and then they are connected. Following this principle, it is easy to guess where another name for the box came from - “connecting”.
Thus, when going to the store to buy a distribution box, you should not be surprised if the product you need is on the counter, but under a different name. Also pay attention to the dimensions of the device, according to which you will have to create a recess in the wall. For example, rectangular apartment boxes are usually produced standard size– 100x100x50 mm.
Is it possible to do without installation junction boxes?
Theoretically, this option is possible and acceptable, but to make sure that it is practically impossible to implement it, it is enough to imagine a simple picture: an introductory electrical panel is installed at the entrance to the apartment; boxes are not used in the rooms, so you have to run separate cables to each switch, socket and lighting fixture. This will lead to significant costs for the purchase of cable, expansion and deepening of grooves (or installation of wider cable channels, which will disrupt aesthetics). Conclusion: installing a distribution box is an economically feasible and rational solution.
Many people mistakenly believe that an additional connection assembly appearing inside the distribution box (in line with the input panel from a particular outlet) will lead to poor safety, while a solid cable is much better. In fact, if everything is done correctly and correctly, then the selected switching method will not pose a threat. Finally, a product like this makes it easier to find faults on the line, so you don't have to dig through the entire wall to find a damaged section of the electrical circuit.
Types of distribution boxes
Above we indicated the first criterion for classifying boxes - the method of fastening (built-in and external). Regardless of this, the boxes are closed with a tight lid, providing quick access to the contents and integrity of the wiring. If necessary, an electrician can examine the contents of the housing by removing the cover.
The main materials for making distribution boxes are plastic and metal. In the second case, tinned steel sheets and alloys containing aluminum are used. Important condition: metal box must be reliably protected from corrosion.
If products are placed strategically important object, where any damage is unacceptable, it is recommended to buy a box with a lid with screws and waterproofing gaskets. Metal is more reliable in terms of fire protection, since it is able to maintain the integrity of the contents for several minutes. This time is usually enough to promptly de-energize the network.
Plastic elements are also characterized by certain positive qualities. They are resistant to any oxidation processes and are excellent dielectrics. In both cases, the degree of protection against dust and moisture is at least IP65.
By geometric shape boxes are round, square and rectangular. The former are used in situations where a small number of cables are switched, the latter - a large number. The specific dimensions of the device depend on the cross-section and number of wires.
Advice! If you need to install a distribution box in a concrete wall, then it is much easier to use round-shaped products.
Where and how to install distribution boxes
Usually the boxes are located under the ceiling at a distance of 100-200 mm from it. The specific value depends on the height of the room. If the wiring is hidden, then the product is placed inside the wall to a certain depth so that the surface of the cover is flush with the wall. For electrical wiring open type Outer boxes will do.
In accordance with the rules of the device electrical installations(PUE) it is important to provide free access to the junction box cover, which is necessary in case of inspection or troubleshooting. If the product is external and attached directly to the wall, then this condition is met automatically.
When placing the device in a wall recess, two requirements must be met. Firstly, you need to know where it is installed, and secondly, you should ensure timely access to the product without compromising its aesthetics. If the latter can be neglected without violating the PUE, then the first requirement is mandatory and important.
You can maintain an aesthetic appearance by gluing beautiful wallpaper, then carefully cut around the junction box cover without removing the part that is glued to it. Choosing alternative options finishing, make sure that the color of the surface of the cover and the wall are identical. Try to make sure that if you need to remove the cover, the wall is in this place did not collapse. If installed stretch ceiling, then small hatches should be created to provide access to the boxes.
Wire connection methods
The PUE specifies five main methods for switching two wires:
- twist;
- welding;
- terminal blocks;
- soldering;
- crimping.
Twist
The fastest, simplest, but extremely unreliable switching method. To insulate the wires, use electrical tape, plastic caps or heat shrink tubing.
Twist with mounting caps
The connection made using special mounting caps will be much better and more stable. The products consist of two parts - an outer plastic, non-flammable, and an inner metal, conical shape with threads. The latter allows you to literally screw a cap onto the end of the wire, providing a large contact area and excellent electrical parameters. This method allows you to connect two or more wires without soldering.
To perform the operation, remove up to 20 mm of insulation and twist the wires together. Place a cap on the twist and twist several times. When choosing a cap, be guided by the number of wires to be twisted and their cross-section. This option saves space, allowing you to place the cable more compactly.
Soldering
A standard method of connecting wires using tin and solder. It is characterized by high reliability and durability, but takes much more time.
Welding wires
The first difficulty of the method is that it is necessary welding machine inverter type. This option is considered even more reliable and of high quality, allowing you to turn two cores into one. It should be used only in extreme cases: when grounding a private house with a powerful load, connecting pumps or sources uninterruptible power supply for operation of gas boilers.
Terminal blocks
In accordance with the recommendations in the PUE when switching two wires from different materials you need to use special screw clamps or spring type. A simple method that requires a screwdriver. Be careful not to overtighten the clamp bolts.
Crimping
This method involves the use of press jaws and sleeves. The latter are selected depending on the cores being connected - aluminum sleeves are used for aluminum, copper sleeves are used for copper, etc. Please note that using pliers you will not be able to ensure a reliable and high-quality connection.
Basic wiring diagrams
After studying and choosing a method for connecting wires in a junction box, read the information on connecting specific conductors.
How to connect sockets
In most cases, sockets are connected in groups, for which a separate current-carrying line is used. Three cables with two or three conductors go inside the box. Brown color usually indicate “phase”, blue - “zero”, yellow-green - “grounding”. There are alternatives to these colors with the following standard - red, blue and black respectively.
The wires need to be grouped by color, folded, pulled and cut to obtain equal lengths. Be sure to do this with a small margin of up to 10 cm to leave room for repeated distribution and switching. Next, perform switching using the selected method. If two wires are connected (without grounding), then the circuit remains the same, only simplified.
Connecting a single-key switch
With switching the switch, things are more complicated. There will be three groups of wires with a different connection. One wire supplies voltage from a nearby box or electrical input panel, the other comes from the chandelier, and the third from the switch.
The phase wire must be fed to the switch connected to the chandelier. Make sure that voltage will only flow to the lighting fixture when the switch is in the closed position. The neutral and grounding wires of the chandelier are connected directly to the panel.
Connecting a two-gang switch
A cable consisting of three wires (without a ground wire, which is connected directly to the box) is laid to a switch with two keys. One wire goes to the common contact of the switch, the second to the first, and the third to the second key. Remember the color of the conductor connected to the common contact.
The phase wire must be connected to a common contact; neutral wires from the input panel and two lighting fixtures are connected directly. The phase wires from the lamps should be connected to the conductors on separate switch keys.
Finally, I would like to remind you to comply with basic electrical and fire safety rules. Never directly connect two conductors made of different metals– for example, aluminum and copper. If such switching cannot be avoided, then use terminal boxes.
Make sure that the phase, neutral and ground wires are connected correctly. If you confuse “phase” and “grounding”, you can cause short circuit. Following the proverb “measure twice, cut once,” before hiding a built-in distribution box under decorative elements, make sure that all consumers connected through it are in working order.
