How to install a junction box - 2 easy ways

Today we’ll talk about how to install a junction box in concrete. An electric distribution box is a small container made of plastic or metal, in which all groups of conductors of a certain room are connected.

The purpose of this product is as follows:

  1. Providing the possibility of repair and maintenance of home electricity. For example, if the connection of the input wires to the room with the outlet group fails, you can easily repair the problem place.
  2. Possibility of connecting new lines to room wiring. If you decide install a new outlet block, you will not need to pull another cable from the main shield, but just create a new route from the junction box.
  3. Ensuring a uniform distribution of electrical energy throughout the room by creating several main lines of the power grid, connecting into a single whole.

As you can see, this product plays an important role in installation of electrical wiring in the house or another room.


The design is quite simple and consists of a container with a lid, as well as lead-in seals (if the tank is an outdoor installation type). The photo shows in detail the constituent parts of the hidden and external distribution boxes:


As you can see, the products are different from each other, but still perform the same function.

We draw your attention to the fact that the junction box for hidden wiring on the sides can be equipped with tabs with springs. Their purpose is additional fixation if they are mounted on a drywall.


As you already understood, today there are several types of electrical junction boxes. As a rule, separation occurs according to the following characteristics:

  • manufacturing material (metal or plastic);
  • installation method (open or hidden);
  • product shape (rectangular, round, square);
  • the size.

Metal and plastic

Metal junction boxes have been used since the last century, when the plastic version was not yet invented.

It is not uncommon for the metal version of products to be used at present. Most often, the installation of metal junction boxes is carried out withinstallation of electrical wiring in the bath or a wooden house. This is due to the fact that the metal during spontaneous combustion of the cable will prevent the spread of flame.

The plastic version is more modern. There are products of both external and hidden type. Their advantage in the low price, convenient design and attractive appearance. By the way, there are fireproof distribution boxes made of self-extinguishing plastic.

Plastic containers of various shapes

Outdoor and hidden

If the wiring in the room is carried out in an open way, an external distribution box is used. When installing under plaster, a hidden product is used.

Both options perform their work pretty well, but still repair and maintenance of the wall-mounted object is easier to complete.

In addition, there are junction boxes with terminals that allow high-quality connection of wires to each other. Such products, as a rule, are made in the external version.

Connection terminals

Rectangular, square, round

Distribution boxes are also available in various geometric shapes. The reason for this is a different purpose. If a few veins are brought in, a round shape is quite enough. With a large number of cores, it is necessary to use rectangular or even square containers, because They have a large capacity.

We draw your attention to the fact that the installation of a round junction box in concrete takes less time, because There is no need to set the product up to level! At the same time, for an open electrical wiring, a square-shaped product will look prettier.

As for the sizes, they can be different, depending on what section of the cable you have chosen. Immediately recommend that you read the article: calculation and selection of cable cross-section for electrical work.

Connection Instructions

As we said earlier, the installation of the junction box can be carried out in an open and hidden way. Consider the main stages of each of the methods.

Outdoor installation

This type of installation is simpler and does not take much time.

Electricity WorksTo your attention is a step-by-step instruction that will help you independently install the junction box in the wall:

  1. Turn off the electricity in the house and check for its presence with an indicator screwdriver. About, how to use an indicator screwdriver, we told in the corresponding article.
  2. Mark the attachment points with a simple pencil.
  3. Fasten the box to the concrete wall with dowels. The design of the product includes 2 holes for self-tapping screws.
  4. Cut off the ends of the gaskets to insert all wire groups. Slices should have a diameter slightly smaller than the cable section to protect the wiring from dust and moisture.
  5. Connect the wires together. To do this, we recommend that you familiarize yourself with color coded wires. All you need is to correctly connect the phase to phase, zero to zero and ground to ground (for the outlet group). To connect the introductory group to the switch and lighting group, read the article:how to connect the light switch.
  6. Insulate the PVC joints with insulation if necessary.
  7. Close the cover.

That's the whole technology of installing a junction box in concrete with your own hands. I also wanted to immediately note that the most reliable wire connection method is soldering and wagon terminals.

Flush mounting

Installing in a hidden way is more time-consuming, but still a novice electrician can do it.


  1. First you need to create strobes for planting the product in a concrete wall. To do this, use a drill with a special crown nozzle. We pay attention to an important requirement - the diameter of the gate must fully correspond to the size of the junction box. If the landing site is small, you will have to align the contours, if too large - apply more solution.

    Wiring strobes

    Creating a Strob

  2. Lead the line to the junction box connection. Installation height - 10..20 cm from the ceiling.
  3. Dilute the alabaster solution and put it in a shtrob, having previously moistened it with a small amount of water. You can also close the strobes with gypsum mortar.
  4. Place the box flush with the wall and hold it for a while until the solution sets, then use a spatula to remove the remaining alabaster.Concealed wiring in the room
  5. Connect the cores to each other.
  6. Install the protective cover.Conductor Connection Protection
  7. Paste the place of installation with wallpaper or apply a thin layer of plaster (finish) on the cover. If it was not possible to disguise the electric point, carefully cut the wallpaper along the contour (the plastic cover will not stand out on light wallpaper).

In the end, I would like to give one useful advice - during the connection of wires sign each group (for example, sockets, switches, chandeliers, etc.). This will allow you to quickly find the necessary vein during repair work in the apartment.

That's the whole technology of installing a junction box with hidden wiring in concrete. This option will take a little longer, but the appearance of the room will not be spoiled. It remains only to provide you with some useful video instructions and diagrams.

Wiring diagrams

To your attention, visual diagrams that will allow you to correctly disconnect the distribution box:

Video instruction

If any nuance was missed or incomprehensible, we recommend that you familiarize yourself with the video instruction for installing the junction box yourself:

Options for fastening wires inside the tank

Do you like the article? We also recommend that you look at no less useful material: how to install the outlet!

Options for fastening wires inside the tank


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