The traditional element of electrical networks is the junction box for exposed and concealed wiring, protecting the live conductors (cables) at their connection points. It has a simple design and does not cause difficulties with installation, the main thing is to choose the right accessory. And it is worth paying special attention to this issue.
When selecting an electrical element, it is necessary to take into account a number of important parameters. These include the type of wiring, the material of the walls and the junction box itself as well as other factors.
We will tell you how not to get confused in the variety of proposals, help you choose the best option and perform a competent installation.
The contents of the article:
- Classification of junction boxes
- Designs for open wiring
- Concealed-type products
- Installation box - sub-socket
- What makes metal products different
- Installation instructions with your hands
- Tools and materials for Installation
- Installation of the fittings in the different types
- Installation of the metal terminal box
- Conclusion and useful video on the subject
Classification of terminal boxes
The different types of structures are suitable for the installation on different types of materials - brick, concrete, plasterboard, etc. д. This type of electrical accessories is actively used in home wiring, thus ensuring electrical and fire safety.
Based on the purpose, electrical junction boxes should be divided into two kinds:
- Raspayky. Their purpose is to protect wires and cables from moisture and mechanical damage during the operation of a household electrical circuit.
- Installation boxes. Used to create convenient communications when carrying out installation works associated with the installation of electrical equipment.
Both types of products are suitable for use in ambient temperatures ranging from -25 to +40ºC.
A huge number of junction boxes for installation in electrical circuit boards are manufactured by industrial production. The variety of variations is astounding but the basic configuration remains the same
The advantages of junction boxes are obvious:
- A wide choice for networks of different powers;
- strong protection for wiring connections;
- convenient and easy to install;
- variety of housing materials;
- diversity of decoration.
The design of the products is simple and is usually represented by rectangular, round or other shaped boxes which are closed with covers. The lids fit and lock tightly with differently shaped latches.
An example of flush mounting junction box and execution of conductor connection with insulated terminal boards
All existing junction box shapes are manufactured for flush or surface mounting. The mounting of outdoor boxes is done in a standard way - with screws, dowels, self-tapping screws.
Tap junction boxes
Tap sockets and light
Socket boxes for complex system
Model box for branching system
Disconnect box for concealed wiring
Use of terminals to form connections
Positioning of the branch box on the ceiling
Access to maintenance and repair
Fixing the branch boxes for concealed wiring is done by placing them directly in the building structure (wall walls, partitions, ceilings) and then filled with mortar.
Boxes for exposed wiring
Installed boxes for exposed wiring are generally rectangular or circular. Material is polypropylene, ABS plastic in white, grey or black. Number of side holes for wires (cables) from 4 to 10.
Standard modification for open wiring circuits: 1 - mounting screw hole plug; 2 - enclosure wall; 3 - terminal slots; 4 - cover lever; 5 - entry hole; 6 - latch lock; 7 - lever collar (+)
As an illustrative example of an open wiring box, consider the AP9 model designed for installation in environments with high humidity. The housing of the product is two-piece molded and equipped with membrane cable entries.
The top case (lid) of such junction boxes, made for outdoor installation, has a special groove on the inside all around the perimeter. A PVC gasket is inserted in this groove to keep moisture and dust safely inside the product.
The cover is \"tied\" to the housing by a flexible lever - an extra serviceability.
However simple in execution, the constructional features of boxes like AP9 give these products an IP 55 protection degree. The design can be supplemented with accessories such as fuses and terminal strips for a more convenient and reliable connection of the conductors.
Hidden type products
Hidden wiring boxes actually have the same technical parameters and qualities as the products for outdoor installation. They too are mainly made of polypropylene and polystyrene. Moreover, polypropylene is usually used for the body and polystyrene is the cover material.
Faulty wiring junction boxes designs. On the body of the body there are stenciled cable entry holes, for the use of which a piece of polypropylene
For installation in the body of brick and concrete walls, distribution boxes with IP20 to IP30 protection class are produced. The shape of the products is predominantly round or rectangular. Color hull coloring - white, blue, black. The covers are traditionally white or light gray.
Coupling and locking of the cover with the housing is usually made by means of a pin lock. The body has grooves in which the plastic pins of the cover are inserted.
Installation box - slots
There is a type of plug-in unit: the junction box. Their main purpose is installation inside hollow or solid walls of buildings (brick, concrete) with subsequent installation of electrical switches, sockets and other elements of electrical networks. Junction boxes are made for IP20 protection class.
The so called junction boxes are a kind of modification of the same products of concealed wiring. They differ in a slightly modified configuration of fixing. Otherwise they are completely similar
Brand products are made of good quality plastic with high resistance and dielectric protection characteristics.
Installation boxes can be installed in ambient temperatures from -5ºC to +60ºC. The operating temperature range is between -25ºC/+40ºC. There are two types of products: for installation in hollow walls or in solid walls.
Connections inside the junction box are easier, better and faster using spring clamps:
Step 1: Stripping the insulation to fit into the terminal
Step 2: Installing stripped conductors
Step 3: Distribution of the connections in the enclosure
Step 4: Check the quality of the connections with a multimeter
The designs differ from one another in fixing technique:
- fixing with support feet;
- fixing with mounting dowels or screws.
For more details on the installation of the sub-disconnectors see this article.
There are also differences in the rigidity of the body and the colouration.
What makes metal products different
The points of connection of lightening cables as well as power cables up to 1000W are often installed inside metal junction boxes.
Metal junction box: 1 - lid fixing hole; 2 - inner enclosure wall (aluminium); 3 - DIN rail fixing hole; 4 - epoxy coated outer enclosure wall; 5 - earth clamp; 6 - lid seal (+)
The metal configuration is a kind of universal variant for such products.
These boxes can be used not only for AC or DC networks but also for networks:
The metal boxes are made of alloys with chemical and corrosion resistance. The external surface is coated with a special epoxy resin which provides additional mechanical strength and UV protection. The enclosure may contain from 2 to 6 inlets with threaded fittings.
In the closed state, the penetration of foreign media into the metal box is prevented thanks to the high-quality sealing of the cover and the cable inlets. Installation of boxes of this configuration is allowed indoors and outdoors.
They are usually installed in combination with rigid metal pipes, acting as cable channels. The products have protection classes IP66 to IP67.
Installation instructions by hand
Buying the mounting products one should bear in mind: every branded product is usually packed and accompanied by a product label.
Every branded product is obligatory accompanied by a label stating technical parameters and other information. In this way it is possible to distinguish an original product from a fake
The product label contains: technical information, product barcode, certification mark.
Installation tools and materials
The electrician uses the following standard tools to carry out the installation:
- Flat crosshead screwdriver;
- Knife with thin sharp blade.
Accessories for assembly:
- insulating tape;
- electrical terminals;
- DIN rails;
- fittings - screws, screws, dowels etc.
We should note: Installation work associated with the installation of electrical networks and associated fittings may only be carried out by persons who have the appropriate knowledge and qualifications.
In an extreme case, it is possible to make the installation of boxes with your own hands and lay cable channels. But connections, wiring, testing on electrical networks, according to the instructions, may only be carried out by persons qualified to do so.
Installation of fittings of various kinds
Installation for outdoor installation:
- The box body is cut with a sharp, thin knife to cut the plugs of sealed inlets. The cuts are made according to the marking lines on the plug in accordance with the diameter of the cable duct or the cable itself.
- Tubular ducts - corrugated or straight plastic tubes - are inserted into the holes left after cutting.
- Wire ends are inserted through the channels inside the box body.
Install the terminal block in special guides and connect the conductors according to the circuit if necessary. To finish, the terminal box is closed with a lid which is pressed with some force until it is fully locked with the latch.
Picture instructions for the installation of the outdoor terminal box. The standard version used in most household wiring applications
Installation instructions for the outer universal conduit box:
- Make cuts with a knife to the standard markings on the body of the box to match the size of the rectangular conduit. The standard marks are designed to fit cable ducts with a minimum cross section of 10*7 mm, maximum 40*25 mm.
- Gently break off the notched part of the case plastic, thus obtaining an opening for the cable duct.
- Fit the terminal blocks on the base of the universal box to mechanically bundle the electric conductors.
Wiring through the conduit, connect the ends of the conductors according to the diagram on the terminals.
Finish the job by fitting the box cover and fixing it with the fixing screw.
Picture instructions for the installation of a junction box in combination with a rectangular plastic cable duct. This is also an outdoor installation option
Installation procedure for an installation (concealed) box:
- Prepare the product by prefabricating the required number of entry holes in the enclosure. The holes are created by breaking in the edges of the finished stencil. Up to 11 insertion hole stencils can be placed on the body of the junction box.
- Make an insertion hole in a hollow wall, such as plasterboard, using a drill bit to match the diameter of the product. Or use a prefabricated drill hole in a solid wall.
It remains to insert the conduits with the wire, connect them to the box, insert the ends of the wiring and fix the body of the box by screwing (for plasterboard) or filling it with mortar.
In this way the installation is carried out according to the installation instructions for flush mounting boxes. This variant is often used for the installation of electrical wiring in apartments in town houses
With the flush-mounted wiring in accordance with the wiring diagram, the box(s) is (are) closed with a cover. Externally, such a design is well suited to the existing interior.
The assembly steps of the Wago junction box are illustrated in the following photo selection:
Step 1: Entering the cables into the junction box
Step 2: Removing cable insulation with a stripper
Step 3: Stripping the insulation of the wires to be connected
Step 4: Splitting the wires in different directions
Step 5: Installing the terminals on the input wires
Step 5: Securing the connected wires with ties
Step 7: Laying the assemblies in the junction box
Step 8: Fastening the faceplate
Mounting the metal junction box
The metal junction box design provides for external mounting of such products only.
In this case the instructions are simple:
- Let the tubular conduits with the conductors enter the boxes.
- Fit the mechanical screw-fastening of the tubes to the enclosure walls and leading the cable ends into its inner area.
Fasten the box enclosure to the wall with screws through the holes provided for fixing. Then the cables are connected according to a diagram, the box is covered and the cover is screwed on.
This is roughly what the installation of the wiring looks like with the switchable metal box. A tool kit for the mounting of the different types of boxes is similar
Units of distribution boxes of different designs are mounted in this way.
More installation examples can be found in the video.
Conclusions and useful video on the topic
Visual instructions for the mounting of junction boxes:
Impossible to cover all existing junction box variations in one overview. However, the design and mounting features are almost identical for all existing products.
The above instructions can therefore be considered universal for the installation of many models of junction boxes.
If you are interested in the selection and installation of junction boxes, please leave comments, ask questions and participate in the discussions. The feedback form is located in the bottom block.