Electricity is the area in which everything needs to be done correctly and thoroughly. In this regard, many prefer to understand everything independently, and not trust outside people. One of the key moments is connecting the wires in the junction box. On the quality of work depends firstly, the correct operation of the system, and secondly - safety - electrical and fire.
What is the junction box
From the electrical shield wires run through the rooms in the house or apartment. In each room, as a rule, not one point of connection: several outlets and a switch are exactly. To standardize the ways to connect the wires and collect them in one place, use junction boxes (they are sometimes called branching or splicing). In them, cables are routed from all connected devices, the connection of which takes place inside the hollow body.
In order not to search for wiring during the next repair, it is laid according to certain rules, which are prescribed in the PUE - Rules of the Device of Electrical Installations.
One of the recommendations is to conduct all the connections and branches of the wires in the junction box. Therefore, the wires are allowed on the top of the wall, at a distance of 15 cm from the ceiling. After reaching the branch site, the cable falls vertically down. A junction box is installed at the branch site. In it, all the wires are connected according to the required scheme.
By type of installation, the distribution boxes are internal (for flush mounting) and external. Under the inner in the wall make a hole in which the box is built in. With this installation, the lid is flush with the finishing material. Sometimes in the process of repair, it is closed with finishing materials. However, such installation is not always possible: the thickness of walls or finishes does not allow. Then use a box for outdoor installation, which is attached directly to the surface of the wall.
According to the shape of the box, it can be round or rectangular. There are usually four conclusions, but there may be more. The terminals have a thread or a fitting, to which the corrugated hose is conveniently attached. After all, it is more convenient to lay wires in corrugated tubing or a plastic pipe. In this case, it will be very easy to replace the damaged cable. First disconnect it in the junction box, then from the consumer (outlet or switch), pull and pull out. In its place, tighten a new one. If, on the other hand, it is laid in the old fashioned way - in a shtrobe, which is then plastered with plaster - to replace the cable, you will have to chisel the wall. So this is the recommendation of the Council of Ministers, which is definitely worth listening to.
What do junction boxes generally give:
- Increased maintainability of the power supply system. Since all connections are available, it is easy to determine the damage site. If the conductors are laid in cable channels (corrugated tubing or pipes), the replacement of the damaged area will be easy.
- Most of the problems with electrics occur in the connections, and in this type of installation they can be periodically inspected.
- The installation of junction boxes increases the level of fire safety: all potentially dangerous places are in certain places.
- It requires less money and labor than laying the cable to each of the outlets.
Ways of connecting wires
In the box, the conductors can be connected in different ways. Some of them are more complicated, they are realized, others are easier, but if done correctly, they all provide the required reliability.
The most popular method among folk craftsmen, but the most unreliable. It is not recommended for use because it does not provide proper contact, which can lead to overheating and fire. This method can be used as a temporary one, for example, to check the operability of the assembled circuit, with the mandatory subsequent replacement by a more reliable one.
Even if the connection is temporary, it is necessary to do everything according to the rules. The methods for twisting stranded and solid conductors are similar, but they have some differences.
When twisting stranded wires, the procedure is as follows:
- insulation is peeled by 4 cm;
- conductors are untwisted by 2 cm (position 1 in the photo);
- Connect to the junction of untwisted conductors (pos. 2);
- veins are twisted by fingers (pos 3);
- twisting is tightened by pliers or pliers (pos. 4 on the photo);
- Isolated (insulating tape or a thermoshrinkable tube before fitting).
The connection of wires in the junction box with one dwelling with the help of twisting is easier. Insulated conductors are crossed and twisted by fingers along the entire length. Then take the tool (pliers and pliers, for example). In one, the conductors are clamped near the insulation, the second tightly twists the conductors, increasing the number of turns. The connection point is isolated.
Screw with mounting caps
Even easier is the twisting with the use of special caps. With their use, the connection is more securely insulated, contact is better. The outer part of such a cap is cast from plastic that does not support burning, a metallic conical part with thread is inserted inside. This insert provides a large contact surface, improving the electrical characteristics of the connection. This is a great way to connect two (or more) wires without soldering.
The twisting of wires with the help of caps is even simpler: the insulation is removed by 2 cm, the wires are slightly twisted. They put on the cap, with the force turns several times, until the metal is inside the cap. Everything, the connection is ready.
The caps are selected depending on the cross-section and the number of conductors to be connected. This method is more convenient: the space takes up less than the usual twist, everything fits more compactly.
If there is a soldering iron in the house, and you know how to handle it a little, it is better to use a soldering. Before twisting the wires are puddled: a layer of rosin or solder flux is applied. The heated soldering iron is dipped in rosin, and it is carried out several times on the part that has been cleaned from the insulation. On it appears a characteristic touch of reddish color.
After that, the wires are twisted as described above (twist), then they take the tin on the soldering iron, heat the twist until the molten tin begins to flow between the turns, enveloping the connection and providing good contact.
This way installers do not like: it takes a lot of time, but if you connect the wires in the junction box for yourself, do not regret time and effort, but you will calm down.
Welding of wires
If there is an inverter welding machine, you can use the welding connection. This is done on top of the twist. The welding current is set on the apparatus:
- for a cross section of 1.5 mm2 about 30 A,
- for a cross section of 2.5 mm2 - 50 A.
The electrode is graphite (this is for welding copper). The grounding clamps are neatly clinging to the upper part of the twist, we bring the electrode to it from below, touch it briefly, trying to ignite the arc, and remove it. Welding takes place in a fraction of a second. After cooling, the connection point is isolated. The process of welding wires in the junction box is shown in the video.
Another connection of wires in the junction box is by means of terminal blocks - terminal blocks, as they are also called. There are different types of pads: with clamps and screw, but, in general, the principle of their device is one. There is a copper sleeve / plate and wire fastening system. They are arranged so that by inserting into the right place two / three / four conductors, you securely connect them. In the editing it's very simple.
Screw terminal blocks have a plastic housing in which the contact plate is fixed. They are of two types: with hidden contacts (new) and with open ones - of the old sample. In any one of them, a conductor is cleaned from the insulation (length up to 1 cm) and is clamped with a screw and a screwdriver.
Their disadvantage is that it is not very convenient to connect a large number of wires in them. Contacts are arranged in pairs, and if you need to connect three or more wires, you have to squeeze two wires into one socket, which is difficult. But they can be used in branches with a significant current consumption.
Another kind of pads is Vago's terminal blocks. These are pads for quick mounting. Basically two types are used:
- With a spring-loaded mechanism. They are called one-time, since their repeated use, if possible, then with a significant deterioration in the quality of contact. The case in the internal structure: in the body is a plate with spring petals. By inserting the conductor (only solid), the tab is bent, clamping the wire. Providing contact, it crashes into the metal. If the conductor, with the proper effort, and can pull out, then the petal is not the same form. Therefore, this type is considered to be disposable. Despite this, the connection is reliable, and you can use them. There are also special terminal blocks of the same shape, but in a black case. They have electrical wiring inside. These connectors are necessary if you have to combine copper and aluminum, which simply do not mix because of the active electrochemical processes that occur between them. The paste prevents oxidation, allowing the two metals to be easily combined.