Most often, fires occur due to a fault in the wiring. Fire may occur in the event of insulation failure, as well as heating of the conductors at their junctions. Most often, when installing electrical wiring, twist the wires. When twisting the wires, the contact area is small in size, which leads to heating of the core with an increase in load. It is this factor that leads to a sharp increase in temperature at the junction and, as a result, to ignition of the insulation.
Welding the wires in the junction box is the most reliable connection of the two wires of the electrical wiring. Therefore, before proceeding with the installation of the electrical network, it is necessary to carefully study the rules for such work. It will be useful to get acquainted with step-by-step instructions for the welding process, as well as the tips and recommendations of experienced installers.
Features of welding wires
The electrical wiring in modern homes is made of copper wire, previously aluminum was also used. Therefore, we will mainly get acquainted with the welding process of copper cores.
A feature of copper conductors is that at a temperature of 300 ℃ the material becomes brittle, and at 1080 ℃ melting occurs. Therefore, it is very important to strictly observe the temperature regime during welding of wires in the junction box to avoid damage to the insulation and wires.
Overheating is eliminated by connecting to the place of twisting of the cooling radiator. It is better if the radiator is made of copper material and is tightly pressed to twist.
Twist during welding must be placed vertically so that the molten metal takes the form of a spherical drop and covers the entire bundle of wires. Stranded conductors are welded after preliminary installation of a special crimp sleeve.
Advantages of connecting wires by welding
Do-it-yourself welding of wires in the junction box has an undeniable advantage over all types of connection of conductors in that it allows you to achieve the complete absence of transition resistance, which exists during bolting and twisting. This advantage is especially evident when connecting wiring for powerful power devices.
The benefits of welding wires in an electrical junction box are easier to consider than soldering:
- no tinning of exposed veins is required;
- no filler material (tin) is used;
- the speed of the work is much higher, therefore, the efficiency increases with a large volume of connections;
- the ability to weld wires of any section.
The main disadvantage is the cost of the required equipment to perform high-quality connections.
Welding technology
Welding of copper wires in the junction box consists in creating an electric arc, with the help of which the ends of the wires are melted and a strong connection is created.
The wire connection technology is as follows:
- First of all, it is necessary to prepare the wires for connection. To do this, we clean the cores from insulation by 60-70 mm in order to exclude its melting during the welding process.
- Next, you need to connect the wires by twisting. The type of twist does not matter, since close contact is formed by welding.
- The twist should have a length of 50 mm. The fluffy part of the conductors is carefully bitten off with nippers.
- At a distance of 25-30 mm from the end of the joint, we clamp the cores with a clamping device, which is the negative contact of the cable from the welding machine. It is for this device that the connected wires are held.
- With his free hand, the holder with the electrode is brought to the junction.
- A short touch of the end of a special electrode to the end of the twist ignites an electric arc. Depending on the cross-section of the wires and the current strength, the arc holding time (1-2 seconds) is selected.
- After connecting the wires, which is determined by the molten ball that has arisen at the end of the twist, we take the electrode to the side, thereby interrupting the electric arc.
- Allow the compound to cool.
- Next, the welded wires are insulated with a heat shrink tube and placed in a junction box.
Electrodes for welding copper wires
For welding wires in the junction box, special graphite or carbon electrodes with copper plating are required. Such electrodes have a melting point several times higher than the melting of copper. They are easy to cut, which makes the rods convenient for working lengths.
When using a home-made apparatus for welding wires in a junction box, it is better to use carbon electrodes having a higher temperature of the electric arc than graphite. This property allows welding at minimum currents.
Graphite electrodes are widely used in welding with an inverter, since such a device has an adjustment of the current strength. Inverter welding turns out to be of higher quality. In the absence of factory rods, rods from batteries or brushes from an electric motor can be used.
Devices for welding wires
The following types of welding are used for electrical work at industrial enterprises: spot, arc, plasma, ultrasonic, and also sometimes welding of wires in a junction box by a semiautomatic device. In domestic conditions, welding of spot or arc type is most often used. At home, to ensure the welding process, various transformers, inverters, as well as special devices for welding wires in the junction box are used.
Welding transformers
In order for the twisting of the ends of the twisting to occur qualitatively, the welding apparatus must produce the necessary current strength. The welding machine transformer provides an adjustable current strength of up to 400 A, while welding is carried out by special carbon electrodes coated with copper.
The use of a welding transformer is most justified in switchboards with a large number of connections, since the transfer of a heavy transformer is not required.
To create a connection, you must turn on the transformer in the network, connect the negative contact to the clamp, and the positive contact to the electrode holder. Set the desired amperage on the device, depending on the cross-section of the wires.
Inverter welding
To increase the mobility of welding, it is convenient to use an inverter apparatus with a minimum weight. Often, such devices are equipped with special belts that allow you to hang the device on your shoulder and make the connection of wires even at heights.
Welding the wires in the junction box with an inverter can be carried out with alternating or direct current with a small voltage of 12-36 volts. Current control is present in almost all inverter devices.
The inverter welding process is similar to working with a transformer. The positive contact connects to the electrode holder, and the negative connects to the clamp. Welding with an inverter is much more convenient and efficient, since there is no unit noise, and there is no blinking electricity in the room due to the small power consumption of the device.
Currently, manufacturers offer special welding machines for electricians. Such devices have a welding current adjustment range of 30-120 A, as well as a power of 1-1.5 kW. But unlike standard inverters, its mass and dimensions are significantly less. Small-sized devices are also equipped with a special holder of carbon electrodes and a clamp with a wide platform.
Self-made welding machine
Usually at home it is easiest to make a unit for welding wires in a transformer type junction box. For these purposes, you may need the following materials:
- a transformer with a power of at least 600 W, which has a voltage on the secondary winding of about 30 V;
- Crocodile clamps are needed to fix the electrode;
- aluminum connecting cables;
- to change the voltage you need a regulator;
- screwdrivers, pliers for connecting operations.
The process of self-assembly of the welding device is best done by people who are familiar with electrical engineering in order to correctly assemble the circuit of the device.
The main stages of manufacturing are as follows:
- First of all, you need to choose the body of the device, while it is necessary to pay attention to its weight, so that the device is easier to move in the future.
- Between the transformer and the supply wire, you must install a switch that will supply current and turn off the unit.
- Connect the power cable to the transformer.
- From the secondary winding of the transformer with a large cross-section wire, you need to connect a clamping device and an electrode holder.
Tips and tricks from experienced installers
To perform high-quality welding of wires in the junction box, it is not superfluous to heed the advice of experienced installers:
- The wires must be cleaned from insulation with special care in order to avoid damage to the core, which may later break.
- During welding, the twist must be placed in an upright position so that the metal melts evenly.
- It is imperative to use protective equipment during welding (protective mask, heat-resistant gloves, special clothing).
- For beginners, it is advisable to practice a little on separate pieces of wire in various modes of the welding process.
Remember that the connection of wires in the electrical junction box by welding guarantees the highest quality result and in future operation will not create problems with the power supply system at home. The use of a do-it-yourself apparatus will allow to achieve the strength of the connecting contact no worse than the factory models.