Power supply plays an important role in human life. It is delivered to every home or office with power cables. And then the internal wiring provides electricity to individual rooms. Cable laying and installation are carried out by different methods. Each method has specific requirements. For example, the cable installation temperature in the room should be from -20ºС to +40ºС.
Basic wire installation information
The main point in the performance of electrical work and not only is the availability of project documentation compiled by government agencies. Cable installation must be carried out in accordance with certain requirements, which depend on the place and conditions of laying.
For example, a special type of cable is used for outdoor and underground. The design engineer is responsible for designing and searching for the place of installation of electrical networks. At the same time, hemust take into account not only safe laying options, but also the personal preferences of the customer. Consider the methods of laying cables in detail.
Outdoor
Experts say that this is the cheapest and fastest way. If the wire gets damaged, then its repair does not require much effort. The cable is mounted on the walls using special brackets. This method is not very popular, so you can rarely meet it.
Concealed wire routing
Before installing the cable, it is necessary to perform wall chasing.
This process consists in making a recess in the wall, the width of which depends on the type of cord being laid. This method gives the room not only a neat appearance, but is also quite safe. It has its positive and negative sides. Benefits include:
- no wires on the walls;
- inaccessible to children and animals;
- Protect the wire from moisture and mechanical damage.
Installers note only one drawback of this method. This is a high probability to stumble upon the cable during the drilling process. To prevent this from happening, it is necessary to have a power supply project. Damage to the wire makes it difficult to repair.
Gasket in box
Installation of wires and cables in this way can be found in offices, country houses, shops and enterprises.
There are two types of boxes: withopening with a lid and sealed. To give a more pleasant appearance, corners and tees are additionally purchased. This method does not take much time and effort. The size of the box depends on the amount of wire being laid. Cables can be easily accessed and repaired if necessary.
Underground installation
Installation of a power cable in this way requires significant funds for earthworks. The cable can be laid through a special tunnel or simply buried. However, the degree of its protection depends on the power supply project.
You should also consider the operating conditions of the cable. Earthworks are carried out manually or with the help of equipment (depending on how deep the trench is needed).
Air laying
Installation of electrical cables is carried out by air from pole to pole in two ways:
- on porcelain insulators - connection from the pole to the house occurs with the help of a porcelain insulator;
- with the help of stretching - the laying and installation of the wire occurs with the help of a lanyard, cable, tie and clamps. The first device is used to attach the cable and adjust the degree of tension. Its size and thickness depend on the weight and length of the cable. To deliver it to the top of the pillar, use a belt and claws.
Pad temperature
Any cables are laid only at a positive temperature, regardless of the type of insulation and voltage. If it becomes necessary to installnegative temperature, then the soil should first be warmed up. Why do they do it?
Paper insulation is impregnated with a special oil, which loses its viscosity and lubricity under the influence of negative temperatures. If it is not warmed up, cracks may occur at the cable bends. In addition, the cable composition will not lubricate the paper, but stick together, which will lead to its rupture. In any case, negative temperatures will affect the destruction of the material, and, consequently, will lead to a decrease in electrical strength.
It is allowed to lay cables without heating in the room. Moreover, the temperature range is from minus twenty to zero degrees Celsius.
Mounting the cable sleeve
Let's consider the most popular types of these elements and their purpose.
Cable box. Designed for connecting the ends of the wire and their supply to power lines (usually overhead) and high power electrical appliances.
Cable termination. Serves for supplying cables to electrical appliances, which can be located both indoors and outdoors.
Connecting cable part. Used to fasten two cables together.
Experts recommend removing pieces of factory insulation located at the end of the cable before using the coupling. This procedure is performed in the following sequence: removal of the jute coating, paper or fiber base of the entireinsulation, as well as individual cores. Such a removal is called stepwise. The dimensions of the cutting are given in the reference literature and depend on the brand and thickness of the cores.
Before connecting paper-insulated cables, check the moisture content.
To do this, a piece of paper is cut off from the end of the insulation and lowered into a container with preheated paraffin (temperature 140-150ºС). If there is moisture on the paper insulation, a small amount of foam will appear.
Epoxy and lead types of couplings are used to connect cables with voltage up to 10 kW. The main advantage of the former is resistance to aggressive substances. Their properties are similar to stop collars. Therefore, they are also used to connect cables with paper insulation. They are made by mixing epoxy components with a special thickener. The last element is added to the epoxy mixture immediately before the coupling is made. This is necessary in order for the curing process to go faster.
When using epoxy sleeves when laying in tunnels or channels, it is necessary to provide them with reliable protection. As a rule, this is a steel pipe with a diameter of at least 150 millimeters and a length of 1250 millimeters. 2 layers of asbestos are laid on its inside. The edges of the pipe are covered with asbestos cement covers.
Lead connectors are used for cables with voltage up to 10 kW. They are used together with shells, which are lead pipes of different diameters and lengths. These figures depend on the thickness and voltage of the wire.
The ends are cleaned in the same sequence as for epoxy couplings. Next, a lead sleeve is put on, and the cores are twisted or connected by soldering. After installation is completed, the factory insulation is restored with oil-soaked paper. To restore the insulation near the location of the cores, the same cable paper is used.
Lead couplings are located only inside the building, enclosing them in special steel protective casings. In the case of underground laying, leaky casings or fiberglass pipes are used.
They will protect the coupling from mechanical damage. Another type is sling-connecting couplings. They serve to limit level differences in power cables with impregnated paper insulation.
Conclusion
In order to provide a building or structure with electricity, it is necessary to correctly lay the power cables. There are many methods for this, for example, underground and air. There are also ways to install indoors. Installation of cables takes place after the preparation of project documentation. This procedure is carried out by design engineers. The whole process is controlled by state authorities in the field of electricity supply. Various types of couplings serve as connecting elements. They can connect both cables to each other, and attach to various electrical appliances of high and low power.
So we figured outhow to install electrical cables and wires.
