Power supply plays an important role in human life. It is delivered to every home or institution 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 special requirements. For example, the temperature of cable installation in the room should be from -20º to + 40º.
Wire Installation Basics
The main point when performing electrical installation works and not only is the availability of design documentation drawn up by state institutions. The cable must be installed in accordance with certain requirements, which depend on the location and installation conditions.
For example, for outdoor and underground use a special type of cable. The design engineer is responsible for the design and search for the place of installation of electrical networks. At the same time, he must 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 find it.
Concealed wire routing
Before installing the cable, it is necessary to perform the gating of the walls.
Such a process consists in making a recess in the wall, the width of which depends on the type of cord to be laid. This method gives the room not only a neat appearance, but is also quite safe. It has its positive and negative sides. The benefits include:
- lack of wires on the walls;
- inaccessibility to children and animals;
- protection of a wire against moisture and mechanical damages.
Installers note only one drawback of this method. It is very likely to stumble on a cable while drilling. To prevent this from happening, you must have a power supply project. Damage to the wire makes it difficult to repair.
Box gasket
Installation of wires and cables in this way can be found in office premises, country houses, shops and enterprises.
There are two types of boxes: with an opening lid and sealed. To give a more pleasant appearance, additionally get corners and tees. This method does not take much time and effort. The size of the box depends on the amount of wire being laid. If necessary, you can easily get to the cables and carry out repairs.
Underground laying
Installing a power cable in this way requires significant funds for earthworks. The cable can be laid through a special tunnel or just dug. Moreover, the degree of protection depends on the project for electricity supply.
Also note the operating conditions of the cable. Earthwork is carried out manually or using equipment (depending on what depth of the trench is needed).
Air laying
Installation of electric cables is carried out by air from pillar to pillar in two ways:
- on porcelain insulators - joining from a pillar to a house occurs using a porcelain insulator;
- using stretching - laying and installation of wires occurs with the help of a lanyard, cable, coupler and clamps. The first device serves 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.
Gasket temperature
Any cables are laid only at a positive temperature, regardless of the type of insulation and voltage. If there is a need for installation at a negative temperature, then the soil should first be heated. Why are they doing this?
Paper insulation is impregnated with special oil, which under the influence of negative temperatures loses its viscosity and lubricity. If it is not warmed up, cracks can occur at the points of cable bending. In addition, the cable composition will not grease the paper, but stick together, which will cause it to break. 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 indoors. Moreover, the temperature range is in the range from minus twenty to zero degrees Celsius.
Cable gland mounting
Consider the most popular types of these elements and their purpose.
Cable box. Designed to connect the ends of the wire and their supply to power lines (usually air) and to high-power electrical appliances.
Cable termination. Serves for the supply of cables to electrical appliances, which can be located both indoors and outside.
Connection cable piece. Used to fasten two cables together.
Experts recommend removing pieces of factory insulation located at the end of the cable before using the sleeve. This procedure is performed in the following order: removal of the jute coating, paper or fiber base of all insulation, as well as individual cores. This removal is called stepwise. Cutting sizes 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, cut a piece of paper from the end of the insulation and lower it into a container with preheated paraffin (temperature 140-150º). If moisture is present on the paper insulation, a small amount of foam will appear.
To connect cables with voltages up to 10 kW, epoxy and lead types of couplings are used. The main advantage of the former is resistance to aggressive substances. Their properties are similar to stop couplings. Therefore, they are still 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 manufacture of the coupling. This is necessary so that the hardening process is faster.
When using epoxy couplings 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 closed with asbestos cement caps.
Lead couplings 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 indicators depend on the thickness and voltage of the wire.
Stripping ends in the same sequence as for epoxy couplings. Next, a lead-in sleeve is put on, and the cores are twisted or soldered. After installation is complete, the factory insulation is restored using oil-soaked paper. To restore insulation near the location of the cores, all the same cable paper is used.
Lead couplings are located only inside the building, enclosing them in special steel protective covers. In the case of underground installation, leaking casings or fiberglass pipes are used.
They will protect the coupling from mechanical damage. Another type - slings and couplings. They serve to limit the level differences of power cables having 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 indoor installation methods. Installation of cables occurs after the preparation of design documentation. Design engineers are involved in this procedure. The whole process is controlled by government authorities in the field of electricity. As the connecting elements are various types of couplings. They can connect both cables to each other, and attach to various electrical appliances of large and low power.
So, we found out how the installation of electric cables and wires is made.