The construction of various facilities requires the implementation of numerous power and low-current cable lines. To ensure their reliable operation, cables are laid in pipes.
Why are cables laid in pipes?
Laying the cable in pipes must be technically and economically justified. The popularity of such a gasket at various facilities is determined by a number of advantages, the main of which are considered to be:
- ease of installation, operation, and replacement of cable lines, provided that they are properly organized and comply with loading standards;
- a significant increase in the level of protection of cables and wires from external mechanical influences of various kinds;
- metal pipe is an electromagnetic shield;
- Increasing the service life of cables due to the absence of exposure to sunlight and precipitation;
- Significant reduction in the risk of fire during cable installation in pipes.
Vidi pipes for electrical wiring:
Steel – perfectly fulfill the protective function. To increase the service life of such a cable channel, the pipe is painted with moisture-resistant paint on the inside and outside. Laying cables in steel pipes allows not only to reliably protect the conductor from mechanical impact, but also to completely eliminate the electromagnetic effect emitted by a live cable.
Stainless ones are expensive, but they are more resistant to negative influences. It is successfully used to organize cable laying.
Polyethylene conduits are ideal for organizing underground electrification of buildings. Pipes made of low-pressure polyethylene allow you to save significant money when carrying out large volumes of work. In the HDPE pipe, the cable is reliably protected from the negative effects of aggressive environments, and can be used both in the intra-house wiring and to connect the building to the power line.
Polypropylene – this material is characterized by plasticity and heat resistance. Such pipes are easy to shape.
Asbestos-cement pipes are used very rarely, due to the significant weight and harmful substances contained in these pipes. This material is considered to be relatively outdated: in the Soviet and early post-Soviet years, asbestos-cement pipes were laid in trenches and then wires were laid along them. It was convenient because of their relative cheapness, the ability to use large-diameter pipes that could fit even a person, and good insulating properties At the same time, the installation of such products is difficult due to the huge weight of asbestos cement, but it does not provide the required structural strength.
PVC is a modern, inexpensive material used to manufacture corrugated pipes to protect electrical wiring from damage and high humidity. It is ideal for open wiring in non-residential premises. The use of plastic corrugated pipe can significantly reduce the cost of laying protected electrical wiring. PVC pipes can be produced in corrugated, double-walled, or a combination of the two. Among them, there are also reinforced and unreinforced models that differ only in strength, as an indicator of the permissible load on the body. This strength is achieved by incorporating steel wire into the thickness of the polymer material during its manufacture.
Features of cable installation in pipes
The cable is laid in the pipe by pulling. To accomplish it, they use:
- a bail wire or thread inserted into the tube at the factory;
- homemade pulling from a piece of rigid cable up to 10 meters long;
- a device for preparing channels based on rigid plastic wire (length from 30 to 150 m depending on the diameter).
Recently, the technology of pneumatic laying has gained some popularity in communication networks, according to which the cable is blown into a tube up to 1.5 km long with a stream of dried air. In this case, the tube has smooth inner walls with a low coefficient of friction.
When working in the traditional way, the cable to be laid or a group of them is fixed by the end of the pulling element and pulled smoothly without jerking from one pulling box/well to another.
When cornering the track, a loop hood is used or a chute is installed to help control the minimum bending radius.
The end of the pipes must be free of burrs and sharp edges. If there is a risk of damage to the cable sheath during pulling, a protective sleeve is placed on the end of the pipe.
The laying technology is identical for all types of pipes.
Laying cables in corrugated pipes
Corrugation of the pipe’s outer surface is used to increase its flexibility. Additionally, corrugation increases the pipe’s resistance to crushing forces.
The plastic corrugated pipe of the inner gasket is made of fireproof polymer.
Laying the cable in a metal corrugated pipe, provided that it is properly grounded, additionally protects against electric shock.
Laying the cable in a metal corrugated pipe is mandatory inside wooden structures because it significantly increases the fire safety of electrical wiring.
Laying the cable in the cable duct
Cable sewerage is one of the types of pipe wiring and is carried out on the basis of pipes laid in the ground outside the property. When laying the cable in a trench and pipe, it is allowed to use such types of tubular products as:
- plastic (polypropylene, PVC and high and low pressure polyethylene)
- metal (steel and cast iron);
- asbestos-cement and concrete (the latter in the form of blocks);
- ceramic (practically not found in practice).
Due to the additional protection of the earth layer, the cable sewer provides the highest level of operational reliability.
Application of couplings for pipe connections
Pipe couplings most often look like a small cylinder in which the ends of the pipes to be connected are fixed in a certain way. The installation method depends on the specifics of the fitting. The couplings can be used both for simple connection of two pipeline segments and as an adapter. With the help of special types of these fittings, it is possible to connect the components of the line made of different materials or different diameters. If the instructions are followed during installation, the couplings can ensure high reliability of the pipeline joints.
The couplings have the following advantages:
- low price;
- relatively quick and easy installation in most cases;
- durability;
- reliability;
- availability and a wide range of products;
- Possibility of quick disassembly of the structure (subject to threaded connection).
Types of couplings:
- metal-polymer;
- polypropylene;
- polyethylene;
- plastic;
- cast iron, copper;
- steel.
