How to lay a cable underground - practical advice. Requirements for laying electrical cables Here are some factors that determine the choice of connector

When organizing indoor wiring, many do not think about choosing a wire and often use the first option that comes across. When laying on the street, this approach is unacceptable, because there are a number of negative factors - temperature fluctuations, the influence of UV rays, high humidity, the risk of mechanical stress, and others. That is why it is important to know which wire to use for outdoor wiring, and what to consider when laying it.

Design and marking features

In order not to make a mistake with the choice, it is important to understand the intricacies of marking and deciphering each letter in the product name. All cables are conditionally divided into two categories - single-core and multi-core.

The core itself can be solid or formed from many wires of small cross section. In the second case, the wire acquires additional softness, bends better and practically does not break in the event of a kink.

In the manufacture of cores, as a rule, two types of metal are used - aluminum and copper. The exception is special products where the use of alloys is allowed. By the way, the SIP street wiring cable has aluminum-steel cores.

For laying at home, wires with copper conductors having best performance and designed for high currents. Aluminum strands were previously used because of their cheapness and greater availability, but are now being phased out due to poor corrosion resistance and brittleness.

In the manufacture of insulation for wires can be used:

• Rubber.
• PVC material.
• Polyethylene.
• Lead and other materials.

Wire marking

If the core material is aluminum, the wire is marked with the letter A. Copper is the default core material and, therefore, is not reflected in the marking.

By purpose, the wires are marked as follows: W - installation, K - control, M - mounting and others.

Insulation (material):

• P - polyethylene.
• N - non-flammable rubber.
• B - PVC.
• K - capron.
• PS - self-extinguishing polyethylene.
• C - lead.
• Pv - vulcanizing polyethylene and others.

Cable protection level:

• B - with an armored shell.
• G - without armor (flexible).
• A - asphalted and so on.

In addition to letter designation there is also a digital marking. In it, the first character reflects the number of cores, the second - the section, and the third - the class of rated voltage. If there is no first digit, the cable has one core.

Which wire to use for outdoor wiring: the best options

We smoothly approached the main question, which wire to use for outdoor wiring, in order to be sure of its reliability and ability to withstand negative environmental impacts. The main requirements for such products are resistance to burning, strength and non-hygroscopicity.

The most popular types include:

Able to conduct voltage up to 1000 V. Structurally, the product is a group of wires with individual insulation and aluminum conductors. Such products have their own subspecies (SIP -1, 2, 3, and so on) and are produced in many countries around the world. The main feature is the black insulation of the wires. The use of such a cable guarantees greater reliability in aerial laying and reduces installation costs. An additional advantage is its compactness, which makes it possible to use the cable even in conditions of limited space.

AVBbShv - a product based on a group of wires with aluminum cores, combined under one armored sheath. One of the types of cable is VBBSHV - a variant with copper wires. Feature - the possibility of laying in the ground without the use of additional protection and resistance to mechanical stress. Main characteristics:

• The presence of a steel tape in the shell.
• The insulation of the wires is made in different colors for the convenience of dialing and connection.
• The outer shell is made in black.
• Resistant to moisture and temperature extremes.
• Resource - 30 years.

Due to the presence of armor, cable products of this type are characterized by increased rigidity, which creates additional problems during the laying process.

NYY is a cable characterized by versatility and reliability in operation. May have copper or aluminum conductors. This product is increasingly used for external wiring in the ground or in the air, as well as for connecting electrical receivers indoors. Main characteristics:

• Resistant to water and fire.
• Compliance with international standards.
• The presence of multi-colored wire insulation.
• Convenience of organizing wiring on the street.
• Black outer shell of their PVC plastic.
• Resistance to temperature changes.
• Resource - 30 years.

Such a cable is produced in many factories, due to its versatility and reliability. The main competitor of the product is the VBbShv cable, which was mentioned above.

Which are actively used in production and when creating wiring on the street. Its peculiarity lies in its versatility and the possibility of operation in various conditions. Characteristics:

• Compliance with the standards of the association of electrical engineers of Germany.
• Heat resistance and ability to work in a wide temperature range.
• Non-hygroscopicity and strength, which allows laying the product in concrete or in a layer of plaster.
• Section is round, color - gray.
• Fire resistance.

When laying wiring outdoors using NYM, protection from sunlight is recommended. Such cable products are produced at many factories located in Europe and Russia. Some manufacturers make cables according to individual specifications, but such products have a lower price and, accordingly, worse quality. The use of such cables for organizing external wiring is not recommended.

Alternative Solutions

In addition to those discussed above, it is worth highlighting a number of other brands of cables used in the organization of street wiring:

• with PVC sheath and marked wires. The number of veins is from two to five.
• . Features a flat shape and double insulation, allowing the wire to be used outdoors .
• PV, APV, PV1 and other wires are suitable for laying external wiring, but only if they are in pipes. The main disadvantage is the presence of single insulation, which makes them unprotected to mechanical stress.
• VBbvng is a product characterized by fire resistance and flexibility. The number of veins is from one to six. Most often used to connect portable devices.

After the tragedy that occurred in New York in 2000 at the Bell Telecom building, cable manufacturers changed safety standards. The reason is the release of toxic gases by the braided wires during combustion, due to which she died most of of people. In addition, toxic gases adversely affect complex electronics. That's why on present stage manufacturers focus on the manufacture of non-flammable wires, characterized by a low level of gas and smoke emission.

Rules for installing wiring on the street

When choosing wires for outdoor wiring it is important to take into account the features of its gasket. There are a number of rules regarding protection and distance from residential buildings. So, the distance from the cable to the porch should be at least 250 cm, and to the balcony or window - 100 and 50 cm, respectively. If the wiring is vertical, the distance from the ground should be 275 cm, to the balcony or window opening - 100 and 75 cm, respectively.

If the wire is laid along the wall, it is worth observing a number of rules:

• In the case of using individual wires, the use of plastic or metal pipes is mandatory.
• The wires must be connected using terminal blocks (twisting is prohibited).
• When hanging a cable between buildings, it is mandatory to use a cable and a corrugated sleeve.
• Connection of wires should be made only in sealed junction boxes.
• Installation of wiring on the roof is prohibited.

In the process of laying wires on the street, it is worth considering a number of important nuances. So, the network of a private house can be connected to a power source of 3 or single-phase voltage (380 or 220 Volts, respectively). If the wiring is done by air, it is recommended to use the SIP-4 wire.

Armored wires of the VBShv or AVBShv brands are more suitable for underground installation. The peculiarity of such products is resistance to water and mechanical damage. For outdoor wiring, as a rule, wires with a larger aluminum core are used, which reduces installation costs.

Another factor to be considered is the laying method. Most popular options:

• Air. This option is suitable for cases where the cable has a length of 3 meters. The advantages of the method are high installation speed and ease of maintenance. On the other hand, aesthetics suffer and the resource of the product is reduced. In the process of such laying, a steel cable is used, to which the cable itself is attached with the help of ties.
• Underground. This method is used in most cases when it is required to lay a long cable. Installation is carried out in several stages - choosing the type of cable, marking the place and laying. The depth of the trench is about 70 cm. From the bottom there should be a “cushion” of sand about 8-10 centimeters thick. The cable must be laid without tension, after which it is covered with sand, soil and finally rammed.

An example of laying a cable in a trench is shown in this video:

Results

When choosing a wire for outdoor installation, it is worth considering many factors, as well as thinking over the laying method in advance. Remember that your peace of mind, safety, and sometimes life depend on the correct choice of cable and compliance with the rules of the PUE during the laying process.

First, let's deal with the general rules for laying electrical wiring. Electrical wires and cables must be laid strictly vertically or strictly horizontally with rotation angles of 90 degrees. The diagram below clearly shows the wiring diagram with all the recommended indents, as well as the recommended installation height of switches and sockets:

It should be noted right away that wiring can be done in two ways: open or hidden:

Open wiring is the simplest and most inexpensive solution, as well as one of the advantages of this type electrical wiring, in addition to the simplicity and cheapness of installation, is the convenience of its repair, but the main disadvantage of such a gasket is a violation appearance room interior. Typically, such wiring is carried out in one of three ways: in a box (cable channel), on brackets, corrugation (or metal hose), or in PVC pipes.

Examples of open wiring in the box and on the brackets:

Wiring in a box

Bracket wiring

Gasket in box Gasket on brackets in corrugation

Installation of hidden electrical wiring is a more time-consuming process in which electrical wiring is hidden under wall cladding or placed in strobes:

First step

Second phase

Third stage

The main advantage of this method of laying electrical wiring is the preservation of the appearance of the interior, and in addition, good protection of electrical wiring from mechanical damage is provided (although of course it is still possible to drill it or pierce it with a nail while hanging a picture). The disadvantages are the complexity of installation and the complexity of repairing such wiring, in addition, this method of laying, as a rule, is more expensive.

Sockets, switches, junction boxes and switchboards also have 2 types of execution: for open and for indoor (concealed) installation:

1. Installation of open wiring

STEP 1 (general) Drawing up the wiring diagram

This stage is common when laying both hidden and open wiring.

We determine the installation locations for sockets, switches, lamps and an electrical panel (if needed). For example, let's make the following diagram installation of electrical wiring in one of the rooms (for clarity, all our electrical wiring will be located on one wall):

Ready! We determined where we want to install sockets, a switch, where the lamp will be located, and also where we will install the electrical panel and made a wiring diagram. Now you can proceed directly to its installation.

STAGE 2 (Open wiring installation) Electrical installation

To begin with, we will stipulate that the most common ways of laying open wiring are laying in a box and laying on brackets, so we will consider them:

Installation video:

installation of open wiring step - 2

STAGE 3 (Installation of open wiring) Installation of boxes (cable channels), cable laying.

Now that everything is in place, we can proceed with the installation of the box (cable channel) along the planned lines for laying electrical wiring.

A cable channel is a plastic box in which electrical wiring is laid. It consists of a base and a cover:

Boxes come in a variety of sizes and colors, and typically have a standard length of 2 meters. For installation, the boxes are cut into sections of the required length (usually the box is cut with a hacksaw), for example, as can be seen from our installation diagram below, we need to cut the box into the following sections:

Segments 2 meters long - 2 pcs

Segments 1.5 meters long - 3 pcs

Segments 0.5 meters long - 2 pcs

Segments 0.3 meters long - 1 pc.

Segments 0.2 meters long - 1 pc

In total, the total length of the box we need is 10 meters (that is, you can buy 5 strips of the box, 2 meters each).

After the boxes are cut, you can proceed with their installation, they are mounted very simply: you need to open the lid of the box and screw the base of the box to the wall with self-tapping screws (in case the wall is made of wood or drywall) or on plastic dowel-nails (in case the wall is brick , concrete, etc.). After the box is attached to the wall, a cable is laid in it and the box is closed with a lid. The angles of rotation of the box can be closed with special plastic corners, you can also make angles with trimming the box at 45 o:

Video of the installation of the box (the video is not the best, but nothing better could be found on the Internet, maybe in the future we will shoot our own video on this topic, but for now we have to use what we have):

installation of open wiring step - 3

If you decide to install the wiring on brackets, then instead of installing the box, after installing sockets, switches and everything else, a cable is immediately laid, which is attached to the wall with brackets. Staples (clips) for fastening cables are plastic in different sizes, designed for certain types and sizes of cables:

Also brackets can be universal:

IMPORTANT! When laying the wiring on the brackets, remember that in this way it is forbidden to fasten ordinary cables to combustible bases (for example, to a wooden wall), for this you must use special cables that do not support combustion (do not spread combustion).

STEP 4 (Fixed wiring) Assembling the circuit.

Now that everything is mounted and the cabling is done along the walls, you can start connecting sockets, switches, lamps and assembling by connecting wires in junction boxes.

1. Installation of hidden electrical wiring

STEP 1 Drawing up the wiring diagram

This stage is common when installing both hidden and open wiring and has already been described above.

STAGE 2 (Installation concealed wiring) Drilling holes in the wall

If you are installing hidden electrical wiring, then after drawing up the installation diagram (STAGE 1), you need to start drilling holes in the wall with a diameter of 72mm (standard diameter for socket boxes) in places where switches, sockets and junction boxes will be installed. Drilling holes is usually performed with a puncher (or drill) with a special crown for concrete:

STAGE 3 (Installation of flush wiring) Wall chasing

After the holes are ready, we ditch the wall along the planned lines for laying electrical wiring. According to the technology, this is done as follows: First, 2 parallel cuts are made in the concrete wall with a special wall chaser, after which the concrete between these cuts is knocked out with a perforator:

However, there are other ways to make a strobe, instead of a strobe cutter, you can use an angular grinder(grinder), or you can even do drilling strobes (but this method is only suitable if you need to lay a maximum of a couple of meters of cable, because the method is too laborious.):

Video of the execution of the strobe:

STAGE 4 (Flush-wiring installation) Cabling

Now it is necessary to lay the cable in the prepared strobes so that the cable does not fall out of the strobe during the laying process, it must be fixed there, this can be done either by grabbing the cable with gypsum plaster, because. it quickly hardens, either with a special bracket:

Video of laying the cable in the strobe:

STEP 5 (Flush-wiring installation) Installation of back boxes

It's time to fix the mounting boxes in the holes drilled during the second stage (the boxes in which our switches and sockets will be installed in the future). It is better to fix mounting boxes on gypsum plaster (Tip: gypsum dries very quickly, so it is better to breed in small portions, because there is a risk that while you are mounting one socket all your remaining mortar will turn into stone).

In order to fix mounting box(socket box) you need:

• Clean our hole from dust and concrete fragments, after which we wet the surface of the hole.
• Put plaster in the hole, with the expectation that after installing the socket box in the hole, there would be no places left unfilled with plaster along the edges, but without fanaticism.
• We insert the socket box into the hole, having previously broken out the hatch for the cable insertion from above, this hatch should be opposite the shtraba.
• We press the box until it is flush with the wall.
• After the solution has dried, remove excess plaster with a spatula.

If you did everything right, you should end up with this:

Video of installation of socket boxes:

10

Cable laying in the ground is increasingly being taken over by home craftsmen. It is now beyond the power of organizations operating electric and communication networks to maintain a planned unprofitable army of fitters, and for this reason, repairing unreliable air bushings is excessively expensive. In addition, now people are trying to build not near the road with poles along it, in order to be closer to nature. Under such conditions, the device of air entry into the building is often technically impossible. However, laying a cable in the ground is much more expensive than an air device, but at the same time it is doable with your own hands. Therefore, private homeowners spare no effort and time to ensure a reliable power supply. This article is intended to explain how to properly lay a cable in the ground.

Gordian knot

pad power cable must be carried out in compliance with applicable requirements and standards, regardless of who conducts it. The rules for the construction of electrical networks and their safe operation are regulated by a variety of regulatory documents from valid laws to codes of practice (SP) for the production of specific types of work and job descriptions employees. Between them - intersectoral, sectoral, departmental and production rules in the form of by-laws. These are not the fruits of bureaucratic rule-making. After all, as they say, it's a no brainer that the power supply of a residential building, a hospital, a metalworking shop, a train, and a ship cannot be organized uniformly. IN this case from vaults at the top of the hierarchy, i.e. having the force of law, we will need the Rules for the Installation of Electrical Installations of Consumers (PUE), with a continuous eye on the Safety Rules for the Operation of Electrical Installations by Consumers (PTB).

"Holy Trinity": PTB, PUE, PTE(Rules for the technical operation of consumer electrical installations) and their "colleagues" for electrical workers, who make up the "ruling elite" are written, like army regulations, with human lives and huge material losses. Due to the great breadth of coverage of topics, it is far from always possible to find a direct answer to a question like: “Which and how to bring the cable to this particular house, if such a tree sticks out in front of it?” Sometimes a specialist with a higher electrical engineering education, about 40 years of experience and, in addition, a 6th working category cableman has to rack his brains - how can everything be done so that it works safely, reliably, and the owner's wallet is not turned inside out. This is the essence of electrical standards, as the essence of charters is to achieve victory at the cost of the least losses.

For example, Ch. 1 and 2 of the EMP of the 6th edition (the 7th is not yet fully completed). But it is useless to look for a brand of cable for a specific job in the PUE: all that can be extracted is that the cable must be operated in accordance with the manufacturer's specifications, specifications for this type of product and be reliably protected from external influences. There is also a recommendation in paragraph 2.3.37 to use predominantly armored cables, but they are expensive and far from equivalent in quality. And at the same time, GOST 15845-80 "Cable products" (terms and definitions) reads (verbatim):

“CABLE PRODUCT - an electrical product designed to transmit electrical energy, electrical information signals through it or used to manufacture windings of electrical devices, characterized by flexibility.

ELECTRIC CABLE (Cable) - a cable product containing one or more insulated cores (conductors) enclosed in a metal or non-metallic sheath, over which, depending on the laying and operation conditions, there may be an appropriate protective cover, which may include armor, and suitable, in particular for laying in the ground and under water.

ELECTRIC WIRE (Wire) - a cable product containing one or more twisted wires or one or more insulated cores, on top of which, depending on the laying and operation conditions, there may be a light non-metallic sheath, winding and (or) braid of fibrous materials or wire, and not intended, as a rule, for laying in the ground.

"In particular" and "as a rule" in the document of the force of law is a subject of special discussion; one can only notice that the Russian Federation is far from being in the forefront of the leading world powers. GOST 571.15-97 is formulated somewhat differently, but it does not solve the problem of where and how to lay which cable, and an error due to “in particular” and “as a rule” can cost lives. Perhaps a random passerby who fell under step voltage. Answer then all the same to the owners, because. now the wiring from the pole or TP (see below) to the house is their property. The principle of responsibility "to the house" quietly died along with the USSR.

One of the author's acquaintances said during it: “If I had not always known exactly when it was impossible to violate the charter, when it was possible, and when it was necessary, I would have retired as a colonel. If I had always done everything according to the charter, I would have been dismissed by the major. And so - a lieutenant general, and still serving!

In this publication, we do not intend to promote anyone to the generals, or even to the sergeants. We will tell unprepared readers how to properly lay the cable in the trench so that the supervisory authority accepts the work, gives the go-ahead for operation, and then there have been no problems with cable entry for at least 40 years. Not in the form of a tedious enumeration of PUE points that the inspector of the RES (electricity grid area) knows better than you anyway, but what and how to do so that the same inspector nods his head approvingly and signs the commissioning certificate.

Procedure

Homeowners may need to lay an electrical cable in the ground not only for the power input equipment, but also for its distribution around the site in order to provide electricity to the following secondary consumers, in descending order of priority:

• Supplying electricity to a water supply pump and other vital devices and assemblies.
• Power supply for utility rooms.
• Security alarm and outdoor lighting connections.
• Garden lighting, gazebos and other places of recreation.
• Power supply of the pump and illumination of the fountain, pond and other decorative objects.
• Power supply of other secondary consumers.

Regardless of the nature of the consumer, the requirements for the supply of a power cable to it are unchanged, because. the danger of electric shock, the responsibility for its consequences and the cost of electricity are the same. In essence, only the connection scheme to the power supply changes, see below, as well as about the nuances of the smaller “master” wiring around the site. The laying of an electric cable in the ground is carried out in the following order:

1. The material of the current-carrying conductors of the cable is selected;
2. According to the consumption rate, the maximum current consumed and the connection scheme, the cross section of the current-carrying conductors and their number are calculated;
3. According to local conditions, the type of cable is selected and its footage is calculated;
4. The presence of third-party underground utilities and obstacles on the way of the proposed cable route is determined, and ways of crossing / bypassing them are also determined;
5. Sketches are being drawn up cable route, input to the building (output from it for wiring along the site) and connection of secondary consumers for the precinct network;
6. According to paragraphs. 1-5, a work production plan (PPR) is drawn up and approved by the local supervisory authority (RES, department of the municipality);
7. Digging/digging a trench/trenches for cable/cables;
8. The inspector of the supervisory authority is called to accept the trench. These shortcomings are corrected, a second call for acceptance is made, etc. until the trench is accepted;
9. On its acceptance, cable laying work is carried out, possibly with supervision, see below;
10. By laying the cable, it is made electrical measurements by a specialist of the supervisory authority (their payment is usually included in the cost of acceptance);
11. In the case of a favorable result according to clause 10, the cable is connected to the input-distribution device (ASU) or input shield (VSC) at home. Secondary consumers are also connected to the network at the site. It is permissible to carry out work according to clause 11 independently;
12. Representatives of the power supply organization are called to connect the cable to the local overhead line, transformer substation (TS), and other power supply source. If the house is powered by a transformer substation, then the input to it and the connection of the cable is carried out only by employees of the power supply organization. In this case, the plan-scheme in the PPR (see below) should indicate where you need to lead the trench yourself;
13. Upon connection to the power supply source, a representative of the supervisory authority is called to perform a trial inclusion and take primary readings of the electricity meter;
14. According to the favorable result of clause 13, an act of acceptance and commissioning of the cable line (network on the site) is drawn up and signed by the inspector of the supervisory authority.

Note: if the house is connected from an air power feeder, “from a pole”, then paragraphs. 12 and 13 can be combined and produced by an employee of an energy supply organization with a working qualification, endowed with acc. authority from the supervisory authority.

Cable for laying in the ground

Cu or Al?

That is, should the cable be taken with copper or aluminum conductors? It would seem, what kind of question? Any household electrician knows that aluminum is bad, and copper is good. Actually bad - aluminum mixed with copper, because. a contact potential difference arises on the twists, which is why they heat up. And as for hidden wiring (cable in the ground - its kind), then PUE requirements in this case are quite definite, paragraph 2.1.49:

“For stationary electrical wiring, mainly wires and cables with aluminum conductors should be used. For exceptions, see 2.1.70, 3.4.3, 3.4.12, 5.5.6, 6.5.12-6.5.14 [7th edition 6.6.15-6.6.20], 7.2.53 [7th edition] edition 7.2.51] and 7.3.93".

A cable laid underground, if its ends are equipped with lugs that ensure reliable contact with the ASU/VSH terminal blocks, is not included in the list of exceptions. Are you surprised? Take 2 wires of the same diameter, copper and aluminum, and try to bend. Which bends easier? And now bend-unbend until a break appears. Which one lasted longer? It remains to remember that the cable in the ground is subject to slow mechanical stress from ground movements. Now not surprised? PUE are written by the smartest and most experienced people. There is, however, an option when copper in the ground will be more reliable: a cable with oxygen-free copper cores. But it costs so much that laying a silver one will come out a little more expensive.

Note, from the statements of the same friend of the author:“Statutes are written by brilliant people. Just think of it - to paint our whole life in such a way that the last dolbo ... it was clear!

And another argument in favor of aluminum conductors: a cable with them for the same power is lighter and will withstand a greater slope when laying. When crossing existing communications and avoiding obstacles (see below), this circumstance can be critical.

Cross section

The calculation and selection of the cross section of current-carrying conductors and wires are discussed in Ch. 1 PUE. For the cable there is a table. 1.3.4. If we compare the results for it with those for calculating the cross section of the cores of house wiring, see for example. video below, you get a clear overstatement towards the cable. This is caused by the trace. reasons:

• Conditions for heat dissipation in the ground are worse than in the wall.
• The cable sheath is thicker, which makes the heat removal from the cores even worse.
• The cores of the cable for the whole house are also thicker, i.e. the ratio of their surface to volume is less, which further impairs heat dissipation.
• The cable in the ground is subject to mechanical loads, which are also transferred to its cores, incl.

Video: cable section selection, errors

Video: how to calculate the cable cross section

Based on this, the PUE standards for the cross section of the cable cores for the electrical input to the house are as follows: copper at least 12 square meters. mm, aluminum not less than 17 sq. mm . If the calculation for power / current gives a larger value, it should be taken. However, from practice it can be concluded that the current-carrying conductors of the cable for entry into the house must be taken with a cross section of 20 sq. mm: cables with a minimum allowable core cross section account for over 80% of ruptures due to ground movements. And along a vein of 20 squares at a current density of 5 A / sq. mm (this is normal for a private house) can be transmitted at 220 V with a power of 22 kVA, which is 2.2 times more than 10 kW, which a private household can consume, paying at the usual rate. A safety factor of 2.2 gives the service life of the entire bushing, almost equal to the service life of the cable; usually at least 40 years old. The next is also important. circumstance: "alternative" manufacturers, incl. domestic, systematically underestimate the cross section of the veins against the declared one. Therefore, a cheaper cable should be bought not on the Internet, but on the spot, and with a rod.

Note: precinct wiring from the house of the PUE of previous editions is not unambiguously standardized. In practice, it is considered as a house / apartment, setting a current consumption of 1.6-1.7 times the real and minimum allowable cross section of a 3-wire cable of 2.5 square meters. mm, subject to the mandatory presence of protective grounding and automatic protective shutdown, see below.

Which cable to take?

A wide range of cables for underground installation is commercially available. When choosing a suitable one for the cost, you need to be guided, in addition to the reputation of the manufacturer and seller (nowadays this is especially important), and the design of the cable. It should include elements, the composition and purpose, we will consider the example of well-proven samples. Simply - take cables that are structurally similar to these.

Cables AVBBSHV (cores - aluminum) and VBbshV (copper cores) for general purposes, i.e. for laying under normal conditions. Explanation of designations: A - aluminum conductors; B - PVC insulation; Bb - steel tape armor of the usual type (2 tapes with an overlap of 50%) with a bitumen pad, but without an additional plastic pad; Shv - in a PVC hose.

AVBbShv and VBbshV cables are produced with the number of cores 1, 2, 3 (for single-phase wiring with a separate grounding conductor PE), 3 + 1 (3 phases and a smaller neutral for 3-phase networks with a solidly grounded neutral), 4 and 5 -ti core for systems with isolated neutral. The cores are round or sector, solid or twisted with a cross section of 2.5-626 sq. mm (solid) and 2.5-240 sq. mm (twisted). In AVBbShv and VBbshV with current-carrying conductors up to 6 sq. mm bituminous cushion under the armor is missing.

AVBbShv and VBbshV are designed for laying in soil of normal bearing capacity (from 1.7 kg / sq. cm) and normal chemical activity, not flooded, not subsiding and not excessively heaving. Permissible general slope along the entire length of the route depends on the material and cross-section of the cores, but for powers up to 10 kVA it will fit into the norm if it does not exceed 1:15 for aluminum and 1:20 for copper on a route up to 100 m long. The operating temperature range of AVBbShv and VBbshV is from -50 to +50 degrees Celsius. They consist of (left and center in the figure):

1. Current-carrying conductors;
2. Core insulation;
3. Belt insulation made of PVC, tightening the bundle of cores;
4. Additional winding made of polyethylene terephthalate (PET) for cables with cores from 6 sq. mm;
5. Bituminous pillow;
6. Armor;
7. External insulating hose - sheath.

Cables PvBbShp and PvBbPg (on the right in the figure) are decoded as:

• PV - core insulation made of cross-linked polyethylene.
• BB - ordinary 2-band armor without a plastic pillow.
• Shp - external insulating hose made of polyethylene.
• Pg - a polyethylene hose with additional sealing with water-proof tapes (swell in the presence of literally individual water molecules).

PvBbShp and PvBbPg are designed for laying in difficult conditions: in unstable, weak, chemically active and watered soils (except for marshy and marshy soils), up to laying in water bodies with a stable hydrological regime and a stable bottom. PvBbShp and PvBbPg, like any other cables, cannot be placed in the swamp. In the swamp, in exceptional cases, it is permissible, in the light, along the flyover. PvBbShp and PvBbPg can be laid without additional protection measures in the area of ​​stray currents (see below). Permissible slope routes up to 45 degrees in a section up to 30 m and up to 30 degrees in a section up to 100 m. Permissible temperature range -50 ... +50 Celsius; allow heating up to 120 Celsius for 6 hours. Special installation conditions: strong tensile forces are not allowed, therefore, when pulling lengths over 30 m into a clean free channel, intermediate stockings must be used, see below. Pulling PvBbShp and PvBbPg into channels with operating cables is possible in agreement with the supervisory authority and organizations operating other cables, and swum into channels is unacceptable.

PvBbShp and PvBbPg are produced only for 3-phase networks with bundles of copper conductors 3 + 1, 4 and 5. The cross section of the conductors is 4-50 sq. mm solid (single-wire) and 16-240 sq. mm twisted from many wires. PvBbShp and PvBbPg consist of (on the right in the figure):

1. Current-carrying conductors;
2. Core insulation;
3. Load-bearing fiberglass core;
4. Spiral winding, tightening the bundle of cores - for cables with cores from 50 sq. mm;
5. Belt insulation, which simultaneously serves as a damper pad of armor;
6. Armor;
7. External insulating hose.

Note: lead-sheathed cables are still being produced, because their real service life exceeds 100 years and they are more reliable than plastic ones (the reliability of a lead-based coupling is not less than that of a solid shell), but they are very expensive. If you fork out for such, remember - it is necessary to lay the cable in lead strictly horizontally!

veins

Solid cable cores or twisted, it is essential for the technology of their production, but it also matters when choosing a cable. Cables with twisted cores are more reliable in mobile soils, but light, loose and less pressing on the cable - sand, loam, light sandy loam, gravelly and cartilaginous. That is why PvBbShp and PvBbPg are produced only in copper in PE: the coefficient of friction of copper on copper and polyethylene is less than that of aluminum on aluminum and PVC; As you can see, even in the PUE there are no rules without exceptions.

More about the color of the insulation lived. The PCT / GOST once again gave birth to its standardization, but these births, like the previous ones, are premature. Firstly, the colors for networks of 1-phase, 3-phase with isolated and solidly grounded neutral are not coordinated. Secondly, the market is full of foreign-made cables, the manufacturers of which have GOST as the flag of Moldova. Only the colors of the PE ground wire are exactly observed; we still have to remember about it - yellow with a longitudinal green stripe. The color of the neutral N is more or less observed - blue or blue. But at the same time, the sale is full of single-phase cable with black / brown and gray / white wires. According to him, interfacial 380 V without zero to let? In general, when joining cables, strictly observe PE and N, and tie the remaining colors, as far as possible, to the previously laid cable or the existing one.

stray currents

Electric currents circulating in the ground are one of the most serious sources of cable accidents, because. destroy its outer shell and armor. In addition, stray currents can induce a dangerous voltage on a cable disconnected from the power supply. The main sources of stray currents are rail electric transport and metallurgical production, but any electrical installation with working grounding, for example, also gives them. baking oven. The US is full of problems with stray currents from laundromats popular there. Water pipes are also a source of stray currents: flowing water is a conductor moving with the Earth's magnetic field.

The best way to protect cables from stray currents is the so-called. anode protection, but this is a very complex and expensive undertaking, incl. and current costs: aluminum protectors need to be periodically replaced with new ones to replace those corroded by electrocorrosion. Sufficiently effective protection against stray currents - cable laying in a plastic hose in an insulating channel; both should be normalized to the degree of moisture diffusion, see below.

What if you don't have armor?

An armored cable is much more expensive than an unarmored wire for the same power. At the same time, the armor protects the cable from rodents and manual digging, but it is powerless against earth-moving equipment (see below). With a lack of funds in the budget, the question is: is it possible to lay unarmored wires in the ground and, if so, which ones and how? - is quite legitimate.

It is possible, but not all and not at random; several degrees of cable protection are required. First, HDPE pipes provide fairly reliable protection against rodents and manual digging, see below. Second, the outer sheath of the wire must be able to withstand the chemical activity of the soil and also be unattractive to rodents. Thirdly, unarmored wire can be laid in the ground in your area, where no one will dig without your knowledge, and you know exactly how the wires go. Fourth - outside the site, say, from the fence to the support with the switchgear (a box, simply), the cable must be protected with a signal tape of increased width (see below) in combination with an additional protective layer; better - concrete, also see below.

It remains to figure out which wires can be laid in the ground. Since 2007, PUNP, PUGNP and rubber KG (at the top of the figure) have been banned from being used in newly built networks due to the high accident rate they create. KG electricians of the past among themselves called names the obscene name of a condom. VVG, AVVG, PVS, NYM (below in the figure) and others of a similar design (PVP, PBPP, etc.) have proven themselves well in internal wiring, but they cannot be placed in the ground: their shells are not rated for moisture diffusion. Simply - mechanically, such a wire in the ground can close.

For laying in the ground from unarmored wires, firstly, NYY-J is suitable, at the top in fig. on right. Its thick outer shell is made of dense rubber or similar plastic; it is normalized by diffusion and is unattractive to rodents, except for those who are completely mad from overcrowding of the population. NYY-J analogues are commercially available, but they must be taken from a reliable manufacturer, with a certificate of suitability and a guarantee. For wiring from the house to the site, in the presence of protective automation (see below), you can use PvPg (in the same place below); they can even supply power to the motor of a submersible pond filter. The moisture resistance of PvPg is ensured by a sealing winding under the insulation of the cores and the outer sheath, but rodents sharpen their teeth on it more readily, so it is advisable to lay PvPg into the ground in a metal hose or HDPE corrugation.

Tricky notation

You have probably already noticed the addition of -ng to PvPg in Fig. This is the first of the additional properties suffixes important for underground cable. –ng means non-combustible, combustion does not spread through it when laying alone and in bundles. Suddenly, an accident, it will be localized and the elimination of its consequences, perhaps, will do without replacing the entire line.

The second thing that is important is hf (halogen free, without halogens). This suffix is ​​often used to falsify cable products in order to increase the price. For example, there are plenty of VVG-hf on sale. But, excuse me, what kind of “halogen free” can a cable with PVC insulation have? The only thing you can expect to buy from such a seller with a 100% quality guarantee is noodles for teapots.

As for other suffixes characterizing the toxicity of the insulation, the volume of gases emitted by it in the source of ignition, filling the cavities of the bundle of cores with talc or non-combustible plastic powder (such a cable can be bent along a small radius), etc., they can be significant in internal wiring, but for a cable laid in the ground, they do not really matter.

Note: the golden rule when choosing a cable yourself - do not take cables with oil or other hydrophobic filling! They are for special applications, and then the hassle and unforeseen expenses will then be unimaginable in your area with them!

Route, entry, intersections and entries

At this stage, we will consider the layout of the route and the device for entering the building "from pole to house". The features of the distribution of the power supply network in the area were partially indicated above, and we will deal with the rest further.

track

It is highly recommended to run the power cable route in straight sections. Gut lines are an electrician's nightmare: they are highly accident-prone, and the consequences of accidents on them are difficult to eliminate. But it is also impossible to make the corners of the route straight: the bending radius of the cable must be from 20 of its diameters, and the cable must not touch the walls of the trench, see more about this below. How the angle of the cable route is correctly performed is shown in Fig. on right; for one cable, only dimension A and the trench profile change, also see below.

Input and inputs

General schemes of cable entries into the building are given on the next page. rice. On the left - an old model with steel pipe elbows. It is still widely practiced despite serious shortcomings. The first is that stray currents are drawn to steel pipes. The second - when the building shrinks, the cable in the ground or the ground moves, the edge of the steel pipe can cut into the cable. As for the supposedly increased security of the above-ground sections of the cable, with the current power tool and the economic feasibility of stealing electricity and non-ferrous metal, it is already a fiction.

Note: in this section, another advantage of cables with aluminum conductors is manifested - stealing them is just as dangerous, but much less profitable than copper ones.

Much more reliable in modern conditions it turns out to be a pipe for laying a cable made of polyethylene low pressure(PND). The scheme of cable entry in HDPE pipes is given in fig. in the center. Advantages of HDPE pipes for cable laying over other scales:

• HDPE is unattractive to rodents: it is too viscous and slippery for the point of teeth.
• HDPE, provided that the pipe joints are sealed with silicone, insulates the cable from groundwater and stray currents.
• HDPE pipes for cable laying are produced incl. with "rods" embedded in them - broaches made of steel wire.
• The cable goes into the HDPE pipe much easier and the probability of damage when pulled into the channel is much lower.
• Due to their lightness and flexibility, a cable channel made of HDPE pipes can be assembled in the light (on the ground above), and then simply put together in a trench.
• The overall strength and elasticity of HDPE corrugated pipes are quite high, especially double-walled ones. This virtually eliminates damage to the cable in the ground with a hand tool and significantly reduces the likelihood of it being torn by earthmoving equipment.

Note: HDPE pipes for cable ducts must be taken with a clearance diameter of at least 20 mm larger outside diameter cable. Bending radius of cable channels - from 20 diameters of the thickest cable pulled into the channel.

On the right in fig. a diagram of cable entry into a house on a pile or column foundation is given. This design of the input of an electric cable in the country dramatically reduces the possibility of unauthorized connection from the outside in the absence of the owners.

Note: corrugated pipes of any type are often sold under common name"corrugation". In fact, a corrugated pipe for a cable is necessarily equipped with a standard broach inserted inside, and if the pipe is without a broach, then this is a corrugated sleeve.

The subject of special attention when developing a sketch of the cable route should be the design of its direct entry into the building: cable entries into houses made with violations account for most of the power supply failures. On fig. given drawings standard designs cable entries to a house with a basement and a basementless one, and in fig. on the right is shown how the external entry into the subfloor through the base in the HDPE pipe is arranged. Sealing cuffs in this case can be replaced with silicone sealant.

intersections

When developing schemes for cable crossings of existing communications and bypassing obstacles, it is necessary, firstly, to minimize their number as much as possible. Practice shows unambiguously: it is better to buy a surplus of cable in order to circle the whole “porridge” with it and at the same time straighten the route. In the future, the initial overspending is repeatedly paid off by savings on emergency recovery work. The design method "premium ahead, if only shorter" is one of the reasons for the collapse of the economy of "developed socialism". Second, you should strictly adhere to the minimum allowable distances (a value that is opposite in meaning to approach, but expressed in the same units of measurement) of the cable from crossed objects and obstacles:

• From the foundations of the house, outbuildings, columns, supports, etc. - 0.6 m, except for the entrance to the building.
• From "their", "master's" cables (wiring from the house along the site) - 0.1 m.
• From communications of third-party organizations (except for gas pipelines and heating mains), if the cable and existing communications for voltage up to 10 kV - 0.25 m, subject to mandatory agreement with the operators.
• From the underground gas pipe to the house (not the main one!) - 0.5 m.
• From the heating main - 2 m or, if there is an additional one on it. thermal insulation, which reduces the overheating of the soil directly adjacent to it to 10 degrees or less - 0.5 m.

If the cable in some section runs parallel to the pipeline, its distance from the pipe must be maintained from 0.5 m or, if the pipe is a heating main without additional insulation, at least 2 m. The cable running parallel to the pipelines must be laid away from the pipes, not below or above them.

Note: the value of 2 m is taken for a reason. This is double the width of the cable guard zone (see below). For 2 m and further with a cable, you can approach any communications up to 10 kV without agreement with their operators.

Also, no closer than 2 m, you can approach the trees with a cable, see below. Typical diagrams of cable crossing existing communications, except for the gas pipeline, are given in fig. Cable crossings of collectors should be avoided at all costs. The construction of a collector is an expensive and time-consuming business. Even if the collector is buried according to the norm, the cable above it turns out to be lying shallower than necessary for safety reasons.

Suddenly, the intersection according to the typical scheme fails, do not be wiser, this is not the case when fresh ideas can be useful. Seek advice from a specialist of the supervisory authority, without this it will not do anyway, see below. In some cases, it is possible to bring intersecting communications closer together up to 10 cm and protect the cable instead of the pipe with a sheet of flat slate, etc. non-combustible non-fusible material. But - only in agreement with the supervisory authority. That is, you go to the distribution zone or who supervises you there, show a sketch: here is the problem, what to do? They explain it to you and you do exactly as directed.

Electric cable crossing gas pipeline

A special case is the crossing of a gas pipeline by a cable. At the same time, the distance is maintained, as a rule, without problems - gas pipes are buried deep. But in the process of laying the cable, sparking and damage to the insulation of the gas pipe must be excluded. Typical scheme the intersection of the gas pipeline cable is given in fig. The load-bearing beam-log and suspensions are removed only after the trench is completely backfilled to the level of the top of the box. The box remains in the ground.

How to deal with trees

A garden, ornamental tree plantations, or a piece of forest on the property is great. But, how, if it were not all right, to pass such a grove with a cable, without approaching the trunks closer than 2 m? Dense planting - nothing but bypassing. It is impossible to get around - you will have to abandon the underground input in favor of the air one. More or less reliable "airs" are built from SIP - self-supporting insulated wire. If 1-2 trees interfere, then punctures (horizontal wells) can be made under the roots at a depth of 900 mm (T10-T15 trenches, see below). An asbestos-cement or steel pipe is laid in the puncture, protruding to the sides by at least 2 m counting from the trunk, but beyond the root system.

A puncture in the ground under the cable is made with a special pneumatic projectile for horizontal drilling - a mole. Punctures by cablemen without urgent need (for example, under the road) are avoided in every possible way, therefore specialized firms operate moles. Their work is expensive, and a puncture under a tree will cost even more, because. the probability of losing a projectile in the roots is greater. In this case, if hard work is not a pity, you can pierce the channel for the cable (more precisely, the pipe for it) manually:

• On both sides of the tree, pits are dug from 2x1 m in plan and from 1.5 m deep, oriented along the length along the route.
• The starting points of the puncture are marked by a compass or GSM indicator in direction and by a hose hydraulic level in depth.
• The puncture is made with a manual auger drill with sharply sharpened cutting edges alternately from 2 sides to the hitch.
• In the process of drilling, the horizontalness of the drill is periodically controlled.
• After the shutdown, the well is drilled again with the same drill with an elongated steel pipe rod so that the puncture channel is obtained without a ledge.

trenches

The profile of the most common trench for power cable and the scheme of laying the cable into it

The profile, dimensions and scheme of laying the cable in a trench, suitable for the entire temperate zone of the Russian Federation and therefore the most common, are shown in Fig. on right. From the bottom and sides of the trench should not protrude sharp, hard, or other objects that can damage the cable, for example. live tree roots. That is why a “bare” trench must be inspected by a representative of the supervisory authority before the start of cable laying.

The sides of the trench in dense stable soils (clay, loam, dense heavy sandy loam, podzol) can be sheer. This in many cases makes it possible to do without manual digging, see below. Backfilling the cable with sifted excavated soil instead of sand is permissible in places with a standard freezing depth of less than 600 mm on loose loose dry soils - sand, sandy loam, fine rounded gravel and cartilage. You can save a lot on sand purchases.

Pipe (preferably asbestos-cement) cable is protected under any driveways for self-propelled vehicles, even if it is a path for a scooter. Shocks and vibrations are transmitted into the ground deeply, strongly and can damage the cable. Removal of the pipe beyond the edge of the passage - from 1 m. About the signal tape and a solid protective layer will be discussed below.

It is also impossible to reduce the cable laying depth to less than 700 mm in places with non-freezing soil for safety reasons, but in certain cases (see, for example, above, crossing patterns and a puncture under a tree), it may be necessary to deepen the trench, as in regions with a standard freezing depth of over 900 mm. A diagram of a typical profile of a power cable trench with a table of dimensions and values ​​​​for calculating labor and material consumption is given in Fig.:

Along the route, a trench of one profile can pass into another; then the slope of the transition section must be maintained within the specifications for the cable used.

Note: in permafrost soils, it is generally impossible to lay cables in trenches. Only in collectors or overpass.

"Signalka"

The signal tape (see the inset at the bottom left in the figure with the "expendable" trench) has proven to be a very reliable means of protecting the cable and now it is allowed to lay power cables in trenches under the signal tape without additional protection with a hard coating. The standard width of the tape is 250 mm, but for a section of the route outside the boundaries of home ownership, it is highly desirable to take a tape of a greater width, even expand the trench to 600 mm and lay the same tape.

The fact is that the “signaling” gives a reliable signal only to the operator of the bucket excavator, on the left in Fig. If the trench across your cable is being dug by a chain trencher (trencher; simply a bar), in the center, then when the chain brings up orange pieces of tape 250 mm wide, the operator will no longer have time to stop the machine before the digger teeth crash into the cable . But in the case of a 600 mm tape, the time to pull the levers will be at least 5 s; this is enough for an attentive operator of average and below average qualification, and the mechanics will have time to respond to his actions.

The issue of a wide signal tape is all the more relevant since chain trenchers on the chassis of mini-excavators are rented with delivery to the place of work, and you can learn how to operate them in half an hour (on the right in the figure). By the way, this can also save you from manually digging under cable network on the site: a bar on the Bobcat chassis with a 13.5 kW engine with a 250 mm chain digs ordinary, not very clogged soils to a depth of 900 mm. And to enter the house with a bar, you can dig a pioneer trench, but keep in mind: only from the house to the border of the site. Otherwise, there will be a serious violation of traffic rules and land use rules if you do not have a tractor-excavator driver's license and permission from local authorities to work with special equipment outside your territory.

Note: it is convenient to use a trencher to fill up a dug trench - the working body is lifted and driven back along the cable route, turning on the augers-rakers for reverse rotation. It remains only to tamp the resulting neat bed.

Brick or concrete?

Additional protection with brick protects the cable from careless manual digging, and with reinforced concrete from mechanized digging. The teeth of the chain digger do not take concrete, and the bucket excavator, having hooked on the plate, crouches and twitches so that the completely drunk operator comes to his senses and catches himself. Technique, so to speak, gives pendel to the muddler. Reinforced concrete protection may also be cheaper than brick protection: any used slabs with a thickness of 40 mm or more that fit into a trench are suitable for it, even if up to 10% of the reinforcement is exposed at their edges.

Bricks to protect the cable are laid tightly across the trench dry. Brick for protection you need to take a solid worker (red). Silicate and facing finishing bricks in the ground quickly collapse, releasing substances that corrode the cable sheath. Additional hard cable protection is needed in the following areas:

• At the entrance to the building from the wall of the house or the edge of the blind area around it - 2 m.
• For unarmored wire under passages, despite the protective tube, with an offset equal to the extension of the ends of the pipe.
• At intersections with existing communications, if the standard cable penetration is not maintained.
• Outside the boundaries of the site - highly desirable; if an unarmored wire is laid, it is mandatory.
• On sections of the cable passing under the garden, flower bed, etc. places where earthworks are carried out regularly.

PPR

The cable laying work plan is something like a hybrid of a project with an estimate. The PPR sketch for the power cable must contain:

1. Explication of the site plan indicating the location in the light (i.e., as if visible through the ground) and the depth of the existing communications;
2. Calculation of the cross section of current-carrying cores and justification for choosing the type of cable;
3. Plan-scheme of the cable route with a section of the trench profile and a scheme for laying the cable in it. If the profile and / or laying pattern changes along the route, cuts are needed for each section;
4. Scheme of the cable channel, if it is made of solid HDPE pipes;
5. Schemes of intersections of existing communications and bypassing obstacles;
6. Scheme of cable entry into the building;
7. Connection diagram to the house ASU and protective automation (see below) - for the cable network from the house along the site;
8. Calculation of material and labor intensity of work. Their cost is not needed, that's up to you;
9. Plan-schedule of production of works by stages. Start/end dates can be specified relative, for example. “Within 24 hours of delivery by the distributor to the facility”; "Immediately upon completion of n. NN." The main thing is that all work be completed during the warm season. At an average daily temperature below +12, new cables are pulled only in exceptional cases with special permission. If you know how to draw up network schedules for the production of work, the better in every way.

The sketch of the PPR must be properly drawn up and summarized in a document to be approved. There is no single form of PPR due to the same variety of cable laying conditions, there are only recommended samples. Therefore, with a sketch of the PPR, you need to go to the local supervisory authority and find out there how they need it to be drawn up. If you have the skills of engineering graphics such as "handles-legs-cucumber", they will also tell you where to apply for the design so that it is accepted.

The best way out in this situation is to humanly agree with a supervisory specialist on a private consultation. This is not forbidden to them; to some extent it is even encouraged - technical literacy is spreading among people, and the specialist has an honest extra income and accumulates experience. Perhaps (in the outback - most likely), he will undertake to bring your PPR to mind. And he or his immediate superior will approve it. As a result, you will get an “iron” PPR without red tape and cheaper than hanging around firms.

We swarm and collect

The golden rule when laying a cable with your own hands - do not lay in pieces and do not muff! Only a cable splicer of at least 5th category can make a reliable coupling on a power cable! Also, do not try to connect the pieces at the top with terminal blocks in boxes - supervision will not accept, because. it's easier to steal electricity from such connectors.

How to dig a trench is your business, the route and profiles would be sustained. But before the start of digging, it is necessary to manually carefully hammer the pits at the intersections until the intersected communications are exposed. The gas pit below 0.5 m from the depth of the cable being laid is clogged in the presence of a representative of the gas workers. They must be notified of this in advance and, at their request, beat the entire pit under supervision.

In the case when the entry channel to the house is made of HDPE pipes, it is very often more convenient to assemble it upstairs (in the light), tighten the cable, and put everything together in a trench. In this case, the L-elbows and the horizontal corrugation are laid out on the ground separately at some intervals. The cable is pulled all the way into the outgoing elbow, leaving the “tail” for connection, then into the double-walled corrugation and the other elbow. After that, the channel is assembled and mounted in a trench.

Note: before starting work with the cable, it must be allowed to warm up / cool down to the outside temperature for at least a day. If the cable is purchased in one piece on a drum, the integrity of its sheath is checked during the purchase. To do this, press the nipple pin on the free end of the cable. Conscientious manufacturers supply cables under excess air pressure. If the shell is intact, a hiss of escaping air will be heard. PvBbShp, PvBbPg and other cables for difficult conditions on a drum not under pressure - either marriage or falsification.

How to tighten cables

For God's sake, do not watch videos on YouTube, how the cable is pulled into the channel by the cores! The probability of an accident in the coming years from this increases not at times - by orders of magnitude! The cables are tightened with a special stocking, pos. 1 and 2 in fig. An almost complete analogue of it can be quickly made with your own hands from a pair of U-shaped soft steel wires with a length of 1.5 m and a diameter of 1.5-2 mm. The eye for pulling is obtained from bends, and the tails of the wires, so that the home-made stocking does not slip when tightened and that they do not scratch the channel, are tied to the PVC cable with electrical tape.

If it is necessary to pull the cable intermediately, a detachable intermediate stocking is used, pos. 3. To it, if the cable is pulled into the channel, 2 broaches are needed: working and disconnecting (releasing), for which the fixing pin is pulled out. I mark the releasing broach with something very catchy, so as not to accidentally pull it until the end of the cable tightening.

If the channel is not assembled from pipes with standard broaches, a broach of elastic steel wire is first inserted into it. For entry into the house and wiring around the site, its diameter, as a rule, is sufficient 2-2.5 mm. The cable is pulled into channels with other cables by a fiberglass rod with a rounded end, but this is not an option for householders, especially since it is much more difficult to work with a rod.

Pulling cable into elbows already installed in the trench and done in the old fashioned way is often difficult; there are also other short but difficult places of the canals. In this case, a 2-stage vacuum broach can learn:

• A wad is made from a crumpled PE bag or a ping-pong ball and a fishing line is attached to it.
• The wad is inserted into the canal (it should not touch the walls) and sucked out with a vacuum cleaner from the other end.
• A steel broach is pulled into the channel with a fishing line.
• Pull the cable through the channel.

"Snake" in the trench

Installation of the entry into the house in the old fashioned way begins with the installation of L-elbows (drops) in the trench. Their limbs are fixed above the bottom of the trench at a level of 10-12 cm with pairs of one-and-a-half bricks, etc. Then the drops are securely attached to the wall of the house or a pole. If the entrance to the house is through the basement, the opening with the entry pipes is cemented and those are made in the installation of the cable. break until concrete mortar reaches 50% strength, approx. 3 days.

In the meantime, the bottom of the trench is covered with sand or sifted excavated soil (see above) to the level of the lower edges of the mouths of the drops and the bedding is carefully rammed. Then the cable is pulled into the drops, starting from the outgoing elbow (on the pole) and wedged at the mouths from contact with steel with detachable cuffs or pieces of dense rubber. In the latter case, the mouth is filled raw rubber or silicone sealant. Also, when pulling the cable, it is necessary to ensure that its sheath does not rub against the sharp edges of the steel. To do this, before broaching, either special trays are inserted into the mouths, or, as tightly as possible, trimmings plastic pipes, pieces of irrigation hose, etc.

Then the cable is laid in a trench, but in no case is it tight (on the left in the figure), this is unacceptable. For thermal deformations, it is necessary to give an allowance of 2-3% of the total length of the route. But it is also impossible to launch a “mad snake” with frequent bends touching the sides of the trench (in the center), this will only increase the accident rate of the site. The cable is laid in the trench, as shown on the right in the figure, with small smooth bends spaced at least 10 cm from the sides of the trench. If several cables are laid, their bends should be located in one direction with an offset by half the length of the bend.

With a channel made of HDPE pipes, there is much less hassle, regardless of whether the cable is tightened in advance in the light or when installing the channel in a trench. Here is the only “but”: the arrow of the “snake” bends must be increased by the diameter of the horizontal pipe clearance.

Fall asleep and protect

After laying the cable in the trench, it is backfilled to the level according to the profile and laying scheme. The backfill over the cable does not need to be heavily rammed; just a little "slap" is enough to be able to put solid protection- bricks or concrete. Then they put a solid protection and cover it in layers with earth to the level of the signal tape, ramming without any special precautions. After laying the tape, the trench is covered to the top in the same way. Excess land should not remain, on the contrary, a bed should form above the trench. Over time, it will settle to the ground level. A failure over the highway a year later is a sign of its accident rate and the basis for applying sanctions to the owner/operator.

From the house to the site

The ability to do-it-yourself automatic protective shutdown for cable wiring from the house around the site allows you to:

• Reduce the cross section of current-carrying conductors to the minimum allowable.
• Apply unarmoured wire.
• Reduce the volume and labor intensity of earthworks by narrowing the trenches and possibly using earthmoving equipment, see above.

All this significantly reduces the cost of external wiring of households, without reducing its safety and reliability, provided that it is divided into branches and equipped with protective automation. It is also necessary that the house is equipped with a protective earth circuit. Typical division of precinct wiring into branches:

1. Outdoor Lighting, security alarm and LSS (for example, a water supply pump - an automatic machine for 16 A;
2. Garage and outbuildings - automatic 32 A;
3. Garden lighting, pergola/lounge area, fountain, pond pumps, etc. - automatic 16 A.

In addition, a common residual current device (RCD) of reduced sensitivity must be installed on all external circuits, for a current imbalance of 100 mA, see the diagram in fig. Moreover, it is better to install not a high-speed electronic RCD, but a “stupid” slow electromechanical difavtomat. It is necessary to put the RCD on the washing machine and the bathroom more sensitively and faster, but here the matter is different.

A network of long cables has a rather high intrinsic capacitance and the electrical asymmetry of the capacitive leakage when switched on. That is, with a too fast and sensitive RCD, a situation is possible when it is simply impossible to turn on the external circuits - you clicked the automatic switch on, the RCD claps and turns off. Also, the RCD should be with built-in thermal protection to cut off the outdoor circuit, suddenly some circuit closes and gives an active leak. It is also dangerous for life, and the counter starts to wind like crazy.

What if there's an accident?

Absolutely reliable equipment does not exist, and there are no completely trouble-free cables either. On the own capacity of a disconnected cable, a significant electric charge, and hazardous voltages may be applied to the cable. Therefore, it is impossible to start emergency recovery work (AR) immediately after shutting down the emergency section. By the way, if there is an accident at the entrance to the house, then an employee of the power grid operator must turn it off at the ASP on the pole; You won't get into TP. Suddenly there is a visible power cable failure or a suspicion of it, you need to act next. way:

1. Turn off the emergency circuit breaker and hang a sign on its lever “Do not turn on! People are working!”;
2. After at least 20 minutes, check with a tester or phase indicator for the presence of voltage on the cores (checked at the outgoing end);
3. If there is no voltage, remove the disconnected cores/core from the terminal block of the machine and securely connect it to the protective grounding busbar/terminal block, or put a temporary ground terminal on the bare parts of the cores;

Replacing or laying new wiring in an apartment or private house is a very, very time-consuming task. Since it has been decided to modernize the electrical network, you will have to deal with such work as cable laying. Depending on the location of the wiring, the operating conditions of the premises and individual preferences, it must be done in various ways. What are the ways of laying, is described in this article.

Cable laying in corrugation is one of the most common ways

Corrugation is used to lay the cable along the floor, wall or ceiling. In this case, the wiring can be both hidden and open.

Corrugation is a corrugated pipe made of polyvinyl chloride or metal. A metal wire is laid inside, with which you can stretch the cable inside the pipe. Recently, polyvinyl chloride corrugations have been increasingly used for laying electrical cables and wires indoors. This is due to the fact that their weight and price are somewhat less than metal ones.

Corrugated pipes can be used in residential, technical, administrative and industrial premises. The material of the corrugation serves as an additional insulator for the cable and has the ability to self-extinguish, which significantly reduces the possibility of spontaneous combustion due to a short circuit.

The corrugation is suitable for different types of cable of various diameters, as it is produced in several variations with sections: 16 mm, 20 mm, 25 mm, 32 mm, 40 mm, 50 mm and 63 mm. Through it, you can stretch both power cables and those related to information networks.

Important! Polyvinyl chloride corrugation can only be used for laying cables indoors. The material from which it is made is sensitive to ultraviolet solar radiation, temperature fluctuations and high humidity. Although for laying in open spaces there is a separate class of corrugations.

Work on laying the cable in the corrugation is more convenient to do together. First you need to pull a piece of wire from the pipe. Then make a hole in the cable winding and thread the wire into it, twist it carefully. It is desirable to level the corrugated pipe, one person should hold the far end of the corrugation, and the second should pull the cable, pulling the steel wire out of the corrugation. When the cable is fully stretched, we connect it tightly with the corrugated electrical tape so that the structure does not move.

It is convenient to fix the corrugation to the wall using clips - clamps, the diameter of which can be selected for the pipe section. This method is often used for laying cables in false ceilings and drywall partitions. If you lay the corrugation on the floor under a concrete screed, you need to buy a special one - reinforced, able to withstand loads.

Cable laying in a trench is convenient and practical, but not always possible

In summer cottages and in country houses, it is possible to stretch the power cable between buildings and for outdoor lighting by air and underground. The air method is appropriate if the distance between objects is small. The underground method is suitable for laying cables over long distances or outdoor lighting equipment. This method is more aesthetic, since there are no hanging garlands over your head, but it has a number of limitations:

• Cable laying in a trench is prohibited if the groundwater level is high. For example, in swampy areas it can reach 1 m and above.
• The soil contains a large amount of substances that can damage or break the cable sheath.
• Stray currents in the ground have an extremely negative effect on electrical wiring.
• The soil structure is too mobile.
• In places where soil excavation will occur too often, it is also undesirable to lay the cable.

If no contraindications have been identified in your area, you can start laying the cable. First you need to mark up the area. The cable should be located no closer than 1 m from the trees, bypass car parks, areas for the arrival of a sewage truck and other places of increased load on the ground.

The further sequence of actions for laying the cable into the trench looks like this:

1. We dig a trench according to the previously made markings. The minimum allowable depth is 0.7 m. But for greater convenience, it is better to make 0.8 - 0.9 m.

2. We remove all kinds of materials and substances from the trench that can damage the cable sheath: glass, stones, iron, wire, etc.

3. Pour sand into the bottom with a layer of 10 cm.

4. We purchase a cable:

• For low powers and cross sections - VVG cable;
• For medium and high power - AVBbShv cable, armored with galvanized steel tapes and flame retardant.
• For medium and high power - cable VBbShv - armored copper cable (more expensive).

5. We check and make sure that there are no short circuits between the conductive cores and with the armor using a megohmmeter.

Important! Be sure to remove the charge from the cable after checking with a megger. To do this, we connect the cores and armor together and close it all to the ground. At the same time, we observe precautionary measures: we stand on a rubber mat, in rubber boots and gloves, and in the presence of a partner.

6. We protect the cable. For this, various materials can be used: corrugated plastic pipes, metal corrugation or metal double-walled pipes. The choice depends on your budget and preferences. We stretch the cable through the protective material. If you decide to use a PVC corrugation, we additionally protect the places of contact with large solid objects and others that can damage the cable with cases. The case can be made from an asbestos-cement pipe by sawing it in half and putting on both halves.

7. Lay the cable at the bottom of the trench. We do this not tightly, but in waves so that the cable lies freely.

Important! It is advisable to draw a plan - a diagram of the location of the cable on the site, so as not to damage it in the future.

8. Fall asleep with sand - 10 cm.

9. Top with soil - 15 cm. Lightly tamp.

10. We lay the signal tape over the cable.

11. We fall asleep completely with soil, making a small hill. Check again for availability short circuits. If everything is in order, you can use it.

When pipes are needed

Cable laying in a pipe is shown at high level fire hazard, humidity and temperature fluctuations

Pipes when installing electrical wiring are used in rooms with increased level humidity and extreme temperature fluctuations. For example, in a bathhouse, basement, unheated buildings. Also, an indication for the use of steel pipes can serve as a high fire hazard of the room. For example, if the house is completely made of wood.

In addition to residential premises, this cable laying method is used in industrial premises, production workshops and other buildings where there are high mechanical loads, caustic chemical substances, vapors and gases, as well as a high possibility of dust and explosives entering the wiring.

For laying the cable outside, plastic, asbestos-cement, steel and other pipes are used to protect the wiring from the effects of aggressive soils, stray currents and mechanical damage.

In residential premises, cable laying in a pipe is carried out both in hidden and open ways. If laying in a strobe is planned, the pipe is mounted directly in the strobe in the wall or floor, and then plastered. When laying in an open way, pipes are attached to the walls with brackets or clamps.

Important! In vertically laid pipes, cable pulling must be done from the bottom up.

To connect pipes to each other, welding, sleeves and cuffs without sealing can be used if the room is dry. And you can use threaded couplings. In turning places, it is desirable to use threaded elbows. At the same time, in order not to damage the cable when pulling it against the sharp edge of the pipe, plastic bushings are laid in such places.

Important! So that condensate does not accumulate on the surface of the pipes, but rolls off them, the pipes are mounted with a slight slope.

Cable laying in trays is carried out in technical rooms and interfloor spans

This method of mounting a power cable is used in electrical rooms, in technical floors of buildings, basements, pump rooms, compressor rooms, in passages behind shields and other technical rooms.

Power cable laying in trays open type has a number of advantages in relation to laying in pipes:

• Trays are much cheaper.
• You can always check the health of the cable, as the tray cover is easily removed. You can replace the section or add another cable.
• The cable is not pulled, but laid mechanically which helps to avoid unwanted abrasion of the cable sheath.

Trays are fixed at a height of at least 2 m from the floor level. Are established on arms and suspension brackets. Connections are made with threaded elements.

The practicality of cable channels

Cable laying in a cable channel is the most aesthetic option for open wiring.

There are situations when the fine finishing of the premises has already been done, and suddenly there is a need to make cable routing around the apartment. Or, for example, the house is completely made of wood, how to lay the cable in this case? A good way out is to lay the cable in the cable channel. Its second name is an electrical box. This method is considered open.

Most often, the cable - channel is made in white, but if you set a goal, you can find various shades under wood. Thus, the box will practically not visually stand out on a wooden wall. The material used is plastic, steel or aluminium.

Cable installation is reduced to the following works:

• Remove the lid from the box. We fix it to the wall with dowels. If the walls are too uneven, this will not be easy to do.
• Laying the cable. It's not attached to anything in the box.

Important! Cable - the channel is laid in segments of 2 m. If total length the wiring is large, for temporary fixing of the cable at some intervals, you can install temporary fasteners in the form of pieces of a cover.

• After the entire cable is laid, we remove the temporary ones and put the stationary covers on the box.

Plinth with a cable channel is a convenient option for laying Internet, telephony or other cables

In the same way, the cable is laid in the plinth with a cable channel. Through it you can stretch telephony wires, Internet, computer and antenna cables.

Laying a cable in the sewers of the urban jungle is a guarantee of its safety

The cable duct consists of manholes, pipes and installation devices. A special organization is hired to lay a cable in an existing sewer or to create a new one, and the necessary permits are obtained.

This method is considered the most reliable in the city. It ensures that the cable will not be damaged by earthworks and will be protected from negative external influences. In this case, it is necessary to use a special cable for underground installation.

Video guide for home electricians

Each of the above cable laying methods is good at its laying stage in certain starting conditions. Remember, before you choose one or another method and start laying the cable, you should consult with a specialist. They may recommend a specific type of cable that will suit your situation, or suggest a completely different installation method.

How electrical cables are laid, we recommend that you read the second section of the PUE 6. The "outdated" version. The provisions listed in the document are advisory in nature. Those who comply with the requirements for laying electrical cables will certainly avoid violations. The information is presented within one document, it remains to be read. Let's see how the laying of power electrical cables is carried out.

How and where to lay the cable

First examine the end of PUE 6, dispelling doubts. An endless list of approvals will convince readers: a real document appeared before your eyes, which has seen the hands of many builders and officials. New requirements may appear, but later. PUE 6 electric lines classifies:

1. The first part considers the types of electrical wiring, choice, typical conditions: premises, street, attic.
2. Lines with voltages below 35 kW (separately before/after 1 kV).
3. Lines with voltages below 220 kV (including cables up to 35 kV).
4. Overhead cable lines (up to/above 1 kV).

The first discusses PUE 6 (section 2) the scope. The following requirements must be met for cables with a cross section of phase conductors up to 16 square millimeters. Unfortunately, omitted, take copper or aluminum. We conclude: always good until proven otherwise. Consider first the classification of electrical wiring:

• By the nature of the occurrence:
  1. Open. It happens stationary, portable, mobile. It is laid outdoors along the surfaces of structures, between supports. Along the way, insulators, rollers, pipes, boxes, sleeves, baseboards, poles are used.
  2. Closed. It is laid inside the walls: hidden with plaster, strobes, inside concrete (walls, floor, ceiling) as a monolith, using cavities.
• External wiring is laid along the outer walls. Suspended length no more than 100 meters (four spans of 25 meters each). Other concerns overhead lines, underground routes.

It is allowed to lay an electric cable in the bathroom floor. Another question concerns the protective measures envisaged (grounded grid). The matter is limited to trifles.

Laying wires inside buildings

Among general requirements indicates the inadmissibility of laying a number of voltage circuits up to / above 42 volts with rare exceptions (see clause 2.1.16). It is relevant to today's reality, when I wanted to light the bathroom without restrictions with constant 12 volts. Fortunately, the DIN-rail adapter is sold for 800 rubles. It turns out that it is forbidden to merge in one branch. Make a house wiring from 12 volts. Safe, allows the use of a minimum cross-section of wiring.

PUE 6 gives the answer here: use fireproof partition walls between the wires. Much more interesting will be the requirement of joint following of phase, zero (return) wires (it is forbidden to use adjacent pipes). Villagers should know: the cable is not laid in combustible cavities, niches of wooden walls. Ceramic rollers-insulators are used (the distance to the plane is over 10 mm, or by laying fireproof material).

With open laying, the distance from the floor is at least 2.5 meters. We believe that in private houses the villagers do not comply with the requirement. For hazardous areas only. They are not required to reduce the voltage, fitting into the upper limit of 42 volts, placing the electric cable for internal installation at a height of two meters. But it is possible to do. Remember the 12 volt adapter, put in the switchboard. The purpose of lighting is definitely enough to supply a village house. With regard to sockets, a protected gasket (cable channels) should be used. With a degree of protection of the box IP20 and above, the height is not standardized. Connections are allowed in the form:

• crimping;
• terminal blocks;
• welding;
• soldering.

By the way, bare twists are prohibited even for ground circuits. Joint insulation is not worse than linear sections. Next come the obvious requirements: the absence of tension, the availability of nodes, connections (for service specialists). Under the cladding, a cable protected from combustion should be laid: many installers forgot. YouTube will give out as many plots as you like: the lining of PVC panels hides the traditional PVA for several cores. The mentioned part of the PUE is inactive, the installation process itself does not become less dangerous. The conclusions are clear: we do it for ourselves (so that nothing is guaranteed to happen).

Thus, laying an electrical cable in wooden house crafted with fine art. Useful aluminum corrugation. It is clear that plastic is not always suitable for reasons of lack of fire resistance. Take comfort: the aluminum corrugation is easy to ground, certainly improving the electromagnetic environment of the house, simplifying the replacement of wiring, saving against fire. Like other metal parts of the building, sleeves, pipes, cable channels are zeroed. Able to serve as a screen. Read more about the standards for laying an electric cable in Table. 2.1.3 PUE 6, according to the peculiarities of laying in various climatic conditions (heat, dampness), many rules are prescribed in section 2.1.

Increased attention is paid to pipeline intersections. The laying of the electrical cable is carried out, leaving a gap of at least 5 cm. If the water in the pipeline is hot, or something flammable (read, gas), the distance doubles. Moreover, protection of 25 cm against mechanical damage should be provided on each side of the intersection. On a parallel line from a pipeline, cable, the distance is taken at least 10 or 40 cm, depending on the content (gas, kerosene, hot water, steam).

Outdoor wiring of the building

Rules for laying outdoor wiring

Finally, the color marking of the electric cable for outdoor installation from the substation will be a curiosity:

1. Yellow - phase A.
2. Green - phase B.
3. Red - phase C.
4. Blue - zero working wire.
5. With yellow and green stripes - zero protective wire.
6. The reserve tire is marked with transverse stripes to the main ones.

The coloring differs from PVA cables (slightly), not intended to pull three-phase lines. The laying of an electric cable in the ground in the country is carried out by other types. Pipe marking is in accordance with GOST R IEC 61386.24, GOST 16442 will tell you examples of cables. The latter document will indicate which brand of electric cable is unsuitable for laying in the ground. The subtleties of installation are indicated by PUE 6, starting from paragraph 2.3.83. It is said that the cable line lies no closer than 0.7 meters to the surface. From below, backfilling is performed (sand, crushed stone), from above it is slightly covered with soil, free from various kinds of debris.

Selection of the wiring section (cable cores)

According to PUE 6, the cable is divided into two categories by the cross-sectional size of the cores:

• Within 6 square millimeters for copper, 10 for aluminum is selected from tables 1.3.4 and 1.3.5 directly. As for long-term operation.
• Otherwise, when the core thickness is higher, the table current must be multiplied by a correction factor of 0.875 / √ TPV. Where TPV is the relative duration of equipment activity in the operating cycle. Simply put, the equipment works less for a period of time, it is thinner to take a core.

Please note that the figures indicated in the table are widely cited in the literature without indicating the source. PUE 6 says: the maximum continuous current of the core is determined by the type of cable (the number of conductors in insulation), the laying method discussed above. By grouping the data, readers will easily choose an electrical cable for laying over the air, underground. It's nice that the parameters are graded according to the type of insulation, voltage. There is not enough space to call the information exhaustive, some of which are withdrawn from official circulation by the current legislation.

It has become difficult to find requirements for the cross section of the neutral conductor of a three-phase network cable. PUE 6 directly says: it should be at least 50% of the phase, sometimes it increases to 100%. Correction factors for selecting the limiting current depending on the ambient temperature will seem useful. You will see, depending on the conditions, the cable cross-section can be reduced, or, conversely, it will have to be increased. Correction factors are entered for soil type. It is important for those who want to lay the track correctly.

Readers will like table 2.1.1, indicating the smallest cross-sections of conductors for copper, aluminum. For stationary cable laying on rollers indoors, the value is at least 1 square millimeter copper. The current can reach 17 A (PVC cords with PVC insulation), approximately 3.7 kW of power. wanted LED lamp connect with a thinner section - it is impossible. We assume that PUE 6 came out long before the appearance of home versions of sources in our area. Surely the engineers will have to revise the measurements, make adjustments for the type of light bulbs.

cable blocks

The allowable current of cable blocks is widely discussed depending on the structure. The laying process is described in section 2.3 (now removed). It is said that cast-iron, concrete, asbestos-cement pipes are suitable for a cable block. Calculation of the number of channels, structuring is carried out in accordance with clause 1.3.20, and 15% (at least 1 piece) is allocated for reserve (in case it is necessary to lay an additional line).

The depth of the cable blocks is selected in accordance with clause 2.3.84. In most cases, it is 0.7 - 1 meter. There are assumptions to reduce the distance to half a meter on a section of no more than 5 meters. It will allow you to correctly lay the channels, which should have a slope of 0.2% towards the wells (the depth is growing). When laying, we take into account: the minimum distance between the lines is determined by the voltage, it grows with increasing.

The definition of cable blocks is hushed up, so readers probably have a question the size of a mountain. Meanwhile, the structures are formed by channels of various kinds connecting the wells. Due to the structure, the underground laying of an electrical cable is carried out without the involvement of construction equipment. Most importantly, there is no need to open expensive coatings. We bet there's some sort of cable conduit under the Piazza.

A similar technology helps cable laying under the riverbed. A special unit drills an arc-shaped tunnel in the ground, overlooking the opposite bank. The cable is laid inside. If necessary, the walls, of course, are reinforced. It makes it possible in the future to freely repair a section of the route, change certain veins (add, replace, remove). It is clear that underwater types of cable laying are not available to most private traders, you need to know in case you need to go through a difficult section.

Output

We remind you that the specified PUE 6 is "outdated". It is still permissible to be guided while carrying out work. Similarly, the laying of an electrical cable in an apartment is carried out in accordance with documents marked by the trust of professionals.