Underground electrical wiring in a summer cottage. How to lay a power cable underground. Laying electrical cables underground: video

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Underground input cable into the house has a lot significant benefits. Here are the main ones: the risk of fire is minimized; the cable is reliably protected from theft, vandalism and adverse weather influences; the architectural design is not spoiled. To experience all these benefits, you need to know not only how to run a cable into a house underground, but also what kind of cable to put into a house underground?

Underground cable entry into the house using armored cable

To connect a house to the electrical network, it is necessary to use a cable that can withstand the pressure of soil masses and other similar influences. Take armored cable for example. Underground cable entry into the house must be carried out in the following order:

1. Dig a trench from the pillar to the entrance to the building through the foundation (its depth should be 70-90 cm).
2. Pour sand into the trench (the sand layer should be 20 cm thick). Sand is needed to remove excess moisture in autumn and spring.
3. Place the cable in the trench. It is important that it lies in a wavy manner. Lowering from the pole into the ground must be done in a pipe (its height should be 2 meters).
4. Enter the cable into the house underground. This can be done through a wall or foundation. In the first case, a hole is drilled in the wall. A pipe is laid in it. The end of the cable is passed through a pipe made of metal or plastic.

5. If you decide to enter through the foundation, then create a hole of a suitable diameter in it. Insert a piece of metal pipe into the hole and lay the cable into it. The pipe must be fixed using cement-concrete mortar. The pipe should be insulated on both sides. This will require non-flammable material. This must be done in order to prevent the penetration of water and soil.
6. Connect the cable to the protective device in the distribution panel, and on the support to the wires overhead line- using piercing clamps. The cable is fixed to the pole with metal tapes with a pitch of no more than 100 cm. Be sure to ground the armor, both from the side of the pole and from the side of the shield.
7. Once you are satisfied that everything is done correctly, dig the trench. After some time, the soil will shrink, so a mound should be created above the trench (its height should be 15-20 cm).

Underground cable entry into the house using an unarmored cable and HDPE pipe

It is also possible to supply power using an unarmored cable to the house underground. IN in this case You will need an unarmored cable and HDPE pipe. Such a pipe can withstand very severe frosts. It does not smoke or burn, is characterized by high strength, increased ductility, and resistance to chemicals.

Before you begin connecting, carefully inspect the VVG cable. It is important that the shell is not damaged. Otherwise, the HDPE pipe will not be able to perform its intended functions. Then you can safely perform the following steps:

Dig a trench.
. Place a pipe of the required diameter into it.
. Pull the cable. It is important that it is not in tension.
. Enter the cable into the house underground. This can be done above the foundation (on external wall home) or through it. When entering through a wall or foundation, a passage of suitable diameter must be created. Place a pipe and cable into this passage.
. Backfill the pipe. Use sand first (layer thickness should be 10 cm). Then fill in the soil (layer thickness should be 15 cm).

Now you know how to run a cable underground into a house. But before you do this, you must obtain the appropriate permission. To do this, it is necessary to develop an energy supply project (drawings and plans). The permit will have to be approved by the services that are responsible for various objects and communications (gas pipeline, water supply, communication systems, heating mains, etc.). If one or another communication is located near the installation, it is necessary to call the person responsible for it in order to coordinate the location of the trench.

The company "Kabel.RF ®" is one of the leaders in the sale of cable products and has warehouses located in almost all regions Russian Federation. By consulting with the company’s specialists, you can purchase the brand you need at competitive prices.

Among existing methods installation power lines laying cables in a trench is considered one of the most economically feasible and reliable methods. In this article we will analyze the main types and brands of cables that are suitable for underground installation.

Cable for laying in trenches

Carrying out earthworks and cable installation require strict adherence to standards, established by the rules PUE and PTEEP.

The criteria for selecting cables for laying in trenches are as follows:

• soil type. This criterion is important for assessing the degree of freezing and natural deformations of various sections of the cable route;
• soil corrosion activity, which is characterized by humidity and acidity;
• operating conditions, including the proximity of foundations and green spaces, cars and railways, oil/gas/heat pipelines, power lines and electrified transport.

Cable products can be laid underground, either protected by armor or without special protective covers. Classification of cable types for laying in the ground (trenches) is also made using insulation material, which can be made:

The minimum depth of underground installation of cable products is regulated regulatory documentation and depends on the operating parameters of the power line and the type of soil. For example, the depth of the trench for cables up to 20 kV should be at least 0.7-0.8 m, up to 35 kV - 1 m.

Armored grades usually do not require additional protection when installed underground. When installing power lines from unarmored grades, as well as when it is necessary to cross roads or railways with armored cables, it is possible to use several types of protective structures:

• concrete slabs that are laid on top of a layer of soft soil or sand of at least 0.1 m. To protect power lines from 35 kV, slabs with a thickness of at least 50 mm are used;
• brickwork, which is mounted similarly to concrete slabs;
• asbestos-cement or concrete, steel, ceramic or plastic pipes(corrugated hoses) made of polyethylene low pressure(HDPE) or PVC.

Signal tape of ordinary or protective type(LS or LZS) is an element additional protection power lines from mechanical damage.

Brands of armored cables for laying in the ground

The choice of brands of armored cables for laying in the ground is optimal solution, allowing to ensure reliable operation of underground power lines.

Laying an armored cable in the ground usually does not require additional funds protection. Products of this type have excellent resistance to mechanical damage, moisture, rodents and other external influences. Let's consider the most popular brands used when laying armored cable underground in Table 1.

Table 1.

What kind of cable can be laid underground?

Quite often, our clients receive questions about the possibility of laying this or that brand underground (in trenches). We have selected the most common of them in order to competently answer them within the framework of this article.

Is it possible to lay VVGng cable in the ground?

Is it possible to lay VVG cable in the ground?

Similar to the VVGng brand, this cable does not have protective coverings, therefore, its installation in underground trenches is not recommended without additional protection. Installation in a pipe is acceptable.

Is it possible to lay SIP cable in the ground?

This brand belongs to the group of self-supporting cables that are used in the process of installing overhead power lines. According to PUE-6 clause 2.1.48 “Wires and cables should be used only in those areas that are specified in the standards and technical conditions on cables (wires)."

Is it possible to lay the KG cable in the ground?

The KG cable is designed for connecting moving mechanisms. Its laying in the ground open method unacceptable according to PUE-6 clause 2.1.48.

In which pipes are cables laid in the ground?

To protect unarmored marks, which are used for installing power lines in the ground, double-walled ones are most often used corrugated pipes and technical polyethylene pipes. Steel pipes not permissible for outdoor installation (according to PUE-6 clause 2.1.78)

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Before deciding on the depth to which an electrical cable should be buried, research is required to study the characteristics of the soil and weather conditions in the region. Based on the information received, design engineers will be able to not only accurately determine the depth of laying electrical cables in the ground, but also the design of the trench in which, in fact, the electrical wiring will be laid.
All criteria for performing construction and installation work are established by the relevant regulatory and technical documentation. And here the depth of the electrical cable in the ground is far from the only parameter. Distance between cables, quality and type of trench sealing, type of embankment (substrate) for wiring, type drainage system(if required) - all this directly or indirectly depends on the characteristics of the soil and weather phenomena in a specific region. Let's consider individual situations.

What kind of electrical cable can be buried in the ground?

To understand whether it is possible to lay electrical cable underground, we recommend that you familiarize yourself with the following table:

In the table presented, cable brands are arranged in order of their preferred use in certain conditions.

General requirements

Is it possible to lay an electrical cable underground? This question is perhaps fundamental when solving the problem of delivering electricity (or an electrical/optical signal) from one point to another. From this we can conclude that a lot depends on the type of wiring being installed. As an example, here are the requirements for laying a cable through which it is planned to transmit electricity with voltages up to 35 kV:
. The depth of laying electrical cables in the ground (when using trenches) should be 70 cm or more. The width of the trench is selected based on the requirement that the distance between the cables, as well as the distance between the cable and the trench wall, must be at least 250 mm.
. In some cases (presence groundwater, heaving soil, etc.) the bottom and walls of the dug trench are lined concrete slabs or other building material, the thickness and type of which depend on weather conditions in the region, soil conditions and other criteria.
. The bottom and walls of the trench are cleared of objects and elements with cutting edges, as they can damage the cable sheath. If you cannot delete an element (for example, block of stone), its edges should be blunt. You can also cover the cable where it comes into contact with sharp objects or structural elements.
. A cushion about 10 cm thick is placed at the bottom of the trench. This can be sand, gravel or other material. The cable is laid on the created substrate.
. After installation, the cable is again covered with sand (or other material). The thickness of the embankment is 10 cm (above the cable).
. For additional protection of the cable, it is recommended to cover the embankment layer with special ones (cable cover plates). SPDs also serve as a signaling device (an inscription on the front side of the plate indicates the presence of cables underneath). If the use of slabs is not planned, a warning tape is laid, which also indicates the presence of a high-voltage cable in the ground.
. A fill of soil is made on top, and the installation procedure is considered complete.
These requirements are valid both for “ordinary” soil with a moderate level of corrosion, moisture and hardness, and for heaving soils that have the characteristic of seasonal swelling when exposed to negative temperatures. A substrate and embankment made of sand, gravel or crushed stone here plays the role of a balancer, preventing the cables from bending. For this installation method, any cables with tape armor (for example,) or cables without armor are suitable, provided they are laid in protective pipes.
Now let's briefly look at how to lay an electrical cable in the ground in permafrost and rocky areas.

Permafrost

At what depth to bury an electric cable in permafrost conditions (the soil is thawed no more than once every 3 years) largely depends on the average annual temperature in the region, the thickness of soil freezing, as well as the presence/absence of such phenomena as:
. thermokarst - collapse of soil during thawing;
. solifluction - sliding of soil down a slope during thawing;
. frost cracks are cracks that form due to uneven compression of the soil during its cooling.;
. ice - the release and freezing of river or groundwater to the surface in winter.
Let's give an example of how to lay an electrical cable in the ground in permafrost conditions, and also consider some of the features of this process.
. All work to prepare the route in permafrost conditions, including cutting down forest clearings (if any), is carried out before the ground begins to thaw.
. Cable laying is usually carried out in the active layer (subject to seasonal freezing and thawing) of the soil.
. If the thickness of the active layer is less than the design depth of cable laying, work is carried out in early spring or late autumn. During these periods, the soil is still frozen, and the air temperature is within acceptable limits for cable-laying work.
. The laying of cables begins with a process of repeated soil digging. For this purpose, special equipment with appropriate attachments. Propping can significantly reduce labor costs in constructing a cable route.
. In the process of flogging and other preparatory work it is necessary to monitor the preservation of the turf and moss covers of the soil. Their violation can lead to undesirable changes when the soil thaws.
Not all types of cables are suitable for use in permafrost conditions. In such situations, special cables with round wire armor are used (for example, these are brands,). Wiring with tape armor (,) is also suitable, but before laying them, the route is subjected to embankment (a gravel-sand embankment is laid). In both cases (laying cables with wire or tape armor), drainage channels can be additionally installed along the trenches to drain water and snow retention systems can be erected.

Rocky terrain

The depth at which to lay an electrical cable in rocky soil depends rather on the possibility of making trenches of a certain depth in the rock. It's about about the possibility of use in a specific area technical means, with the help of which the destruction of rock is carried out - here, uprooters, jackhammers or even dynamite may be required (it all depends on the hardness, type and location of the rock being processed).
All other requirements for the trench are valid, as in the case of laying cables in “ordinary” soils. The difference may lie in the need for additional supporting structures(for increase bearing capacity trench walls) and structures protecting against landslides and rockfalls.
However, an invariable requirement for the construction of cable routes in rocky areas is the use of special grades of cable with wire armor (for example,), capable of resisting mechanical stress, stray currents, corrosion and other external influences.

Purchase for laying in Various types soils can be obtained from the company "Kabel.RF ®". We offer products manufactured in accordance with approved GOST and TU. We have set affordable prices for the entire range.

Usually on summer cottage How many buildings are being built: country house, bathhouse, summer cuisine, utility block, etc. and so on.

Initially, electricity was supplied to one of them, but everything needs to be electrified. Yes, and I would like to do outdoor lighting. And the problem of choosing arises - which method of laying electrical communications, overhead or underground, is more suitable for your dacha.

Choosing a method

The air method is simple and cheap if the distance between objects is small. If the distance is large, then you will have to install an additional pole or support. And hanging garlands overhead do not at all decorate the country landscape.

The underground method of laying cables in a country house is more aesthetically pleasing and is suitable for laying over long distances or for outdoor lighting equipment.

In order to lay a cable underground in a dacha, you must comply with all necessary requirements safety rules, and you should also study the features of your summer cottage.

Rules for laying cables underground

First you need to choose the optimal route for laying the cable underground in your summer cottage. It is important here that the cable runs at least a meter (and usually more!) from big trees and in places where digging will obviously not be carried out. The cable path should not run under places where there is an increased load on the ground, for example, a site that is used to park your car in the country. Think over the laying route so that communications do not interfere with your further construction. Let the communications be a little longer than running them under the arable land or future building. It is best to place the cable under the tracks, or preferably next to them. We strongly recommend drawing a plan of its location.

You should not use the same cable to connect buildings and external lighting - first conduct communications between buildings. They must be done once and for all. When everything is done, start experimenting with outdoor lighting: this is creative work and does not always work out the first time.

Laying cables underground in a dacha begins with marking and excavating a trench. Its optimal depth should be at least 70 centimeters, and taking into account the pillow, 80 centimeters is better. This is for communication between buildings. For laying cables underground for external lighting, these figures are usually 40-50 cm.

After the trench is dug, it must be cleared of objects such as stones, pieces of iron or glass shards that could damage the cable insulation. Then you need to make a sand pillow. The thickness of the cushion should be at least 5, and preferably 10 centimeters, and the sand itself should be fairly evenly distributed along the entire length of the trench.

Material used

It's time to select a cable. All modern views cables and wires have the necessary water resistance for laying in the ground. Even ordinary installation wires of the series (PBPP / PUNP, PVS, ShVVP) can be safely laid underground or in water.

Power cables VVG(especially VVGz), KG are even better suited for these purposes. All these wires do not require any additional waterproofing.

But it’s still better to lay these cables in HDPE pipes. If there is a need to lay a cable protected by a case, then HDPE technical pipes are ideal technical solution. The most popular use of these pipes is to protect electrical, television and telephone (Internet) cables. The use of Gost HDPE pipe in this case is possible, but not advisable, because high price raw materials and compliance with all drinking pipe production standards increases the cost of the project significantly. During production technical pipe HDPE uses various polyethylene additives (the basis is secondary raw materials and defects of “pipe” production), which significantly reduces its price.

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The base color of the pipes is black, but the presence of recycled materials can give different shades. By technical requirements the presence of recycled low and low polyethylene is allowed high pressure certain brands. Pipes must be round, smooth and even both outside and inside.

HDPE pipes They are connected by couplings (fittings), but this does not guarantee 100% tightness - it is better to lay them in one piece from building to building.

There is also a special armored cable for underground laying– VBBSH. This cable has a steel sleeve already built into it and has very good waterproofing. It can be placed without additional protection.

For laying cables underground in a country house between buildings, it is highly recommended to use it.

Carefully inspect the cable from all sides to check the integrity of its sheath. The cable must be laid in a trench (or pipe) in such a way that it lies freely and not under tension.

You can now start backfilling. The cable must be covered with sand 10 centimeters thick. The cable should not protrude anywhere from the layer of sand. A 15-centimeter layer of soil is poured on top of the sand. Then you can (if you're an amateur) lay the signal tape so that the middle of the tape is located just above the cable.

We fill the entire trench, leaving a small mound, since the soil tends to settle. When using HDPE pipes, the outlet to the building must be provided with fittings.

Some additional tips. Firstly, when laying a cable underground in a country house between buildings, use a cable with a cross-section of at least 4 mm. Secondly, lay only a solid cable underground, do not make connections.

When electrifying a private house or cottage, you have to decide whether the route will run through the air or in the ground. Laying a cable in the ground requires more work, but it provides greater safety: it is more difficult to pull wires out from under the ground than to cut them from the cable. Therefore, despite the high cost, this method is often chosen.

The route for underground cable laying from the pole to the house will be drawn for you in the project and all that remains for you is to follow all the instructions. But when distributing electricity along the site, you have to design the route yourself. The most economical option is a straight line from one point to another. But a real route like this practically never happens. Most often this is a broken line, since you have to go around many obstacles.

How to lay a route

When planning a route, you must adhere to the following rules:

Drawing a plan

Once you have a rough idea of ​​the route, transfer it to a piece of paper. This plan should also include main structures, water supply, sewerage, etc. After you dig a trench and lay the cable (before backfilling), measure the distance to all “long-term” objects and transfer them to the plan.

Professionals call this process “localization.” This plan with distances can be very useful later - when redeveloping the site, planning new buildings, etc. He will also be there if there is a need to repair the transmission line. According to the plan, you will restore the location of the route.

Cable protection on top

When laying a cable in the ground, there is always a high probability that it may be damaged during any excavation work. Therefore, the PUE provides for the presence of protection above the route. For powerful cables - 1 kV (1000 Volts) and above - protection with concrete slabs or solid brick. For low-power lines, which usually power our homes, it is allowed to lay the cable in the ground with signal plastic tapes. This method of protection is permitted if there are no more than two conductors in the trench.

Signal tapes are laid along the cables at a distance of 250 mm from their outer cover. If there is only one power line, the tape is placed above it; if there are two or more, two or more tapes are placed. Their edges should protrude beyond the cable by at least 50 mm, and adjacent tapes should be placed with an overlap of 50 mm.

Underground cable laying technology

Laying a cable in the ground means digging a trench along the entire route. The recommended depth is 70-80 cm. If for some reason it is not possible to dig into such a depth, you can reduce it, but lay a line into pipes or a protective shell. This can be a corrugated hose or special pipes in which the outer shell is made of more rigid polypropylene, and inner part- made of softer polyethylene.

You can also use asbestos-cement or water pipes plastic pipes suitable diameters. Why not sewer? Their walls are thinner and they cannot protect against serious loads. It is not recommended to use metal pipes, but because of their excessive rigidity: when the soil moves, their hard edge can (and often does) grind the shell. Therefore, if you lay the cable in metal pipes, they will need to be welded along the entire route and figure out how to make the edges not so hard.

If pipe cases are used on the cable route, it is better to seal their edges. So the earth will not fill in them, the water will not flood. The easiest way is to add a little from the edge polyurethane foam, but you can also use a cement-sand mortar or rags soaked in cement milk. Which one is more convenient? Just remember that the cable inside should not be stretched. There should be a little slack.

In addition to the depth, you also need to decide on the width of the trench. For one cable, it is recommended to be 25-30 cm wide. When laying two or more, there must be at least 100 mm of distance between them. In addition, the distance from the outer cables to the wall is at least 15 cm. In accordance with these recommendations, the width of the trench is determined.

List and order of work

Laying cables in the ground begins with earthworks. Using the marked route and selected parameters, we dig a trench, simultaneously removing all hard and sharp objects from the walls. It is advisable to make the walls with a slight slope - this way they will crumble less and work more conveniently. When the trench is ready, the order of work is as follows:

This completes the laying of the cable in the ground. But there are also features and nuances.

Before laying the cable in the ground and after backfilling, it is very advisable to check the insulation resistance. For this purpose, a megohmmeter is used, which feeds high voltage, checking the quality and condition of the insulation.

After checking, do not forget to remove the residual voltage by shorting the wires to ground. This operation must be carried out with great caution, since good quality insulation and a long route, the voltage can be very considerable. Defeat to them has serious consequences, including death. Therefore, when working with an ohmmeter and when removing residual voltage, do not forget about dielectric gloves and glasses.

Since the ohmmeter is in household Rarely encountered, vinyl insulated cables can be checked using a conventional tester or voltmeter. They will not measure the insulation resistance, but they will show the presence of a breakdown or short between the conductors. We call all the conductors with each other, as well as each with the ground, screen or armor. If there are any problems, it is better not to use this piece.

When laying and filling with sand, make sure that the insulation is not damaged. After installation, also check the insulation or ring the wires. You probably know what happens if you apply voltage to a conductor with broken insulation.

It is better to bury a single piece of cable in the ground without connections. If this is not possible, connect the two pieces above the ground in a special installation box for the street. The box can be mounted on a post that is dug in where the cables exit to the surface. It is unwise to make homemade couplings, since they have low quality and they are usually the sources of problems.

If several lines are laid in a trench, and they must pass through a protective shell, then each should have its own shell.

How to enter the house

Entering a cable laid underground into a house can be done in several ways, but the PUE does not allow simply running it through the foundation. There are other methods:

Laying cables in the ground requires attention. It is very important not to damage the insulation during work, otherwise you will have to redo everything all over again.

Which cable can I use?

To lay cables in the ground, you need to use products with high degree protection from moisture, in a hard shell. Vinyl and polyethylene shells satisfy these conditions. These are the cables that are usually used: VVB (armored), VVBbG (armor + waterproofing), VBBShv (armor + polyethylene hose). But they are expensive, although they last a long time. It is advisable to use them to supply electricity from the pole to the house.

When choosing the type of armor, you need to pay attention to the acidity of the soil, the amount large stones, construction waste. For neutral soils Steel armor with small inclusions of stones is suitable. It is also suitable for clays and loams. For acidic or alkaline soils you need lead or aluminum armor. The same cables are best used on soils with normal acidity but with big amount stones.

Wiring around the site can be done using cheaper conductors. NYM and SIP feel normal. They can work up to 5 years. VVG is definitely not worth using for underground installation. It lasts for a maximum of a couple of years, which, given the volume of land work, is not at all pleasing.

In general, it makes more sense to install more expensive cables, but with a better protective sheath. It may cost more at the installation stage, but there will be no problems and you won’t have to think about replacing it with a new one in a couple of years.