Routing cables in the ground is a laborious process, but this approach guarantees a long service life, because in this case there is less risk of damage as a result of the influence of weather factors. In addition, this installation option reduces the risk of theft.
However, not all types of wires are suitable for laying underground, and there are some norms of work, which must be taken into account to ensure that the cable normally functions and does not create conditions for emergencies due to a violation of the integrity of the insulation.
Contents
What kind of cable can be used?
In order for the cable in the ground could remain functional for a long time, it must meet a number of parameters of GOST. Only armored cables that have a quality waterproofing coating meet all regulations. When selecting a wire should take into account the characteristics of the soil in which it will be located. Under gentle operating conditions, i.e. at normal levels of soil acidity, the following grades of armored cables can be used for laying in the ground:
- Avbbshv;
- VBBShV;
- PvbShv;
- AAShp;
- AAB2L.
The brand AVBbShv is most often used in such conditions. This is a wire with aluminum conductors. It is armored with two galvanized strips and a protective sheath. Another commonly used brand is PvBShv. This kind of wire is distinguished by the presence of aluminum conductors, covered with steel bands and polyethylene insulation.
On soils with a high level of chemical activity, including marshes and salt marshes, the following cable grades can be used for laying in the ground:
- AABL;
- AAB2l;
- AAShv;
- AAPl.
If you want to lay cable in a short area to connect a shed, cottage or bath, you can use unarmored wire covered with PVC sheathing. Such wire is highly durable and sealed, so it can last for a long time. When connecting street lighting, you can use CIP or NYM. However, they are not suitable for high-voltage lines. When laying cable in the Far North regions, you should use specially adapted to such aggressive conditions brands, including PvKShp.
List and order of work
There are a number of rules for laying cable on the site. First of all, you need to make a plan of trenches on the site. The paths along which the wires will be laid should be at least 1.5 m away from large bushes and trees. If it is not possible to bypass such obstacles, a metal pipe should be laid in the problem area. HDPE can also be used to lay the cable in the ground. It is worth avoiding areas exposed to high loads, including car parking areas, access of a sewage truck, etc.
If it is not possible to bypass such areas, special protective cases should be used. When planning the laying of the cable in the trench, it should be taken into account that it should be located at least 60 cm from the foundation.
When digging a trench, the depth of the trench must comply with regulations. The recommended depth of laying is 70 cm. The laying depth can be reduced if necessary. The width of the trench for laying is about 20-30 cm.
When the question arises as to how to lay the cable underground on a large plot, more technological methods of trenching can be used, as the use of a shovel in this case is extremely time-consuming. In this case, trenchless cable laying can be recommended. This method uses a special mechanism that pulls the wire in a protective tube underground without the need to form a trench.
Developing the route
When laying cables underground, it is often not possible to use special equipment and the trench has to be made with a shovel. Roots and stones that get caught in the process of digging the trench should be removed immediately. It is not necessary to level the bottom, but it is required to ensure that there are no sharp differences.
After that, about 10 cm of sifted sand is poured. This layer should also be tamped. In areas with higher loads, protective elements should be immediately laid, i.e. pieces of pipes, which will avoid tearing the laid wires. The use of cases is required in the areas of laying sewer pipes, etc.
How to lay the route?
Before you start laying an electrical cable in the ground is required to check the integrity of the protective sheathing with a megohmmeter. Cables should be in special protective cases. HDPE protective elements cannot replace laying a metal pipe when laying cable under a road, parking lot, or other areas with high loads. If several wires are laid in the same trench at once, they must be separated from each other with plastic clips. The distance should be at least 5 cm.
Wires should not be stretched when laying in cases. This will prevent them from being damaged. It is necessary to take into account the following: the depth of laying the cable is such that in the autumn-spring period a lot of moisture can accumulate in the ground. This increases the risk of a short circuit if the integrity of the insulation is compromised.
If it is necessary to splice cables, special splice couplings should be used. Do not use stranding or duct tape on wires that are laid in the ground.
Protecting the cable from above
After the wire is laid in the trench, it should be covered with a 10 cm layer of sifted sand. After that, about 15 cm more soil is laid. It is obligatory to lay a plastic signal tape for the cable on top. It not only allows you to reduce the load on the wire, but will also protect it from damage during future works. Thus, this protective element will be about 25 cm higher than the cable.
Signaling tape is characterized by increased strength. On it the manufacturer puts the inscription "Caution, cable". After that, the ditch is backfilled with the previously pulled out soil. It is necessary to fill it so that there was a small slide, because in the future it will be a little compacted under the action of precipitation.
How to enter the house?
The process of entering the underground cable into the house or outbuildings has some subtleties. The wire should not be allowed to run under the foundation, as the shrinkage of the house will lead to a violation of its integrity. It is desirable to still be walled in when pouring the foundation of the house, i.e. pipes with a diameter at least 4 times larger than the cross-section of the high-voltage wires. If the tabs were not arranged during the construction of the house, you should make a hole in the foundation yourself and place in it a pipe of the required diameter.
After that, the wire is introduced into the house through the hole. It is obligatory to seal the place of laying. To do this, you can fill all the remaining cavities in the embedding with a rag moistened with cement mortar. In addition, assembly foam can be used for this procedure. This will prevent dirt, water, and rodents from getting into the embedding.
There is another method of inserting the cable into the house. To do this, it should be laid along the wall of the house to the place where the input cabinet is located. After that, the wire is lifted along the wall to the desired level. At the required height in the wall is made a hole, in which laid a metal or plastic pipe. Through it the communications are entered into the house. It is necessary to seal the entrance with installation foam.
Armored wire must be grounded. This will prevent accidents if the wires running underground are damaged. To do this, a wire is welded to the armor, which is led to the "zero" in the panelboard.
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