Cable laying under ground

Laying of power cables is carried out according to the EMP.Note that the current seventh edition is only part of a general set of rules. Prefer to consider the sixth. The second section focuses on how the cable is laid, including laying under the ground. To make the right knowledge, you need to take into account that the lines are divided into groups by voltage, the general rules are in the section “above 110 kV”.Constant reservations are made for which cases these practical tips apply.

How to lay a cable underground

Communication cables are laid underground. And only in exceptional cases is it possible to use poles on local and interzone lines. The definitions of the route structure are given, for example, in the BCH 116. Other documents regulating the laying of communication lines and cables are known:

1. BCH 600( replaced by OSTN 600) canceled in 2003 by the order of the Ministry of Russian Federation for Informatics and Standardization, developers continue to use it today. Look through the document and find useful information. Frequently valid variants of various instructions refer to the BCH 600 and OSTN 600.
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2. PM 13-2 is valid today. The document is entirely devoted to fiber-optic communication lines. Consideration is given to the selection and calculation of methods, materials, etc.

A good general list of documents is located on the official website of the NormaCS project. Here you can find information about the current editions, the initial legislative base and references( links).Software developers give their own tips and tricks. Minus - separate texts of documents are available only in the commercial version.

Rules for cable laying under the ground

An important part of the cable laying is earthworks. These include:

• Trenching trenches directly for cable laying.
• Similar for mounting regeneration devices( amplifier blocks that support the desired signal level in the network).
• Trenchless method of drilling under the slopes. Usually consists in laying of a pipe( most often PND) in which the cable is already laid.
• Drilling and digging holes under the posts of overhead transmission lines.
• Planning work on the ground, for example, the placement of tags. Laying the route belongs to this category.
• Restoration of disturbed soil.

Laying activities are carried out only according to the finished documentation. Implied project work. The document shows what, where and how to do. If necessary, substantiations are provided( for example, laying communication cables by air, or with a cut of the corners of highways, etc.).Prior to the commencement of work, the customer obtains the permission of the local administration, which is given to the contractor. Organizations maintain personnel with appropriate qualifications and possess the necessary licenses. The Contractor in the Technical Commission issues a warrant in two stages:

• . The first is taken to the preparatory work, for example, geodesy. To obtain a cable laying order, an outage should be provided, where the factor of equipment of the place of work is necessarily taken into account for the urban area by means of preventing pollution of the surrounding area. For example, devices for washing wheels. A breakdown of the route is carried out according to the drawing, during which marks are placed relative to local landmarks and the line of the future route. Milestones 3–4 meters high are set on the verge of sight. The space between them is divided in 40 - 50 meters with pegs( up to half a meter).Straightness is determined visually relative to the first two milestones.
• At the second stage, the preparatory work is accepted by the commission, in case of a successful outcome, the installation of the cable begins directly under the ground.

When working in protective zones of engineering structures and highways, the presence of a representative of the operating organization is required. Especially if you plan to put the cable underground, for example, right in the roadside. Typical rules for laying communication lines are spelled out in the order of the Ministry of Transport of January 13, 2010In particular, it is said that the pillars are at least 50 meters away from the right of way. Otherwise installation is allowed if the customer pays for the reconstruction of the highway in the future( if the need arises).For federal roads, it is envisaged to leave a reserve on each side for a certain number of meters( 50–150) depending on the situation and passage( more strict than other requirements for Moscow and St. Petersburg directions).

The rules require the construction team brigade to instruct personnel. In the course of the instruction, it is examined what cable is needed for laying underground, nearby engineering structures are shown on the ground, and the rules of work are explained in order not to cause harm. Then compulsory punching is carried out( creating a network of inspection pits to eliminate illegal actions).Depth and shape depend on the specific situation. In the general case, the length of the hole is 1 meter along the axis of the route, the depth exceeds the total by 20 cm.

If during the excavation of the cable, communications unknown to builders are detected, the course is immediately suspended until the circumstances are ascertained. Similar occurs when unintentional damage to foreign routes or sabotage. A protective fence is being built, the operating organization is being informed.

The cable is laid along roads and railways. Mostly federal value. The liaison is buried with rare exceptions, and power are more often mounted on poles( which simplifies the repair process, provides the necessary degree of safety).Sometimes the route is allowed to cut( need to justify).In off-road conditions it is allowed to use other lands, including arable. When crossing highways and railways, the angle should be, as a rule, 90 degrees. A deviation of up to 45 degrees is allowed, but justification is required.

Soil characteristics for laying cable

Hardly need a section for a person who needs only the laying of the cable to the house underground. For informational purposes, the material is certainly interesting. Soils are divided according to the signs( a more complete classification is given in GOST 25100. Five groups are known, from which the progress of the work depends):

1. Specific density per cubic meter in the natural( undisturbed) state.
2. Specific density after compaction( depending on the means the figure is different).
3. Resistance to shear helps to calculate the need for a certain technique when laying the cable under the ground.
4. Specific density of a cubic meter after loosening.
5. Humidity, water saturation.
6. The maximum slope angle when the ground in its natural state holds its shape.

For handwork, the edges of the trench are fenced in so that the builders can see where to dig. The site of work is fenced with signaling devices on portable slingshots( within the city), sometimes at the request of the administration it is necessary to hang warning boards or fence the territory. There must be inscriptions with the name of the organization, leading work, telephone numbers. If you plan to dig near roads, the project is consistent with the local traffic police. When crossing the pits of the route, detours are indicated or a temporary bridge is erected to withstand a load of 10 tons( main streets) or 7 tons( entrance to the courtyard).Pedestrian bridges with handrails.

The opening of the roadbed - if required by laying the electric cable under the ground - is made by asphalt cutters( a trolley with a stone cutting disc, electric or gasoline) or jackhammers. There are specialized devices based on tractors and bulldozers. The process is accompanied by increased noise and the release of a huge amount of dust. The staff works in protective clothing. Cobblestone roads are allowed to dig immediately with an excavator. On each side of the trench, a small margin is taken( from 0.1 to asphalt to 0.2 for cobble stones).The development of deep pits requires additional wall reinforcement:

1. Sandy - with a depth of more than 1 meter.
2. Loamy - with a depth of 1.25 meters.
3. Clay - with a depth of 1.5 meters.
4. Especially dense - at a depth of more than 2 meters.

The maximum steepness of the slopes is taken in accordance with Table 2.4 of OSTN 600. Fixation is carried out according to the following schemes:

1. Horizontal-frame: several boards running along the trench are fixed with struts.
2. Solid horizontal: boards run lengthwise completely, from bottom to top.
3. Horizontal with prozor is the middle option between the two listed. Boards are not entirely, but they are enough to hold in place the soil.
4. Vertically frame: boards go across the trench, upwards.
5. Solid vertical: by analogy.
6. Mixed: joint options are used.

The boards are usually taken 4 cm thick, but for wet soils, the size should be increased to 5. Spacers are placed at least 1.5 meters with a vertical distance of 1 meter.

Laying the cable route under the

roadway. Rules for laying the cable underground require a large number of approvals. Often builders resort to horizontal drilling. It is carried out in several ways:

1. Puncture with soil compaction without excavation.
2. Drilling.
3. Puncture with steel case( pipe).

In most cases, regardless of the way the well is made, a PND pipe is subsequently installed for laying the cable under the ground. To facilitate sliding inside pour water, sometimes with the addition of oil. This greatly reduces the coefficient of friction, reduces the load when pulling the cable along the route. This fact allows you to put large pieces without the need to install couplings.

Products without armor require additional protection. Usually used corrugation for laying the cable under the ground. For power lines, there is a protective layer of slabs or bricks on top, above which a signal tape is laid. These measures are often not respected for voltages up to 1 kV.No need to think that the cable for laying underground in the country requires so many manipulations. Under arable land( read, garden), it is desirable to increase the depth of the trench to 1 meter( plus the height of the sand bedding cable).

The controlled trajectory of the punching of the line under the highway is realized with the help of various kinds of piercers. By means of flexible wiring, compressed air or another type of medium is injected. They differ in speed, the process can not be called fast. But in the same way, canals, rivers and other obstacles are being passed, where laying would require a lot of time and money. Some cables allow the organization of lines directly - on the bottom. As a rule, the screen shell is woven from small veins, the product is not afraid of small( but strong) deformations like ice.

Cable routing underground requires a thorough knowledge of the law.