Shopping mall for installation of load-bearing cable structures. Technological map for the installation of cable structures. Laying cable lines in cable blocks, pipes and reinforced concrete trays

Inside cable structures (premises), cables are laid on steel structures of various designs. A cable structure is a room specially designed for placing cables, cable and other equipment in it, designed to ensure normal operation.

General principles for laying cable lines

Cable structures include cable tunnels, channels, boxes, blocks, shafts, floors, double floors, cable racks, galleries, chambers, feed points.

Cable structures must be separated from other rooms and neighboring cable structures by fireproof partitions and ceilings.

With the same partitions, long tunnels should be divided into compartments no longer than 150 m when laying power and control cables and no more than 100 m with oil-filled cables. In cable structures, measures must be taken to prevent the ingress of process water and oils into them, and soil and storm water must also be drained.

Inside cable structures, cables are laid on steel structures of various designs. Cables of large cross sections (aluminum with a cross section of 25 mm2 or more, copper with a cross section of 16 mm2 or more) are laid directly on the structures.

Power cables of smaller cross sections and control cables are laid in trays (welded or perforated) or in boxes that are mounted on cable structures or on walls. Laying in trays is more secure and has a better appearance than open laying on structures.

Cable structures, with the exception of overpasses, wells for couplings, channels and chambers, must be provided with natural or artificial ventilation.

Ventilation devices are equipped with dampers to stop air access in case of fire, as well as to prevent freezing of the tunnel in winter time.

When laying cables indoors, overheating of the cables must be prevented by increasing the ambient temperature and the influence technological equipment(it is not allowed to lay cables near the oil pipeline, above and below oil pipelines and pipelines with flammable liquid). In the floor and interfloor ceilings, cables are laid in channels or pipes. It is forbidden to lay cables in ventilation ducts, as well as openly in stairwells.

Cable crossings of passages must be carried out at a height of at least 1.8 m from the floor.

Rules for laying cables in cable tunnels

Cable tunnels (and collectors, in which pipelines are also laid), are recommended to be built in cities and enterprises with compacted development of the territory or when the territory is highly saturated with underground engineering communications, as well as in the territories of large metallurgical, machine-building and other enterprises. Cable tunnels are constructed, as a rule, with the number of cables being laid from 20. Tunnels usually serve as trunk tunnels.

cable tunnels rectangular section are designed for double-sided and one-sided laying of cables and come in pass-through and semi-pass-through versions.

With a large number of cables, tunnels and rectangular collectors can be three-walled (double). In table. 5.6 shows the main dimensions of rectangular tunnels.

The use of semi-passage tunnels is allowed in places where underground communications prevent the passage tunnel from being completed; at the same time, a semi-through tunnel is accepted with a length of not more than 15 m and for cables with a voltage of not more than 10 kV.

The width of passages in cable tunnels and collectors must be at least 1 m, however, it is allowed to reduce the width of passages to 800 mm in sections no longer than 500 mm.

Long cable tunnels and collectors are divided along the length by fire-resistant partitions into compartments no longer than 150 m long with doors installed in them. The laying of cables in collectors and tunnels is calculated taking into account the possibility of additional laying of cables in an amount of at least 15%.

With double-sided arrangement of cable structures, control cables should be placed, if possible, on the opposite side from the power cables. With one-sided arrangement of structures, control cables should be placed under power cables and separated by a horizontal partition.

Power cables up to 1 kV should be laid under the cables voltage above 1 kV and separate them with a horizontal partition. Various groups of cables (working and standby voltages above 1 kV) are recommended to be laid on different shelves with their separation by horizontal fireproof partitions. As partitions, it is recommended to use asbestos-cement pressed unpainted slabs with a thickness of not less than 8 mm.

Application in cable tunnels of unarmored cables with a polyethylene sheath according to the conditions fire safety prohibited.

Cables laid horizontally along the structures are rigidly fixed at the end points, at the turns of the route, on both sides of the cable bend, at the connecting and end terminations. Cables laid vertically along structures and walls are fixed on each cable structure. In places of attachment between unarmoured cables with a lead or aluminum sheath, metal support structures and a metal bracket, gaskets made of elastic material (rubber sheet, polyvinyl chloride sheet) with a thickness of at least 2 mm must be laid, protecting the sheath from mechanical damage. Unarmored cables with a plastic sheath can be fastened with brackets (clamps) without gaskets.

The metal armor of cables laid in tunnels must have an anti-corrosion coating.

Rules for laying cable in channels

Cable laying in cable channels are widely used. Cable channels are made standard from prefabricated reinforced concrete elements or from monolithic reinforced concrete (Fig. 5.7). AT industrial premises the channels are covered with slabs at floor level.

When passing outside buildings in unprotected areas, the channels are laid underground at a depth of at least 300 mm, depending on the loads that may occur on the route.

If the territory is protected, then semi-underground channels with natural or artificial ventilation are used. But such channels should not interfere with transport communications and should not be combined with the general layout of the territory of the enterprise, since the level of overlap of such channels rises above the planning mark by 50 ... 250 mm.

Cables in the channels are laid on structures of various designs; laying along the bottom of the channel is also possible. The number of cables in the channel can be different and depends on the diameters of the cables and the brand of the typical channel; up to 50 ... 60 power cables can be placed in channels of maximum dimensions. If it is necessary to lay a large number of cables, it is possible to use double or three-walled channels, but this complicates the implementation of branches to individual consumers.

The method of laying cables in channels allows for inspections and repairs of cable lines during operation, as well as laying a new or replacing an existing cable without production earthworks.

When laying cables in channels, their reliable protection from mechanical damage.

In table. 5.7 shows the main dimensions of unified cable channels (designations B, B, H in Fig. 5.7).

The main straight tray channels, ceilings to them, as well as the main elements of prefabricated channels have a length of 3 m. 3×240 mm2, with cable bending radius R = 25d.

In areas where molten metal, liquids with high temperatures or substances that destroy the cable sheaths can be spilled, the construction of cable channels is not allowed.

Cable ducts outside buildings should be covered with earth over removable slabs with a layer thickness of 300 mm or more. In fenced areas accessible only to service personnel, for example, at substations, backfilling of cable channels over removable plates is prohibited.

Backfilling of power cables laid in channels is prohibited. The location of cables on structures, depending on the size of the channels, can be:

• on one wall of the channel on suspensions;
• on one wall of the channel on the shelves;
• on both walls on suspensions;
• on one wall of the channel on hangers, on the other wall on shelves;
• on both walls of the channel on the shelves;
• at the bottom of the channel with a depth of not more than 0.9 m.

Cable channels should be calculated taking into account the possibility of additional laying of cables at least 10% of those laid. The horizontal clear distance between the structures with their two-sided arrangement (passage width) must be at least 300 mm for channels up to 600 mm deep and at least 400 mm for channels with a depth of 900 and 1,200 mm.

Wiring are integral part electrical power and lighting networks of alternating and direct current with voltage up to 1 kV. Depending on the designs of conductors, the characteristics of the premises and environment conductors are laid in various ways: openly on insulating supports or directly on building foundations and structures, in pipelines, on steel trays, in steel boxes, along stretched steel cables and strings, and also hidden in structural elements buildings.

According to the accepted method of laying conductors, electrical wiring is divided into open and hidden. In industrial buildings, in order to generally reduce the cost of work and save metal, it is recommended to use open tubeless wiring or replace steel pipes with non-metallic ones.

For open pipeless wiring, unprotected insulated wires and unarmored cables are used, so the routes of such wiring at their location must ensure the safety of the wiring from possible damage. Under normal operating conditions, indoor wiring is considered sufficient protection. at a height of at least 2.0 ... 2.5 m from the mark of the clean floor or service platform and at a height of at least 3.5 ... 6.0 m from the ground level outside the premises. In necessary cases, open wiring is protected from touch and mechanical damage with special boxes or pipes.

Open wiring takes up a lot of space and increases fire hazard, worsen the appearance of buildings and premises, but in general they are much more economical than hidden wiring. Hidden electrical wiring is carried out in the structural elements of buildings, in walls, floors, ceilings, special channels. Office, office, residential premises are now carried out only by hidden wiring.

Rules for laying cable in trays

When the number of wires and cables laid along common routes in industrial premises is very large, it is advisable to use cable laying on trays. Trays are designed for:

• open laying of cables in dry, damp and hot rooms;
• premises with a chemically active environment;
• fire hazardous premises for laying wires and cables allowed for such premises;
• cable half-floors and basements of electric machine rooms;
• passages behind shields and panels of control stations and transitions between them;
• technical floors of buildings and structures.

This electrical power sewerage system is highly flexible, greatly facilitating installation and operation. Tray wiring provides good cooling conditions for the cables, provides great savings and reduces the cost of work compared to other types of wiring.

The trays create free access to the cables throughout their length. If necessary, the cables can be easily removed and replaced by others; at the same time, you can change their number, section, brand, and also the route.

When using trays, it is easier to carry out wiring on complex routes, it is possible to arrange a branch on any section of the route of the tray line.

Trays are made of steel profiles and strips. Two types of trays are used: welded (length 2; 2.5 and 3 m, width 400, 200, 100 and 50 mm) and from perforated strips (length 2 m, width 50 and 105 mm). Trays of both types are equipped with connecting corners and bolts for connecting the trays into a trunk. Individual trays and tray lines can be positioned horizontally, vertically and obliquely.

Cables on trays should be laid in one row.

Unarmored cables with voltage up to 1 kV with a cross section of conductors up to 25 mm2 are allowed to be laid in trays in multilayer, bundles and single-layer without gaps. The height of the layers of cables laid in multilayer should be no more than 150 mm. The height (diameter) of the beam should be no more than 100 mm. The distance between bundles of power cables must be at least 20 mm; the distance between bundles of control cables, as well as power and control cables, is not standardized.

Fastening of cables laid in trays on straight sections of the route, with horizontal installation trays are not required; at any other location of the trays, the cables are attached to the trays with an interval of no more than 2 m.

Rules for laying a cable on a cable

In cases where other types of cable laying cannot be applied for technological, structural or economic reasons, cable laying on cables (on a steel rope) is used. The laying of power cables on cables is used in networks with a voltage of up to 1 kV, both indoors (workshops) and outside them. Cable wiring on cables indoors is carried out along columns along and across the building, as well as between walls, and outdoors - as a rule, between the walls of buildings.

For power lines laid on a cable, the same cables are used as for laying inside buildings and structures. Cables laid outside buildings, including under open sheds, must have a protective non-combustible outer coating.

The choice of cable is made depending on the bearing load.

Ropes woven from galvanized steel wires and hot-rolled galvanized steel wire are used as a carrier cable.

The distance between the anchor fastenings of the carrying cable should be no more than 100 m.

The distance between intermediate fasteners should be no more than 30 m when laying one or two cables with a cross section of up to 70 mm2, 12 m when laying more than two cables with a cross section of 70 mm2 and in all cases of laying cables with a cross section of 95 mm2 or more. The distance between cable hangers should be 0.8…1.0 m.

Anchor end structures are attached to building walls or building columns; fastening them to beams and trusses is not allowed.

Rules for laying cables on overpasses and galleries

Flyovers and galleries are an alternative to tunnels and blocks; functionally, they have the same purpose - to organize large cable flows and protect them from mechanical and other damage.

Laying cables with voltage up to 10 kV with a cross section up to 240 mm2 on overpasses and in galleries is used for main and intershop electrical networks in the territories of industrial enterprises.

The use of special cable racks is recommended as the main type of cable laying on the territories of chemical and petrochemical enterprises, where the possibility of spillage of substances destructively acting on cable sheaths is not excluded, at enterprises where the level ground water close to the surface.

It is allowed to use technological racks for combined laying of pipelines and cables. The main types of cable racks are impassable reinforced concrete, metal and combined.

Impassable overpasses are used for:

• laying up to 16, 24 and 40 cables with spans between supports of 6 m,
• for laying 24 and 48 cables - 12 m;

One and two-section flyovers - for laying up to 64 and 128 cables with spans of 6 and 12 m.

The vertical distance between the shelves on impassable overpasses is 200 mm, on walk-throughs - 250 mm.

The horizontal distance between the shelves is 1 m, but it can be increased when developing a specific project, taking into account the load-bearing capacity of cable structures. When laying cables in an aluminum sheath with a cross section of 50 mm2 or more, the distance between cable structures is allowed up to 6 m.

The cable sag between structures should be 0.4 m.

For laying on overpasses, cables without an outer combustible cover, having anti-corrosion protection, or with an outer protective cover made of non-combustible material, should be used.

Systems of cable structures designed for laying cables and installing other electrical equipment on them, electrical installations and / or communication networks, can also be used to separate cables and form them into streams (groups). The system of cable structures includes mounting trays LM (cable trays), load-bearing trays NL (cable ladders), cable racks and supports (cantilever brackets), brackets and connectors.

Each type of special structure for laying cables is characterized by the maximum number of power cables that can be laid in it. Trench - 6 cables, channel -24, block - 20, tunnel - 72, flyover - 24, gallery - 56.

There is rarely a preference for any one type of cabling. Usually a mixed gasket is used when, depending on the specific conditions, a combined version is appropriate. various ways laying cable lines.

Cable lines of industrial enterprises can be divided into intra-shop and non-shop. Intra-workshop cable networks include laying cables openly on structures, in trays, boxes, channels, tunnels and pipes.

In rooms, hidden laying of wires and cables in steel pipes is gradually being replaced by open laying. Exposed cable routing almost completely eliminates production dependency installation work for laying cables from the readiness of the construction part of the structure. Open laying of cables allows you to complete the zero cycle of construction work without waiting for the completion of electrical work, which is impossible with hidden laying. Open cable runs are visible, accessible, convenient for inspection and replacement of cables, and are flexible when changing routes during the reconstruction of electrical installations.

When laying cables openly, one should observe fire safety measures, justify the choice of brands of cables and sheaths, choose the right cable for heating, control the quality of connections and the order of cable laying, separate the zones of mass cable laying from equipment. When laying open cables in electrical and industrial premises, one should strive to combine routes, combine cables for various purposes(power, lighting, control cables) into common flows, laying them on common structures, trays or boxes.

Laying cable lines on walls and cable structures

In industrial premises and cable structures, various designs are used for laying cables and wires. The installation of structures at the facility is a significant amount of electrical work, so the structures must meet a high degree of prefabrication and have a small mass. Cable structures are produced in normal and chemically resistant.

a - cable rack, b - shelf, c - bracket for attaching the cable rack, d - key for attaching the shelf to the rack

Figure 3. - Prefabricated cable structures

Prefabricated cable structures (Figure 3) are designed for laying electrical cables, as well as installing trays and boxes on them. They are installed along the walls of rooms, canals, tunnels, wells and other building structures. The distance between cable structures on horizontal sections of the route is 0.8 - 1 m, on vertical sections - 2 m.

The structure of the cable structure includes racks, shelves, brackets and a key. Racks are made with a height of H 400 - 1800 mm (Fig. NUMBERING, a) from sheet steel with perforation, which has a pitch of 50 mm, which allows you to install shelves with distances between them of 100, 150 mm, etc. The cable structure does not require welding shelves to racks. The shelf is inserted into the rack and mechanically secured with a key. The reliability of the mechanical engagement of the shelf with the rack provides the necessary electrical contact for grounding the shelves. Racks are attached to building bases with brackets by shooting or welding to embedded parts.

To obtain a cable structure of the required height, the racks can be vertically joined together in any combination. The shelves are made in length (overhang l) 160 - 450 mm (Figure 3, b), which allows you to complete the rack with shelves of different lengths.

1 - perforated channel, 2 - embedded suspension

Figure 4 - Cable structures for single cables

For laying single cables, cable structures are used, consisting of perforated channels and embedded hangers (Figure 4), which are inserted into the channel perforation hole with the narrow side of the shank and rotated by 90 °. Hangers are produced in three standard sizes for cables with an outer diameter of 20, 35 and 50 mm.

For fastening cables to various bases, single-blade and two-blade brackets are used (Figure 5).

a, b - single-arm and two-arm for fastening with screws or bolts, c - two-arm for shooting

Rice. 5 - Clamps for cables

Trays are used for laying power and control cables and wires with voltage up to 1000 V and are made of perforated bent metal sheet. The width of the tray is 50, 100, 200 and 400 mm, the length is 2 m. The range of trays includes elements ready for assembly that ensure the creation of a route with the necessary turns and branches in the horizontal and vertical planes (Figure 6).

1, 2 - straight lines with a width of 50, 100 or 200, 400 mm, 3 - angular. 4, 5 - transition and swivel connectors, 6 - clamps, 7 - hangers

Figure 6 - Trays

The trays are connected with bolts, which ensures a reliable electrical circuit, which is necessary for the grounding network. Mount trays on brackets, hangers and prefabricated cable structures. Trays mounted on supporting structures are fixed in such a way that the possibility of slipping, overturning and falling them is excluded.

When trays intersect with other communications, the trays are laid indented from the walls, if this is not possible, bypasses are performed.

Boxes have a purpose similar to trays.

For straight sections of the route, a straight box is used, for branching into four directions - a cruciform box, for changing the direction of the route in the horizontal and vertical planes - an angular one, for entering electrical devices - a connecting one. In addition, the box set includes: an end cap for closing the end of the box and a clamp for fixing wires and cables. The boxes are made single-channel with a length of 2 and 3 m and are calculated for uniformly distributed loads (the distance between the attachment points is 3 m).

The boxes are designed for laying wires and cables in them with a bending radius of up to 50 mm.

In cable tunnels, channels, shafts and industrial premises, cables are laid along cable structures and in boxes. Cable structures, ducts and fasteners necessary for laying and fastening cables are produced by industrial enterprises of Glavelektromontazh.

Prefabricated cable structures consist of racks with special holes in which consoles are installed, made with and without perforation. Prefabricated cable structures are intended for direct laying of armored cables over them. When laying unarmored cables on prefabricated cable structures, solid fireproof partitions made of asbestos-cement boards under metal cable trays should be laid.

Cable ducts are produced in the KP and KKB series. Boxes of the KP series (Fig. 5) are used for multilayer laying of control cables under and above service platforms in the main building and auxiliary facilities of power plants, as well as in galleries along overpasses and in cable floors. The set of boxes includes straight, angled and tee sections, which makes it possible to assemble any cable route from them. The gearbox box section consists of a body, a cover and fasteners.

Boxes block series KKB (Fig. 5) are used for joint laying of power and control cables both inside the main building and auxiliary structures, and across the territory of power plants and outdoor switchgear. The boxes have an angle steel frame and a steel sheet skin. Cable consoles are installed inside the boxes. For the possibility of completing the cable route, elements of straight and corner boxes are produced.

Installation of cable structures should be started after the completion of plastering, whitewashing and painting of walls and building structures along which the cable route passes.

To fasten cable structures along the entire length of the cable route, 50x5 mm guide strips are laid from strip steel, two in number for tunnels and channels 900 and 1200 mm high and one for channels less than 900 mm high. These strips are also used as grounding lines and therefore must be securely welded along the entire length and connected along the route in two places to a common ground loop. The guide strips are welded to the embedded parts or attached to the building base with dowels fired with a mounting gun.

Fig 5. Left KP series box: 1-pin; 2 - cover; 3 - clamping bar; 4 - gasket; 5 - box body; 6 - cables or wires; 7 - cable structure bracket: 8 - insulating tube; 9-nut: 10-pillar On right- Cable boxes of the KKB series: a - box assembly; b - self-supporting span of the box; 1.2-corner box for horizontal rotation by 225 ° type KKB-UGN; 3 - direct type KKB-P; 4. 5 - angular type KKB-UN; 6 - direct type KKB-PO

Prefabricated cable structures are welded to the guide strips vertically and at the same height so that the corresponding shelves of all structures are on the same straight line. The distance between cable structures is maintained within 800-1000 mm. In places where the cable route turns, the distance between the structures is chosen in such a way that the permissible bending radius of the cables is maintained.

Metal trays are installed over cable structures when unarmored cables are laid through them. Trays are attached to structures with bolts or wedges or welded by electric welding. The connection of the trays is also carried out by bolts or welding. On the vertical sections of the cable route, the distance between the supporting structures should be no more than 2 m for cables of all brands, except for unarmored cables with rubber insulation of small sections, for which this distance should be no more than 0.7 m.

KP series cable ducts are installed on cable shelves, brackets or suspended on cables. The connection of the duct sections and the continuous earthing circuit are carried out by means of bolts or by welding. Boxes of the KKB series are self-supporting and can be attached to the supports assembled in blocks with a distance between the supports from 3 to 12 m. To increase fire safety, fire barriers are provided in the boxes KP and KKB. The boxes must be grounded in each room at least in two places.

Staples, buckles and other parts are used to fasten cables to structures.

2.3.1. This chapter of the Rules applies to cable power lines up to 220 kV, as well as lines performed by control cables. Cable lines of higher voltages are made according to special projects. Additional requirements for cable lines are given in Ch. 7.3, 7.4 and 7.7.

2.3.2. A cable line is a line for the transmission of electricity or its individual impulses, consisting of one or more parallel cables with connecting, locking and end sleeves (terminals) and fasteners, and for oil-filled lines, in addition, with feeders and an oil pressure alarm system.

2.3.3. A cable structure is a structure specially designed to accommodate cables, cable boxes, as well as oil feeders and other equipment designed to ensure the normal operation of oil-filled cable lines. Cable structures include: cable tunnels, channels, boxes, blocks, shafts, floors, double floors, cable racks, galleries, chambers, feeding points.

A cable tunnel is a closed structure (corridor) with supporting structures located in it for placing cables and cable boxes on them, with free passage along the entire length, which allows cable laying, repairs and inspections of cable lines.

A cable channel is a closed and buried (partially or completely) in the ground, floor, ceiling, etc., an impassable structure designed to accommodate cables in it, laying, inspecting and repairing which can only be done with the ceiling removed.

A cable shaft is a vertical cable structure (usually of rectangular section), whose height is several times greater than the side of the section, equipped with brackets or a ladder for people to move along it (walk-through shafts) or a completely or partially removable wall (impassable mines).

A cable floor is a part of a building bounded by a floor and a floor or cover, with a distance between the floor and the protruding parts of the floor or cover of at least 1.8 m.

A double floor is a cavity bounded by the walls of the room, the interfloor overlap and the floor of the room with removable slabs (on the whole or part of the area).

A cable block is a cable structure with pipes (channels) for laying cables in them with wells related to it.

A cable chamber is an underground cable structure, closed with a deaf removable concrete slab, designed for laying cable boxes or for pulling cables into blocks. A chamber that has a hatch to enter it is called a cable well.

A cable overpass is an elevated or ground open horizontal or inclined extended cable structure. Cable overpass can be passable or non-passage.

A cable gallery is an overground or ground closed completely or partially (for example, without side walls) horizontal or inclined extended cable structure.

2.3.4. It is called a box - see 2.1.10.

2.3.5. It is called a tray - see 2.1.11.

2.3.6. Cable oil-filled line of low or high pressure the line is called, in which the long-term permissible overpressure is:

0.0245-0.294 MPa (0.25-3.0 kgf/cm) for low-pressure lead-sheathed cables;

0.0245-0.49 MPa (0.25-5.0 kgf/cm) for low pressure cables in aluminum sheath;

1.08-1.57 MPa (11-16 kgf/cm) for high pressure cables.

2.3.7. A section of a low-pressure oil-filled cable line is the section of the line between the stop sleeves or the stop and end sleeves.

2.3.8. A feeding point is an above-ground, ground or underground structure with feeding devices and equipment (feed tanks, pressure tanks, feeding units, etc.).

2.3.9. A branching device is a part of a high-pressure cable line between the end of a steel pipeline and end single-phase couplings.

2.3.10. A feeding unit is an automatically operating device consisting of tanks, pumps, pipes, bypass valves, valves, an automation panel and other equipment designed to provide high-pressure cable line oil feeding.

General requirements

2.3.11. The design and construction of cable lines should be carried out on the basis of technical and economic calculations, taking into account the development of the network, the responsibility and purpose of the line, the nature of the route, the laying method, cable structures, etc.

2.3.12. When choosing a cable line route, areas with soils that are aggressive with respect to the metal sheaths of cables should be avoided, if possible (see also 2.3.44).

2.3.13. Above underground cable lines, in accordance with the current rules for the protection of electrical networks, security zones should be established in the size of the area above the cables:

for cable lines above 1 kV, 1 m on each side of the outermost cables;

for cable lines up to 1 kV, 1 m on each side of the outermost cables, and when cable lines pass in cities under sidewalks - 0.6 m towards buildings and 1 m towards the carriageway of the street.

For submarine cable lines up to and above 1 kV, in accordance with the indicated rules, a security zone should be established, defined by parallel straight lines at a distance of 100 m from the outermost cables.

Security zones of cable lines are used in compliance with the requirements of the rules for the protection of electrical networks.

2.3.14. The route of the cable line should be selected taking into account the lowest cable consumption, ensuring its safety under mechanical stress, ensuring protection against corrosion, vibration, overheating and damage to neighboring cables by an electric arc in the event of a short circuit on one of the cables. When placing cables, avoid crossing them with each other, with pipelines, etc.

When choosing the route of a low-pressure oil-filled cable line, the terrain is taken into account for the most rational placement and use of make-up tanks on the line.

2.3.15. Cable lines must be designed in such a way that during installation and operation, the occurrence of dangerous mechanical stresses and damages in them is excluded, for which:

cables must be laid with a margin in length sufficient to compensate for possible displacements of the soil and temperature deformations of the cables themselves and the structures along which they are laid; laying the cable stock in the form of rings (coils) is prohibited;

cables laid horizontally along structures, walls, ceilings, etc., must be rigidly fixed at the end points, directly at the end fittings, on both sides of the bends and at the connecting and locking couplings;

cables laid vertically along structures and walls must be fixed in such a way that deformation of the sheaths is prevented and the connections of the cores in the couplings are not broken under the action of the own weight of the cables;

structures on which unarmored cables are laid must be designed in such a way that the possibility of mechanical damage to the cable sheaths is excluded; in places of rigid fastening, the sheaths of these cables must be protected from mechanical damage and corrosion with the help of elastic gaskets;

cables (including armored ones) located in places where mechanical damage is possible (movement of vehicles, mechanisms and goods, accessibility for unauthorized persons) must be protected in height by 2 m from the floor or ground level and by 0.3 m in earth;

when laying cables next to other cables in operation, measures must be taken to prevent damage to them;

cables should be laid at a distance from heated surfaces, which prevents the cables from heating above the permissible level, while protecting the cables from the breakthrough of hot substances at the installation sites of valves and flange connections should be provided.

2.3.16. Protection of cable lines against stray currents and soil corrosion must meet the requirements of these Rules and SNiP 3-04.03-85 "Protection of building structures and structures against corrosion" of the State Construction Committee of Russia.

2.3.17. The structures of underground cable structures must be calculated taking into account the mass of cables, soil, road surface and the load from passing traffic.

2.3.18. Cable structures and structures on which cables are laid must be made of non-combustible materials. It is forbidden to perform any temporary devices in cable structures, store materials and equipment in them. Temporary cables must be laid in compliance with all requirements for cable laying, with the permission of the operating organization.

2.3.19. Open laying of cable lines should be carried out taking into account the direct action of solar radiation, as well as heat radiation from various types of heat sources. When laying cables at a geographic latitude of more than 65 °, protection from solar radiation is not required.

2.3.20. The radii of the inner bending curve of the cables must have, in relation to their outer diameter, a multiplicity of not less than those specified in the standards or specifications for the corresponding brands of cables.

2.3.21. The radii of the internal bending curve of the cable cores when making cable terminations must have, in relation to the reduced core diameter, a multiplicity of at least those specified in the standards or specifications for the corresponding cable brands.

2.3.22. The tensile forces during laying cables and pulling them in pipes are determined by the mechanical stresses allowed for the cores and shells.

2.3.23. Each cable line must have its own number or name. If the cable line consists of several parallel cables, then each of them must have the same number with the addition of the letters A, B, C, etc. Openly laid cables, as well as all cable boxes, must be tagged with the designation on the cable tags and end couplings of the brand, voltage, section, number or name of the line; on the tags of the couplings - the number of the coupling and the date of installation. Labels must be resistant to environmental influences. On cables laid in cable structures, tags must be located along the length at least every 50 m.

2.3.24. Protective zones of cable lines laid in the ground in undeveloped areas must be marked with information signs. Information signs should be installed at least every 500 m, as well as in places where the direction of cable lines changes. The information signs should indicate the width of the security zones of cable lines and the telephone numbers of cable line owners. (see Appendix "Requirements for information signs and their installation")

Choice of laying methods

2.3.25. When choosing methods for laying power cable lines up to 35 kV, you must be guided by the following:

1. When laying cables in the ground, it is recommended to lay no more than six power cables in one trench. With a larger number of cables, it is recommended to lay them in separate trenches with a distance between cable groups of at least 0.5 m or in channels, tunnels, overpasses and in galleries.

2. Laying cables in tunnels, overpasses and in galleries is recommended when the number of power cables running in one direction is more than 20.

3. Laying cables in blocks is used in conditions of great constraint along the route, at intersections with railway tracks and driveways, with the likelihood of a metal spill, etc.

4. When choosing methods for laying cables across urban areas, the initial capital costs and costs associated with the production of maintenance and repair work, as well as the convenience and cost-effectiveness of maintaining structures, should be taken into account.

2.3.26. On the territories of power plants, cable lines should be laid in tunnels, ducts, channels, blocks, overpasses and in galleries. Laying power cables in trenches is allowed only to remote auxiliary facilities (fuel depots, workshops) with no more than six. In the territories of power plants with a total capacity of up to 25 MW, it is also allowed to lay cables in trenches.

2.3.27. On the territories of industrial enterprises, cable lines should be laid in the ground (in trenches), tunnels, blocks, channels, overpasses, in galleries and along the walls of buildings.

2.3.28. On the territories of substations and switchgears, cable lines should be laid in tunnels, ducts, channels, pipes, in the ground (in trenches), ground reinforced concrete trays, along overpasses and in galleries.

2.3.29. In cities and towns, single cable lines should, as a rule, be laid in the ground (in trenches) along the impassable part of the streets (under sidewalks), in yards and technical lanes in the form of lawns.

2.3.30. On streets and squares saturated with underground utilities, it is recommended to lay cable lines in the amount of 10 or more in a stream in collectors and cable tunnels. When crossing streets and squares with improved coatings and with heavy traffic, cable lines should be laid in blocks or pipes.

2.3.31. When constructing cable lines in permafrost areas, one should take into account physical phenomena associated with the nature of permafrost: heaving soil, frost cracks, landslides, etc. Depending on local conditions, cables can be laid in the ground (in trenches) below the active layer, in the active layer in dry, well-draining soils, in artificial embankments from large-skeletal dry imported soils, in trays on the surface of the earth, on overpasses. Joint laying of cables with heating pipelines, water supply, sewerage, etc. in special structures (collectors) is recommended.

2.3.32. Implementation different types cable laying in permafrost areas should be carried out taking into account the following:

1. For laying cables in earthen trenches, the most suitable soils are draining soils (rocky, pebble, gravel, crushed stone and coarse sand); heaving and subsidence soils are unsuitable for laying cable lines in them. It is allowed to lay cables directly in the ground with no more than four cables. Due to ground-frozen and climatic conditions, it is prohibited to lay cables in pipes laid in the ground. At intersections with other cable lines, roads and underground utilities, cables should be protected with reinforced concrete slabs.

Laying cables near buildings is not allowed. The entry of cables from the trench into the building in the absence of a ventilated underground must be carried out above the zero mark.

2. Laying cables in channels is allowed to be used in places where the active layer consists of non-rocky soils and has a flat surface with a slope of not more than 0.2%, which ensures the runoff of surface water. Cable channels should be made of waterproof reinforced concrete and covered with reliable waterproofing from the outside. From above, the channels must be closed with reinforced concrete slabs. Channels can be made deep into the ground and without deepening (above the ground). In the latter case, under the channel and near it, a pillow with a thickness of at least 0.5 m from dry soil should be made.

2.3.33. Inside buildings, cable lines can be laid directly along building structures (openly and in boxes or pipes), in channels, blocks, tunnels, pipes laid in floors and ceilings, as well as on machine foundations, in mines, cable floors and double floors.

2.3.34. Oil-filled cables can be laid (with any number of cables) in tunnels and galleries and in the ground (in trenches); the way they are laid is determined by the project.

Cable selection

2.3.35. For cable lines laid along routes running in various soils and environmental conditions, the choice of cable designs and cross-sections should be made for the section with the most severe conditions, if the length of the sections with lighter conditions does not exceed the construction length of the cable. With a significant length of individual sections of the route with various conditions gaskets for each of them, you should choose the appropriate design and cable cross-sections.

2.3.36. For cable lines laid along routes with different cooling conditions, the cable sections should be selected along the section of the route with the worst cooling conditions, if its length is more than 10 m. It is allowed for cable lines up to 10 kV, with the exception of submarine ones, the use of cables of different sections, but not more than three, provided that the length of the smallest segment is not less than 20 m (see also 2.3.70).

2.3.37. For cable lines laid in the ground or water, armored cables should be used predominantly. The metal sheaths of these cables must have an outer jacket to protect them from chemical attack. Cables with other external designs protective coatings(non-armored) must have the necessary resistance to mechanical stress when laying in all types of soil, when drawn in blocks and pipes, as well as resistance to thermal and mechanical stress during maintenance and repair work.

2.3.38. Pipelines of high-pressure oil-filled cable lines laid in earth or water must be protected against corrosion in accordance with the design.

2.3.39. In cable structures and industrial premises, if there is no danger of mechanical damage in operation, it is recommended to lay unarmored cables, and if there is a danger of mechanical damage in operation, armored cables or their protection from mechanical damage should be used.

Outside cable structures, it is allowed to lay unarmored cables at an inaccessible height (at least 2 m); at a lower height, the laying of unarmored cables is allowed provided that they are protected from mechanical damage (boxes, angle steel, pipes, etc.).

For mixed laying (ground - cable structure or industrial premises), it is recommended to use the same brands of cables as for laying in the ground (see 2.3.37), but without combustible outer protective covers.

2.3.40. When laying cable lines in cable structures, as well as in industrial premises, armored cables should not have protective covers made of combustible materials over the armor, and unarmored cables over metal sheaths.

For open laying, it is not allowed to use power and control cables with combustible polyethylene insulation.

Metal sheaths of cables and metal surfaces along which they are laid must be protected with a non-combustible anti-corrosion coating.

When laying in rooms with an aggressive environment, cables resistant to this environment must be used.

2.3.41. For cable lines of power plants, switchgears and substations specified in 2.3.76, it is recommended to use cables armored with steel tape protected by a non-combustible coating. At power plants, the use of cables with combustible polyethylene insulation is not allowed.

2.3.42. For cable lines laid in cable blocks and pipes, as a rule, unarmoured cables in a lead reinforced sheath should be used. In sections of blocks and pipes, as well as branches from them up to 50 m long, it is allowed to lay armored cables in a lead or aluminum sheath without an outer cover of cable yarn. For cable lines laid in pipes, it is allowed to use cables in a plastic or rubber sheath.

2.3.43. For laying in soils containing substances that have a destructive effect on cable sheaths (salt marshes, swamps, bulk soil with slag and building material etc.), as well as in areas hazardous due to the effects of electrical corrosion, cables with lead sheaths and reinforced protective covers of types B, B or cables with aluminum sheaths and especially reinforced protective covers of types B, B (in continuous moisture resistant plastic hose).

2.3.44. In places where cable lines cross swamps, cables should be selected taking into account geological conditions, as well as chemical and mechanical influences.

2.3.45. For laying in soils subject to displacement, cables with wire armor should be used or measures should be taken to eliminate the forces acting on the cable during soil displacement (reinforcement of the soil with sheet piles or pile rows, etc.).

2.3.46. In places where cable lines cross streams, their floodplains and ditches, the same cables should be used as for laying in the ground (see also 2.3.99).

2.3.47. For cable lines laid on railway bridges, as well as on other bridges with heavy traffic, it is recommended to use armored cables in an aluminum sheath.

2.3.48. For cable lines of mobile mechanisms, flexible cables with rubber or other similar insulation that can withstand multiple bends should be used (see also 1.7.111).

2.3.49. For submarine cable lines, cables with round wire armor should be used, if possible of the same construction length. For this purpose, the use of single-core cables is permitted.

In places where cable lines cross from the shore to the sea in the presence of strong sea surf, when laying the cable in sections of rivers with strong currents and eroded banks, as well as at great depths (up to 40-60 m), a cable with double metal armor should be used.

Cables with rubber insulation in a PVC sheath, as well as cables in an aluminum sheath without special waterproof coatings for laying in water are not allowed.

When laying cable lines through small non-navigable and non-alloyable rivers with a width (together with a floodplain) of no more than 100 m, with a stable channel and bottom, it is allowed to use cables with tape armor.

2.3.50. For oil-filled cable lines with a voltage of 110-220 kV, the type and design of the cables are determined by the project.

2.3.51. When laying cable lines up to 35 kV on vertical and inclined sections of the route with a level difference exceeding the allowable according to GOST for cables with viscous impregnation, cables with non-draining impregnating mass, cables with depleted impregnated paper insulation and cables with rubber or plastic insulation should be used. For the specified conditions, cables with viscous impregnation can only be used with locking sleeves located along the route, in accordance with the permissible level differences for these cables in accordance with GOST.

The difference in vertical marks between the locking sleeves of low-pressure oil-filled cable lines is determined by the corresponding specifications on the cable and calculation of make-up at limiting thermal conditions.

2.3.52. Four-wire networks must use four-wire cables. Laying of zero conductors separately from phase conductors is not allowed. It is allowed to use three-core power cables in an aluminum sheath with a voltage of up to 1 kV using their sheath as a neutral wire (fourth core) in four-wire AC networks (lighting, power and mixed) with a solidly grounded neutral, with the exception of installations with an explosive environment and installations in which, under normal operating conditions, the current in neutral wire is more than 75% of the allowable continuous current of the phase conductor.

The use of lead sheaths of three-core power cables for this purpose is allowed only in reconstructed urban electrical networks 220/127 and 380/220 V.

2.3.53. For cable lines up to 35 kV, it is allowed to use single-core cables if this leads to significant savings in copper or aluminum in comparison with three-core ones, or if it is not possible to use a cable of the required construction length. The cross section of these cables must be selected taking into account their additional heating by currents induced in the sheaths.

Measures must also be taken to ensure equal distribution of current between cables connected in parallel and safe contact with their sheaths, to exclude heating of metal parts located in the immediate vicinity and to securely fasten the cables in insulating clamps.

Feeding devices and oil pressure signaling of cable oil-filled lines

2.3.54. The oil feed system must ensure reliable operation of the line in any normal and transient thermal conditions.

2.3.55. The amount of oil in the oil feeding system should be determined taking into account the consumption for feeding the cable. In addition, there must be a supply of oil for emergency repairs and oil filling of the longest section of the cable line.

2.3.56. Feed tanks of low pressure lines are recommended to be placed indoors. A small number of feed tanks (5-6) at open food points are recommended to be placed in light metal boxes on portals, supports, etc. (at an ambient temperature of at least minus 30 ° C). Make-up tanks must be equipped with oil pressure gauges and protected from direct sunlight.

2.3.57. Feeding units of high-pressure lines must be placed in enclosed spaces with a temperature not lower than +10°C, and located as close as possible to the point of connection to cable lines (see also 2.3.131). Several feeding units are connected to the line through an oil manifold.

2.3.58. When laying several high-pressure oil-filled cable lines in parallel, it is recommended that each line be fed with oil from separate feeding units, or a device should be installed to automatically switch the units to one or another line.

2.3.59. Feeding units are recommended to be supplied with electricity from two independent power sources with a mandatory automatic transfer switch (ATS). Feeding units must be separated from one another by fireproof partitions with a fire resistance limit of at least 0.75 hours.

2.3.60. Each cable oil-filled line must have an oil pressure alarm system that provides registration and transmission to duty personnel of signals about a decrease and increase in oil pressure in excess of permissible limits.

2.3.61. At least two sensors must be installed on each section of the low pressure oil-filled cable line, and a sensor on each feeding unit should be installed on the high pressure line. Emergency signals should be transmitted to a point with constant duty of personnel. The oil pressure alarm system must be protected from the influence of electric fields of power cable lines.

2.3.62. Feeding points on low pressure lines must be equipped with telephone communication with control points (power grids, network area).

2.3.63. The oil pipeline connecting the collector of the feeding unit with the high-pressure oil-filled cable line must be laid in rooms with a positive temperature. It is allowed to lay it in insulated trenches, trays, channels and in the ground below the freezing zone, provided that a positive ambient temperature is ensured.

2.3.64. Vibration in the room of the switchboard with devices for automatic control of the feeding unit should not exceed the permissible limits.

Connections and cable terminations

2.3.65. When connecting and terminating power cables, coupling designs should be used that correspond to their operating conditions and the environment. Connections and terminations on cable lines must be made so that the cables are protected from the penetration of moisture and other harmful substances from the environment into them and that the connections and terminations withstand the test voltages for the cable line and comply with the requirements of GOST.

2.3.66. For cable lines up to 35 kV, terminations and couplings must be used in accordance with the current technical documentation for couplings approved in the prescribed manner.

2.3.67. For connecting and locking sleeves of oil-filled low-pressure cable lines, only brass or copper sleeves must be used.

The length of the sections and the location of the stop sleeves on the low-pressure oil-filled cable lines are determined taking into account the replenishment of the lines with oil in normal and transient thermal conditions.

Locking and semi-locking couplings on cable oil-filled lines must be placed in cable wells; when laying cables in the ground, it is recommended to place couplings in chambers that are subject to subsequent backfilling with sifted earth or sand.

In areas with electrified transport (metro, trams, railways) or with soils that are aggressive towards metal sheaths and cable line couplings, couplings must be accessible for control.

2.3.68. On cable lines made by cables with normally impregnated paper insulation and cables impregnated with non-draining mass, cable connections should be made using stop-and-go couplings if the level of laying cables with normally impregnated insulation is higher than the level of laying cables impregnated with non-draining mass (see also 2.3 .51).

2.3.69. On cable lines above 1 kV, carried out by flexible cables with rubber insulation in a rubber hose, cable connections must be made by hot vulcanization coated with anti-damp varnish.

2.3.70. The number of couplings per 1 km of newly constructed cable lines should be no more than: for three-core cables 1-10 kV with a cross section of up to 3x95 mm 4 pcs.; for three-core cables 1-10 kV with sections 3x120 - 3x240 mm 5 pcs.; for three-phase cables 20-35 kV 6 pcs.; for single-core cables 2 pcs.

For cable lines 110-220 kV, the number of couplings is determined by the project.

The use of small-sized cable segments for the construction of extended cable lines is not allowed.

grounding

2.3.71. Cables with metal sheaths or armor, as well as cable structures on which cables are laid, must be grounded or neutralized in accordance with the requirements given in Ch. 1.7.

2.3.72. When grounding or grounding the metal sheaths of power cables, the sheath and armor must be connected by a flexible copper wire between themselves and with the housings of the couplings (terminal, connecting, etc.). On cables of 6 kV and above with aluminum sheaths, the sheath and armor grounding must be carried out by separate conductors.

It is not required to use grounding or zero protective conductors with a conductivity greater than the conductivity of the cable sheaths, however, the cross section in all cases must be at least 6 mm.

Cross-sections of grounding conductors of control cables should be selected in accordance with the requirements of 1.7.76-1.7.78.

If an external end sleeve and a set of arresters are installed on the structure support, then the armor, metal sheath and sleeve must be connected to the grounding device of the arresters. The use of only metal sheaths of cables as a grounding device in this case is not allowed.

Overpasses and galleries must be equipped with lightning protection in accordance with RD 34.21.122-87 "Instructions for the installation of lightning protection for buildings and structures" of the USSR Ministry of Energy.

2.3.73. On cable oil-filled low-pressure lines, end, connecting and locking couplings are grounded.

On cables with aluminum sheaths, feeders must be connected to the lines through insulating inserts, and the end sleeve housings must be insulated from the aluminum sheaths of the cables. This requirement does not apply to cable lines with direct entry into transformers.

When using armored cables for oil-filled low-pressure cable lines in each well, the cable armor on both sides of the coupling must be welded and grounded.

2.3.74. The steel pipeline of high-pressure oil-filled cable lines laid in the ground must be grounded in all wells and at the ends, and those laid in cable structures - at the ends and at intermediate points determined by the calculations in the project.

If it is necessary to actively protect the steel pipeline from corrosion, its grounding is carried out in accordance with the requirements of this protection, while it must be possible to control the electrical resistance of the anti-corrosion coating.

2.3.75. When a cable line passes into an overhead line (VL) and if there is no grounding device at the overhead line support, cable boxes (masts) can be grounded by attaching the metal sheath of the cable if the cable box at the other end of the cable is connected to the grounding device or the grounding resistance of the cable sheath meets the requirements of Ch. 1.7.

Special requirements for cable management of power plants, substations and switchgears

2.3.76. The requirements given in 2.3.77-2.3.82 apply to cable facilities of thermal and hydroelectric power plants with a capacity of 25 MW or more, switchgears and substations with a voltage of 220-500 kV, as well as switchgears and substations of particular importance in the power system (see. also 2.3.113).

2.3.77. The main electrical connection diagram, auxiliary circuit diagram and operating current circuit, equipment control and layout of equipment and cable facilities of a power plant or substation must be carried out in such a way that in the event of fires in the cable facilities or outside it, disruptions in the operation of more than one power plant unit are excluded, simultaneous loss of mutually redundant connections of distribution devices and substations, as well as failure of fire detection and extinguishing systems.

2.3.78. For the main cable flows of power plants, cable structures (floors, tunnels, shafts, etc.) should be provided, isolated from process equipment and excluding access to cables by unauthorized persons.

When placing cable flows at power plants, cable line routes should be selected taking into account:

preventing overheating of cables from heated surfaces of process equipment;

prevention of damage to cables during exhausts (fires and explosions) of dust through the safety devices of dust systems;

preventing the laying of transit cables in technological tunnels for hydraulic ash removal, chemical water treatment facilities, as well as in places where pipelines with chemically aggressive liquids are located.

2.3.79. Mutually redundant critical cable lines (power, operational current, communications, control, signaling, fire extinguishing systems, etc.) should be laid so that during fires the possibility of simultaneous loss of mutually redundant cable lines is excluded. In sections of the cable industry, where the occurrence of an accident threatens its great development, cable flows should be divided into groups isolated from one another. The distribution of cables into groups is accepted depending on local conditions.

2.3.80. Within one power unit, it is allowed to build cable structures with a fire resistance limit of 0.25 hours. At the same time, technological equipment that can serve as a source of fire (tanks with oil, oil stations, etc.) must have fences with a fire resistance limit of at least 0.75 h, excluding the possibility of ignition of cables in the event of a fire on this equipment.

Within one power unit of a power plant, it is allowed to lay cables outside special cable structures, provided that they are reliably protected from mechanical damage and dust, from sparks and fire during the repair of process equipment, ensuring normal temperature conditions for cable lines and ease of maintenance.

To provide access to cables when they are located at a height of 5 m or more, special platforms and passages should be constructed.

For single cables and small groups of cables (up to 20), operational sites may not be built, but it must be possible to quickly replace and repair cables in the field.

When laying cables within one power unit outside special cable structures, it should be ensured, if possible, that they are divided into separate groups passing along different routes.

2.3.81. Cable floors and tunnels, in which the cables of various power units of the power plant are placed, including cable floors and tunnels under block control panels, must be divided block by block and separated from other rooms, cable floors, tunnels, shafts, ducts and channels by fireproof partitions and ceilings with a fire resistance limit not less than 0.75 h, including in places where cables pass.

In places where cables are supposed to pass through partitions and ceilings, in order to ensure the possibility of replacement and additional laying of cables, a partition made of fireproof, easily pierced material with a fire resistance of at least 0.75 hours should be provided.

In extended cable structures of thermal power plants, emergency exits should be provided, located, as a rule, at least 50 m apart.

Cable facilities of power plants must be separated from outgoing network cable tunnels and collectors by fireproof partitions with a fire resistance limit of at least 0.75 hours.

2.3.82. The places where cables enter the rooms of closed switchgears and the rooms of control and protection panels of open switchgears must have partitions with a fire resistance of at least 0.75 hours.

The places where cables enter the block control panels of the power plant must be closed with partitions with a fire resistance limit of at least 0.75 hours.

Cable shafts must be separated from cable tunnels, floors and other cable structures by fireproof partitions with a fire resistance of at least 0.75 hours and have ceilings at the top and bottom. Extended shafts when passing through ceilings, but at least every 20 m, should be divided into compartments by fireproof partitions with a fire resistance of at least 0.75 hours.

Passage cable shafts must have entrance doors and be equipped with ladders or special brackets.

Laying cable lines in the ground

2.3.83. When laying cable lines directly in the ground, the cables must be laid in trenches and have backfilling from below, and backfilling from above with a layer of fine earth that does not contain stones, construction debris and slag.

Cables throughout their entire length must be protected from mechanical damage by coating at a voltage of 35 kV and above with reinforced concrete slabs with a thickness of at least 50 mm; at voltages below 35 kV - with slabs or ordinary clay bricks in one layer across the cable route; when digging a trench with an earthmoving mechanism with a cutter width of less than 250 mm, as well as for one cable - along the cable line route. The use of silicate, as well as clay hollow or perforated bricks is not allowed.

When laying at a depth of 1-1.2 m, cables of 20 kV and below (except for city power cables) may not be protected from mechanical damage.

Cables up to 1 kV should have such protection only in areas where mechanical damage is likely (for example, in places of frequent excavations). asphalt pavement streets, etc. are considered as places where openings are made in rare cases. For cable lines up to 20 kV, except for lines above 1 kV, supplying electrical receivers of category I *, it is allowed to use signal plastic tapes instead of bricks in trenches with no more than two cable lines that meet technical requirements. It is not allowed to use signal tapes at the intersections of cable lines with utilities and above cable boxes at a distance of 2 m in each direction from the crossed communication or box, as well as at the approaches of lines to switchgears and substations within a radius of 5 m.
____________
* According to local conditions, with the consent of the owner of the lines, it is allowed to expand the scope of signal tapes.

The signal tape should be laid in a trench above the cables at a distance of 250 mm from their outer covers. When one cable is located in a trench, the tape should be laid along the axis of the cable, with a larger number of cables, the edges of the tape should protrude beyond the outermost cables by at least 50 mm. When laying more than one tape across the width of the trench, adjacent tapes must be laid with an overlap of at least 50 mm wide.

When using a signal tape, laying cables in a trench with a cable cushion device, sprinkling the cables with the first layer of earth and laying the tape, including sprinkling the tape with a layer of earth along the entire length, must be carried out in the presence of a representative of the electrical installation organization and the owner of the power grid.

2.3.84. The depth of cable lines from the planning mark should be at least: lines up to 20 kV 0.7 m; 35 kV 1 m; at the intersection of streets and squares, regardless of voltage 1 m.

Cable oil-filled lines 110-220 kV must have a laying depth from the planning mark of at least 1.5 m.

It is allowed to reduce the depth to 0.5 m in sections up to 5 m long when lines are introduced into buildings, as well as at their intersections with underground structures, provided that the cables are protected from mechanical damage (for example, laying in pipes).

The laying of 6-10 kV cable lines on arable land should be carried out at a depth of at least 1 m, while the strip of land above the route can be occupied by crops.

2.3.85. The clear distance from the cable laid directly in the ground to the foundations of buildings and structures must be at least 0.6 m. Laying cables directly in the ground under the foundations of buildings and structures is not allowed. When laying transit cables in the basements and technical undergrounds of residential and public buildings, one should be guided by the SNiP of the Gosstroy of Russia.

2.3.86. With parallel laying of cable lines, the horizontal distance in the light between the cables must be at least:

1) 100 mm between power cables up to 10 kV, as well as between them and control cables;

2) 250 mm between 20-35 kV cables and between them and other cables;

3) 500 mm* between cables operated by different organizations, as well as between power cables and communication cables;

4) 500 mm between 110-220 kV oil-filled cables and other cables; at the same time, low-pressure oil-filled cable lines are separated from one another and from other cables by reinforced concrete slabs placed on edge; in addition, the electromagnetic influence on communication cables should be calculated.

It is allowed, if necessary, by agreement between operating organizations, taking into account local conditions, reducing the distances specified in clauses 2 and 3 to 100 mm, and between power cables up to 10 kV and communication cables, except for cables with circuits sealed by high-frequency telephone communication systems, up to 250 mm, provided that the cables are protected from damage that may occur during a short circuit in one of the cables (laying in pipes, installing fireproof partitions, etc.).

The distance between the control cables is not standardized.

2.3.87. When laying cable lines in the plantation area, the distance from the cables to the tree trunks should, as a rule, be at least 2 m. It is allowed, in agreement with the organization in charge of the green spaces, to reduce this distance, provided that the cables are laid in pipes laid by digging .

When laying cables within the green zone with shrub plantings, the indicated distances can be reduced to 0.75 m.

2.3.88. With parallel laying, the horizontal distance in the light from cable lines with voltage up to 35 kV and oil-filled cable lines to pipelines, water supply, sewerage and drainage must be at least 1 m; to gas pipelines of low (0.0049 MPa), medium (0.294 MPa) and high pressure (more than 0.294 to 0.588 MPa) - at least 1 m; to high pressure gas pipelines (more than 0.588 to 1.176 MPa) - at least 2 m; to heat pipelines - see 2.3.89.

In cramped conditions, it is allowed to reduce the specified distances for cable lines to 35 kV, with the exception of distances to pipelines with flammable liquids and gases, up to 0.5 m without special cable protection and up to 0.25 m when laying cables in pipes. For oil-filled cable lines 110-220 kV in the approach section with a length of not more than 50 m, it is allowed to reduce the horizontal clear distance to pipelines, with the exception of pipelines with flammable liquids and gases, to 0.5 m, provided that a protective wall is installed between the oil-filled cables and the pipeline excluding the possibility of mechanical damage. Parallel laying of cables above and below pipelines is not allowed.

2.3.89. When laying a cable line in parallel with a heat conductor, the clear distance between the cable and the wall of the heat pipe channel must be at least 2 m, or the heat pipe in the entire area of ​​approach to the cable line must have such thermal insulation that additional heating of the earth by the heat pipe at the place where the cables pass at any time of the year is not exceeded 10°C for cable lines up to 10 kV and 5°C - for lines 20-220 kV.

2.3.90. When laying a cable line in parallel with railways, cables should be laid, as a rule, outside the exclusion zone of the road. Laying cables within the exclusion zone is allowed only upon agreement with the organizations of the Ministry of Railways, while the distance from the cable to the axis of the railway track must be at least 3.25 m, and for an electrified road - at least 10.75 m. In cramped conditions it is allowed to reduce the specified distances, while the cables in the entire approach section must be laid in blocks or pipes.

With electrified roads on direct current, blocks or pipes must be insulating (asbestos-cement, impregnated with tar or bitumen, etc.).

2.3.91. When laying a cable line in parallel with tram tracks, the distance from the cable to the axis of the tram track must be at least 2.75 m. 2.3.90.

2.3.92. When laying a cable line in parallel with highways categories I and II (see 2.5.145), cables must be laid on the outside of the ditch or the bottom of the embankment at a distance of at least 1 m from the curb or at least 1.5 m from the curbstone. Reducing the specified distance is allowed in each individual case in agreement with the relevant road administrations.

2.3.93. When laying a cable line in parallel with an overhead line of 110 kV and above, the distance from the cable to the vertical plane passing through the outermost wire of the line must be at least 10 m.

The clear distance from the cable line to grounded parts and ground electrodes of overhead lines above 1 kV must be at least 5 m at voltages up to 35 kV, 10 m at voltages of 110 kV and above. In cramped conditions, the distance from cable lines to underground parts and ground electrodes of individual overhead lines above 1 kV is allowed at least 2 m; at the same time, the distance from the cable to the vertical plane passing through the overhead line wire is not standardized.

The clear distance from the cable line to the overhead line support up to 1 kV must be at least 1 m, and when laying the cable in the approach area in an insulating pipe, 0.5 m.

In the territories of power plants and substations in cramped conditions, it is allowed to lay cable lines at distances of at least 0.5 m from the underground part of the overhead lines (conductors) and overhead lines above 1 kV, if the grounding devices of these supports are connected to the substation ground loop.

2.3.94. When cable lines cross other cables, they must be separated by a layer of earth with a thickness of at least 0.5 m; this distance in cramped conditions for cables up to 35 kV can be reduced to 0.15 m, provided that the cables are separated along the entire intersection plus 1 m in each direction by slabs or pipes made of concrete or other equal strength material; the communication cables must be located above the power cables.

2.3.95. When cable lines cross pipelines, including oil and gas pipelines, the distance between the cables and the pipeline must be at least 0.5 m. It is allowed to reduce this distance to 0.25 m, provided that the cable is laid at the intersection plus at least 2 m in each direction in pipes.

When crossing a cable oil-filled line of pipelines, the clear distance between them must be at least 1 m. For cramped conditions, it is allowed to take a distance of at least 0.25 m, but provided that the cables are placed in pipes or reinforced concrete trays with a lid.

2.3.96. When crossing cable lines up to 35 kV heat pipelines, the distance between the cables and the overlap of the heat pipeline in the light must be at least 0.5 m, and in cramped conditions - at least 0.25 m. In this case, the heat pipeline at the intersection plus 2 m in each direction from the outermost cables must have such thermal insulation that the temperature of the earth does not rise by more than 10 ° C in relation to the highest summer temperature and by 15 ° C in relation to the lowest winter temperature.

In cases where the specified conditions cannot be met, one of the following measures is allowed: deepening of cables to 0.5 m instead of 0.7 m (see 2.3.84); use of a cable insert of a larger cross section; laying cables under the heat pipeline in pipes at a distance of at least 0.5 m from it, while the pipes must be laid in such a way that the cables can be replaced without excavation (for example, inserting pipe ends into chambers).

When crossing a cable oil-filled heat pipe line, the distance between the cables and the overlap of the heat pipe must be at least 1 m, and in cramped conditions - at least 0.5 m. thermal insulation so that the temperature of the earth does not rise by more than 5 ° C at any time of the year.

2.3.97. When cable lines cross railways and roads, cables must be laid in tunnels, blocks or pipes across the entire width of the exclusion zone at a depth of at least 1 m from the roadbed and at least 0.5 m from the bottom of drainage ditches. In the absence of an exclusion zone, the specified laying conditions must be met only at the intersection plus 2 m on both sides of the roadbed.

When cable lines cross electrified and subject to direct current electrification railways, blocks and pipes must be insulating (see 2.3.90). The crossing point must be at least 10 m away from switches, crosses and places where suction cables are attached to the rails. The crossing of cables with the tracks of electrified rail transport should be carried out at an angle of 75-90 ° to the axis of the track.

The ends of the blocks and pipes must be sunk with jute braided cords coated with waterproof (crumpled) clay to a depth of at least 300 mm.

When crossing dead-end industrial roads with low traffic intensity, as well as special routes (for example, on slipways, etc.), cables, as a rule, should be laid directly in the ground.

When crossing the route of cable lines by a newly constructed non-electrified railway or a motor road, it is not required to re-lay existing cable lines. At the intersection should be laid in case of repair of cables in required quantity redundant blocks or pipes with tightly sealed ends.

In the event of a cable line transitioning into an overhead cable, it must come out to the surface at a distance of at least 3.5 m from the bottom of the embankment or from the edge of the canvas.

2.3.98. When cable lines cross tram tracks, cables must be laid in insulating blocks or pipes (see 2.3.90). The crossing must be carried out at a distance of at least 3 m from the switches, crosses and places where suction cables are attached to the rails.

2.3.99. When cable lines cross entrances for vehicles to yards, garages, etc., cables should be laid in pipes. In the same way, cables must be protected at the intersection of streams and ditches.

2.3.100. When installing cable boxes on cable lines, the clear distance between the cable box body and the nearest cable must be at least 250 mm.

When laying cable lines on steep routes, the installation of cable boxes on them is not recommended. If it is necessary to install cable boxes in such sections, horizontal platforms must be made under them.

To ensure the possibility of remounting the couplings in case of their damage on the cable line, it is required to lay the cable on both sides of the couplings with a margin.

2.3.101. If there are stray currents of dangerous values ​​along the cable line route, it is necessary:

1. Change the route of the cable line in order to avoid dangerous areas.

2. If it is impossible to change the route: provide for measures to minimize the levels of stray currents; use cables with increased resistance to corrosion; implement active protection cables from the effects of electrocorrosion.

When laying cables in aggressive soils and areas with the presence of stray currents of unacceptable values, cathodic polarization should be used (installation of electrical drains, protectors, cathodic protection). For any method of connecting electrical drainage devices, the norms of potential differences in the suction areas, provided for by SNiP 3.04.03-85 "Protection of building structures and structures against corrosion" of the Gosstroy of Russia, must be observed. It is not recommended to use cathodic protection with external current on cables laid in saline soils or saline water bodies.

The need to protect cable lines from corrosion should be determined from the aggregate data of electrical measurements and chemical analyzes soil samples. Corrosion protection of cable lines should not create conditions dangerous for the operation of adjacent underground structures. The designed corrosion protection measures must be implemented before the new cable line is put into operation. If there are stray currents in the ground, it is necessary to install control points on cable lines in places and at distances that allow determining the boundaries of dangerous zones, which is necessary for the subsequent rational selection and placement of protective equipment.

To control potentials on cable lines, it is allowed to use the places where cables exit to transformer substations, distribution points, etc.

Laying cable lines in cable blocks, pipes and reinforced concrete trays

2.3.102. For the manufacture of cable blocks, as well as for laying cables in pipes, it is allowed to use steel, cast iron asbestos-cement, concrete, ceramic and similar pipes. When choosing a material for blocks and pipes, one should take into account the level of groundwater and their aggressiveness, as well as the presence of stray currents.

Oil-filled single-phase low pressure cables must be laid only in asbestos-cement and other pipes made of non-magnetic material, while each phase must be laid in a separate pipe.

2.3.103. The allowable number of channels in blocks, the distances between them and their size should be taken in accordance with 1.3.20.

2.3.104. Each cable block must have up to 15% redundant channels, but not less than one channel.

2.3.105. The depth of laying cable blocks and pipes in the ground should be taken according to local conditions, but not less than the distances given in 2.3.84, counting to the top cable. The depth of laying of cable blocks and pipes in closed areas and in the floors of industrial premises is not standardized.

2.3.106. Cable blocks must have a slope of at least 0.2% towards the wells. The same slope must be observed when laying pipes for cables.

2.3.107. When laying pipes for cable lines directly in the ground, the smallest clear distances between pipes and between them and other cables and structures should be taken as for cables laid without pipes (see 2.3.86).

When laying cable lines in pipes in the floor of the room, the distances between them are taken as for laying in the ground.

2.3.108. In places where the direction of the route of cable lines laid in blocks changes, and in places where cables and cable blocks go into the ground, cable wells should be constructed to ensure convenient pulling of cables and their removal from blocks. Such wells should also be built on straight sections of the route at a distance from one another, determined by the maximum allowable tension of the cables. With the number of cables up to 10 and voltage not higher than 35 kV, the transition of cables from the blocks to the ground is allowed to be carried out without cable wells. In this case, the exit points of the cables from the blocks must be sealed with waterproof material.

2.3.109. The transition of cable lines from blocks and pipes to buildings, tunnels, basements, etc., should be carried out in one of the following ways: by direct insertion of blocks and pipes into them, by constructing wells or pits inside buildings or chambers near their outer walls.

Measures should be provided to prevent water and small animals from penetrating through pipes or openings from trenches into buildings, tunnels, etc.

2.3.110. Channels of cable blocks, pipes, their exit, as well as their connections must have a treated and cleaned surface to prevent mechanical damage to cable sheaths during pulling. At the exits of cables from blocks to cable structures and chambers, measures should be taken to prevent damage to the sheaths from abrasion and cracking (use of elastic linings, compliance with the required bending radii, etc.).

2.3.111. At high level groundwater on the territory of the outdoor switchgear, preference should be given to above-ground methods of laying cables (in trays or boxes). Above-ground trays and slabs for their covering must be made of reinforced concrete. Trays must be laid on special concrete pads with a slope of at least 0.2% along the planned route in such a way as not to impede the runoff of storm water. If there are openings in the bottoms of above-ground trays that ensure the release of storm water, it is not required to create a slope.

When using cable trays for laying cables, passage through the territory of the outdoor switchgear and access to the equipment of machines and mechanisms necessary for performing repair and maintenance work should be provided. For this purpose, crossings through the trays should be arranged using reinforced concrete slabs, taking into account the load from passing vehicles, while maintaining the location of the trays at the same level. When using cable trays, it is not allowed to lay cables under roads and crossings in pipes, channels and trenches located below the trays.

The exit of cables from the trays to the control and protection cabinets must be carried out in pipes that are not buried in the ground. Laying of cable jumpers within one cell of the outdoor switchgear is allowed in a trench, and in this case, the use of pipes to protect cables when they are connected to control cabinets and relay protection is not recommended. Protection of cables from mechanical damage must be carried out in other ways (using an angle, channel, etc.).

Laying cable lines in cable structures

2.3.112. Cable structures of all types should be carried out taking into account the possibility of additional laying of cables in the amount of 15% of the number of cables provided for by the project (replacement of cables during installation, additional laying in subsequent operation, etc.).

2.3.113. Cable floors, tunnels, galleries, flyovers and shafts must be separated from other rooms and adjacent cable structures by fireproof partitions and ceilings with a fire resistance limit of at least 0.75 hours. power and control cables and no more than 100 m in the presence of oil-filled cables. The area of ​​each compartment of the double floor should be no more than 600 m2.

Doors in cable structures and partitions with a fire resistance of 0.75 hours must have a fire resistance of at least 0.75 hours in electrical installations listed in 2.3.76, and 0.6 hours in other electrical installations.

Exits from cable structures should be provided outside or into rooms with industries of categories G and D. The number and location of exits from cable structures should be determined based on local conditions, but there should be at least two of them. With a cable structure length of not more than 25 m, it is allowed to have one exit.

The doors of cable structures must be self-closing, with sealed porches. Exit doors from cable structures must open outward and must have locks that can be unlocked from cable structures without a key, and doors between compartments must open in the direction of the nearest exit and be equipped with devices that maintain them in the closed position.

Passage cable racks with service bridges must have entrances with ladders. The distance between the entrances should be no more than 150 m. The distance from the end of the overpass to the entrance to it should not exceed 25 m.

Entrances must have doors that prevent free access to the flyovers for persons not related to the maintenance of the cable industry. Doors must have self-locking locks that can be opened without a key from the inside of the flyover.

The distance between the entrances to the cable gallery when laying cables not higher than 35 kV in it should be no more than 150 m, and when laying oil-filled cables - no more than 120 m.

External cable racks and galleries must have main supporting building structures (columns, beams) made of reinforced concrete with a fire resistance of at least 0.75 hours or of rolled steel with a fire resistance of at least 0.25 hours.

The supporting structures of buildings and structures that can dangerously deform or reduce the mechanical strength during combustion of groups (streams) of cables laid near these structures on external cable racks and galleries must have protection that ensures the fire resistance of the protected structures is at least 0.75 hours.

Cable galleries should be divided into compartments by fireproof fireproof partitions with a fire resistance limit of at least 0.75 hours. The length of the gallery compartments should be no more than 150 m when laying cables up to 35 kV in them and no more than 120 m when laying oil-filled cables. For external cable galleries, partially closed, these requirements do not apply.

2.3.114. In tunnels and channels, measures must be taken to prevent the ingress of process water and oil into them, and soil and storm water must be drained. The floors in them must have a slope of at least 0.5% towards the water collectors or storm sewer. The passage from one section of the tunnel to another, when they are located at different levels, must be carried out using a ramp with an elevation angle of not more than 15 °. The arrangement of steps between compartments of tunnels is prohibited.

In cable channels constructed outdoors and located above the groundwater level, an earthen bottom is allowed with a draining bedding 10-15 cm thick made of compacted gravel or sand.

Drainage mechanisms should be provided in tunnels; at the same time, it is recommended to use their automatic start-up depending on the water level. Starting devices and electric motors must be of a design that allows them to work in particularly damp places.

When crossing a flyover and a walk-through gallery from one mark to another, a ramp with a slope of no more than 15 ° must be made. As an exception, stairs with a slope of 1:1 are allowed.

2.3.115. Cable channels and double floors in switchgears and rooms should be covered with removable fireproof plates. In electric machine and similar rooms, it is recommended to block the channels with corrugated steel, and in control rooms with parquet floors - with wooden panels with parquet, protected from below with asbestos and with asbestos tin. Overlapping of channels and double floors should be designed for the movement of the corresponding equipment on it.

2.3.116. Cable ducts outside buildings must be backfilled over removable slabs with a layer of earth at least 0.3 m thick. In fenced areas, backfilling cable ducts with earth over removable slabs is not necessary. The weight of an individual floor slab removed by hand must not exceed 70 kg. Plates must have a lifting device.

2.3.117. In areas where molten metal, high-temperature liquids or substances that destroy the metal sheaths of cables can be spilled, the construction of cable channels is not allowed. Manholes in collectors and tunnels are also not allowed in these areas.

2.3.118. Underground tunnels outside buildings must have a layer of earth at least 0.5 m thick on top of the ceiling.

2.3.119. At joint laying cables and heat pipelines in buildings, additional heating of air by a heat pipeline at the location of cables at any time of the year should not exceed 5 ° C, for which ventilation and thermal insulation on pipes should be provided.

1. Control cables and communication cables should be placed only under or only above power cables; however, they should be separated by a partition. At intersections and branches, it is allowed to lay control cables and communication cables above and below power cables.

2. Control cables may be laid next to power cables up to 1 kV.

4. Various groups of cables: working and reserve cables above 1 kV of generators, transformers, etc., supplying power consumers of category I, are recommended to be laid at different horizontal levels and separated by partitions.

5. Dividing partitions specified in paragraphs 1, 3 and 4 must be fireproof with a fire resistance limit of at least 0.25 hours.

When using automatic fire extinguishing using air-mechanical foam or sprayed water, the partitions specified in paragraphs 1, 3 and 4 may not be installed.

On external cable racks and in external partially closed cable galleries, the installation of dividing partitions specified in clauses 1, 3 and 4 is not required. At the same time, mutually redundant power cable lines (with the exception of lines to electrical receivers of a special group of category I) should be laid with a distance between them of at least 600 mm and it is recommended to locate: on overpasses on both sides of the span supporting structure (beams, trusses); in the galleries on opposite sides of the aisle.

2.3.121. Oil-filled cables should be laid, as a rule, in separate cable structures. It is allowed to lay them together with other cables; at the same time, oil-filled cables should be placed in the lower part of the cable structure and separated from other cables by horizontal partitions with a fire resistance limit of at least 0.75 hours. Oil-filled cable lines should be separated from one another with the same partitions.

2.3.122. The need for the use and volume of automatic stationary means for detecting and extinguishing fires in cable structures should be determined on the basis of departmental documents approved in the prescribed manner.

Fire hydrants must be installed in the immediate vicinity of the entrance, hatches and ventilation shafts (within a radius of no more than 25 m). For flyovers and galleries, fire hydrants should be located in such a way that the distance from any point on the axis of the flyover and gallery route to the nearest hydrant does not exceed 100 m.

2.3.123. In cable structures, the laying of control cables and power cables with a cross section of 25 mm or more, with the exception of unarmored cables with a lead sheath, should be carried out along cable structures (consoles).

Control unarmoured cables, unarmoured power cables with a lead sheath and unarmoured power cables of all designs with a cross section of 16 mm or less should be laid along trays or partitions (solid or non-solid).

It is allowed to lay cables along the bottom of the channel at a depth of not more than 0.9 m; in this case, the distance between a group of power cables above 1 kV and a group of control cables must be at least 100 mm, or these groups of cables must be separated by a fireproof partition with a fire resistance of at least 0.25 hours.

The distances between the individual cables are given in table. 2.3.1.

Backfilling of power cables laid in channels with sand is prohibited (for an exception, see 7.3.110).

In cable structures, the height, width of passages and the distance between structures and cables must be at least those given in Table. 2.3.1. Compared with the distances given in the table, local narrowing of the passages up to 800 mm or a decrease in height up to 1.5 m over a length of 1.0 m is allowed with a corresponding decrease in the vertical distance between the cables with one-sided and two-sided arrangement of structures.

Table 2.3.1. Minimum distance for cable installations

Distance	The smallest dimensions, mm, when laying
	in tunnels, galleries, cable floors and overpasses	in cable ducts and double floors
clear height		Not limited, but not more than 1200 mm
Horizontally in the light between structures with their two-sided arrangement (passage width)		300 at a depth of up to 0.6 m; 450 at a depth of more than 0.6 to 0.9 m; 600 at a depth of more than 0.9 m
Horizontally clear from the structure to the wall with one-sided arrangement (passage width)
Vertical between horizontal structures *:
		Not less than cable diameter

* The useful length of the console should not exceed 500 mm on straight sections of the track.
** When cables are arranged in a 250 mm triangle.
*** Including for cables laid in cable shafts.

2.3.124. Laying of control cables is allowed in bundles on trays and in multilayers in metal boxes, subject to the following conditions:

1. Outside diameter cable bundle should be no more than 100 mm.

2. The height of the layers in one box should not exceed 150 mm.

3. Only cables with the same type of sheaths should be laid in bundles and multilayers.

4. Fastening cables in bundles, multilayered in boxes, bundles of cables to trays should be carried out in such a way that deformation of the cable sheaths under the action of its own weight and fastening devices is prevented.

5. For the purpose of fire safety, fire protection belts should be installed inside the ducts: in vertical sections - at a distance of no more than 20 m, as well as when passing through the ceiling; on horizontal sections - when passing through partitions.

6. In each direction of the cable route, a capacity margin of at least 15% of the total capacity of the boxes should be provided.

Laying of power cables in bundles and multilayer is not allowed.

2.3.125. In places saturated with underground utilities, it is allowed to perform semi-through tunnels with a height reduced in comparison with that provided for in Table. 2.3.1, but not less than 1.5 m, subject to the following requirements: the voltage of the cable lines must not exceed 10 kV; the length of the tunnel should be no more than 100 m; other distances must correspond to those given in table. 2.3.1; at the ends of the tunnel there should be exits or hatches.

2.3.126. Low pressure oil-filled cables must be fastened to metal structures in such a way that the possibility of the formation of closed magnetic circuits around the cables is excluded; the distance between the attachment points should be no more than 1 m.

Steel pipelines of high-pressure oil-filled cable lines can be laid on supports or suspended on hangers; the distance between supports or hangers is determined by the line design. In addition, pipelines must be fixed on fixed supports to prevent thermal deformations in pipelines under operating conditions.

The loads taken by the supports from the weight of the pipeline should not lead to any movement or destruction of the foundations of the supports. The number of these supports and their locations are determined by the project.

Mechanical supports and fastenings of branching devices on high-pressure lines should prevent the branching pipes from swinging, the formation of closed magnetic circuits around them, and insulating gaskets should be provided at the points of fastenings or touches of the supports.

2.3.127. The height of cable wells must be at least 1.8 m; chamber height is not standardized. Cable wells for connecting, locking and semi-locking couplings must have dimensions that ensure the installation of couplings without breaking.

Shore wells at underwater crossings should be sized to accommodate backup cables and feeders.

In the floor of the well, a pit should be arranged to collect groundwater and storm water; a drainage device shall also be provided in accordance with the requirements given in 2.3.114.

Cable wells must be equipped with metal ladders.

In cable wells, cables and couplings must be laid on structures, trays or partitions.

2.3.128. The hatches of cable wells and tunnels must have a diameter of at least 650 mm and be closed with double metal covers, of which the lower one must have a locking device that can be opened from the side of the tunnel without a key. Covers must be equipped with tools for their removal. Indoors, the use of a second cover is not required.

2.3.129. On the couplings of power cables with a voltage of 6-35 kV in tunnels, cable floors and channels, special protective covers must be installed to localize fires and explosions that may occur during electrical breakdowns in the couplings.

2.3.130. Terminations on high-pressure oil-filled cable lines should be located in rooms with a positive air temperature or be equipped with automatic heating when the ambient temperature drops below +5°C.

2.3.131. When laying oil-filled cables in the galleries, it is necessary to provide heating of the galleries in accordance with the specifications for oil-filled cables.

The premises of the oil-feeding units of the high-pressure lines must have natural ventilation. Underground feeding points are allowed to be combined with cable wells; in this case, the wells must be equipped with drainage devices in accordance with 2.3.127.

2.3.132. Cable structures, with the exception of overpasses, wells for couplings, channels and chambers, must be provided with natural or artificial ventilation, and the ventilation of each compartment must be independent.

The calculation of the ventilation of cable structures is determined based on the temperature difference between the incoming and outgoing air of no more than 10 ° C. In this case, the formation of hot air bags in the narrowing of tunnels, turns, detours, etc. must be prevented.

Ventilation devices must be equipped with dampers (gates) to stop air access in the event of a fire, as well as to prevent the tunnel from freezing in winter. The design of ventilation devices should ensure the possibility of using automation to stop air access to buildings.

When laying cables indoors, overheating of the cables must be prevented due to the increased ambient temperature and the effects of process equipment.

Cable structures, with the exception of wells for couplings, channels, chambers and open overpasses, must be equipped with electric lighting and a network for powering portable lamps and tools. At thermal power plants, the network for powering the tool may not be performed.

2.3.133. Cable laying in collectors, technological galleries and technological overpasses is carried out in accordance with the requirements of SNiP Gosstroy of Russia.

The smallest clear distances from cable racks and galleries to buildings and structures should correspond to those given in Table. 2.3.2.

Intersection of cable racks and galleries with air lines it is recommended to perform at an angle of at least 30 ° for power transmission lines, intra-plant railways and roads, fire passages, cable cars, overhead communication and radio communication lines and pipelines.

When crossing, vertically

From the construction of the overpass and gallery to the nearest parts of the pipeline

Overhead power line

From the design of the overpass and gallery to the wires

Air communication and radio communication line

The location of overpasses and galleries in hazardous areas - see Ch. 7.3, the location of overpasses and galleries in fire hazardous areas - see Ch. 7.4.

With parallel passage of flyovers and galleries with overhead communication and radio lines, the smallest distances between cables and wires of a communication and radio line are determined based on the calculation of the effect of cable lines on communication and radio lines. Communication and radio communication wires can be located under and above flyovers and galleries.

The smallest height of the cable overpass and the gallery in the impassable part of the territory of the industrial enterprise should be taken from the calculation of the possibility of laying bottom row cables at a level of at least 2.5 m from the planned ground level.

Laying cable lines in industrial premises

2.3.134. When laying cable lines in industrial premises, the following requirements must be met:

1. Cables must be accessible for repair, and openly laid cables for inspection.

Cables (including armored ones) located in places where mechanisms, equipment, cargo and transport are moved must be protected from damage in accordance with the requirements given in 2.3.15.

2. The clear distance between the cables must correspond to that given in Table. 2.3.1.

3. The distance between parallel power cables and all kinds of pipelines, as a rule, must be at least 0.5 m, and between gas pipelines and pipelines with flammable liquids - at least 1 m. At shorter distances of approach and at intersections, the cables must be protected from mechanical damage (metal pipes, casings, etc.) throughout the approach area plus 0.5 m on each side, and, if necessary, are protected from overheating.

Cable crossings of passages must be carried out at a height of at least 1.8 m from the floor.

Parallel laying of cables above and below oil pipelines and pipelines with flammable liquid in a vertical plane is not allowed.

2.3.135. Laying cables in the floor and interfloor ceilings should be carried out in channels or pipes; sealing cables in them tightly is not allowed. Passage of cables through ceilings and internal walls can be made in pipes or openings; after laying the cables, the gaps in the pipes and openings must be sealed with an easily pierced non-combustible material.

Laying cables in ventilation ducts is prohibited. It is allowed to cross these channels with single cables enclosed in steel pipes.

Open cable laying in stairwells is not allowed.

Underwater cable laying

2.3.136. When cable lines cross rivers, canals, etc., cables should be laid mainly in areas with a bottom and banks that are little prone to erosion (crossing streams - see 2.3.46). When laying cables through rivers with an unstable channel and banks subject to erosion, the burial of cables into the bottom should be done taking into account local conditions. The cable laying depth is determined by the project. Laying cables in the areas of piers, berths, harbors, ferry crossings, as well as regular winter moorings of ships and barges is not recommended.

2.3.137. When laying cable lines in the sea, data on the depth, speed and style of water movement at the crossing point, prevailing winds, the profile and chemical composition of the bottom, and the chemical composition of water should be taken into account.

2.3.138. Cable lines should be laid along the bottom in such a way that they are not suspended in uneven places; sharp protrusions must be removed. Shoals, stone ridges and other underwater obstacles on the route should be bypassed or trenches or passages should be provided in them.

2.3.139. When cable lines cross rivers, canals, etc., cables, as a rule, must be buried in the bottom to a depth of at least 1 m in coastal and shallow areas, as well as on shipping and rafting routes; 2 m when crossing oil-filled cable lines.

In reservoirs where dredging works are periodically carried out, cables are buried in the bottom to a mark determined in agreement with water transport organizations.

When laying oil-filled cable lines 110-220 kV on navigable rivers and canals, in order to protect them from mechanical damage, it is recommended to fill trenches with sandbags, followed by throwing stones.

2.3.140. The distance between cables buried in the bottom of rivers, canals, etc. with a reservoir width of up to 100 m, is recommended to be at least 0.25 m. Newly constructed submarine cable lines should be laid at a distance from existing cable lines of at least 1.25 depth reservoir, calculated for the long-term average water level.

When laying low-pressure cables in water at a depth of 5-15 m and at a flow velocity not exceeding 1 m/s, it is recommended to take the distances between the individual phases (without special fastenings of the phases to each other) at least 0.5 m, and the distances between the extreme cables of parallel lines - at least 5 m.

With underwater laying at a depth of more than 15 m, as well as at flow rates of more than 1 m/s, the distances between individual phases and lines are taken in accordance with the project.

When oil-filled cable lines and lines up to 35 kV are laid in parallel under water, the horizontal distance between them in the light must be at least 1.25 times the depth calculated for the long-term average water level, but not less than 20 m.

The horizontal distance from cables buried in the bottom of rivers, canals and other water bodies to pipelines (oil pipelines, gas pipelines, etc.) should be determined by the project depending on the type of dredging performed when laying pipelines and cables, and be at least 50 m. It is allowed to reduce this distance to 15 m in agreement with the organizations in charge of cable lines and pipelines.

2.3.141. On shores without improved embankments, at the place of the underwater cable crossing, a reserve of at least 10 m in length for river and 30 m for sea laying, which is laid in a figure of eight, should be provided. On improved embankments, cables should be laid in pipes. In the place where the cables exit, as a rule, cable wells should be arranged. The upper end of the pipe must enter the coastal well, and the lower end must be at a depth of at least 1 m from the lowest water level. Onshore sections of the pipe must be firmly sealed.

2.3.142. In places where the channel and banks are subject to erosion, it is necessary to take measures against the exposure of cables during ice drifts and floods by strengthening the banks (paving, breaking dams, piles, sheet piles, slabs, etc.).

2.3.143. Crossing of cables under water is prohibited.

2.3.144. Underwater cable crossings must be marked on the shores with signal signs in accordance with the current rules for navigation along inland navigation routes and sea straits.

2.3.145. When laying three or more cables up to 35 kV in water, one backup cable should be provided for every three working ones. When laying oil-filled cable lines in water from single-phase cables, a reserve must be provided: for one line - one phase, for two lines - two phases, for three or more - according to the project, but not less than two phases. Reserve phases must be laid in such a way that they can be used to replace any of the active working phases.

Laying cable lines on special structures

2.3.146. Laying cable lines on stone, reinforced concrete and metal bridges should be carried out under the pedestrian part of the bridge in channels or in fireproof pipes separate for each cable; it is necessary to provide measures to prevent the runoff of storm water through these pipes. On metal and reinforced concrete bridges and when approaching them, cables are recommended to be laid in asbestos-cement pipes. In places of transition from bridge structures to the ground, cables are also recommended to be laid in asbestos-cement pipes.

All underground cables when passing through metal and reinforced concrete bridges, they must be electrically isolated from the metal parts of the bridge.

2.3.147. Laying cable lines on wooden structures (bridges, piers, piers, etc.) should be carried out in steel pipes.

2.3.148. In places where cables pass through the expansion joints of bridges and from bridge structures to abutments, measures must be taken to prevent the occurrence of mechanical stresses in the cables.

2.3.149. Laying cable lines along dams, dams, piers and berths directly in an earthen trench is allowed with a thickness of the earth layer of at least 1 m.

Publication date: 09/13/2018

What is cable structures?

Cable structures are load-bearing structures, these include: cable ducts, cable trays, sections, cable racks, consoles, scarves, tees, adapter brackets and other elements designed for laying power and control cables on outdoors, inside buildings and structures of energy facilities, including nuclear power plants In Russian federation.

What are cable structures made of?

Cable structures are made of bent profiles of increased rigidity. Perforation provides not only ease of installation of structures and fastening of cables, but also their ventilation when heated, as well as rapid detection and elimination of fires on cable routes (including the use of automatic fire extinguishing). Perforation makes it possible to decontaminate cable routes at nuclear power plants and wash off dust from cables in conditions of particularly dusty industries (pulverized coal production, woodworking plants, etc.).

Benefits of using

The use of bent profiles of increased rigidity allows, with a low metal consumption, to provide a large load capacity and increased structural strength. Thanks to the zinc coating, these structures can be used in both cold and maritime tropical climates.

A wide range of cable structure elements is provided, which allows:

• install cable routes of any configuration without welding;
• separate cable systems for fire extinguishing, communications, etc. from the main cable flows in compliance with all norms and rules for the joint laying of cables for various purposes on the same cable structures.

View climatic design- U2. Т1 in accordance with GOST 15150. Nominal values ​​of environmental climatic factors in accordance with GOST 15150. Other types of climatic modification are allowed upon agreement with the customer.