Requirements for laying low-current cables in the ground. Laying cable lines in the ground. Requirements, conditions, standards for laying cables in the ground

Laying cable lines in the ground

CABLE LINES

3.56. These rules must be observed when installing power cable lines voltage up to 220 kV.

Installation of cable lines of the subway, mines, mines should be carried out taking into account the requirements of the VSN, approved in the manner established by SNiP 1.01.01-82.

3.57. The smallest permissible bending radii of cables and the permissible level difference between the highest and lowest points of arrangement of cables with impregnated paper insulation on the route must comply with the requirements of GOST 24183-80*, GOST 16441-78, GOST 24334-80, GOST 1508-78* E and approved technical specifications.

3.58. When laying cables, measures should be taken to protect them from mechanical damage. The tensile forces of cables up to 35 kV must be within the limits given in table. 3. Winches and other traction means must be equipped with adjustable limiting devices to turn off the traction when forces exceed the permissible ones. Pulling devices that crimp the cable (drive rollers), as well as rotating devices, must exclude the possibility of cable deformation.

For cables with voltage 110-220 kV, permissible tensile forces are given in clause 3.100.

3.59. Cables should be laid with a length margin of 1-2%. In trenches and on solid surfaces inside buildings and structures, the reserve is achieved by laying the cable in a “snake” pattern, and along cable structures (brackets) this reserve is used to form a sag.

Laying the cable reserve in the form of rings (turns) is not allowed.

Table 3

_____________________

* Made of soft aluminum with elongation not exceeding 30%.

Notes:

1. Pulling of a cable with a plastic or lead sheath is allowed only by the cores.

2. The tensile forces of the cable when pulling it through the block sewer are given in table. 4.

3. Cables armored with round wire should be pulled by the wires. Permissible voltage 70-100 N/sq.mm.

4. Control cables and armored and unarmored power cables with a cross-section of up to 3 x 16 sq. mm, in contrast to the cables of large cross-sections shown in this table, can be laid mechanically by pulling behind the armor or behind the sheath using a wire stocking, the pulling forces should not be exceed 1 kN.

3.60. Cables laid horizontally along structures, walls, floors, trusses, etc. should be rigidly secured at the end points, directly at the end couplings, at route turns, on both sides of bends and at connecting and locking couplings.

3.61. Cables laid vertically along structures and walls must be secured to each cable structure.

3.62. The distances between supporting structures are taken in accordance with the working drawings. When laying power and control cables with an aluminum sheath on support structures with a distance of 6000 mm, a residual deflection in the middle of the span must be ensured: 250-300 mm when laying on overpasses and galleries, at least 100-150 mm in other cable structures.

The structures on which unarmored cables are laid must be designed to exclude the possibility of mechanical damage to the cable sheaths.

In places where unarmored cables with a lead or aluminum sheath are rigidly attached to structures, gaskets made of elastic material (for example, sheet rubber, sheet polyvinyl chloride) must be laid; unarmored cables with a plastic sheath or plastic hose, as well as armored cables, may be secured to structures with brackets (clamps) without gaskets.

3.63. Armored and unarmored cables indoors and outdoors in places where mechanical damage is possible (movement of vehicles, loads and machinery, accessibility for unqualified personnel) must be protected to a safe height, but not less than 2 m from the ground or floor level and at a depth of 0 .3 m in the ground.

3.64. The ends of all cables whose sealing is broken during installation must be temporarily sealed before installing the connecting and termination couplings.

3.65. Cable passages through walls, partitions and ceilings in industrial premises and cable structures must be made through sections of non-metallic pipes (free-flow asbestos, plastic, etc.), textured holes in reinforced concrete structures or open openings. Gaps in pipe sections, holes and openings after laying cables must be sealed with fireproof material, for example cement with sand by volume 1:10, clay with sand - 1:3, clay with cement and sand - 1.5:1:11, perlite expanded with building plaster - 1:2, etc., over the entire thickness of the wall or partition.

Gaps in passages through walls may not be sealed if these walls are not fire barriers.

3.66. The trench before laying the cable must be inspected to identify places on the route containing substances that have a destructive effect on the metal cover and cable sheath (salt marshes, lime, water, bulk soil containing slag or construction waste, areas located closer than 2 m from cesspools and garbage pits, etc.). If it is impossible to bypass these places, the cable must be laid in clean neutral soil in free-flow asbestos-cement pipes, coated inside and outside with a bitumen composition, etc. When backfilling the cable with neutral soil, the trench must be additionally expanded on both sides by 0.5-0. 6 m and deepened by 0.3-0.4 m.

3.67. Cable entries into buildings, cable structures and other premises must be made in asbestos-cement free-flow pipes in textured holes in reinforced concrete structures. The ends of the pipes must protrude from the wall of the building into the trench, and if there is a blind area, beyond the line of the latter by at least 0.6 m and have a slope towards the trench.

3.68. When laying several cables in a trench, the ends of the cables intended for subsequent installation of connecting and locking couplings should be positioned with a shift of the connection points of at least 2 m. In this case, a reserve cable of the length necessary for checking the insulation for moisture and installing the coupling should be left. as well as laying the compensator arc (with a length at each end of at least 350 mm for cables with voltages up to 10 kV and at least 400 mm for cables with voltages of 20 and 35 kV).

3.69. In cramped conditions with large cable flows, it is allowed to place expansion joints in a vertical plane below the cable laying level. The coupling remains at the level of the cable routing.

3.70. The cable laid in the trench must be covered with the first layer of earth, mechanical protection or signal tape must be laid, after which representatives of the electrical installation and construction organizations Together with the customer's representative, an inspection of the route must be carried out and a report on hidden work must be drawn up.

3.71. The trench must be finally backfilled and compacted after installing the couplings and testing the line with increased voltage.

3.72. Filling the trench with clods of frozen earth, soil containing stones, pieces of metal, etc. is not allowed.

3.73. Trenchless laying from a self-propelled or traction-driven knife cable-laying machine is allowed for 1-2 armored cables with a voltage of up to 10 kV with a lead or aluminum sheath on cable routes remote from engineering structures. In urban electrical networks and industrial enterprises, trenchless installation is allowed only on extended sections in the absence of underground communications, intersections with utility structures, natural obstacles and hard surfaces along the route.

3.74. When laying a cable line route in an undeveloped area, identification marks must be installed along the entire route on concrete posts or on special signboards that are placed at the turns of the route, at the locations of connecting couplings, on both sides of intersections with roads and underground structures, at entries into buildings and every 100 m on straight sections.

On arable land, identification signs must be installed at least every 500 m.

Laying in block sewer

3.75. The total length of the block channel under the conditions of the maximum permissible tensile forces for unarmored cables with a lead sheath and copper conductors should not exceed the following values:

Cable cross-section, sq.mm.... up to 3x50 3x70 3x95 and above

Maximum length, m.....145115108

For unarmored cables with aluminum conductors with a cross-section of 95 sq. mm and above in a lead or plastic sheath, the length of the channel should not exceed 150 m.

3.76. The maximum permissible tensile forces of unarmored cables with a lead sheath and with copper or aluminum conductors when attaching the traction rope to the conductors, as well as the required forces for pulling 100 m of cable through a block sewer are given in Table. 4.

Table 4

Unarmored cable cores with

lead

Cable cross-section, sq.mm

Permissible tensile force, kN

Required tensile force per 100 m of cable, kN, voltage, kV

shell

Aluminum

Note.

To reduce the tensile force when pulling the cable, it should be coated with a lubricant that does not contain substances that have a harmful effect on the cable sheath (grease, grease).

3.77. For unarmored cables with a plastic sheath, the maximum permissible tensile forces should be taken according to table. 4 with correction factors for cores:

copper........................................ 0.7

made of solid aluminum........................ 0.5

"soft"......................... 0.25

Laying in cable structures and industrial premises

3.78. When laid in cable structures, collectors and production premises, cables should not have external protective coverings made of flammable materials. Metal sheaths and cable armor that have a fireproof anti-corrosion (for example, galvanic) coating made at the manufacturer are not subject to painting after installation.

3.79. Cables in cable structures and collectors of residential areas should, as a rule, be laid in full construction lengths, avoiding, if possible, the use of couplings in them.

Cables laid horizontally along structures on open overpasses (cable and technological), in addition to fastening in places in accordance with clause 3.60, must be secured to avoid displacement under the influence of wind loads on straight horizontal sections of the route in accordance with the instructions given in the project.

3.80. When laying them on plastered and concrete walls, trusses and columns, cables in an aluminum sheath without an outer covering must be at least 25 mm from the surface of building structures. It is permissible to lay such cables on the painted surfaces of these structures without a gap.

Laying on steel rope

3.81. The diameter and grade of the rope, as well as the distance between the anchor and intermediate fastenings of the rope are determined in the working drawings. The sag of the rope after hanging the cables should be within 1/40 - 1/60 of the span length. The distances between cable hangers should be no more than 800 - 1000 mm.

3.82. Anchor end structures must be secured to the columns or walls of the building. Attaching them to beams and trusses is not allowed.

3.83. Steel rope and other metal parts for laying cables on a rope outdoors, regardless of the presence of galvanic coating, must be coated with a lubricant (for example, grease). Indoors, galvanized steel rope should be coated with lubricant only in cases where it may be subject to corrosion under the influence of an aggressive environment.

Laying in permafrost soils

3.84. The depth of cable laying in permafrost soils is determined in the working drawings.

3.85. Local soil used for backfill trenches must be crushed and compacted. Ice and snow in the trench is not allowed. The soil for the embankment should be taken from places at least 5 m away from the axis of the cable route. The soil in the trench after settlement should be covered with a moss-peat layer.

As additional measures against the occurrence of frost cracks, the following should be used:

backfilling the cable trench with sand or gravel-pebble soil;

construction of drainage ditches or slots up to 0.6 m deep, located on both sides of the route at a distance of 2-3 m from its axis;

sowing the cable route with grasses and lining with shrubs.

Low temperature gasket

3.86. Laying cables in the cold season without preheating is allowed only in cases where the air temperature within 24 hours before the start of work has not decreased, at least temporarily, below:

0 °C - for power armored and non-armored cables with paper insulation (viscous, non-drip and lean-impregnated) in a lead or aluminum sheath;

minus 5 °C - for oil-filled cables of low and high pressure;

minus 7 °C - for control and power cables voltage up to 35 kV with plastic or rubber insulation and a shell with fibrous materials in a protective cover, as well as with armor made of steel tapes or wires;

minus 15 °C - for control and power cables with voltage up to 10 kV with polyvinyl chloride or rubber insulation and a sheath without fibrous materials in a protective cover, as well as with armor made of profiled galvanized steel tape;

minus 20°С - for unarmored control and power cables with polyethylene insulation and sheath without fibrous materials in the protective cover, as well as with rubber insulation in a lead sheath.

3.87. Short-term drops in temperature within 2-3 hours (night frosts) should not be taken into account provided the temperature was positive in the previous period of time.

3.88. At air temperatures below those specified in clause 3.86, the cables must be preheated and laid within the following periods:

more than 1 hour............ from 0 to minus 10 °C

"40 min............. from minus 10 to minus 20 °C

"30 min.............from minus 20 °C and below

3.89. Unarmoured cables with an aluminum sheath in a polyvinyl chloride hose, even preheated ones, are not allowed to be laid at ambient temperatures below minus 20 °C.

3.90. When the ambient temperature is below minus 40 °C, laying cables of all brands is not allowed.

3.91. During installation, the heated cable should not be bent at a radius less than permissible. It is necessary to lay it in a trench in a snake with a margin of length in accordance with clause 3.59. Immediately after installation, the cable must be covered with the first layer of loosened soil. The trench should be completely filled with soil and the backfill should be compacted after the cable has cooled.

Installation of cable joints with voltage up to 35 kV

3.92. Installation of power cable couplings with voltages up to 35 kV and control cables must be carried out in accordance with departmental technological instructions approved in the prescribed manner.

3.93. Types of couplings and terminations for power cables with voltage up to 35 kV with paper and plastic insulation and control cables, as well as methods of connecting and terminating cable cores must be indicated in the project.

3.94. The clear distance between the coupling body and the nearest cable laid in the ground must be at least 250 mm. As a rule, couplings should not be installed on steeply inclined routes (more than 20° to the horizontal). If it is necessary to install couplings in such areas, they should be located on horizontal platforms. To ensure the possibility of re-installing couplings in the event of damage, a supply of cable in the form of a compensator must be left on both sides of the coupling (see clause 3.68).

3.95. Cables in cable structures should be laid, as a rule, without making couplings on them. If it is necessary to use couplings on cables with a voltage of 6-35 kV, each of them must be laid on a separate supporting structure and enclosed in a fire protective casing for fire localization (manufactured in accordance with approved regulatory and technical documentation). In addition, the coupling must be separated from the upper and lower cables by fireproof protective partitions with a fire resistance rating of at least 0.25 hours.

3.96. The couplings of cables laid in blocks must be located in wells.

3.97. On a route consisting of a bore tunnel leading into a semi-bore tunnel or a non-bore tunnel, the couplings must be located in the bore tunnel.

Features of installation of cable lines with voltage 110-220 kV

3.98. Working drawings of cable lines with oil-filled cables for voltage 110-220 kV and cables with plastic (vulcanized polyethylene) insulation for voltage 110 kV and PPR for their installation must be agreed with the cable manufacturer.

3.99. The temperature of the cable and ambient air during installation must not be lower than: minus 5 °C for an oil-filled cable and minus 10 °C for a cable with plastic insulation. At lower temperatures, laying can only be permitted in accordance with the PPR.

3.100. Cables with round wire armor during mechanized installation should be pulled by the wires using a special grip that ensures uniform load distribution between the armor wires. In this case, in order to avoid deformation of the lead sheath, the total tensile force should not exceed 25 kN. Unarmored cables may only be pulled by the cores using a grip mounted at the upper end of the cable on the drum. The greatest permissible tensile force is determined from the calculation: 50 MPa (N/sq.mm) - for copper conductors, 40 MPa (N/sq.mm) - for conductors made of solid aluminum and 20 MPa (N/sq.mm) - for soft aluminum cores.

3.101. The traction winch must be equipped with a recording device and an automatic shutdown device when the maximum permissible pull value is exceeded. The recording device must be equipped with a recording device. Reliable telephone or VHF communication must be established during installation between the locations of the cable drum, winch, route turns, transitions and intersections with other communications.

3.102. Cables laid on cable structures with a span between them of 0.8-1 m must be secured on all supports with aluminum brackets with two layers of rubber 2 mm thick, unless otherwise indicated in the working documentation.

Cable line marking

3.103. Each cable line must be marked and have its own number or name.

3.104. Labels must be installed on exposed cables and cable joints.

On cables laid in cable structures, tags must be installed at least every 50-70 m, as well as in places where the direction of the route changes, on both sides of passages through interfloor ceilings, walls and partitions, in places where cables enter (exit) into trenches and cable structures.

On hidden cables in pipes or blocks, tags should be installed at the end points at the end couplings, in the wells and chambers of the block sewer system, as well as at each connecting coupling.

On hidden cables in trenches, tags are installed at the end points and at each coupling.

3.105. Tags should be used: in dry rooms - made of plastic, steel or aluminum; in damp rooms, outside buildings and in the ground - made of plastic.

Designations on tags for underground cables and cables laid in rooms with a chemically active environment should be made by stamping, punching or burning. For cables laid in other conditions, markings may be applied with indelible paint.

3.106. Tags must be secured to the cables with nylon thread or galvanized steel wire with a diameter of 1-2 mm, or plastic tape with a button. The place where the tag is attached to the cable with wire and the wire itself in damp rooms, outside buildings and in the ground must be covered with bitumen to protect it from moisture.

CURRENT CONDUCTORS WITH VOLTAGE UP TO 35 kV

Current conductors with voltage up to 1 kV (busbars)

3.107. Sections with compensators and flexible sections of the main busbar trunking must be secured to two supporting structures installed symmetrically on both sides of the flexible part of the busbar trunking section. The busbar trunking should be fastened to supporting structures in horizontal sections using clamps that allow the busbar trunking to move when the temperature changes. Busbars laid in vertical sections must be rigidly secured to structures with bolts.

For ease of removal of covers (casing parts), as well as to ensure cooling, the busbar should be installed with a gap of 50 mm from the walls or other building structures of the building.

Pipes or metal hoses with wires must be inserted into branch sections through holes made in the busbar trunking casings. Pipes should be terminated with bushings.

3.108. The permanent connection of the busbar sections of the main busbar trunking must be made by welding; the connections of the distribution and lighting busbar trunkings must be dismountable (bolted).

The connection of trolley busbar sections must be carried out using special connecting parts. The current collection carriage must move freely along the guides along the slot of the box of the mounted trolley busbar.

Open conductors with voltage 6-35 kV

3.109. These rules must be observed when installing rigid and flexible conductors with a voltage of 6-35 kV.

3.110. As a rule, all work on the installation of current conductors must be carried out with preliminary preparation of units and sections of blocks at procurement and assembly sites, workshops or factories.

3.111. All connections and branches of buses and wires are made in accordance with the requirements of paragraphs. 3.8; 3.13; 3.14.

3.112. In places of bolted and hinged connections, measures must be provided to prevent self-unscrewing (cotter pins, lock nuts - lock, disc or spring washers). All fasteners must have an anti-corrosion coating (zinc plating, passivation).

3.113. Installation of supports for open current conductors is carried out in accordance with paragraphs. 3.129-3.146.

3.114. When adjusting the suspension of a flexible conductor, uniform tension of all its links must be ensured.

3.115. Connections of flexible conductor wires should be made in the middle of the span after the wires have been rolled out before they are drawn out.

OVERHEAD POWER LINES

Cutting clearings

3.116. The clearing along the overhead line route must be cleared of felled trees and shrubs. Commercial timber and firewood must be stacked outside the clearing.

The distances from wires to green spaces and from the axis of the route to stacks of combustible materials must be indicated in the project. Cutting down bushes on loose soils, steep slopes and areas flooded during floods is not allowed.

3.117. Burning of branches and other logging residues should be carried out within the permitted period of time.

3.118. Wood left in stacks on the overhead line route for the fire-hazardous period, as well as the “shafts” of logging residues remaining during this period, should be bordered by a mineralized strip 1 m wide, from which grass vegetation, forest litter and other combustible materials should be completely removed down to the mineral layer soil.

Page 13 of 52

CABLE LINES

General requirements

3.56. These rules must be observed when installing power cable lines with voltages up to 220 kV.

Installation of cable lines of the subway, mines, mines should be carried out taking into account the requirements of the VSN, approved in the manner established by SNiP 1.01.01-82.

3.57. The smallest permissible bending radii of cables and the permissible level difference between the highest and lowest points of location of cables with impregnated paper insulation on the route must comply with the requirements of GOST 24183-80*, GOST 16441-78, GOST 24334-80. GOST 1508-78* E and approved technical specifications.

3.58. When laying cables, measures should be taken to protect them from mechanical damage. The tensile forces of cables up to 35 kV must be within the limits given in table. 3. Winches and other traction means must be equipped with adjustable limiting devices to turn off the traction when forces appear above the permissible ones. Pulling devices that crimp the cable (drive rollers), as well as rotating devices, must exclude the possibility of cable deformation.

For cables with voltage 110-220 kV, permissible tensile forces are given in clause 3.100.

3.59. Cabali should be laid with a margin of 1-2% in length. In trenches and on solid surfaces inside buildings and structures, the reserve is achieved by laying the cable in a “snake” pattern, and along cable structures (brackets) this reserve is used to form a sag.

Laying the cable reserve in the form of rings (turns) is not allowed.

Table3

	Gravity forces for			Tensile forces on the cores, kN, cable up to 35, kV
Cable cross-section, mm 2	aluminum sheath, kN, cable voltage, kV			copper	aluminum multi-wire	aluminum single wire

	1,7 1,8 2,3 2,9 3,4 3,9 5,9 6,4 7,4	2,8 2,9 3,4 3,9 4,4 4,9 6,4 7,4 9,3	3,7 3,9 4,4 4,9 5,7 6,4 7,4 8,3 9,8

* Made of soft aluminum with elongation not exceeding 30%. Notes: 1. Pulling of a cable with a plastic or lead sheath is allowed only by the cores.

2. The tensile forces of the cable when pulling it through the block sewer are given in table. 4.

3. Cables armored with round wire should be pulled by the wires. Permissible stress 70-100 N/mm 2.

4. Control cables and armored and unarmored power cables with a cross-section of up to 3 x 16 mm 2, in contrast to the larger cross-section cables shown in this table, can be laid mechanically by pulling behind the armor or behind the sheath using a wire stocking, the pulling forces should not exceed 1 kN.

3.60. Cables laid horizontally along structures, walls, floors, trusses, etc. should be firmly secured at the end points, directly at the end couplings, at the turns of the route, on both sides of the bends and at the connecting and locking couplings.

3.61. Cables laid vertically along structures and walls must be secured to each cable structure.

3.62. The distances between supporting structures are taken in accordance with the working drawings. When laying power and control cables with an aluminum sheath on supporting structures with a distance of 6000 mm, a residual deflection in the middle of the span must be ensured: 250-300 mm when laid on overpasses and galleries, at least 100-150 mm in other cable structures.

The structures on which unarmored cables are laid must be designed to exclude the possibility of mechanical damage to the cable sheaths.

3.63. Armored and unarmored cables indoors and outdoors in places where mechanical damage is possible (movement of vehicles, loads and machinery, accessibility for unqualified personnel) must be protected to a safe height, but not less than 2 m from the ground or floor level and at a depth of 0.3 m in the ground.

3.64. The ends of all cables whose sealing is broken during installation must be temporarily sealed before installing the connecting and end couplings.

3.65. Cable passages through walls, partitions and ceilings in production premises and cable structures must be carried out through sections of non-metallic pipes (free-flow asbestos, plastic, etc.), textured holes in reinforced concrete structures or open openings. Gaps in pipe sections, holes and openings after laying cables must be sealed with fireproof material, for example cement with sand by volume 1:10, clay with sand - 1:3, clay with cement and sand - 1.5:1:11 , perlite expanded with building gypsum - 1:2, etc., over the entire thickness of the wall or partition.

Gaps in passages through walls may not be sealed if these walls are not fire barriers.

3.66. The trench before laying the cable must be inspected to identify places on the route containing substances that have a destructive effect on the metal cover and cable sheath (salt marshes, lime, water, bulk soil containing slag or construction waste, areas located closer than 2 m from cesspools and garbage pits, etc.). If it is not possible to bypass these places, the cable must be laid in clean neutral soil in free-flow asbestos-cement pipes, coated inside and outside with a bitumen composition, etc. When backfilling the cable with neutral soil, the trench must be additionally expanded on both sides by 0. 5-0.6 m and deepened by 0.3-0.4 m.

3.67. Cable entries into buildings, cable structures and other premises must be made in asbestos-cement free-flow pipes in textured holes in reinforced concrete structures. The ends of the pipes must protrude from the building wall into the trench, and if there is a blind area, beyond the line of the latter by at least 0.6 m and have a slope towards the trench.

3.68. When laying multiple cables in a trench, the ends of the cables. intended for subsequent installation of connecting and locking couplings, should be located with a shift of the connection points by at least 2 m. In this case, a reserve cable of the length necessary for checking the insulation for moisture and installing the coupling, as well as laying the compensator arc (the length on each end of at least 350 mm for cables with voltages up to 10 kV and at least 400 mm for cables with voltages of 20 and 35 kV).

3.69. In cramped conditions with large cable flows, it is allowed to place expansion joints in a vertical plane below the cable laying level. The coupling remains at the level of the cable routing.

3.70. The cable laid in the trench must be covered with the first layer of earth, mechanical protection or warning tape must be laid, after which representatives of electrical installation and construction organizations, together with a representative of the customer, must inspect the route and draw up a report on hidden work.

3.71. The trench must be finally backfilled and compacted after installing the couplings and testing the line with increased voltage.

3.72. Filling the trench with clods of frozen earth, soil containing stones, pieces of metal, etc. is not allowed.

3.73. Trenchless laying from a self-propelled or traction-movable knife cable laying machine is allowed for 1-2 armored cables with a voltage of up to 10 kV with a lead or aluminum sheath on cable routes remote from engineering structures. In urban electrical networks and industrial enterprises, trenchless installation is allowed only on extended sections if there are no underground communications or intersections with engineering structures, natural obstacles and hard surfaces.

3.74. When laying a cable line route in an undeveloped area, identification marks must be installed along the entire route on concrete posts or on special sign boards that are placed at the turns of the route, at the locations of connecting couplings, on both sides of intersections with roads and underground structures, at entrances to buildings and every 100 m on straight sections.

On arable land, identification signs must be installed at least every 500 m.

Content

font size

RULES FOR CONSTRUCTION OF ELECTRICAL INSTALLATIONS - SECTION 2 - SEWERAGE OF ELECTRIC POWER (Edition 7) (approved by the Ministry of Fuel and Energy of the Russian Federation) (2017) Current in 2017

cable, mm2

Gravity forces for

aluminum

sheath, kN, cable voltage, kV

Tensile forces on the cores, kN,

cable up to 35, kV

aluminum stranded

aluminum single wire

1,7 1,8 2,3 2,9 3,4 3,9 5,9 6,4 7,4

2,8 2,9 3,4 3,9 4,4 4,9 6,4 7,4 9,3

3,7 3,9 4,4 4,9 5,7 6,4 7,4 8,3 9,8

2.3.83. When laying cable lines directly in the ground, the cables must be laid in trenches and have a backfill on the bottom and a layer of fine earth on top that does not contain stones, construction waste and slag.

Cables along their entire length must be protected from mechanical damage by covering them at voltages 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 earth-moving 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 laid at a depth of 1-1.2 m, cables of 20 kV and below (except for city power supply 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 excavation). Asphalt surfaces of streets, etc. are considered as places where digging is carried out in rare cases. For cable lines up to 20 kV, except for lines above 1 kV supplying power receivers of category I<*>, it is allowed in trenches with no more than two cable lines to use signal plastic tapes instead of bricks that satisfy technical requirements, approved by the USSR Ministry of Energy. It is not allowed to use warning tapes at the intersections of cable lines with utility lines and above cable couplings at a distance of 2 m in each direction from the crossed utility line or coupling, 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 line owner, it is allowed to expand the scope of application 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 placing one cable in a trench, the tape must be laid along the axis of the cable; with a larger number of cables, the edges of the tape must protrude beyond the outer cables by at least 50 mm. When laying more than one tape across the width of a trench, adjacent tapes must be laid with an overlap of at least 50 mm wide.

When using signal tape, laying cables in a trench with a cable cushion, 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 electrical networks.

2.3.84. The depth of cable lines from the planning mark must be no less than: lines up to 20 kV 0.7 m; 35 kV 1 m; when crossing streets and squares, regardless of voltage 1 m.

Oil-filled cable 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 entering lines into buildings, as well as where they intersect 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 across arable land must be done at a depth of at least 1 m, while the strip of land above the route can be occupied for crops.

2.3.85. The clear distance from a 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 basements and technical undergrounds of residential and public buildings, one should be guided by the SNiP of the Gosstroy of Russia.

2.3.86. When laying cable lines in parallel, the horizontal clear distance 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 oil-filled cables 110-220 kV and other cables; while oil-filled cable lines low pressure 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, to reduce 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 control cables is not standardized.

2.3.87. When laying cable lines in a planted area, the distance from the cables to the tree trunks must, 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 a green area with shrub plantings, the specified distances can be reduced to 0.75 m.

2.3.88. When laying in parallel, the horizontal clear distance from cable lines with voltages 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 heating pipes - 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, to 0.5 m without special cable protection and to 0.25 m when laying cables in pipes. For oil-filled cable lines 110-220 kV in a convergence section with a length of no 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 , eliminating the possibility of mechanical damage. Parallel laying of cables above and below pipelines is not permitted.

2.3.89. When laying a cable line parallel to a heat pipe, the clear distance between the cable and the wall of the heat pipe channel must be at least 2 m, or the heat pipe throughout the entire area of proximity to the cable line must have such thermal insulation so that additional heating of the ground by the heat pipe in the place where the cables pass does not occur at any time of the year. 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 parallel to railways, the cables must, as a rule, be laid outside the road exclusion zone. Laying cables within the exclusion zone is allowed only in agreement with organizations of the Ministry of Railways, and 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 permissible to reduce the specified distances, while the cables throughout the approach area must be laid in blocks or pipes.

For electrified roads running on direct current, the blocks or pipes must be insulating (asbestos-cement, impregnated with tar or bitumen, etc.)<*>.

2.3.91. When laying a cable line parallel to tram tracks, the distance from the cable to the axis of the tram track must be at least 2.75 m. In cramped conditions, this distance can be reduced, provided that the cables throughout the approach area will be laid in insulating blocks or pipes specified in 2.3.90.

2.3.92. When laying a cable line parallel to highways of categories I and II (see 2.5.145), the 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 edge or at least 1.5 m from the curb stone. Reducing the specified distance is allowed in each individual case in agreement with the relevant road departments.

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 the grounded parts and grounding conductors of overhead line supports above 1 kV must be at least 5 m at voltages up to 35 kV, 10 m at voltages 110 kV and above. In cramped conditions, the distance from cable lines to underground parts and grounding conductors of individual overhead line supports above 1 kV is allowed at least 2 m; in this case, 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 overhead communication supports (current conductors) and overhead lines above 1 kV, if the grounding devices of these supports are connected to the grounding loop of the substations.

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

<*>Agreed with the USSR Ministry of Communications.

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. This distance can be reduced to 0.25 m, provided that the cable is laid at the intersection plus at least 2 m in each direction in pipes.

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

2.3.96. When cable lines up to 35 kV cross heat pipes, the distance between the cables and the ceiling of the heat pipe in the clear must be at least 0.5 m, and in cramped conditions - at least 0.25 m. In this case, the heat pipe at the intersection plus 2 m in each direction from the outer cables must have such thermal insulation that the temperature of the ground does not increase 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 the cables to 0.5 m instead of 0.7 m (see 2.3.84); use of a cable insert with 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 cable replacement can be done without excavation work (for example, inserting pipe ends into chambers).

When an oil-filled cable line crosses a heat pipe, the distance between the cables and the ceiling of the heat pipe must be at least 1 m, and in cramped conditions - at least 0.5 m. In this case, the heat pipe at the intersection plus 3 m in each direction from the outermost cables must have such thermal insulation so that the ground temperature does not rise by more than 5°C at any time of the year.

2.3.97. When cable lines cross railways and highways, the 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 road surface.

When crossing cable lines electrified and subject to electrification on direct current<*> railways blocks and pipes must be insulating (see 2.3.90). The intersection must be at a distance of at least 10 m from the arrows, crosses and points of connection of suction cables to the rails. The intersection of cables with the tracks of electrified rail transport should be made at an angle of 75-90° to the axis of the track.

<*>Agreed with the Ministry of Railways.

The ends of blocks and pipes must be recessed 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 paths (for example, on slips, etc.), cables, as a rule, should be laid directly in the ground.

When the route of cable lines crosses a newly constructed non-electrified railway or highway, relocation of existing cable lines is not required. At the intersection, reserve blocks or pipes with tightly sealed ends should be laid in the required quantity in case of cable repairs.

In the case of a transition of a cable line into an overhead line, the cable must exit to the surface at a distance of at least 3.5 m from the base of the embankment or from the edge of the canvas.

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

2.3.99. When cable lines cross vehicle entrances to courtyards, garages, etc., cables must be laid in pipes. Cables at intersections of streams and ditches should be protected in the same way.

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 steeply inclined routes, installing cable couplings on them is not recommended. If it is necessary to install cable joints in such areas, horizontal platforms must be made underneath them.

To ensure the possibility of reinstalling the couplings in the event of their damage on the cable line, it is necessary to lay the cable on both sides of the couplings with a reserve.

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

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

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

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

The need to protect cable lines from corrosion should be determined based on the combined data of electrical measurements and chemical analyzes of soil samples. Protection of cable lines from corrosion should not create conditions that are 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 make it possible to determine 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.