COORDINATION CENTER
ON PRICING AND ESTIMATE RATE IN CONSTRUCTION
LETTER
On the introduction of elemental estimated norms and single
prices for covering the cable with signal tape to
Collections of GESNm (FERm) - 2001-08 "Electrical installations"
In order to further develop and improve the federal budget regulatory framework pricing in construction:
1. From April 1, 2007, introduce additional elemental estimated norms and unit prices for covering the cable with signal tape (Appendix).
2. Supplement with the indicated norms and prices Department 02. Sewerage of electricity and Electricity of the net, Section 1. Cable lines up to 500 kV Collections GESNm (FERm) -2001-08 "Electrical installations".
3. These elemental estimated norms and unit prices can be used by customer organizations and contractors, regardless of their departmental affiliation and form of ownership, and are intended to determine estimated cost building resource and basis-index methods, as well as for settlements for completed construction, repair and construction and installation work.
4. Unit rates developed for the 1st base area Russian Federation(Moscow region) in the price level as of January 1, 2000 with a regional coefficient of 1.0. When applying prices in the constituent entities of the Russian Federation, their binding to local conditions should be carried out taking into account the territorial adjustment factors in the basic price level as of 01.01.2000.
5. These rates and prices are subject to the copyright of the Coordinating Center for Pricing and Estimated Rationing in Construction. Reprinting and distribution (in whole or in part), as well as making changes to the rates and prices without the permission of the CCCC are not allowed.
Head of the Center
P.V. Goryachkin
Attachment to the letter of CCCC dated 26.04.2006 No. CC/202
ELEMENTAL ESTIMATE RATES
DIVISION 02.
SECTION 1.
CABLE LINES UP TO 500 KV
Introductory Instructions
Supplement the introductory instructions of the section with the following paragraph:
5. For laying over one cable, a signal tape with a width of 150 mm is used, over two - 300 mm, and then for each cable with a multiple of 150 mm (450, 600, etc.)
Table ESN 08-02-143 Coating of the cable laid in the trench
Scope of work:
01. Leveling the base. 02. Covering with signal tape. 03. Powdering the tape with a layer of earth along the entire length.
Meter: 100 m cable
Cable coverage:
08-02-143-5 signal tape type "Electro" of one cable
08-02-143-6 signal tape type "Electro" of each subsequent
Resource ID |
Cost element name |
Unit |
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Labor costs of construction workers |
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Average work grade |
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Machinist labor costs |
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MACHINES AND MECHANISMS |
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Cars onboard with a carrying capacity up to 8 tons |
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MATERIALS |
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FEDERAL UNIT RATES
"Electrical installations"
DIVISION 02.
SEWERAGE OF ELECTRICITY AND ELECTRIC NETWORKS
SECTION 1. CABLE LINES UP TO 500 KV
AT estimated prices as of 01.01.2000
Including, rub. |
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NN rates |
Name and characteristics construction works and structures (equipment) |
Unit change |
Direct costs, rub. |
wages of construction workers |
machine operation |
materials |
Labor costs of construction workers man-hour |
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(Codes of unaccounted materials) |
Name and characteristics of materials unaccounted for by prices |
including driver wages |
consumption of unaccounted materials |
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Tab. 08-02-143 Covering the cable laid in the trench Meter: 100 m cable |
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Cable coverage: |
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signal tape type "Electro" of one cable |
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Tapes signal type "Electro" |
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signal tape type "Electro" of each subsequent |
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OPERATION OF CONSTRUCTION MACHINES
Recently, when consumers purchase signal tape and protective signal tape from our company, we are often asked what kind of tape should be purchased for laying over the cable. We are talking about the width of these tapes and the correctness of their use over the cable in terms of their functionality: designation or protection with the simultaneous designation of an underground cable line.
It should be remembered that the signal tape is only exclusively a means for designating underground cable lines. The beginning of its widespread use in the Soviet energy industry was associated with the possibility of abandoning, in some sections of underground cable lines, where possible, the use of bricks as protection against mechanical damage, limiting themselves only to their designation. This decision is connected primarily with the acute shortage of bricks at that time in the USSR. Judging by the way they are clearly separated in clause 3.70 of SNiP 3.05.06-85 “ Electrical devices”, introduced in 1986, the terms “mechanical protection” or “signal tape”, which should be used above the underground cable before it is backfilled with soil, it becomes clear that the signal tape could only be used in places where the intensity earthworks small and, accordingly, damage to the cable is unlikely. In the USSR, signal tapes began to be produced on the basis of a polyethylene film dyed in red, yellow and orange.
At present, the scope of the signal tape over the cable is regulated by the Decision No. E-4/90 dated June 10, 1990 of the Main Scientific and Technical Department of Energy and Electrification and the Main Department of State Energy Supervision of the Ministry of Energy of the USSR "On the change the requirements of Ch. 2.3 "Cable lines up to 220 kV". The voltage of the cables over which the signal tape is used is up to 20 kV, while for cables of the first category of power supply reliability, the allowable voltage is up to 1 kV. In addition, the number of cables in the trench should be no more than two, that is, the maximum width of the T-3 trench for cables up to 20 kV is 400 mm. If we are dealing with cables of the first category of power supply reliability, then the maximum width of the T-1 trench with one cable should be 200 mm. distribution devices and is laid at a distance of 250 mm. from the top covers of the cable. When one cable is in the trench, the signal tape is laid along the axis of the cable. If there are two cables in the trench, the edges of the tape should protrude beyond the edges of the cables by at least 50 mm. Adjacent tapes are laid with an overlap of 50 mm. To complete the task of marking one cable, it is enough to use a signal tape 150 mm wide. Designation of two cables, taking into account the distance between them in the trench of at least 100 mm, as well as the fulfillment of the necessary conditions for the protrusion of the tape beyond the edges of the cable by 50 mm. with the obligatory overlap of the tapes with each other by the same 50 mm. already requires the use of two signal tapes 150 and 300 mm wide. In the Republic of Belarus, the signal tape is produced according to TU BY 101333870.003-2010 “Signal tape series LS” LLC “INTERBELTRADE”, Minsk.
At the same time, the protective-signal tape is, first of all, a new tool for protecting underground cables from mechanical damage and at the same time marking underground cable lines, and it was created in order to displace bricks and concrete slabs from this area. In 2009, Belenergo GPO agreed specifications TU BY 101333870.002-2009 "Protective and signal tape of the LZS series" LLC "INTERBELTRADE", Minsk. The minimum thickness of this tape is 3.5 mm. At the same time, under the order, it can be produced with a thickness of up to 5 mm., As well as reinforced with fiberglass. After 4 years of successful operation, Belenergo State Production Association, by Order No. 26 dated 08/05/2013, determined the scope of the protective signal tape: protection and designation of cable power lines up to 35 kV, including the first category of power supply reliability. Protective signal tape can also be used above cable boxes, as well as near substations and switchgears. The price for laying the protective signal tape is included in the Belarusian republican base of resource estimates. The new resource estimate standard was developed on the basis of a typical technological map for laying the LZS 22 / 6t-2013.1K.2013 tape of the protective and signal series TTK (TTK100029434.062-2014) and included in the Collection No. 8 "Electrical installations" in May 2014. The release of these documents makes it possible to reasonably reduce by at least a third the cost of protecting power cable lines with this tape compared to brick and concrete slabs. According to our estimates, today the replacement of bricks and concrete slabs with LZS in projects of power cable lines allows customers to save more than 30 billion Belarusian rubles in year.
A tape width of 125 mm is sufficient to protect one cable, and a width of 250 mm is sufficient to protect two cables. When laying protective-signal tapes over a large number of cables, the tapes are laid tightly to each other without a gap and, taking into account the width of the trenches used, from 200 to 1000 mm. Thus, the cable laid in them is completely closed. See table 1.
Question: Good afternoon, Lilia Yakovlevna! Could you tell me, please, what price should be applied for covering the cable with signal tape? Is it correct to use the price FERm08-02-143-01 “Covering a cable laid in a trench with a brick: one cable”, excluding the cost of mechanisms? Do I need to apply a reduction factor to the basic salary? Or should a different rate be used? Thank you.
Answer: Incl. and Question #63.
Hello! The question of determining the cost of laying a signal tape has been standing for a long time. The need to create estimated standards on the this species work is already "overripe". Of course, there is a ready-made recipe, but it does not at all meet the aspirations of the estimators. The only correct answer is contained in paragraph 2.3 (third paragraph from the bottom) and 2.15 of MDS 81-35.2004, as well as paragraphs 1.4 ÷ 1.5 of MDS 81-37.2004, where in such situations it is proposed to develop appropriate individual estimated standards for the work technologies provided for in the project. After analyzing the available solutions of the estimators (methods for determining the estimated cost) of this issue and posted on the forums of various sites, I was once again convinced of the ingenuity of the estimators. The used (proposed) standards of the following Collections: No. 12 GESN-2001 (FER, TER) "Roofs" (roof fencing or as a device for vapor barrier gasket in one layer), GESNm-2001 (FERm, TERm) No. 8 "Electrical installations" (covering cable laid in a trench with bricks with the replacement of basic materials), No. 10 “Communication equipment” (laying an identification tape), do not reflect the consumption of resources, and therefore the cost of working on the use of a signal tape in cases of laying electrical cables for different voltages. Many, I believe, mistakenly believe that the signal tape is laid simultaneously with the cable and the working run, while unwinding the tape roller along the laid cable, will complete the job. It wasn't there! Please study the technology for performing work not only on laying the tape, but also pay special attention to related work, namely the thoroughness and accuracy of backfilling the trench with soil, with the cable and signal tape laid in it. The use of signal tapes is regulated by the PUE and SNiP 3.05.06-85 "Electrical devices". In clause 2.3.83 "Laying cable lines in the ground", chapter 2.3. "Cable lines with voltage up to 220 kV" PUE lists the rules and requirements for these works, and here are some of them:
“It is not allowed to use signal tapes at the intersections of cable lines with engineering communications 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.
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. At the same time, work should be carried out in compliance with such paragraphs of this chapter of the EMP as paragraphs 2.3.84 ÷ 2.3.87, etc.
In addition, you should remember and be aware that signal tapes are used as underground warning signals about cable networks and pipelines laid in the ground and they are not protective, saving insulation, cable sheaths or pipes from mechanical damage. I draw the following conclusion: it is necessary to draw up estimated standards, taking into account the technology and features of the work on laying signal tapes of all sizes and the number of cables in the trench. Signal detection tapes "Electro" LSE 150 ÷ LSE 900 (respectively, the width of the tape: 150, 250, 300, 450, 600, 750 and 900 mm) are used to identify the electrical cable with the logo "CAUTION CABLE" is produced in winding on rollers of 100 p .m, thickness - 300 microns and color red (GOST 2245-002-21696750-04). For comparison, I will give the characteristics of other tapes used, for example:
"Signal detection tapes LSO 40, 70 "Optics" are designed to identify the optical cable. The color is yellow, the text on the tape is "Caution, optical cable". Width 40 and 70 mm, tape thickness 100 microns, roller winding 500 meters.
“Signal detection tapes LSS 40, 50, 75, 100 LSS “Communication” are designed to identify the communication cable. The color is orange, the text on the tape is "Do not dig, below the cable." Available in widths of 40, 50, 75 and 100 mm, thickness 300 microns. Roll winding 250 meters.
It turned out a lot and for a long time, but I wanted it to be clear to everyone, namely: compilers of estimated standards, designers, installers, customers, inspectors, etc. Wish you success! Sincerely, L.Ya. Podyniglazova
Cable lines for the transmission of electricity from the source to the consumer can be laid in trays or channels, along special overpasses or galleries, in pipes, tunnels, or fixed on the walls of buildings. However, the most common way is to lay the cable in the ground. Its popularity is primarily due to its cost-effectiveness, as well as the good protection of the conductor from the effects of weather conditions and electromagnetic fields. Cable laying in the ground takes place in several stages, performed in a strictly defined sequence.
Proper laying of the power cable in the ground and the stages of laying in trenches affect the price of work per linear meter.
The route must meet several requirements. First of all, it is necessary to take into account the safety of operation, as well as to provide for the possibility of its subsequent maintenance. At the same time, in order to reduce the cost of work and materials, the route should, if possible, be laid along the shortest distance.
The distance from the cable to other communications, forest plantations, building foundations, roads, supports and other obstacles should not be less than the minimum established by the standard. If this requirement cannot be met, additional measures are taken to protect the cable.
Mechanized or manual digging of a trench for cable laying
Regardless of the method of carrying out earthworks, they can be carried out only after obtaining the necessary permits issued by the relevant administrative authorities. When crossing with other communications or passing the route in the immediate vicinity of them, coordination with the operating organizations is also required.
Before digging a trench, the route is carefully inspected for the presence of substances in the soil that can destroy the protective sheath of the cable. If there are any, and there are no ways to bypass these sections, measures are taken to additionally protect the cable. The standard trench depth for laying cables in a settlement is 1-1.2 meters, but it can be changed depending on the type of soil and other conditions.
The device for adding a pillow of sand under the power cable
The sand cushion provides a reduction in the mechanical load on the cable during subsequent soil compaction. The thickness of the sand layer is at least 100 mm. It is allowed to use ordinary quarry sand, as well as loosened soil without foreign inclusions.
Cable laying and pulling in pipes
The cable in the trench is laid with a small margin, wavy twists. This is necessary to exclude its tension and rupture during soil subsidence and temperature fluctuations. In places where it intersects with other communications, when passing at a shallow depth, if it is necessary to protect against aggressive environments or in other cases where there is a high risk of damage, the cable is placed in plastic, asbestos-cement, ceramic or steel pipes.
Cable powder
The powdering of the cable is carried out in stages. First, it is covered with a layer of sand 100 mm thick. It is also allowed to backfill with soft soil, in which there should be no foreign solid inclusions. Before backfilling, the insulation resistance of the cable is checked, the absence of a short circuit to the ground and between the cores.
Brick cable protection
In cases where there is a high risk of mechanical damage to the cable, for example, as a result of maintenance work located in the immediate vicinity of the communications route, additional cable protection with a brick can be used.
Laying signal tape to avoid damage to cable lines
Laying a signal tape reduces the risk of cable damage during mechanical excavation. It is laid at a distance of 250 mm from the cable surface without breaks. The tape is made of polymeric or other materials that are resistant to aggressive environments, and a warning inscription “Caution cable!” is applied to its upper side.
Backfilling the cable line trench with soil
The final backfilling of the cable line trench with soil is carried out sequentially, while every 200 millimeters it is compacted. The soil used for backfilling should not contain solid inclusions - stones, construction debris
Installation of couplings is necessary in cases where the total length of the route exceeds the length of the cable in the coil. Before installing the couplings on the length of the cable determined by the technical documentation, the protective covers are sequentially removed. At the same time, a special heat-shrinkable tube is put on the cleaned conductors, which provides insulation from each other after mounting the coupling. If there is a screen in the cable, it must be restored by soldering.
Posted on 10/27/2009 (valid until 10/27/2010)
The study of TNLA is the way to the emergence of new resource-saving technologies.
It seems that everyone reading this article at least once dug up the earth in his summer cottage. A few years ago, the author of this article purchased a plot in one of the villages near Minsk. Bringing the land in order for planting plants turned out to be a very problematic task, as the previous owners buried garbage and waste in the ground. The shovel did not pierce the polyethylene film buried in the ground, “springing” back from it, so the exhausted summer resident had to first remove the top layer of the earth, remove the obstacle in the form of a film, and only after that continue digging up the summer cottage.
The properties of polyethylene have been known for a long time. In 1933, raw materials in the form of granules and the first products from it were produced in England. The result was a plastic material with good dielectric properties, shock-resistant, not breaking, with a small absorption capacity, physiologically neutral, odorless. It has low vapor and gas permeability. Polyethylene does not react with alkalis of any concentration, with solutions of any salts, carboxylic, concentrated hydrochloric and hydrofluoric acids. Resistant to alcohol, gasoline, water, oils. It is destroyed by 50% nitric acid, as well as liquid and gaseous chlorine and fluorine. Virtually harmless. Polyethylene is easily recycled by all major plastics processing methods.
The study of foreign construction practice has shown that polymeric materials are widely used in the construction of underground engineering networks and communications as gas and water pipes, insulated cables, etc. There is also a "niche" in power grid construction.
In the Republic of Belarus, solid clay bricks are traditionally used to protect cable lines from mechanical damage (despite the sufficient irrationality of this application). Close communication with our power engineers, builders, as well as the study of the technical regulatory framework former USSR showed that the market has been waiting for a new product for a long time, and the issue of replacing brick with another material has been given attention over the past 20 years.
In the late 1980s Soyuzenergo issued a letter No. 106-25/57 dated December 30, 1986 “On the use of tapes made of polymer compositions for cable protection” and “Decision of the Main Technical Administration and Glavgosenergonadzor of the USSR Ministry of Energy dated June 10, 1990 No. E-4 / 90 on the change the requirements of Ch. 2.3 PUE "Cable lines with voltage up to 220 kV", signed by the deputy head of the Main Technical Department and the deputy head of the Main State Energy Supervision Department of the Ministry of Energy of the following content: "... to gain experience in the operation of cable lines laid in trenches using signal plastic tapes instead of bricks, using these tapes when laying cable lines up to 20 kV. The operating experience of these cable lines did not reveal any negative consequences of replacing the brick with signal plastic tape. Considering this, as well as the shortage of bricks, the Main Technical Administration and the Main State Energy Supervision Authority consider it possible to allow a wider use of signal plastic tapes when laying cable lines in the ground. To streamline the use of signal plastic tapes, organizations of the USSR Ministry of Energy and the USSR Ministry of Installation and Construction of the USSR developed technical requirements for the tape (application), which should be followed when choosing the material of the tape and its technical characteristics. In order to expand the scope of signal plastic tapes when laying cable lines in trenches, the Main Technical Department and Glavgosenergonadzor, taking into account the requirements of CHiP 3.05.06-85 "Electrical devices" that regulate the use of signal tape, decide to amend Ch. 2.3 "Cable lines with voltage up to 220 kV" PUE of the sixth edition, supplementing clause 2.3.83 at the end with the text:
“For cable lines up to 20 kV, except for lines above 1 kV, supplying electrical receivers of category 1 *, it is allowed to use signal plastic tapes instead of bricks in trenches with no more than two cable lines that meet technical requirements, approved by the Ministry of Energy of the USSR. 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. The signal tape must 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.
In fairness, I would like to note that on the eve of the complete collapse of the USSR, the NPTO "Belstroynauka" of the Gosstroy of the BSSR developed recommendations for the pilot-industrial introduction of protective polymer coatings when laying electrical cables with a voltage of 0.4–10 kV, where, in particular, to physical and mechanical properties, polymeric materials used to protect underground cables were required to have a tensile strength of more than 10 MPa. Unfortunately, the accumulated potential of the building science of the BSSR was not practically in demand in the power grid construction of the already independent Republic of Belarus, where in the second decade of the 21st century brick continues to be used everywhere to protect underground cable lines, which is regulated by clause 2.3.83, in our opinion, morally and technically obsolete, the 6th edition of the PUE, last changes which were entered before August 31, 1985. At the same time, the use of the protective properties of polyethylene tapes studied by Belarusian scientists was limited to the development of "Temporary instructions for the use of signal tapes" approved by some regional power networks of the Republic of Belarus.
Rice. one. Appearance ribbons.
Communication with Lithuanian power engineers on this issue showed that the Lithuanian SSR, despite its active desire to secede from the USSR, most fully complied with the instructions of Soyuzenergo letter No. for cable protection. It was from that time that Lithuania began to develop its own technical normative documents, regulating and rationalizing the use of building materials for the protection of underground cable lines. Technical terms were introduced: “Polyethylene signal tape for cable lines” and “Polyethylene protective tape for cable lines”, standards for their production were developed, and areas of their application were determined. The Soviet “Electrical Installation Rules” were revised into “Electrical Equipment Installation Rules”, which have gone through several reprints in this short period due to the increasing scientific and technical integration of Lithuania with the European Union. In this regard, I would like to cite the translation of the chapter in the currently valid version of the Lithuanian "Rules for the installation of electrical equipment", dedicated to underground cable lines:
"VII. Cable lines in the ground
169. The protection of cables laid in trenches from mechanical damage depends on the significance of the cable, its stress, depth and location. The mechanical strength of cable protective equipment (protective tapes) must be at least 6 MPa.
Cables with a voltage of 110 kV and above must be covered with reinforced concrete slabs with a thickness of at least 50 mm.
Cables with a voltage of 6–35 kV in the city must be protected from mechanical damage by covering them with special caps, plates, solid clay bricks or protective tapes 1.5–5 mm thick at a distance of 0.10–0.15 m above the cable, or the cables must be laid in ceramic, plastic, asbestos-cement or cast iron pipes. The width of the protective tape for one cable must be at least 100 mm, for two cables - 200 mm. When using protective tapes at a distance of 0.3 m from the ground, for each parallel cable, a signal tape with a thickness of at least 0.5 mm is laid with the inscription “Attention! Cable!".
Cables with a voltage of 6-10 kV, laid in uncultivated land, at a depth of at least 0.7 m, and with a voltage of 35 kV at a depth of at least 1 m, must be protected from mechanical damage by covering them with protective tapes and laying signal tapes at a depth of 0.3 m from the ground.
If cables are laid in pipes or they are covered with special caps, plates, solid clay bricks, then it is not necessary to lay signal tapes.
It is not necessary to protect cables with a voltage of 6-35 kV in arable land from mechanical damage, however, at a depth of at least 0.5 m from the ground, a signal tape must be laid.
Cables with voltage up to 1000 V, laid at a depth of 0.35–0.7 m and in those sections of the routes where there is a possibility of damage (for example, in places of frequent excavations), must be protected with slabs, caps, solid clay bricks or laid in pipes . In other cases, in the city, as well as under the pavement and in uncultivated land at a depth of 0.3 m from the surface of the earth, in arable land at a depth of 0.5 m from the surface of the earth, it is enough to lay only a signal tape ... "
In January 2009, summarizing all the available information and evaluating the relevance for our country in the context of the global economic crisis new resource-saving technology, Interbeltrade LLC decided to start developing technical documentation for the production of products that had never been produced in the Republic of Belarus before. The main problem that had to be solved was the requirements for the product and the properties that this product should have, since there are no technical regulatory legal acts for such products. I will not describe all the attempts to get intelligible information from practitioners in this area, I will only quote verbatim the recommendation received from the power engineers: “We believe that you will have to go to the State Standard, everyone knows there ...” Indeed, the advice turned out to be sensible. The appeal to BelGISS (the leading enterprise of the State Standard in the field of technical regulation and standardization) and the subsequent scientific and methodological assistance not only solved the problem, but also showed the importance and significance of knowledge and application of TNLA. The range of existing polymeric materials is diverse: GOST 26996-86 "Polypropylene and propylene copolymers", GOST 16338-85 "Low pressure polyethylene", GOST 20282-86 "General purpose polystyrene", GOST 19459-87 "Polyamide cast copolymers", GOST 16337- 77 "High pressure polyethylene". These standards set the range of raw materials for protective signal tape.
Analysis of the requirements laid down in the TNLA data determined the requirements for the tape we are developing: tensile strength, frost resistance, specific surface electrical resistance, electrical strength. Comparative analysis of the values of the physical and mechanical properties of the above polymers, as well as end products obtained on the basis of these polymers (GOST 12998-85 "Polystyrene film", GOST 10354-82 "Polyethylene film"), made it possible to draw an unambiguous conclusion in favor of the use of high density polyethylene. pressure for the production of protective signal tape for the protection of underground cable lines.
In June 2009, TU BY101333870.002-2009 “Protective and signal tape of the LZS series” LLC “Interbeltrade”, Minsk, were registered in the State Standard. In September 2009, State Production Association Belenergo agreed on the technical specifications without comment, thereby allowing the use of protective signal tape in the power grid construction of the Republic of Belarus. The protective signal tape is made of high-pressure polyethylene (or its waste) and is used to protect cable lines up to 20 kV from mechanical damage and to mark the places for laying cables laid in trenches underground. The protective-signal tape has a red front side with a warning inscription (Fig. 1) and should be laid in a trench above the cables at a distance of 250 mm from their outer covers on compacted fine soil poured onto the cable, without debris (Fig. 2). With such laying, a 3.5 mm thick polyethylene sheet has an increased resistance to mechanical stress.
Rice. 2. Laying the tape in the trench above the cable.
Despite the fact that, according to European requirements, the minimum value of the withstand mechanical load for the material used in the protection of underground cable lines should be at least 6 MPa, and from the recommendation on the pilot-industrial introduction of protective polymer coatings when laying electrical cables, NPTO "Belstroynauky" Gosstroy of the BSSR follows the requirement for tensile strength of such coatings is more than 10 MPa, the specialists of our company decided to set much higher strength requirements for their tape. From the protocol issued during tests on the protective signal tape by the Testing Center of OAO Stroykompleks, it follows that the minimum value in MPa for longitudinal tension of this product is 14.86, and in transverse tension - 13.99. At the same time, according to STB 1160-99 "Brick and ceramic stones", the average tensile strength of solid clay brick grade 150, used to protect underground cable lines, is 2.8 MPa in bending. In addition, the test report of the Testing Center confirmed the high resistance of the protective signal tape to shock loads.
Estimated calculations for a conditional cable line confirmed the reduction in the cost of its construction when using this tape. For the delivery of protective and signal tape to construction site there is no need for a crane and heavy trucks, as required by the delivery of bricks, and the use of machines and mechanisms is not required when laying this tape directly into the trench to protect the cable, and the laying itself takes little time. The weight of a roll of 50 meters of tape 250x3.5 mm is 35 kg. With a brick width of 12 cm, 417 pieces are needed for a shelter of 50 meters of cable. brick, its weight will be about 1330 kg. We also consider (an important circumstance in favor of the use of tape to protect against mechanical damage to the cable) that the use of solid clay bricks is advisable only for its intended purpose - exclusively for the construction of buildings.
In conclusion, I would like to say that the study and application of domestic standards allows you to create new products and technologies that are not inferior to foreign counterparts.
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When drawing up a project for laying a cable line, the need to lay a signal tape should be taken into account. What value should be taken into account? Is it possible to use the price of FERm, specifying the conditions for covering the cable laid in the trench with a brick? What factors should be taken into account in this case? We answer these questions with the head of the estimated norms department of the TsNIIEUS company, Lidia Podyniglazova.
According to the expert, the need to determine laying costs has existed for a long time. However, there are still no regulations in this area. And to resolve the issue by only excluding the cost of operating mechanisms is not fully correct. It is necessary to develop individual estimated standards that allow you to take into account the types of work provided for in a particular project.
At the same time, most design organizations use standards that are completely unsuitable for this type of work. Non-specialized publications reflect neither technology nor resource consumption. Therefore, in the end, the costs of buying and laying the signal line turn out to be completely different from what was provided for in the project. And this is already a discrepancy with the estimate and significant financial problems.
The inattention shown by designers to the preparation of cost estimates for laying the signal tape is based on an erroneous idea of the features of the work technology. Most of the technique seems to be extremely simple: here the cable is laid, here a man with a reel in his hands runs over the trench and unwinds the signal tape. Then you just need to dig a trench, what other additional costs can there be?
But the installation current regulations looks completely different! The technology includes the main and related works regulated by the PUE for laying cable lines in the ground. In particular, they note that signal tapes cannot pass at the intersections of cable ducts with other engineering communications. That they should not be laid over cable boxes, but only at a distance of two meters from them in each direction. They cannot be located in the immediate vicinity of substations, transformer devices, but only at a distance of at least five meters. There are other norms that are important to consider when drawing up a project estimate. We will talk about them in a new review.
03.11.16What will they teach me there? After all, I already know everything, and if I don’t know, then I’ll find everything on the Internet. Today on specific example I want to analyze a number of mistakes that were made when laying cables in the ground.
Recently, one of my first customers contacted me with a request to eliminate comments on the project. The customer represented by the director of the design organization is unique and I have not been working with him for a long time. I refused this job, but promised to help the one who will do it, i.e. suggest where and what needs to be corrected in the project. The remarks were not at all about laying cables in the trench.
Let's look at the mistakes that were made in that project when laying cables in a trench. Here is a cut that was provided in the project:
I must say that there is no such document where all the requirements for laying cables in a trench would be presented, so you have to use the PUE, GOSTs, standard designs, technological maps to justify certain design decisions.
1 Distance between pipes.
In urban areas, the minimum possible distance is almost always made between cables. I always provide at least 100 mm between cables. And what distance should be between the pipes when laying cables?
If you follow GOST R 50571.5.52-2011, then the cables can be laid even close. Personally, I never do that.
For example, STO 56947007-29.060.20.020-2009 says:
7.4.4 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.
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).
And what do you say about laying cables in blocks:
Is the distance between pipes 100 mm maintained here?
I believe that 0.4 kV cables in pipes can be laid close to each other. But if you want no one to have a reason to comment, then keep a distance of 100 mm between the pipes. Why such a huge trench for two cables? It can be assumed that the cables are mutually redundant and thus protected against damage by short-circuit currents. However, we have cables in pipes...
2 Type of pipe for laying cables in the ground.
For laying cables in the ground, as a rule, technical HDPE pipes or double-wall HDPE / HDPE pipes are used.
Polyethylene pipe PE80 SDR21 is designed for pressure water pipeline for transportation of cold water up to +40°C under pressure.
3 Placement of signal tape.
The signal tape must be at a distance of 250 mm from the cable, and not from the ground.
When laying cables in pipes, signal tape is not required.
The section does not indicate the depth of the cables, and to be more precise, this value is variable. Suppose the author has made a universal cut for 0.7/1.0 m. However, this distance should be taken to the top of the cable (pipe), and not to the cable laying plane.
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.
6 Primer for backfilling cables.
The bedding under the cable and above the cable is made of fine sifted earth or sand.
7.3.1 When laying cable lines directly in the ground, the cables should be laid in trenches and have a backfill at the bottom, and a backfill with a layer of fine earth that does not contain stones, construction debris and slag on top.
The thickness of the backfill layer is determined by the project.
7 Volume of shallow earth for backfilling cables in pipes.
Despite the fact that the thickness of the backfill is determined by the project, according to standard projects, 100 mm of sand is enough above the pipe. An additional 200 mm of shallow earth is an unreasonable cost overrun.
Basic documents for laying cables in the ground:
1 Rules for the installation of electrical installations.
2 GOST R 50571.5.52-2011 Low-voltage electrical installations. Part 5-52. Selection and installation of electrical equipment. Wiring.
3 Arch. No. 1.105.03tm (Laying power cables up to 10 kV in trenches).
4 A11-2011 (Laying cables up to 35 kV in trenches using double-walled corrugated pipes).
5 STO 56947007-29.060.20.020-2009 ( Guidelines on the use of power cables with XLPE insulation for a voltage of 10 kV and above).
Surely you would like to know what this trench cut would look like in my project. If you are interested, then watch the video on my channel
When drawing up a project for laying a cable line, the need to lay a signal tape should be taken into account. What value should be taken into account? Is it possible to use the price of FERm, specifying the conditions for covering the cable laid in the trench with a brick? What factors should be taken into account in this case? We answer these questions with the head of the estimated norms department of the TsNIIEUS company, Lidia Podyniglazova.
According to the expert, the need to determine laying costs has existed for a long time. However, there are still no regulations in this area. And to resolve the issue by only excluding the cost of operating mechanisms is not fully correct. It is necessary to develop individual estimated standards that allow you to take into account the types of work provided for in a particular project.
At the same time, most design organizations use standards that are completely unsuitable for this type of work. Non-specialized publications reflect neither technology nor resource consumption. Therefore, in the end, the costs of buying and laying the signal line turn out to be completely different from what was provided for in the project. And this is already a discrepancy with the estimate and significant financial problems.
The inattention shown by designers to the cost estimate for laying the signal tape is based on an erroneous idea of the features of the work technology. Most of the technique seems to be extremely simple: here the cable is laid, here a man with a reel in his hands runs over the trench and unwinds the signal tape. Then you just need to dig a trench, what other additional costs can there be?
But installation according to current regulations looks completely different! The technology includes the main and related works regulated by the PUE for laying cable lines in the ground. In particular, they note that signal tapes cannot pass at the intersections of cable ducts with other engineering communications. That they should not be laid over cable boxes, but only at a distance of two meters from them in each direction. They cannot be located in the immediate vicinity of substations, transformer devices, but only at a distance of at least five meters. There are other norms that are important to consider when drawing up a project estimate. We will talk about them in a new review.
03.11.16Cable lines for the transmission of electricity from the source to the consumer can be laid in trays or channels, along special overpasses or galleries, in pipes, tunnels, or fixed on the walls of buildings. However, the most common way is to lay the cable in the ground. Its popularity is primarily due to its cost-effectiveness, as well as the good protection of the conductor from the effects of weather conditions and electromagnetic fields. Cable laying in the ground takes place in several stages, performed in a strictly defined sequence.
Proper laying of the power cable in the ground and the stages of laying in trenches affect the price of work per linear meter.
The route must meet several requirements. First of all, it is necessary to take into account the safety of operation, as well as to provide for the possibility of its subsequent maintenance. At the same time, in order to reduce the cost of work and materials, the route should, if possible, be laid along the shortest distance.
The distance from the cable to other communications, forest plantations, building foundations, roads, supports and other obstacles should not be less than the minimum established by the standard. If this requirement cannot be met, additional measures are taken to protect the cable.
Mechanized or manual digging of a trench for cable laying
Regardless of the method of carrying out earthworks, they can be carried out only after obtaining the necessary permits issued by the relevant administrative authorities. When crossing with other communications or passing the route in the immediate vicinity of them, coordination with the operating organizations is also required.
Before digging a trench, the route is carefully inspected for the presence of substances in the soil that can destroy the protective sheath of the cable. If there are any, and there are no ways to bypass these sections, measures are taken to additionally protect the cable. The standard trench depth for laying cables in a settlement is 1-1.2 meters, but it can be changed depending on the type of soil and other conditions.
The device for adding a pillow of sand under the power cable
The sand cushion provides a reduction in the mechanical load on the cable during subsequent soil compaction. The thickness of the sand layer is at least 100 mm. It is allowed to use ordinary quarry sand, as well as loosened soil without foreign inclusions.
Cable laying and pulling in pipes
The cable in the trench is laid with a small margin, wavy twists. This is necessary to exclude its tension and rupture during soil subsidence and temperature fluctuations. In places where it intersects with other communications, when passing at a shallow depth, if it is necessary to protect against aggressive environments or in other cases where there is a high risk of damage, the cable is placed in plastic, asbestos-cement, ceramic or steel pipes.
Cable powder
The powdering of the cable is carried out in stages. First, it is covered with a layer of sand 100 mm thick. It is also allowed to backfill with soft soil, in which there should be no foreign solid inclusions. Before backfilling, the insulation resistance of the cable is checked, the absence of a short circuit to the ground and between the cores.
Brick cable protection
In cases where there is a high risk of mechanical damage to the cable, for example, as a result of maintenance work located in the immediate vicinity of the communications route, additional cable protection with a brick can be used.
Laying signal tape to avoid damage to cable lines
Laying a signal tape reduces the risk of cable damage during mechanical excavation. It is laid at a distance of 250 mm from the cable surface without breaks. The tape is made of polymeric or other materials that are resistant to aggressive environments, and a warning inscription “Caution cable!” is applied to its upper side.
Backfilling the cable line trench with soil
The final backfilling of the cable line trench with soil is carried out sequentially, while every 200 millimeters it is compacted. The soil used for backfilling should not contain solid inclusions - stones, construction debris
Installation of couplings is necessary in cases where the total length of the route exceeds the length of the cable in the coil. Before installing the couplings on the length of the cable determined by the technical documentation, the protective covers are sequentially removed. At the same time, a special heat-shrinkable tube is put on the cleaned conductors, which provides insulation from each other after mounting the coupling. If there is a screen in the cable, it must be restored by soldering.
Question: Good afternoon, Lilia Yakovlevna! Could you tell me, please, what price should be applied for covering the cable with signal tape? Is it correct to use the price FERm08-02-143-01 “Covering a cable laid in a trench with a brick: one cable”, excluding the cost of mechanisms? Do I need to apply a reduction factor to the basic salary? Or should a different rate be used? Thank you.
Answer: Incl. and Question #63.
Hello! The question of determining the cost of laying a signal tape has been standing for a long time. The need to create estimated standards for this type of work has already "overripe". Of course, there is a ready-made recipe, but it does not at all meet the aspirations of the estimators. The only correct answer is contained in paragraph 2.3 (third paragraph from the bottom) and 2.15 of MDS 81-35.2004, as well as paragraphs 1.4 ÷ 1.5 of MDS 81-37.2004, where in such situations it is proposed to develop appropriate individual estimated standards for the work technologies provided for in the project. After analyzing the available solutions of the estimators (methods for determining the estimated cost) of this issue and posted on the forums of various sites, I was once again convinced of the ingenuity of the estimators. The used (proposed) standards of the following Collections: No. 12 GESN-2001 (FER, TER) "Roofs" (roof fencing or as a device for vapor barrier gasket in one layer), GESNm-2001 (FERm, TERm) No. 8 "Electrical installations" (covering cable laid in a trench with bricks with the replacement of basic materials), No. 10 “Communication equipment” (laying an identification tape), do not reflect the consumption of resources, and therefore the cost of working on the use of a signal tape in cases of laying electrical cables for different voltages. Many, I believe, mistakenly believe that the signal tape is laid simultaneously with the cable and the working run, while unwinding the tape roller along the laid cable, will complete the job. It wasn't there! Please study the technology for performing work not only on laying the tape, but also pay special attention to related work, namely the thoroughness and accuracy of backfilling the trench with soil, with the cable and signal tape laid in it. The use of signal tapes is regulated by the PUE and SNiP 3.05.06-85 "Electrical devices". In clause 2.3.83 "Laying cable lines in the ground", chapter 2.3. "Cable lines with voltage up to 220 kV" PUE lists the rules and requirements for these works, and here are some of them:
“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.
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. At the same time, work should be carried out in compliance with such paragraphs of this chapter of the EMP as paragraphs 2.3.84 ÷ 2.3.87, etc.
In addition, you should remember and be aware that signal tapes are used as underground warning signals about cable networks and pipelines laid in the ground and they are not protective, saving insulation, cable sheaths or pipes from mechanical damage. I draw the following conclusion: it is necessary to draw up estimated standards, taking into account the technology and features of the work on laying signal tapes of all sizes and the number of cables in the trench. Signal detection tapes "Electro" LSE 150 ÷ LSE 900 (respectively, the width of the tape: 150, 250, 300, 450, 600, 750 and 900 mm) are used to identify the electrical cable with the logo "CAUTION CABLE" is produced in winding on rollers of 100 p .m, thickness - 300 microns and color red (GOST 2245-002-21696750-04). For comparison, I will give the characteristics of other tapes used, for example:
"Signal detection tapes LSO 40, 70 "Optics" are designed to identify the optical cable. The color is yellow, the text on the tape is "Caution, optical cable". Width 40 and 70 mm, tape thickness 100 microns, roller winding 500 meters.
“Signal detection tapes LSS 40, 50, 75, 100 LSS “Communication” are designed to identify the communication cable. The color is orange, the text on the tape is "Do not dig, below the cable." Available in widths of 40, 50, 75 and 100 mm, thickness 300 microns. Roll winding 250 meters.
It turned out a lot and for a long time, but I wanted it to be clear to everyone, namely: compilers of estimated standards, designers, installers, customers, inspectors, etc. Wish you success! Sincerely, L.Ya. Podyniglazova
