Installation of warning tape. Protective and signal tape for underground cable lines

Posted 10/27/2009 (valid until 10/27/2010)

Studying TNLA is the path to the emergence of new resource-saving technologies.

It seems that everyone reading this article has at least once dug up the earth on their summer cottage. Several years ago, the author of this article purchased a plot of land in one of the villages near Minsk. Putting the land in order for planting turned out to be a very problematic task, since the previous owners buried garbage and waste in the ground. The shovel didn't penetrate plastic film, buried in the ground, “springing” back from it, so the exhausted summer resident had to first remove upper layer soil, remove the obstacle in the form of a film and only then 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 made from them were produced in England. The result is a plastic material with good dielectric properties, impact-resistant, unbreakable, with low absorption capacity, physiologically neutral, and odorless. 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. 50% destroyed nitric acid, as well as liquid and gaseous chlorine and fluorine. Virtually harmless. Polyethylene is easily recycled by all major plastics processing methods.

A study of foreign construction practice has shown that polymer materials are widely used in the construction of underground utility networks and communications as gas and water pipes, insulated cables, etc. There is also a “niche” in electrical grid construction.

In the Republic of Belarus for protection against mechanical damage cable lines Traditionally, solid clay bricks are used (despite the rather irrational nature of this application). Close communication with our power engineers, builders, as well as studying 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 received attention over the past 20 years.

At the end of the 1980s. Soyuzenergo issued a letter No. 106-25/57 dated December 30, 1986 “On the use of tapes from polymer compositions for cable protection" and "Decision of the Main Technical Directorate and Main State Energy Supervision of the USSR Ministry of Energy dated June 10, 1990 No. E-4/90 on changing the requirements of Ch. 2.3 PUE “Cable lines with voltage up to 220 kV”, signed by the Deputy Head of the Main Technical Directorate and the Deputy Head of the Main State Energy Supervision Department of the Ministry of Energy with the following content: “... to gain experience in operating cable lines laid in trenches using signal plastic tapes instead of bricks, using the specified tapes when laying cable lines up to 20 kV. Experience in operating these cable lines has not revealed any negative consequences of replacing brick with warning plastic tape. Taking this into account, as well as the shortage of bricks, the Main Technical Directorate and the Main State Energy Supervision Office consider it possible to allow wider use of signaling 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 Montazhspetsstroy have developed technical requirements for the tape (application), which should be used to guide the choice of tape material and its specifications. In order to expand the scope of application of signal plastic tapes when laying cable lines in trenches, the Glavtekhupravlenie and Glavgosenergonadzor, taking into account the requirements of CHiP 3.05.06-85 " Electrical devices regulating the use signal tape, decide to make changes to ch. 2.3 “Cable lines with voltage up to 220 kV” PUE, sixth edition, adding clause 2.3.83 at the end with the following text:

“For cable lines up to 20 kV, except for lines above 1 kV feeding power receivers of category 1*, 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 signal 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 distribution devices 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 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 outermost 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 warning 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.”

To be fair, I would like to note that on the eve of the complete collapse of the USSR, the Scientific and Production Association “Belstroynauka” of the State Construction Committee of the BSSR developed recommendations for the pilot industrial implementation of protective polymer coatings when laying electrical cables with a voltage of 0.4–10 kV, where, in particular, to physical and mechanical properties, polymer materials used to protect underground cables were required to have a tensile strength of over 10 MPa. Unfortunately, the accumulated potential of the construction science of the BSSR was not practically in demand in the electrical 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 outdated, 6th edition of the PUE, last changes which were included until 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 electrical networks of the Republic of Belarus.

Rice. 1. Appearance tapes.

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. 106-25/57 dated December 30, 1986 “On the use of tapes made of polymer compounds to protect cables." It was from this time that Lithuania began to develop its own technical regulatory documents regulating and rationalizing the use of building materials to protect 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 their areas of application were determined. The Soviet “Rules for the Construction of Electrical Installations” were revised into the “Rules for the Installation of Electrical Equipment”, which have already gone through several reissues in this short period of time due to the increasing scientific and technical integration of Lithuania with the European Union. In this regard, I would like to provide a translation of the chapter in the current edition of the Lithuanian “Rules for the installation of electrical equipment” dedicated to underground cable lines:

"VII. Cable lines in the ground

169. Protection of cables laid in trenches from mechanical damage depends on the significance of the cable, its voltage, depth and location of installation. Mechanical strength protective equipment cables (protective tapes) must be at least 6 MPa.

Cables with voltages of 110 kV and above must be covered reinforced concrete slabs thickness not less than 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, slabs, solid clay bricks or protective tapes 1.5–5 mm thick at a distance of 0.10–0.15 m above the cable or 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 surface, for each parallel laid cable, a warning 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 soil 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 warning tapes at a depth of 0.3 m from the surface of the earth.

If cables are laid in pipes or covered with special caps, slabs, or 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 lands from mechanical damage, however, it is necessary to lay a warning tape at a depth of at least 0.5 m from the ground surface.

Cables with voltages up to 1000 V, laid at a depth of 0.35–0.7 m and in those sections of routes where there is a risk of damage (for example, in places of frequent excavation), 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 soil at a depth of 0.3 m from the surface of the earth, in arable soil at a depth of 0.5 m from the surface of the earth, it is enough to lay only a warning tape ... "

In January 2009, having summarized all available information and assessed the relevance of new resource-saving technology for our country in the context of the global economic crisis, Interbeltrade LLC decided to begin developing technical documentation for the production of products that have never previously been produced in the Republic of Belarus. 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 regulations for this kind of product. I will not describe all the attempts to obtain intelligible information from practitioners in this area, I will only quote verbatim the recommendation received from power engineers: “We believe that you have to go to Gosstandart, everyone knows there...” Indeed, the advice turned out to be practical. An appeal to BelGISS (the head enterprise of Gosstandart in the field of technical regulation and standardization) and the subsequent scientific and methodological assistance not only solved the problem at hand, but also showed the importance and significance of the knowledge and application of technical regulations. Range of existing polymer materials diverse: GOST 26996-86 “Polypropylene and propylene copolymers”, GOST 16338-85 “Low pressure polyethylene”, GOST 20282-86 “Polystyrene” general purpose", GOST 19459-87 "Polyamide cast copolymers", GOST 16337-77 "Polyethylene high pressure" These standards established the range of raw materials for security and signal tape.

An analysis of the requirements contained in the TNLA data determined the requirements for the tape we are developing: tensile strength, frost resistance, specific surface area electrical resistance, electric strength. Comparative analysis values ​​of the physical and mechanical properties of the above polymers, as well as the final 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 for 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, was registered with Gosstandart. In September 2009, GPO Belenergo approved these technical specifications without comments, thereby allowing the use of protective signal tape in the electrical grid construction of the Republic of Belarus. The protective signal tape is made of high-density polyethylene (or its waste) and is used to protect cable lines with voltages up to 20 kV from mechanical damage and to mark places for laying cables laid in trenches underground. The protective signal tape is red front side with a warning inscription (Fig. 1) and must 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). When laid in this way, a 3.5 mm thick polyethylene sheet has 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 withstood mechanical load for the material used to protect underground cable lines must be at least 6 MPa, and from the recommendation for the pilot industrial implementation of protective polymer coatings when laying electrical cables, the Scientific and Production Association "Belstroynauki" of the State Construction Committee of the BSSR follows Since the tensile strength requirement for such coatings is over 10 MPa, the specialists of our company decided to set much higher strength requirements for their tape. From the protocol issued during testing of protective signal tape by the Testing Center of JSC Stroykompleks, it follows that the minimum value in MPa for longitudinal stretching of this product is 14.86, and for transverse stretching is 13.99. At the same time, according to STB 1160-99 “Ceramic bricks and stones” the average tensile strength clay brick solid grade 150, used to protect underground cable lines, when bending is equal to 2.8 MPa. In addition, the test report of the Testing Center confirmed the high resistance of the protective signal tape to impact loads.

Estimated calculations for a conventional cable line confirmed the reduction in construction costs when using this tape. To deliver the protective signal tape to the construction site, a crane and heavy trucks are not required, as is required for the delivery of bricks; the use of machines and mechanisms when laying this tape directly into the trench to protect the cable is not required, and the installation itself takes little time. The weight of a roll of 50 meters of 250x3.5 mm tape is 35 kg. With a brick width of 12 cm, 417 pieces are needed to cover 50 meters of cable. brick, its weight will be about 1330 kg. We also believe (an important circumstance in favor of using tape to protect the cable from mechanical damage) that the use of clay solid brick It is only suitable 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 makes it possible to create new products and technologies that are not inferior to foreign analogues.

Question: Good afternoon, Liliya Yakovlevna! Please tell me what price should be applied for covering a cable with signal tape? Is it correct to use the price FERm08-02-143-01 “Coating a cable laid in a trench with bricks: one cable”, excluding the cost of mechanisms? Is it necessary to apply a reduction factor to the basic salary? Or should I use a different rate? Thank you.

Answer: Incl. and to Question No. 63.
Hello! The question of determining the costs of laying signal tape has been around for a long time. The need to create estimated standards assets on this type the work is already “overripe.” Ready recipe, of course there is, but it does not at all meet the aspirations of the estimators. The only correct answer is contained in clauses 2.3 (third paragraph from the bottom) and 2.15 of MDS 81-35.2004, as well as clauses 1.4 ÷ 1.5 of MDS 81-37.2004, where in such situations it is proposed to develop appropriate individual estimate standards for the work technologies provided for in the project. Having analyzed the available decisions of estimators (methods for determining estimated cost) of this question and posted on the forums of various sites, I was once again convinced of the ingenuity of the estimate compilers. The used (proposed) standards of the following Collections: No. 12 GESN-2001 (FER, TER) “Roofs” (roof fencing or as a vapor barrier device for a gasket in one layer), GESNm-2001 (FERm, TERm) No. 8 “Electrical installations” (coating cable laid in a trench with bricks with the replacement of basic materials), No. 10 “Communication equipment” (laying identification tape), do not reflect the consumption of resources, and therefore the costs of carrying out work on the use of 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 worker running, unwinding a roller with tape along the laid cable, will complete the job. Not so! Please study the technology of performing work not only on laying the tape, but also pay attention to Special attention for related work, namely the thoroughness and accuracy of execution backfill trenches with soil, with cables and signal tape laid in it. The use of warning tapes is regulated by 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 provides the rules and requirements for carrying out this work and here are some of them:
“It is not allowed to use signal 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.
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 outermost 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 warning 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.” In this case, work should be carried out in compliance with such points of this chapter of the PUE as clauses 2.3.84÷2.3.87, etc.
In addition, you should remember and know that signal tapes are used as underground warning signals about cable networks and pipelines laid in the ground and they are not protective, protecting against mechanical damage to the insulation, sheathing of cables or pipes. I draw the following conclusion: it is necessary to draw up estimate 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 (according to the tape width: 150, 250, 300, 450, 600, 750 and 900 mm) are used for identification electric cable with the logo “CAUTION CABLE” is produced wound on rollers of 100 linear meters, 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 intended for identification of optical cables. 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 “Svyaz” are intended for identification of communication cables. 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. Roller winding 250 meters.”
It turned out a lot and took a long time, but I wanted it to be clear to everyone, namely: compilers of estimate standards, designers, installers, customers, inspectors, etc. I wish you success! Sincerely, L.Ya. Podyniglazova

When drawing up a project for laying a cable line, you should take into account the need to lay signal tape. What price should be taken into account in this case? Is it possible to use the FERm pricing, which specifies the conditions for covering a cable laid in a trench with bricks? What coefficients should be taken into account in this case? We answer these questions with the head of the department of estimate standards of the company “TsNIIEUS” Lidia Podyniglazova.

According to the expert, the need to determine installation costs has been around for a long time. However, there are still no standards in this area. And it is not entirely correct to solve the issue by simply eliminating the cost of operating the mechanisms. Individual estimate standards should be developed that take into account the types of work provided for in a specific project.

Most design organizations use standards that are completely inappropriate for this type of work. Non-specialized publications do not reflect either technology or resource consumption. Therefore, ultimately the cost of purchasing and installation signal line turn out to be completely different from what was envisaged in the project. And this already means a discrepancy with the estimate and significant financial problems.

Accounting for installation technology

The inattention that designers show to drawing up cost estimates for laying signal tape is based on an erroneous understanding of the specifics of the work technology. To most people, the technique seems extremely simple: a cable is laid, 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 could there be?

But installation according to current standards looks completely different! The technology includes basic and related work regulated by the PUE for laying cable lines in the ground. In particular, they note that signal tapes cannot pass at the intersection of cable ducts with other utilities. That they should not be laid above the cable joints, but only at a distance of two meters from them in each direction. They cannot be located in close proximity to substations or transformer devices, but only at a distance of at least five meters. There are other standards that are important to consider when drawing up project estimates. We will talk about them in a new review.