Laying sip wires underground - is it possible or not and why?

Underground cable installation technology

Laying an electrical cable in the ground at a summer cottage, the territory of a private household or other facility begins with excavation work. Before this, you need to decide on the depth and width of the trench. The depth must be at least 80 cm, and the width 30 cm for each cable, if there are several of them. In accordance with the developed plan and route markings, soil sampling is carried out. The trench is cleared of foreign hard and sharp objects, and its walls should have a slight slope. After excavation work is completed, the cable is laid according to the following algorithm:

• the bottom of the trench is leveled, covered with sand in a layer of 15 cm and compacted;
• Protective cases are placed on the prepared pillow, if necessary;
• the cable is pulled through the cases, maintaining the required slack;
• the protection pipes are connected into one whole in one of several ways;
• a layer of sand 25 cm thick is poured on top of the laid cable in protection;
• the top filling is slightly compacted, preferably with your own feet;
• plastic warning tape must be laid with the lettering facing up;
• the trench is filled with soil, layer by layer, with mandatory compaction.

It is advisable to lay the cable in one single piece, without any connections. If this option cannot be implemented, then the individual pieces must be connected in mounting boxes specially designed for outdoor use. The device is installed on a post above the soil surface, at the junction of the cable, where its ends are brought to the surface. Do not bury the box, as this will quickly damage the line.

At this point, the laying of cable lines in the ground ends and the stage of connecting underground electrical communications to the general power supply networks and input into buildings located on the site begins. Each stage of work, both when laying the cable and connecting it, has its own nuances, which will be highlighted below. We will begin this description with the choice of cable for underground routes.

Cable management protection

Signal tape

The standard trench depth is 90 cm, the thickness of the sand cushion is up to 20 cm. The cable is laid without tension, in a wave-like manner, always below the freezing point of the soil. Next, it is covered with a 30 cm layer of sand and earth, after laying warning tape.

If the soil is subject to shifts, is not dense enough, or is saturated with groundwater, additional protection is installed. Make a tray from concrete blocks or moisture-resistant bricks. The cable is laid in a tray and covered with a concrete slab on top. A reinforced concrete monolithic channel is made on creeping soil and covered with reinforced slabs.

Brick, concrete or stone wall

You can lay a cable without a corrugation or tray only if its insulation is resistant to ultraviolet radiation. But in practice, in most cases, SIP is used, which is intended for installation outdoors and is resistant to ultraviolet radiation, or VVGng-LS, the insulation of which is not resistant to ultraviolet radiation.

In the first case, you can lay the cable along the facade of the building, provided that the distance from the cable to the wall is no more than 6 cm (PUE chapter 2.4, clause 2.4.60).

In the second case, the cable is laid in a metal electrical box. If there is no danger of mechanical damage, you can lay the cable in HDPE corrugation (black), but UV-resistant PVC corrugation is also available on sale (check this point, since regular PVC cracks in the sun). You can also use a metal hose. Cable cleats and corrugated fastening clips are attached to the wall with dowel nails or nail dowels using a construction gun.

The cable fastening pitch in horizontal sections should not exceed 350 mm, in vertical sections - 500, in bending areas - 100. The cable entry into the building must be placed in a pipe or a piece of metal electrical box (chapter 2.1. PUE clause 2.1.58). We talked about how to lay a cable through a wall in a separate article.

The ideal way to install cable lines along the facade would be to lay them in pre-punched grooves and then cover them with plaster, but due to the high labor intensity, this is rarely used in practice.

Structural differences of SIP

In networks with voltages up to 1 kV, only two types of insulated wires are used, although there are more of them. To understand what the difference is between them, we have provided a small informational list:

SIP – 1 Source 1sip-kabel.ru

• SIP-1 is a bundle of twisted phase wires with insulation and one uninsulated neutral conductor made of high-strength ABE alloy. Has from one to four conductive cores.

SIP – 2 Source provodok.site

• A distinctive feature of SIP-2 is the presence of insulation not only on the phase wires, but also on the neutral core, and naturally, it has a higher cost. That is why it is used mainly on high-voltage lines.

SIP – 4 Source promkabel.org

• This type of wire has at least two current-carrying wires, but it does not have a carrier (zero) wire. It is designed specifically for making branches from power lines towards buildings and laying along walls.

Note! Other types of SIP differ from each other not only in the type of insulation, but also in the number of cores. However, to carry out electrical inputs into the house, only SIP-1 and SIP-4 are most often used - the rest are intended for lines with voltages up to 35 kV.

Due to the presence of insulation, the SIP wire has an aesthetic appearance. This is, of course, an important nuance - but more for the consumer. Energy supply organizations value SIP because the insulation does not allow for “throwing” onto the wire, and thus using the resource bypassing metering devices. Another advantage is that the sheath makes it possible to connect two wires to each other without removing the voltage from them - however, this requires special fittings.

Next, let's look at how to connect the SIP cable to each other and perform any other manipulations with it.

Cable output

Finished trench from house to site

At the exit from the ground, before connecting to the pole, a 2-meter section of the cable must be covered with a curved metal pipe. The bending radius is at least 20 times the diameter of the cable sheath.

When laying a cable in the ground at the dacha to the house, it should be introduced through the foundation; for this you need to provide a mortgage. This is a piece of pipe extending 10–15 centimeters from the foundation on both sides. Its cross-section should be 4 times larger than the wire being laid. It is easy to insert the cable into the room through it. For subsequent sealing, use foam or rags soaked in cement laitance.

In another method, the cable in a metal pipe is raised along the house. This is usually where the introductory cabinet hangs. The embed is made in the wall, adhering to the same parameters, and the wire is brought into the house. This method is used if the foundation is made of a monolithic slab and you do not want to disturb it.

Connecting wires in the ground

On both sides of the obstacle, two pits are made, one starting, the other receiving. On the pipe, using a grinder, cut teeth in the form of a crown. The diameter must correspond to the size of the wire, but not less than 20 mm.

It is better to do the work together. The end of the pipe with the crown is installed in the starting hole. The other end is hit with a sledgehammer with great force. After passing 50 cm of the path, the inside of the pipe is washed from soil with water under pressure.

If there is not enough length to the receiving pit, an additional section is welded. When the crown teeth appear on the other side, the process is complete. The protruding ends are cut off on both sides, and the cable is inserted into the middle part. In this case, the pipe remaining in the ground is protection.

Can SIP cable be laid in the ground?

Excavation work and cable installation require strict adherence to the standards established by the rules of the PUE and PTEEP.

The criteria for selecting cables for laying in trenches are as follows:

• soil type. This criterion is important for assessing the degree of freezing and natural deformations of various sections of the cable route;
• soil corrosion activity, which is characterized by humidity and acidity;
• operating conditions, including the proximity of foundations and green spaces, roads and railways, oil/gas/heat pipelines, power lines and electrified transport.

Cable products can be laid underground, either protected by armor or without special protective coverings. The classification of types of cables for laying in the ground (trenches) is also made according to the insulation material, which can be made:

• made of PVC;
• made of cross-linked polyethylene (XPE);
• made of paper impregnated with special compounds.

The minimum depth of underground installation of cable products is regulated by regulatory documentation and depends on the operating parameters of the power line and the type of soil. For example, the depth of the trench for cables up to 20 kV should be at least 0.7-0.8 m, up to 35 kV - 1 m.

Armored grades usually do not require additional protection when installed underground. When installing power lines from unarmored grades, as well as when it is necessary to cross roads or railways with armored cables, it is possible to use several types of protective structures:

• concrete slabs that are laid on top of a layer of soft soil or sand of at least 0.1 m. To protect power lines from 35 kV, slabs with a thickness of at least 50 mm are used;
• brickwork, which is installed similarly to concrete slabs;
• asbestos-cement or concrete, steel, ceramic or plastic pipes (corrugated hoses) made of low-density polyethylene (HDPE) or PVC.

Signal tape of the usual or protective type (LS or LZS) is an element of additional protection of power lines from mechanical damage.

Brands of armored cables for laying in the ground

Selecting brands of armored cables for laying in the ground is the optimal solution to ensure reliable operation of underground power lines.

Laying an armored cable in the ground usually does not require additional protective equipment. Products of this type have excellent resistance to mechanical damage, moisture, rodents and other external influences. Let's consider the most popular brands used when laying armored cable underground in Table 1.

Cautions

The underground cable for electricity in a private house should only be armored.

The metal pipe for wiring should not be solid, since when it is filled with groundwater, the ice formed in severe frost will damage the cable.

The wiring must be grounded. To do this, a separate insulated wire is soldered to the armor. The second end is connected to ground on the shield or neutral terminal. In the event of an emergency, the machine will turn off the power.

Choosing the right cable and complying with all requirements during its installation is the basis for long-term and safe operation of the electrical main.

Underground cable route design

The owner receives a plan of the route from the pole to the building along with the project for connecting to the electrical networks, but he carries out the wiring along the site to the bathhouse, garage and other objects independently. The most economical option is to lay the cable in a straight line, but in reality this is rarely feasible, since you will have to work around various obstacles. When developing a plan for laying underground cables across a site, the following rules must be followed.

1. If possible, avoid intersection with other communications. If this can be done, then the cable without a protective sheath must be placed at a distance of no closer than 0.5 m from gas, water and sewer pipes. When laying the conductor in a casing, this distance is reduced to 0.25 m. When crossing with another electrical cable, this parameter is 15 cm.
2. It is necessary to bypass parking areas and vehicle entry areas. If this condition cannot be met, then it is necessary to increase the depth of the trench or pass the cable through a protective case. Large trees and bushes should be avoided. When passing the route along the foundation, the distance from it must be at least 60 cm.

As a result, the cable laying plan will correspond to a broken line, not a straight line. Marking the trench is best done with a stream of sand or pegs. After the preparatory work, it is necessary to once again check the plan for compliance with the standards and transfer it to paper, linking it to all objects on the site and underground utilities.

This drawing will subsequently be useful during the construction of new facilities, redevelopment of the site, as well as in the event of a need to repair an underground power line, which can happen if the technology for laying an electric cable in the ground is not followed or in other force majeure circumstances. The plan has been developed, transferred to paper - it’s time to start the main work!

Posts 1 page 10 of 20

Share1Thu, 1 Jul 2010 16:55

• Author: yurik
• current strength
• Registered: Fri, 17 Oct 2008
• Posts: 37
• Respect: [+0/-0]
• Positive: [+0/-0]
• Spent on the forum: 1 day 9 hours
• Last seen: Thu, 29 Dec 2016 21:35

Can I lay SIP in the ground? If possible, then how?

Share2Thu, 1 Jul 2010 20:06

• Author: Slava
• master
• Registered: Tue, 22 Dec 2009
• Posts: 1234
• Respect: [+72/-14]
• Positive: [+32/-6]
• Time spent on the forum: 9 days 22 hours
• Last seen: Thu, 16 Aug 2012 10:10

In a sealed (water should not get into it) thick-walled plastic pipe (not corrugated, but a normal HDPE pipe). Everything else is as usual - 0.8 meters, sand bedding, tape.

Edited by Slawa (Thu, 1 Jul 2010 20:08)

Share3Thu, 1 Jul 2010 20:31

• Author: yurik
• current strength
• Registered: Fri, 17 Oct 2008
• Posts: 37
• Respect: [+0/-0]
• Positive: [+0/-0]
• Spent on the forum: 1 day 9 hours
• Last seen: Thu, 29 Dec 2016 21:35

Share4Thu, 1 Jul 2010 22:56

• Author: Slava
• master
• Registered: Tue, 22 Dec 2009
• Posts: 1234
• Respect: [+72/-14]
• Positive: [+32/-6]
• Time spent on the forum: 9 days 22 hours
• Last seen: Thu, 16 Aug 2012 10:10

Trench 0.8 meters deep, 10 cm of sand at the bottom, cable, 10 cm of sand on top, 0.4 m of soil, warning tape “Caution, cable!”, 20 cm of soil. When backfilling, all layers are compacted (you can run around in a crowd). And this. You can install it and it will work. You can’t hand it over to Energy Supervision. Not allowed.

Share5Thu, 1 Jul 2010 23:14

• Author: Gray
• engineer
• From: Ukraine, Zaporozhye
• Registered: Sun, 10 Jun 2007
• Posts: 1949
• Respect: [+142/-38]
• Positive: [+55/-41]
• Age: 39 [1980-04-12]
• ICQ: 242765901
• I work: in an energy generating company
• Time spent on the forum: 13 days 12 hours
• Last seen: Thu, 26 Apr 2012 14:34

Why be so perverted? Is it really impossible to use such a wonderful wire for its intended purpose, and choose another one for the ground?

Share6Fri, 2 Jul 2010 00:01

• Author: yurik
• current strength
• Registered: Fri, 17 Oct 2008
• Posts: 37
• Respect: [+0/-0]
• Positive: [+0/-0]
• Spent on the forum: 1 day 9 hours
• Last seen: Thu, 29 Dec 2016 21:35

The customer ordered SIP. We stretched it in the span between the supports and brought it into an old house, there we twisted the remains, designed for a cottage under construction. Now the owner has changed his mind and wants to put the remaining length into a new house underground. He asked us a question, but I had never heard of such a thing, so I asked.

Share7Fri, 2 Jul 2010 11:47

• Author: Gray
• engineer
• From: Ukraine, Zaporozhye
• Registered: Sun, 10 Jun 2007
• Posts: 1949
• Respect: [+142/-38]
• Positive: [+55/-41]
• Age: 39 [1980-04-12]
• ICQ: 242765901
• I work: in an energy generating company
• Time spent on the forum: 13 days 12 hours
• Last seen: Thu, 26 Apr 2012 14:34

Well, if the customer has a burning desire to save money, then why not lay it in a pipe, as Slawa . Although the cable was not originally intended for laying in the ground, I think there should be no problems.

Share8Sun, 4 Jul 2010 14:22

• Author: lomata
• student
• From: Irkutsk region.
• Registered: Tue, 26 Jan 2010
• Posts: 261
• Respect: [+29/-3]
• Positive: [+13/-0]
• Age: 43 [1976-01-01]
• Time spent on the forum: 5 days 23 hours
• Last seen: Mon, 17 Oct 2011 11:26

A customer who doesn’t know what he wants is a terrible thing! My main customer is our production, so I couldn’t disobey or send, although sometimes I want to do so. During the construction of one new facility, the TP was moved 5(!) times. With the transfer of all outgoing cable lines, and the restructuring (3 times) of the 6 kV power line section, which is on the balance sheet of the Distribution Zone(!)

Share9Mon, 5 Jul 2010 21:56

• Author: MosKomplektatsiya
• contact
• Registered: Mon, 5 Jul 2010
• Posts: 3
• Respect: [+0/-0]
• Positive: [+0/-0]
• Time spent on the forum: 1 hour 29 minutes
• Last seen: Tue, 6 Jul 2010 17:50

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

I'm afraid that even in a HDPE pipe it is not permissible to lay SIM in the ground

Source: electro.5bb.ru

Obtaining permission for underground input

An example of a cable entry project into a house

First you need to complete the project. It should be developed by a specialist. Technical documentation, plans and drawings must comply with all rules and regulations. The designer determines the brand of cable and calculates the cross-section of the conductors.

To receive a project, a number of technical conditions must be met. To connect a house to a common power line, you will need appropriate permission. For example, an agreement for excavation work is drawn up by the service responsible for facilities and communications.

Then the land plot is traced. If there are any communications in the immediate vicinity of the cable being laid, it is necessary to invite their representative to coordinate the position of the trench and control the work being carried out.

Wire tension

The wire is tensioned on the first anchor support of the span. To do this, you will need a hand winch with a special compressive grip on the harness or load-bearing core. Since the tension force must be strictly dosed, a dynamometer is necessary. The magnitude of the tension force can be indicated in the project, otherwise, it can be taken from the installation tables in accordance with the brand of wire and the length of the anchor span.

The work is performed from the AGP platform (“autotower”). The winch is fixed to the supporting core or to the harness, its hook is attached to the support through a dynamometer. By moving the handle, the SIP wire is pulled to the required force, controlled on the dynamometer scale. At the end of the tension, the wire is secured and tightened in the anchor clamp, after which the winch and dynamometer are removed.

Wire rolling

The installation of SIP begins after installing the VLI supports with clamps attached to them.

Anchor clamps are installed on the anchor supports that carry the tension force of the conductors, and supporting clamps are installed on the intermediate supports located between them.

Installation of SIP cable begins with its unrolling. To do this, perform the following steps sequentially:

• Special unrolling rollers are installed on all supports of the anchor span on which the wire is mounted. On the extreme, anchor supports, the rollers are fastened with a belt; on the intermediate supports, the rollers are suspended on a hook in the eyes for supporting clamps;
• A drum with wire is installed behind one of the outer supports of the span. It is located in a vertical position on special stands that allow it to rotate during the rolling process. In order for the wire to enter the roller at a flatter angle, it is recommended to install the drum from the support at a distance not less than its length;
• On the other side of the mounted span there is a drum on which a leader cable is wound, usually a synthetic rope with a diameter of 10–12 mm, depending on the rolling method (manual, mechanized);
• Next, the leader cable is rolled out manually. This operation is performed by sequentially lifting onto each support, threading the cable into the roller and further pulling it;
• After lifting to the last support, the leader cable is connected to the SIP using a special stocking and swivel that prevents the wire from twisting during the rolling process.

This is where the preparatory procedures end, and the actual rolling out of the wire begins. The leader cable slowly, without jerking, is pulled in the opposite direction. During mechanized rolling, the drum winding device is driven by an internal combustion engine with a gearbox; the leader cable can also be pulled out manually.

During the rolling process, the wire, following the leader cable, rises to the support and takes its place on the rollers. Rollers and drums must be located so that when rolling there is no friction of the wire on the ground, support and other structures. It is unacceptable to use a technology in which the wire is rolled out on the ground and then lifted onto a support.

Preparing for work

Installation of SIP on supports is not too different from the technologies used previously. To lay a new line, the first step is to clear the area of ​​trees and bushes. The next step will be the installation of load-bearing supports. At this stage, for ease of installation, specialists attach anchor brackets before installing the support in a vertical position. In this case, steel belts with anti-corrosion properties are used, secured with a clamp clutch. The wires are fastened to the supports and to each other using special fittings produced specifically for the installation of self-supporting insulated wires.

Carrying out the approach to the house

To make a connection to the house, it is necessary to install a bracket for attaching an anchor clamp on the support of the overhead line from which the input is planned. If the supply line is made of bare wire, the bracket is installed below the traverse with insulators. When connecting to VLI, the bracket is mounted below the linear terminals.

The tapping wire is secured in an anchor clamp on the support, leaving the ends of sufficient length to connect to the line. The connection itself is carried out by the personnel servicing the line after complete completion of the installation work. For connection, special clamps for bare wire are used if the overhead line is made with bare wire, or piercing clamps if the connection is made to an overhead line.

At the place where the SIP is attached to the facade of the house, it is also necessary to install a bracket for attaching the anchor clamp. The wire, fixed in an anchor clamp on the support, is inserted into the clamp on the facade of the house, manually tensioned and fixed. Most often, the Technical Conditions require that the metering cabinet be located on the outer wall of the building, and it is stipulated that the power input is carried out by a solid, visible wire. Before entering into the meter or circuit breaker located in the metering cabinet, self-supporting insulated wires are laid along the facade of the building. To secure the wire to the wall, special facade fastenings are used.

Laying cables along a wooden fence

The height requirements are the same as for concrete. The main restrictions according to the PUE are fire protection. If the cable has a sheath made of fireproof or hardly flammable materials, it can be attached directly to the fence. For a shell made of combustible materials, there are a number of requirements. It is enough to do at least one of them:

• The power wire is laid at a distance from the wooden surface using rollers made of fireproof dielectric (most often ceramic).
• The wiring is placed in a non-flammable sleeve (corrugation). It can be metal or plastic that does not support combustion.
• Installation is carried out inside a fireproof box.
• A backing made of non-flammable material is used, with a width of at least 10 mm to the sides of the cable. You can use a supporting structure made of a profile pipe. Only the wire should not touch the tree. A common option is a steel strip nailed to the fence boards. At the same time, it serves as a supporting structure.

How to properly tension SIP between poles

Overhead power lines with SIP wires are called VLI. Their installation traditionally begins with clearing the area of ​​trees, bushes, and other possible obstacles that interfere with rolling out and tensioning the wires on the supports.

You may be interested in this IKK Features

Important! Construction of a new power line requires attaching wire brackets to the pole. It is more convenient to do this work on the ground before laying it.

The brackets are mounted to the supports using a clamp made of corrosion-resistant steel tape. Afterwards, the excess tape is removed.

Laying overhead power lines

Instructions for designing an overhead power line will allow you to perform all the steps without error:

• The pole with mounting brackets is installed and the installation of overhead power lines begins.
• Installation of SIP on supports takes place using components at an outside air temperature of at least +20 degrees.
• SIP installation technology has its own peculiarity associated with wire rolling. It protects the insulation from damage.
• The stretched wire is rolled out from a drum installed on the machine.
• SIPs are distributed on the supports using rollers and a tension rope—the leader.

Technology The technology for unwinding from a SIP coil involves manual execution of the process, provided that the area is limited to one hundred meters and the cross-section of the phase conductors does not exceed 50 square meters.
mm. Manual rolling of the wire is allowed in populated areas where the span length does not exceed 50 m. The manual rolling technology has the following sequence: Near the first anchor support, where the power line will begin, a drum with wire is attached. Its distance to the pillar should be no less than the height of the support itself. The rope is attached to the end of the SIP with a mounting stocking.

Rollers are installed on each intermediate post, while the rope is laid in them. Under the supervision of an electrician, the wire is pulled along the supports. Laying occurs smoothly without jerking with simultaneous rotation of the drum and tension of the rope. The maximum speed of manual rolling should not exceed 5 km/h, while preventing the SIP from touching the ground and any building structures.

Important! On the last pole of the power line, the neutral core is fixed with a clamp to the anchor bracket. A free protrusion of the cores is left behind it for further connection.

Wire stretching

After fastening and laying out the SIP wires on the support, their stretching begins. A winch with a measuring device - a dynamometer - is fixed to the first post. Pulling is carried out with a certain force, displayed by a dynamometer. After stringing the entire power line, you need to insulate the wire, which should hang for a while.

You might be interested in: Features of heat shrink tube

Further installation on the first post involves attaching a clamp to the bracket and fixing the zero core in it. The wiring harness is tightened with clamps, the winch and transport roller are removed. The SIP is cut off from the coil, leaving the ends of the required length.

On the intermediate post, the wires are transferred from the roller to the clamp. Plastic wedges are used to separate the carrier core from the phase wires, while simultaneously securing it with clamps in the clamp. After removing the unrolling roller, all the cores are tightened with clamps at a distance of 150 mm from the clamp on both sides. An intermediate clamp is used to tighten and secure the phase conductors under the clamp.

Negative factors for street wiring

Cable lines laid outdoors are subject to several negative factors:

1. Ultra-violet rays. Sunlight has a detrimental effect on some types of conductor insulation. This process is long and difficult to control. Therefore, you should choose products with insulation made from materials that do not deteriorate when exposed to UV rays.
2. Ambient temperature. Low temperatures can lead to cracking of the insulation. Therefore, when choosing cables and wires, you should find out their operating temperature range. The installation temperature should also be taken into account. Usually it is not lower than 20 degrees below zero.
3. Wind. Strong winds can damage both the cable line sheath and the conductors inside. If the cable is laid outdoors, the climatic area of ​​installation should be taken into account.
4. Ice. If the external network is installed in areas where there is increased ice formation in winter, it is worth taking this factor into account. A conductor covered with an ice crust can become several times heavier and break under its own weight over long spans.

There are three ways to lay cables outdoors, and each of them has its own advantages and disadvantages:

1. By air. The fastest installation method. Disadvantages of this method: it requires reliable fastening of the cables, the lines are exposed to the negative influences of weather conditions.
2. Along the walls of buildings. For this method it is much easier to select the conductor material. Disadvantages: labor-intensive installation, disruption of the appearance of buildings, negative impact on the conductor of ambient temperature and sunlight.
3. In the ground. This method allows you to solve many problems. Weather conditions and sunlight have no effect. The appearance of buildings and surrounding areas is not disturbed. The disadvantage is that electrical installation is labor-intensive, in some cases requiring the use of construction equipment to excavate a trench.

Advantages

Installation of SIP compared to bare aluminum-steel wires has only one significant drawback: the cost of laying such lines is somewhat more expensive. Whereas, compared to cables attached to a supporting cable, it is possible to slightly reduce the price and reduce the overall complexity of installation.

Among the main advantages are increased electrical safety, independence of conductor characteristics from atmospheric conditions and relative ease of installation. Insulating phase wires not only protects the metal from the environment, but also provides protection for objects and creatures surrounding the line from electric shock.

Additionally, insulated wires do not suffer from deterioration of conductive characteristics in the event of icing, like their “bare” predecessors, and they cannot be “overwhelmed” by any wind. Using special fittings and tools for installing SIPs, a specialist is able to complete the entire work process almost single-handedly, provided there are installed supports.

Laying cables along a stone or concrete fence

From the point of view of the PUE, the work is carried out by analogy with the stone wall of a building. With a line height of 2.75 m, an unprotected insulated rein with an outer sheath is sufficient.

According to the Rules, a regular VVG of the appropriate section will do. However, given the layout of the wiring, it is better to use a double-jacketed power cable.

If the fence is monolithic (stone or brickwork, or cast from concrete), the cable is laid directly on the surface using standard clips (clamps) for street installation. They can be plastic or metal.

There are separate rules for self-supporting insulated wire (SIP). Since it has a single layer of insulation, a 60mm clearance is provided during installation. Special mounting clamps are available for this purpose.

If the fence is assembled from concrete panels, you cannot attach the cable directly to the plane. Under wind loads, the panels may move and the wiring will sooner or later break. In this case, the cable is attached to a supporting cable, and the suspension points are placed on support posts.

If the installation is at a height of less than 2.75 m from the ground, external cable protection is required. Firstly, it may be accidentally damaged. Secondly, at such a height there is a risk of electric shock. The wiring is placed in a box, cable sleeve (corrugation), or pipe. The material does not matter - the main thing is to provide mechanical protection.

Is it possible to run SIP wire underground? – Repair tips

However, home owners very often do not want to spoil the appearance of the building facade for aesthetic reasons. And they naturally ask themselves whether it is possible to lay SIP wire underground.

Advantages?

It would seem that there are only advantages:

• Firstly, you can save on cable
• secondly, directly from the support, lead the wire directly to the switchboard in the basement, thereby eliminating unnecessary connections

At the same time, you can save a significant amount on cable. Since you don’t have to buy an expensive copper armored one, it’s enough to replace it with an aluminum SIP of the same cross-section, plus protect it from the outside, for example, with corrugation or HDPE pipe (prices are indicated at the time of writing):

The standard trench depth for laying cables underground is 0.7 m or more.

Craftsmen, in order to protect SIP from possible groundwater and temperature changes during the winter-summer seasons, bury it to a greater depth - 1.2-1.5 meters. But in the end, none of this helps.

Firstly, a SIP wire is not a cable, as some mistakenly call it, but a wire!

And it does not have external insulation of all cores, which should protect:

• from mechanical influences from unauthorized persons and objects
• penetration of moisture between the cores
• chemical impact of an aggressive environment on the insulation shell
• ground movement

In addition, do not forget that rodents and other living creatures live underground, which can taste your input if desired.

Secondly, and most importantly, SIP is simply not intended for this.

All manufacturers of this wire clearly say that this is a material for laying through the air.

It can be used:

• on wooden and reinforced concrete supports
• metal poles and structures
• on the facades of the house

but cannot be used underground!

Even if you think logically, you will not specifically buy an armored cable VBShv or SB in order to suspend it on a cable in the air from a pole to a house, although this is not prohibited. The same goes for SIP, it needs to be used exactly in the conditions where it belongs.

Moreover, not every SIP can be installed inside the house and in the attic, but only certain brands that have the letters Ng in the designation - non-flammable.

No HDPE pipe carefully laid and sprinkled according to all the rules will save you. You will not ensure absolute tightness of such a structure, and double insulation made in this way will be symbolic.

In addition, the HDPE tube will not always protect you from rodents.

Exposure to moisture

There is an option to use an asbestos cement pipe. According to many, with such protection the wire will last at least 100 years. However, firstly, it is not so easy to get such material, unlike HDPE, and its price is completely different.

Secondly, you will be faced with the problem of hermetically joining individual pipe sections to each other. It will be impossible to achieve one hundred percent tightness.

As a result, the SIP in this pipe will be in constant damp conditions. At the inlet and outlet of the pipe, it will invariably collect condensation and moisture due to temperature differences. And how will such operating conditions affect the service life?

Of course, all this will not fail the next day and can even work for several years. It all depends on the installation and operating conditions. But at one “wonderful” moment a short circuit or break will occur.

Wet conductors will inevitably fail sooner or later. Moreover, at subzero temperatures the core will already be stretched and break even with a little effort.

And on top of you, everything will already be arranged - a lawn, paths, maybe some bushes or a decorative fence. How to repair all this, where to look for the place of damage and what costs will it all cost in the end?

You can involve specialists and use a reflectometer to establish the location of the accident. However, doing this for a section 40-50m long is simply not practical. And how to install a coupling on a SIP underground?

As a result, the difference will be several times incomparable with the savings on a normally laid cable, which you abandoned at the construction stage. Here the arguments of those who like to violate technology and still push self-supporting insulated wires underground will no longer seem so convincing.

What they say most often:

• laying the wire underground by placing it in a HDPE pipe provides reliable mechanical protection
• It is enough to seal the ends with couplings and thus you can get rid of moisture forever
• underground there is absolutely no ultraviolet effect on the insulation, which means its service life only increases

Rules and GOST

However, remember the main thing - not a single normal power engineer or energy inspector will ever accept such work from you. Moreover, it will not allow voltage to be applied to this potentially dangerous section of the network if it is constructed incorrectly.

Of course, if you need to lay a SIP underground from a house already connected to the power supply to a neighboring garage or extension, no one can forbid you from doing this.

For yourself, you are free to be as sophisticated as you like. No one will punish you for this or even issue you a fine. It will be only your business until one fateful moment, until someone from outside is killed or maimed. What will be the reason for this - leakage current or step voltage is not important.

As soon as the relevant authorities begin to look for the reason, all the standards and documents that you did not care about or considered not mandatory, or tried to circumvent them with your innovations and improvements, will be raised.

And the rules say this:

Therefore, if you are an electrician who performs work for hire, never follow the customer’s lead. Ultimately, you will have to answer.

No one will pay attention to tectonic shifts in the layers of the earth, or a large invasion of rodents, or abnormal flooding of the area due to rains or floods. When the investigator understands that the cause of the accident is a non-compliance with the technology for using SIP, he will immediately jump into it.

If you do everything according to the rules, in compliance with current standards, then there will be no complaints against you. Here the question will arise not about installation, but about the correct operation of the cable during the entire period of its operation from the moment of connection.

An accident with strangers or with you personally is, of course, an extreme variant of the consequences of laying SIP in the ground. Most often the following happens:

• wire insulation ages and deteriorates over time
• water somehow gets into the pipe in which the SIP is laid
• there is a small but constant current leakage
• For some reason the meter starts to generate a little more kilowatts than usual, and you pay for it all
• add here the voltage drop of a few extra volts
• The longer the wire, the more likely this outcome is. And the more money you will pay for unconsumed electricity.

Sometimes the voltage simply disappears due to a break or broken contact. In this case, a simple loss of light is only half the problem from damage. Most often, many of these accidents are accompanied by current leaks through the shell and subsequent fires.

And if in an armored cable the outer shell is grounded, and thus its protection is ensured, then in a SIP wire there is simply nothing to ground.

In addition, it is not always possible to carry out perfect installation and laying of networks underground.

During the work, you will definitely have to pull the wires through narrow holes, go through bends and turns, and the risk of somehow damaging and scratching the wire without an outer sheath is very high.

In the future, this very place will be the weakest link in the electrical circuit. The cable, unlike SIP, is initially manufactured with the necessary resistance to mechanical stress due to its installation in soil, pipes and blocks.

In general, summing up all of the above, we can make an unambiguous conclusion - laying SIP wires underground is strictly prohibited. There is no need to come up with additional types of protection to circumvent this prohibition. Just initially plan your purchase of materials wisely and use them for their intended purpose.

Source

Share news on social networks « Previous post Next post »

Popular

• 4327
• 3602
• 3511
• 3118
• 2203

psk-remont.ru

SIP supply to the house

If, according to technical conditions, the electricity meter must be installed indoors, then two options can be used to enter the cable into the house. The first method involves the use of self-supporting insulated wires for laying along the facade of the building and entering inside. The second method involves switching from a self-supporting insulated wire to a VVGng cable before entering the house. The disadvantage of the first option is the relatively low fire resistance of the SIP insulating shell, therefore it is not recommended to insert such a cable into wooden buildings. The disadvantage of the second option is the presence of a transition from a cable of one type to a wire of another type. Representatives of the energy supply organization may prohibit the use of connections to the electricity meter.

The problem is solved in the following ways:

1. To increase fire safety, SIPs are introduced into a house using special corrugated hoses, metal or plastic pipes, after pre-treating their surface with a material in the form of paint or paste that is resistant to high temperatures and open fire.
2. To avoid direct connection of two cables of different types, protection devices are installed on the facade of the building. An insulated wire is connected to them, and from them another cable is pulled along the facade, brought inside the house and connected to an electricity meter. To protect circuit breakers, a special box is used.

Which option to use is decided on the spot. The advantage of the first method is the absence of a protection device that requires additional protection and maintenance. The advantage of the second method is the provision of a high fire resistance without the need to use additional protective materials, as well as the protection of the cable passage through the wall of the house with an automatic switch. In this case, there is no need to install additional protective equipment upstream of the electricity meter.

Laying SIP wire underground

When installing electrical input into a house from an overhead power line, connections were often made using SIP wire.
Many network companies even insistently require just such a connection and prescribe it in the technical specifications. However, home owners very often do not want to spoil the appearance of the building facade for aesthetic reasons. And they naturally ask themselves whether it is possible to lay SIP wire underground.

Advantages?

It would seem that there are only advantages:

• Firstly, you can save on cable
• secondly, directly from the support, lead the wire directly to the switchboard in the basement, thereby eliminating unnecessary connections

At the same time, you can save a significant amount on cable. Since you don’t have to buy an expensive copper armored one, it’s enough to replace it with an aluminum SIP of the same cross-section, plus protect it from the outside, for example, with corrugation or HDPE pipe (prices are indicated at the time of writing):

The standard trench depth for laying cables underground is 0.7 m or more.

Craftsmen, in order to protect SIP from possible groundwater and temperature changes during the winter-summer seasons, bury it to a greater depth - 1.2-1.5 meters. But in the end, none of this helps.

Firstly, a SIP wire is not a cable, as some mistakenly call it, but a wire!

And it does not have external insulation of all cores, which should protect:

• from mechanical influences from unauthorized persons and objects
• penetration of moisture between the cores
• chemical impact of an aggressive environment on the insulation shell

• ground movement

In addition, do not forget that rodents and other living creatures live underground, which can taste your input if desired.

Secondly, and most importantly, SIP is simply not intended for this.

All manufacturers of this wire clearly say that this is a material for laying through the air.

It can be used:

• on wooden and reinforced concrete supports

• metal poles and structures

• on the facades of the house

but cannot be used underground!

Even if you think logically, you will not specifically buy an armored cable VBShv or SB in order to suspend it on a cable in the air from a pole to a house, although this is not prohibited. The same goes for SIP, it needs to be used exactly in the conditions where it belongs.

Moreover, not every SIP can be installed inside the house and in the attic, but only certain brands that have the letters Ng in the designation - non-flammable.

No HDPE pipe carefully laid and sprinkled according to all the rules will save you. You will not ensure absolute tightness of such a structure, and double insulation made in this way will be symbolic.

In addition, the HDPE tube will not always protect you from rodents.

Exposure to moisture

There is an option to use an asbestos cement pipe. According to many, with such protection the wire will last at least 100 years. However, firstly, it is not so easy to get such material, unlike HDPE, and its price is completely different.

Secondly, you will be faced with the problem of hermetically joining individual pipe sections to each other. It will be impossible to achieve one hundred percent tightness.

As a result, the SIP in this pipe will be in constant damp conditions. At the inlet and outlet of the pipe, it will invariably collect condensation and moisture due to temperature differences. And how will such operating conditions affect the service life?

Of course, all this will not fail the next day and can even work for several years. It all depends on the installation and operating conditions. But at one “wonderful” moment a short circuit or break will occur.

Wet conductors will inevitably fail sooner or later. Moreover, at subzero temperatures the core will already be stretched and break even with a little effort.

And on top of you, everything will already be arranged - a lawn, paths, maybe some bushes or a decorative fence. How to repair all this, where to look for the place of damage and what costs will it all cost in the end?

You can involve specialists and use a reflectometer to establish the location of the accident. However, doing this for a section 40-50m long is simply not practical.

And how to install a coupling on a SIP underground?

As a result, the difference will be several times incomparable with the savings on a normally laid cable, which you abandoned at the construction stage. Here the arguments of those who like to violate technology and still push self-supporting insulated wires underground will no longer seem so convincing.

What they say most often:

• laying the wire underground by placing it in a HDPE pipe provides reliable mechanical protection
• It is enough to seal the ends with couplings and thus you can get rid of moisture forever
• underground there is absolutely no ultraviolet effect on the insulation, which means its service life only increases

Rules and GOST

However, remember the main thing - not a single normal power engineer or energy inspector will ever accept such work from you. Moreover, it will not allow voltage to be applied to this potentially dangerous section of the network if it is constructed incorrectly.

Of course, if you need to lay a SIP underground from a house already connected to the power supply to a neighboring garage or extension, no one can forbid you from doing this.

For yourself, you are free to be as sophisticated as you like. No one will punish you for this or even issue you a fine. It will be only your business until one fateful moment, until someone from outside is killed or maimed. What will be the reason for this - leakage current or step voltage is not important.

As soon as the relevant authorities begin to look for the reason, all the standards and documents that you did not care about or considered not mandatory, or tried to circumvent them with your innovations and improvements, will be raised.

And the rules say this:

Therefore, if you are an electrician who performs work for hire, never follow the customer’s lead. Ultimately, you will have to answer.

No one will pay attention to tectonic shifts in the layers of the earth, or a large invasion of rodents, or abnormal flooding of the area due to rains or floods. When the investigator understands that the cause of the accident is a discrepancy in the technology for using SIP, he will immediately jump into it.

If you do everything according to the rules, in compliance with current standards, then there will be no complaints against you. Here the question will arise not about installation, but about the correct operation of the cable during the entire period of its operation from the moment of connection.

An accident with strangers or with you personally is, of course, an extreme variant of the consequences of laying SIP in the ground. Most often the following happens:

• wire insulation ages and deteriorates over time
• water somehow gets into the pipe in which the SIP is laid
• there is a small but constant current leakage
• For some reason the meter starts to generate a little more kilowatts than usual, and you pay for it all

• add here the voltage drop of a few extra volts
• The longer the wire, the more likely this outcome is. And the more money you will pay for unconsumed electricity.

Sometimes the voltage simply disappears due to a break or broken contact. In this case, a simple loss of light is only half the problem from damage. Most often, many of these accidents are accompanied by current leaks through the shell and subsequent fires.

And if in an armored cable the outer shell is grounded, and thus its protection is ensured, then in a SIP wire there is simply nothing to ground.

In addition, it is not always possible to carry out perfect installation and laying of networks underground.

During the work, you will definitely have to pull the wires through narrow holes, go through bends and turns, and the risk of somehow damaging and scratching the wire without an outer sheath is very high.

In the future, this very place will be the weakest link in the electrical circuit. The cable, unlike SIP, is initially manufactured with the necessary resistance to mechanical stress due to its installation in soil, pipes and blocks.

In general, summing up all of the above, we can draw an unambiguous conclusion - laying SIP wires underground is strictly prohibited. There is no need to come up with additional types of protection to circumvent this prohibition. Just initially plan your purchase of materials wisely and use them for their intended purpose.

Articles on the topic

domikelectrica.ru