Grounding is the connection of non-current-carrying parts of electrical equipment to the ground electrode. This ensures the presence of ground potential on the housings of electrical appliances. This is necessary to prevent electric shock as a result of touching cases and other structural parts of damaged equipment. Connection to the ground bus is carried out using a wire or cable. In this article, we will tell you what the ground wire should be like so that you can choose the right brand, section and other parameters.

Briefly about terms

To make the article understandable even for those who are far from electrical engineering, we have given an explanation of the terms that will be used in it.

Grounding is called the basis of the grounding system. Usually it is metal pins driven into the ground at an equal distance from each other, forming a figure like a triangle.

A grounding bus or a metal strip is called, laid along the perimeter of the room or near the protected devices, which connects all the grounding conductors of electrical appliances to the ground electrode.

The ground wire or core is the conductor that provides the connection of the ground electrode with the GZSH.

Metal bonding is a concept that characterizes the contact between the metal parts of electrical equipment cases, including the doors of electrical panels or cabinets with their cases.

Ground wire cross section

To ensure reliable protection against electric shock and the operation of protective switching devices, the ground wire is selected depending on the phase section. This is necessary so that in the event of an accident it can withstand high currents and not burn out. If this happens, then the protection will not work, and the dangerous potential will be on the body of the electrical appliance.

The cross section of the ground wire must be:

• If the phase is used with a cross section of up to 16 sq. mm - the ground conductor must be of the same size.
• If the cross-sectional area of ​​the phase is from 16 to 35 sq. mm, then at the "ground" it should be 16 square meters. mm.
• With a phase cross section of more than 35 square meters. mm - the minimum cross section of the ground wire must be at least half the cross section of the phase wire.

Let's give two examples to answer the question of what cross section should be at the grounding of the device:

1. You connect the electric stove with a cable with a cross section of 4 square meters. mm. This means that the cross section of the protective conductor must be the same.
2. An input cable with conductors of 50 square meters is connected to the electrical cabinet. mm. In this case, the grounding cross section must be at least 25 sq. mm. Can be more.

Brand and requirements for conductors

The core of a ground wire or cable can be either single-core or stranded - it only depends on where it will be used. For example, to ground a door in an electrical panel, it is necessary to ensure its mobility. The rigid core from the constant opening of the door and its bending will break at the same time. Therefore, the core must have an appropriate flexibility class that does not prevent opening, for example 3 and higher.

At the same time, to connect, for example, the housing of the electric motor of a pumping station to the GZSH, it is not necessary to provide mobility, since this type of electrical equipment is permanently mounted. Therefore, rigid conductors can be used.

The ground conductor can be:

• isolated;
• uninsulated;
• is included in the cable
• be a separate single-core wire;
• aluminum;
• copper.

This begs the question: so what kind of wire to use to connect the ground?

The stores sell cable products with a different number of cores: 2, 3, 4, 5. This is necessary for assembling certain schemes for switching on devices and connecting electrical equipment to networks with a different number of phases.

To connect grounding in sockets and other electrical equipment of a single-phase network, it is convenient to use three-core cables, for example, VVG 3x2.5. And for connecting three-phase equipment to the network and grounding, four-core cables are designed, for example, AVVG 4x32. At the same time, in thick cables, the grounding conductor usually has a smaller cross section than that of the phase conductors. Let's give examples.

If you got a cable with a color marking that does not comply with GOSTs, you can designate the ground, phase and zero using electrical tape or heat shrink tubing. In addition to color marking, there is also an alphabetic or numerical one:

• L - Line or phase.
• N - Neutral or neutral, zero.
• PEN or PE - protective conductor or earth.

For connection in the input distribution panel (and other places), ground and zero buses are often used. This is a rail with a set of holes and screw terminals where the wires are connected. To connect the earth wire with a stranded core, it is necessary to crimp it or crimp it with a pin tip of the type and the like. This rule also applies to connecting to the terminals of machines and other screw connections of any flexible conductors.

To connect the wire to the ground bus, it is necessary to use round terminals NKI, NVI or other types of cable lugs with ring-shaped terminals.

This may be required when laying grounding from the loop to the shield. They are usually of two types:

• Crimp. In order to fix them on the cable, they are crimped with a special tool. You should not do this with pliers, because you will not achieve a reliable crimp. The best compression is provided by press tongs (another name is a crimper) with hexagonal (hexagonal) clamps.
• With shear screws - to tighten them, simply tighten the screw until its head is sheared.

That's all we wanted to tell you in this article. Now you know what section and brand the ground wire should be. Finally, we recommend watching a useful video

Today, almost every country house is equipped with electrical appliances. The safety of their operation is ensured by connecting the electrical equipment installed in the premises with a grounding device. Properly performed protective grounding will eliminate the possibility of electric shock to people and prevent the failure of household appliances and complex technical devices from overvoltage if they are protected by an SPD. The choice of connection scheme depends on various factors. In a private house, unlike an apartment building, grounding can be done independently. This guide will help you figure out how to connect it.

The main elements of the scheme for connecting the grounding of a country house and the rules for their implementation

The ground connection diagram in a country house is as follows: electrical appliance - socket - electrical panel - ground conductor - ground loop - ground.

The connection begins with the implementation of a grounding device on the local area in accordance with the rules defined in chapter 1.7 of the PUE of the 7th edition. The ground electrode is a metal structure with a large area of ​​contact with the ground. Designed to equalize the potential difference and reduce the potential of grounded equipment, in case of a short circuit to the case or the appearance of excess voltage in the mains. The design and depth of its installation is determined based on the resistance of the soil in the area (for example, dry sand or wet black soil).

From the grounding device (grounding) made at the site, we lay a grounding conductor, which we connect to the main grounding bus using a bolted connection, clamp or welding. We select a conductor with a cross section of at least 6 mm2 for copper and 50 mm2 for steel, while it must meet the requirements for protective conductors specified in table 54.2 of GOST R 50571.5.54-2013, and for a TT system have a cross section of at least 25 mm2 for copper. If the conductor is bare and laid in the ground, then its cross section must correspond to that given in table 54.1 GOST R GOST R 50571.5.54-2013.

In the switchboard, the grounding conductor is connected through the grounding bus to the protective conductors laid to sockets with a grounding contact and other electrical receivers in the house. As a result, each electrical appliance is connected to the grounding system.

Dependence of the ground connection scheme on the ground loop

If a re-grounding is performed at the power line pole, then the grounding connection scheme in a country house is performed using the TN-C-S or TT systems. When the condition of the networks does not cause concern, the re-grounding of the line should be used as the grounding device of the house and the house should be connected in accordance with the TN-C-S grounding system. If the overhead line is old, or the quality of re-grounding is questionable, it is better to choose a TT system and equip an individual grounding device in the local area.

For a grounding device, first of all, natural ground electrodes should be used - third-party conductive parts that have direct contact with the ground (water pipes, well pipes, metal and reinforced concrete structures of a country house, etc.). (see paragraphs 1.7.54, 1.7.109 of the EIC of the 7th edition).

In the absence of such, we perform an artificial grounding device using vertical or horizontal electrodes that we dig into the ground. The choice of the configuration of the ground electrode is mainly based on the required resistance and the characteristics of the local area.

It is most effective to use if the soil in your area is represented by loam, peat, sand saturated with water, watered with clay. The standard length of the rods is from 1.5 to 3 m. When choosing the length of the vertical electrodes, we proceed from the water saturation of the host rocks in the area. Buried ground vertical ground electrodes are combined with a horizontal electrode, for example, a strip, and to minimize shielding, they are located at a distance commensurate with the length of the pins themselves.

Dependence of the connection scheme on the type of grounding system

Grounding of housing facilities is carried out according to the following systems: TN (subsystems TN-C, TN-S, TN-C-S) or TT. The first letter in the name indicates the grounding of the power source, the second - the grounding of open parts of electrical equipment.

Subsequent letters after N indicate the combination in one conductor or the separation of the functions of the zero working and zero protective conductors. S - zero working (N) and zero protective (PE) conductors are separated. C - the functions of the zero protective and zero working conductors are combined in one conductor (PEN-conductor).

Electrical safety is fully ensured when a decrease in the resistance of the ground electrode does not entail an increase in the indicators of the ground fault current. Consider how the grounding connection scheme depends on the electrical network system installed at the facility.

TN-S earthing system

Figure 1. TN-S system

At facilities equipped with a TN-S power grid, the neutral working and protective conductors are separated along the entire length, and in the event of a phase insulation breakdown, the emergency current is diverted through the protective PE conductor. RCD devices and difavtomat, reacting to the appearance of current leakage through a protective zero, turn off the network with the load.

The advantage of the TN-S grounding subsystem is the reliable protection of electrical equipment and a person from damage by emergency current when using electrical networks. Due to this, this system is referred to as the most modern and safe.

To perform grounding using the TN-S system, it is required to lay a separate ground wire from the transformer substation to its building, which will lead to a significant increase in the cost of the project. For this reason, for grounding private sector facilities, the TN-S grounding subsystem is practically not used.

TN-C earthing system. The need to switch to TN-C-S

Figure 2. TN-S system

Grounding according to the TN-C system is most common for old housing stock buildings. The advantage is that it is economical and easy to implement. A significant drawback is the lack of a separate PE conductor, which excludes the presence of grounding in the sockets of a country house and the possibility of potential equalization in the bathroom.

Electric current is supplied to suburban buildings through overhead lines. Two conductors are suitable for the building itself: phase L and combined PEN. You can connect grounding only if there is a three-wire wiring in a private house, which requires the conversion of the TN-C system to TN-C-S, by separating the zero working and zero protective conductor in the electrical panel (see clause 1.7.132 of the EIC of the 7th edition) .

Grounding connection according to the TN-C-S system

The TN-C-S grounding subsystem is characterized by the union of the zero working and zero protective conductors in the area from power lines to the entrance to the building. Grounding on this system is quite simple in technical design, due to which it is recommended for wide application. The disadvantage is the need for constant modernization, in order to avoid breaking the PEN conductor, as a result of which electrical appliances may be at a dangerous potential.

Let's consider the grounding connection scheme in a country house according to the TN-C-S system using the example of transition to it from the TN-C system.

Figure 3. Schematic of the main switchboard

As already noted, in order to obtain a three-core wiring, it is necessary to properly separate the PEN conductor in the switchboard at home. We start with the fact that we install a bus in the electrical panel with a strong metal connection with it, and connect the combined PEN conductor coming from the side of the power line to this bus. We connect the PEN bus with a jumper to the next installed PE bus. Now the PEN bus acts as a bus of the zero working conductor N.

Figure 4. Earth connection diagram (transition from TN-C to TN-C-S)

Figure 5. TN-C-S ground connection diagram

Having completed the indicated connections, we connect the switchboard to the ground electrode: from the grounding device we start the PE busbar. Thus, as a result of a simple upgrade, we equipped the house with three separate wires (phase, zero protective and zero working).

The rules for the installation of electrical installations require re-grounding for PE - and PEN-conductors at the input to electrical installations, using, first of all, natural grounding conductors, the resistance of which at a mains voltage of 380/220 V should be no more than 30 Ohm (see clause 1.7 .103 PUE 7th edition).

TT earth connection

Figure 6. TT system

Another variant of the scheme is to connect the grounding of a country house using the TT system with a solidly grounded neutral of the current source. The open conductive elements of the electrical equipment of such a system are connected to a grounding device that does not have an electrical connection with the grounding conductor of the neutral of the power source.

In this case, the following condition must be observed: the value of the product of the tripping current of the protection device (Ia) and the total resistance of the grounding conductor and the ground electrode (Ra) should not exceed 50 V (see clause 1.7.59 of the Electrical Installation Code). Ra Ia ≤ 50 V.

To comply with this condition, “Instructions for the device of protective grounding and potential equalization in electrical installations” And 1.03-08 recommends making a grounding device with a resistance of 30 ohms. This system is quite in demand today and is used for private, mainly mobile buildings, when it is impossible to provide a sufficient level of electrical safety with the TN system.

TT grounding does not require separation of the combined PEN conductor. Each of the individual wires suitable for the house is connected to a bus isolated from the electrical panel. And the PEN conductor itself, in this case, is considered the neutral wire (zero).

Figure 7. TT earth connection diagram

Figure 8. Connection diagram for grounding and RCD according to the TT system

As follows from the diagram, TN-S and TT systems are very similar to each other. The difference lies in the complete absence of an electrical connection between the grounding device and the PEN conductor in the CT, which, in the event of the latter burning out from the power source, guarantees the absence of excess voltage on the body of electrical appliances. This is the obvious advantage of the TT system, providing a higher level of safety and reliability in operation. The disadvantage of its use can only be called high cost, since in order to protect users from indirect contact, it is necessary to install additional protective power off devices (RCD and voltage relay), which, in turn, requires approbation and certification by an energy supervision specialist.

Conclusion

The grounding scheme in general terms is a connection of its elements: electrical equipment, input distribution board, grounding conductor PE, ground electrode.

To install a grounding device in a country house, you need to understand the features of its connection, depending on the following factors:

• method of supplying the electrical network (overhead lines or cable from a transformer substation)
• type of soil in the adjacent area where the ground loop is performed.
• the presence of a lightning protection system, additional power supplies or specific equipment.

When making the grounding connection yourself, you must be guided by the provisions of section 1.7 of the Electrical Installation Rules. If it is impossible to use natural grounding conductors, we perform a grounding device using artificial grounding conductors. Grounding of a private house can be performed using two systems: TN-C-S or TT. The most widely used modernized system TN-C - TN-C-S, due to the simplicity of its technical design. To ensure the electrical safety of a country house according to the TN-C-S system, it is required to separate the PEN conductor into zero working and zero protective conductors.

Having completed the ground loop, it is necessary to check the quality of its installation, and to measure the resistance for compliance with the PUE standards using special instruments, which may require the involvement of specialists.

Do you need advice on the organization of grounding and lightning protection for your facility? Contact

Operation of modern household and computer equipment without grounding is fraught with its failure. In a significant part of our country, especially in rural areas, there are old-style power transmission systems. They do not provide for the presence of protective grounding or they are in such a state that they simply do not meet the requirements of electrical safety. Therefore, the owners have to do the grounding of a private house or cottage themselves.

What does it give

Protective grounding is necessary to ensure electrical safety in the house. Properly performed, the appearance of a leakage current leads to the immediate operation of the RCD (damage to the electrical insulation or when touching live parts). This is the main and main task of this system.

The second function of grounding is to ensure the normal operation of electrical equipment. For some electrical appliances, the presence of a protective wire in the socket (if any) is not enough. A direct connection to the ground bus is required. For this, there are usually special clips on the case. If we talk about household appliances, then this is a microwave oven, oven and washing machine.

The main task of grounding is to ensure the electrical safety of a frequent home.

Few people know, but a microwave oven without a direct connection to the "ground" during operation can significantly emit radiation, receiving a radiation level can be life-threatening. In some models, a special terminal can be seen on the back wall, although the instructions usually contain only one phrase: “grounding is required” without specifying exactly how it is desirable to do it.

When touching the body of the washing machine with wet hands, a tingling sensation is often felt. It's harmless, but annoying. You can get rid of it by connecting the "ground" directly to the case. In the case of the oven, the situation is similar. Even if it doesn't 'sting', a direct connection is safer, as the wiring inside the unit is subject to very harsh conditions.

With computers, the situation is even more interesting. By directly connecting the "ground" wire to the case, you can increase the speed of the Internet several times and minimize the number of "freezes". It's so simple because of the presence of a direct connection to the ground bus.

Do I need grounding in the country or in a wooden house

In holiday villages, it is necessary to make grounding. Especially if the house is built of combustible material - wood or frame. It's about thunderstorms. There are a lot of elements that attract lightning in summer cottages. These are wells, wells, pipelines lying on the surface or buried to a minimum depth. All these objects attract lightning.

If there is no lightning rod and grounding, a lightning strike is almost tantamount to a fire. There is no fire station nearby, so the fire will spread very quickly. Therefore, together with grounding, also make a lightning rod - at least a couple of meter-long rods attached to the ridge and connected with a steel wire to grounding.

Grounding systems of a private house

There are six systems in total, but in individual developments, mainly only two are used: TN-S-C and TT. In recent years, the TN-S-C system has been recommended. In this scheme, the neutral at the substation is solidly grounded, and the equipment has direct contact with the ground. To the consumer, earth (PE) and neutral / zero (N) are conducted by one conductor (PEN), and at the entrance to the house it is again divided into two separate ones.

With such a system, a sufficient degree of protection is provided by automatic devices (RCDs are not required). The disadvantage is that if the PEN wire burns out or is damaged in the area between the house and the substation, a phase voltage appears on the earth bus in the house, which is not turned off by anything. Therefore, the PUE imposes strict requirements on such a line: there must be mandatory mechanical protection of the PEN wire, as well as periodic backup grounding on poles every 200 m or 100 m.

However, many transmission lines in rural areas do not meet these conditions. In this case, the TT system is recommended. Also, this scheme should be used in free-standing open outbuildings with an earthen floor. They have a risk of touching the ground and the ground at the same time, which can be dangerous in a TN-S-C system.

The difference is that the "ground" wire to the shield comes from an individual ground loop, and not from a transformer substation, as in the previous diagram. Such a system is resistant to damage to the protective wire, but requires the mandatory installation of an RCD. Without them, there is no protection against electric shock. Therefore, the PUE defines it only as a backup if the existing line does not meet the requirements of the TN-S-C system.

Grounding device of a private house

Some older transmission lines do not have a protective earth at all. All of them should change, but when this will happen is an open question. If you have just such a case, you need to make a separate circuit. There are two options - to make grounding in a private house or in the country on your own, with your own hands, or to entrust the execution of the campaign. Campaign services are expensive, but there is an important plus: if during operation there are problems caused by improper functioning of the grounding system, the company that performed the installation will compensate for the damage (should be written in the contract, read carefully). In the case of self-execution, everything is on you.

The grounding system of a private house consists of:

• grounding pins,
• metal strips that combine them into one system;
• lines from the ground loop to .

What to make ground electrodes

As pins, you can use a metal rod with a diameter of 16 mm or more. Moreover, it is impossible to take reinforcement: its surface is hardened, which changes the current distribution. Also, the red-hot layer in the ground is destroyed faster. The second option is a metal corner with 50 mm shelves. These materials are good because they can be hammered into soft ground with a sledgehammer. To make this easier to do, one end is pointed, and a platform is welded to the second, which is easier to hit.

Sometimes metal pipes are used, one edge of which is flattened (welded) into a cone. Holes are drilled in their lower part (about half a meter from the edge). When the soil dries out, the distribution of the leakage current deteriorates significantly, and such rods can be filled with saline, restoring the operation of the ground. The disadvantage of this method is that you have to dig / drill wells under each rod - you won’t be able to hammer them with a sledgehammer to the desired depth.

Depth of driving pins

Ground rods should go into the ground at least 60-100 cm below the freezing depth. In regions with dry summers, it is desirable that the rods be at least partially in moist soil. Therefore, mainly corners or a rod 2-3 m long are used. Such dimensions provide a sufficient area of ​​\u200b\u200bcontact with the ground, which creates normal conditions for dissipating leakage currents.

What Not to Do

The job of a protective earth is to dissipate leakage currents over a large area. This happens due to the tight contact of metal ground electrodes - pins and strips - with the ground. That's why grounding elements are never painted. This greatly reduces the conductance between the metal and the ground, the protection becomes ineffective. Corrosion at welding points can be prevented with anti-corrosion compounds, but not with paint.

The second important point: grounding should have low resistance, and good contact is very important for this. It is provided by welding. All joints are welded, and the quality of the seam must be high, without cracks, cavities and other defects. Once again, pay attention: grounding in a private house cannot be done on threaded connections. Over time, the metal oxidizes, breaks down, the resistance increases many times, the protection deteriorates or does not work at all.

It is very unreasonable to use pipelines or other metal structures that are in the ground as a ground electrode. For some time, such grounding in a private house works. But over time, the pipe joints, due to electrochemical corrosion activated by leakage currents, oxidize and collapse, the grounding turns out to be inoperative, as well as the pipeline. Therefore, it is better not to use such types of ground electrodes.

How to do it right

First, let's deal with the shape of the ground electrode. The most popular is in the form of an equilateral triangle, at the tops of which pins are clogged. There is also a linear arrangement (the same three pieces, only in a line) and in the form of a contour - the pins are hammered around the house in increments of about 1 meter (for houses with an area of ​​​​more than 100 sq. M). The pins are interconnected by metal strips - a metal bond.

Procedure

From the edge of the house to the installation site, the pin should be at least 1.5 meters. In the selected area, they dig a trench in the form of an equilateral triangle with a side of 3 m. The depth of the trench is 70 cm, the width is 50-60 cm - so that it is convenient to cook. One of the peaks, usually located closer to the house, is connected to the house by a trench having a depth of at least 50 cm.

At the vertices of the triangle, pins are hammered (a round bar or a corner 3 m long). About 10 cm are left above the bottom of the pit. Please note that the ground electrode is not brought to the surface of the earth. It is located below the ground level by 50-60 cm.

A metal bond is welded to the protruding parts of the rods / corners - a strip of 40 * 4 mm. The created grounding conductor with the house is connected with a metal strip (40 * 4 mm) or a round conductor (section 10-16 mm 2). A strip with a metal triangle created is also welded. When everything is ready, the welding spots are cleaned of slag, coated with an anti-corrosion compound (not paint).

After checking the ground resistance (in the general case, it should not exceed 4 ohms), the trenches are covered with earth. There should be no large stones or construction debris in the soil, the earth is compacted in layers.

At the entrance to the house, a bolt is welded to the metal strip from the ground electrode, to which a copper conductor in insulation is attached (traditionally, the color of the ground wires is yellow with a green stripe) with a core cross section of at least 4 mm 2.

Ground outlet at the wall of the house with a bolt welded on the end

In the electrical panel, grounding is connected to a special bus. Moreover, only on a special platform, polished to a shine and lubricated with grease. From this bus, the "ground" is connected to each line that is bred around the house. Moreover, the wiring of the "ground" with a separate conductor according to the PUE is unacceptable - only as part of a common cable. This means that if your wiring is wired with two-wire wires, you will have to completely change it.

Why you can not make separate grounding

Redoing the wiring throughout the house, of course, is long and expensive, but if you want to operate modern electrical appliances and household appliances without any problems, this is necessary. Separate grounding of certain outlets is inefficient and even dangerous. And that's why. The presence of two or more such devices sooner or later leads to the output of the equipment included in these sockets. The thing is that the resistance of the contours depends on the condition of the soil in each particular place. In some situation, a potential difference occurs between two grounding devices, which leads to equipment failure or electrical injury.

Modular pin system

All devices described earlier - from hammered corners, pipes and rods - are called traditional. Their disadvantage is a large amount of land work and a large area that is required when installing a ground electrode system. This is because a certain area of ​​​​contact of the pins with the ground is necessary, sufficient to ensure the normal "spreading" of the current. The need for welding can also cause complexity - it is impossible to connect the grounding elements in another way. But the advantage of this system is relatively low costs. If you do traditional grounding in a private house with your own hands, it will cost a maximum of $ 100. This is if you buy all the metal and pay for welding, and carry out the rest of the work yourself

A few years ago, modular pin (pin) systems appeared. This is a set of pins that are hammered to a depth of up to 40 m. That is, a very long ground electrode is obtained, which goes to a depth. Fragments of the pin are connected to each other using special clamps, which not only fix them, but also provide a high-quality electrical connection.

The advantage of modular grounding is a small area and less work that is required. A small pit is required with sides of 60 * 60 cm and a depth of 70 cm, a trench connecting the ground electrode with the house. The pins are long and thin, it is not difficult to drive them into suitable soil. This is where we came to the main disadvantage: the depth is large, and if you meet, for example, a stone on the way, you will have to start over. And removing the rods is a problem. They are not welded, but whether the clamp will withstand or not is a question.

The second disadvantage is the high price. Together with the installation, such grounding will cost you $ 300-500. Self-installation is problematic, since it will not work to hammer these rods with a sledgehammer. We need a special pneumatic tool, which we learned to replace with a percussion hammer. It is also necessary to check the resistance after each clogged rod. But if you don't want to mess with welding and earthworks, a modular grounding pin is a good option.

Modern household appliances and equipment require grounding. Only in this case, manufacturers will maintain their warranties. The inhabitants of the apartments have to wait for the overhaul of networks, and the owners of houses can do everything with their own hands. How to make grounding in a private house, what is the procedure and connection diagrams - read about all this here.

In general, ground loops can be in the form of a triangle, rectangle, oval, line or arc. The best option for a private house is a triangle, but others are quite suitable.

Grounding in a private house - types of ground loops

Triangle

Grounding in a private house or in the country is most often done with a contour in the form of an isosceles triangle. Why is that? Because with such a structure on a minimum area, we obtain the maximum area of ​​​​dissipation of currents. The costs for the installation of a ground loop are minimal, and the parameters correspond to the ratings.

The minimum distance between the pins in the ground loop triangle is their length, the maximum is twice the length. For example, if you drive the pins to a depth of 2.5 meters, then the distance between them should be 2.5-5.0 m. In this case, when measuring the resistance of the ground loop, you will get normal readings.

During work, it is not always possible to make the triangle strictly isosceles - stones come across in the right place or other impenetrable areas of soil. In this case, you can move the pins.

Linear ground loop

In some cases, it is easier to make a ground loop in the form of a semicircle or a chain of pins lined up (if there is no free area of ​​suitable size). In this case, the distance between the pins is also equal to or greater than the length of the electrodes themselves.

With a linear circuit, a larger number of vertical electrodes is needed - so that the scattering area is sufficient

The disadvantage of this method is that a larger number of vertical electrodes is needed to obtain the desired parameters. Since scoring them is still a pleasure, in the presence of meta they try to make a triangular outline.

Materials for the ground loop

In order for the grounding of a private house to be effective, its resistance should not exceed 4 ohms. To do this, it is necessary to ensure good contact of the ground electrodes with the ground. The problem is that it is possible to measure the grounding resistance only with a special device. This procedure is carried out when the system is put into operation. If the parameters are worse, the act is not signed. Therefore, when making the grounding of a private house or cottage with your own hands, try to strictly adhere to the technology.

Parameters and materials of pins

Ground pins are usually made of ferrous metal. Most often, a bar with a cross section of 16 mm or more or a corner with parameters of 50 * 50 * 5 mm (shelf 5 cm, metal thickness - 5 mm) is used. Please note that fittings cannot be used - its surface is hardened, which changes the distribution of currents, besides, it quickly rusts and collapses in the ground. You need a bar, not reinforcement.

Another option for dry regions is thick-walled metal pipes. Their lower part is flattened in the form of a cone, holes are drilled in the lower third. Holes of the required length are drilled for their installation, since they cannot be hammered. When the soil dries up and the grounding parameters deteriorate, a saline solution is poured into the pipes to restore the scattering ability of the soils.

The length of the ground rods is 2.5-3 meters. This is sufficient for most regions. More specifically, there are two requirements:

Specific grounding parameters can be calculated, but the results of a geological study are required. If you have any, you can order a calculation in a specialized organization.

What to make a metal bond and how to connect with pins

All pins of the circuit are interconnected by a metal bond. It can be made from:

• copper wire with a cross section of less than 10 mm 2;
• aluminum wire with a cross section of at least 16 mm 2
• steel conductor with a cross section of at least 100 mm 2 (usually a strip of 25 * 5 mm).

Most often, the pins are interconnected using a steel strip. It is welded to the corners or heads of the bar. It is very important that the quality of the weld be high - it depends on whether your grounding passes the test or not (whether it meets the requirements - the resistance is less than 4 ohms).

When using aluminum or copper wire, a large cross-section bolt is welded to the pins, wires are already attached to it. The wire can be screwed onto the bolt and pressed with a washer and nut, the wire can be terminated with a connector of a suitable size. The main task is the same - to ensure good contact. Therefore, do not forget to strip the bolt and wire to bare metal (can be sanded) and tighten it well - for good contact.

How to make grounding with your own hands

After all the materials have been purchased, you can proceed to the actual manufacture of the ground loop. First, cut the metal into pieces. Their length should be approximately 20-30 cm longer than the calculated one - when driving in the tops, the pins bend, so they have to be cut off.

Sharpen clogged edges of vertical electrodes - things will go faster

There is a way to reduce the resistance when clogging the electrodes - sharpen one end of the corner or pin at an angle of 30 °. This angle is optimal when driving into the ground. The second moment is to weld a metal platform to the upper edge of the electrode, from above. Firstly, it is easier to hit it, and secondly, the metal is less deformed.

Work order

Regardless of the shape of the contour, everything begins with earthworks. A ditch needs to be dug. It is better to make it with beveled edges - so it is less sprinkled. The order of work is as follows:

Actually, that's all. Do-it-yourself grounding in a private house. It remains to connect it. To do this, you need to understand the grounding organization schemes.

Entering the ground loop into the house

The ground loop must somehow be brought to the ground bus. This can be done using a steel strip 24 * 4 mm, copper wire with a cross section of 10 mm2, aluminum wire with a cross section of 16 mm2.

In the case of using wires, it is better to look for them in insulation. Then a bolt is welded to the circuit, a sleeve with a contact pad (round) is put on the end of the conductor. A nut is screwed onto the bolt, a washer is screwed onto it, then a wire, another washer on top, and all this is tightened with a nut (picture on the right).

How to bring "land" into the house

When using a steel strip, there are two ways out - to bring a bus or wire into the house. I really don’t want to pull a steel tire with a size of 24 * 4 mm - the view is unaesthetic. If there is, you can use the same bolted connection to conduct a copper bus. It needs a much smaller size, it looks better (photo on the left).

You can also make a transition from a metal bus to a copper wire (section 10 mm2). In this case, two bolts are welded to the tire at a distance of several centimeters from each other (5-10 cm). Copper wire is twisted around both bolts, pressing them with a washer and nut to the metal (tighten as best as possible). This is the most economical and convenient way. It does not require as much money as when using only copper / aluminum wire, it is easier to pass it through the wall than a bus (even copper).

Grounding schemes: which one is better to do

Currently, only two ground connection schemes are used in the private sector - TN-C-S and TT. For the most part, a two-core (220 V) or four-core (380 V) cable (TN-C system) is suitable for the house. With such wiring, in addition to the phase (phase) wires, a PEN protective conductor comes, in which zero and earth are combined. At the moment, this method does not provide adequate protection against electric shock, therefore it is recommended to replace the old two-wire wiring with three-wire (220 V) or five-wire (380 V).

In order to obtain a normal three- or five-wire wiring, it is necessary to separate this conductor to ground PE and neutral N (in this case, an individual ground loop is required). They do this in the introductory cabinet on the facade of the house or in the accounting and distribution cabinet inside the house, but always before the counter. Depending on the separation method, either the TN-C-S or TT system is obtained.

Device in a private house of the TN-C-S grounding system

When using this circuit, it is very important to make a good individual ground loop. Please note that with the TN-C-S system, the installation of RCDs and difavtomatov is necessary to protect against electric shock. Without them, there is no protection.

Also, to ensure protection, it is required to connect all systems that are made of conductive materials to the earth bus with separate wires (inseparable) - heating, water supply, reinforcement cage of the foundation, sewerage, gas pipeline (if they are made of metal pipes). Therefore, the ground bus must be taken "with a margin."

To separate the PEN conductor and create a ground in a TN-C-S private house, three tires are needed: on a metal base - this will be a PE (ground) bus, and on a dielectric base - it will be an N (neutral) bus, and a small splitter bus into four " seating" places.

The metal "earth" bus must be attached to the metal body of the cabinet so that there is a good electrical contact. To do this, at the attachment points, under the bolts, the paint is peeled off the body to bare metal. Zero bus - on a dielectric base - it is better to mount it on a DIN rail. This installation method fulfills the main requirement - after the bus separation, PE and N should not intersect anywhere (they should not have contact).

Grounding in a private house - transition from the TN-C system to TN-C-S

• The PEN conductor that came from the line is wound up on the splitter bus.
• We connect the wire from the ground loop to the same bus.
• From one socket with a copper wire with a cross section of 10 mm 2 we put a jumper on the earth bus;
• From the last free slot, we put a jumper on the zero bus or neutral bus (also a copper wire 10 mm 2).

Now everything is done - grounding in a private house is done according to the TN-C-S scheme. Further, to connect consumers, we take the phase from the input cable, zero - from the N bus, ground - from the PE bus. Be sure to make sure that the earth and zero do not intersect anywhere.

TT grounding

Converting a TN-C circuit to TT is generally simple. Two wires come from the pole. The phase conductor is still used as a phase, and the protective PEN conductor is attached to the “zero” bus and is then considered zero. The conductor from the made circuit is directly fed to the ground bus.

Do-it-yourself grounding in a private house - TT scheme

The disadvantage of this system is that it provides protection only for equipment that provides for the use of a "ground" wire. If there is still household appliances made according to a two-wire circuit, it may be energized. Even if their cases are grounded with separate conductors, in case of problems, the voltage may remain at “zero” (the phase will be broken by the machine). Therefore, of these two schemes, TN-C-S is preferred as more reliable.

An integral element of most modern electrical installations is the ground wire. This device is used for electrical connection of any elements with zero ground potential, which is assumed to be zero in electrical calculations.

Purpose

The ground wire is designed to protect a person from electric shock in emergency situations. For example, during the breakdown of insulation, an electrical contact occurs between the current-carrying elements and the device case. If a person touches such a device, an electric current will flow through it to the ground, which can lead to electrical injury and even death. A current of 100 mA is considered dangerous for a person, because of which the likelihood of current flow must be minimized.

Rice. 1: Scheme of current flow during electric shock

To eliminate the threat to human life in electrical installations, a ground wire is installed. By means of a ground wire, an electrical connection is provided for all conductive elements that are not normally under any operating potential, with. And in the event of a potential on the case or other elements, the charge will flow through the ground wire, and if there is protection, it will initiate its operation.

Despite the fact that the vast majority of grounding conductors are installed in order to protect people, there is also a category that is designed to perform work processes. Therefore, all ground wires, in accordance with their purpose, can be conditionally divided into working and protective conductors. It should be noted that the danger of electric shock exists not only in the absence of a grounding conductor, but also if it does not meet the requirements.

Requirements

The requirements for the ground wire are made in accordance with the local conditions in which the electrical installations are operated. Also, they may differ in accordance with the tasks or mode of operation. All requirements can be divided into the following ground wire parameters:

• Single core or stranded– are applied depending on the specific equipment. So stranded wires should be installed in places where a certain level of flexibility is required and the ground must move easily (cell doors, test equipment, etc.). Single-core wires provide rigid fixation and are attached to the housings of stationary equipment.
• The presence or absence of insulation– an insulating layer is required for open laying or along equipment cases.
• Separately laid or contained in a single cable- with a combined design in single-phase systems, it must be carried out with a three-core cable, and in three-phase five-core. If the system is already mounted, it must be carried out by a separate ground conductor.
• Conductor material (copper, aluminium, steel)- determines the resistivity of the conductor itself and its chemical resistance to various environmental influences. Copper conductors are the most resistant to corrosion and have the lowest resistivity, followed by aluminum and steel.

The most important requirement for the ground loop and the conductor connected to it is the total ohmic resistance. Which is determined by the cross section of the ground wire, and the transition resistance between the circuit knives and the ground, and the places of bolted (terminal) or welded joints in the common circuit. The total resistance value of the circuit is determined by clauses 1.7.101 - 1.7.103 of the PUE, depending on the linear or phase voltage of the electrical installation and its type, these parameters are given in the table below:

Table: earth resistance value

Type of grounded electrical installation	The magnitude of the linear voltage U l, V	The magnitude of the phase voltage U f, V	Grounding resistance R, Ohm, no more
Places of connection of neutrals of generators, transformers and other current sources	660	380	2
	380	220	4
	220	127	8
Connection points located near the connection points for connecting the neutrals of generators, transformers and other current sources	660	380	15
	380	220	30
	220	127	60
Places of repeated grounding of overhead lines and supply lines	660	380	15
	380	220	30
	220	127	60

In addition to copper wires, in accordance with paragraph 1.7.121 of the PUE, for grounding it is allowed to use a metal armored sheath used to protect against mechanical damage when laying cables, boxes and trays, if their placement excludes the possibility of damage, rails and beams in the structure of buildings and structures .

But, according to the requirements of clause 1.7.123 of the PUE, it is forbidden to use metal parts of gas pipelines or water supply pipes, loaded reinforcement of reinforced concrete structures as grounding conductors.

Marking and color

Marking of ground wires provides them with quick recognition and ease of installation work. So, according to the requirements of clause 1.1.29 of the PUE, the conductors for grounding have both letter and color markings. The literal designation of the land is performed by a combination of Latin letters PE. The letters are intended for marking on the corresponding nodes of the circuit, cable ends and ground terminals. The color designation is made in the form of a yellow-green color, located in stripes along the entire length, or another combination of these two colors, which corresponds to the cable brand and manufacturer's standards.

Depending on the method of supplying electrical consumers, a system can be used in which the protective and neutral conductors are combined. Since the marking of the neutral wire according to the same clause 1.1.29 of the PUE is blue or light blue and is denoted by the letter N, in such power supply systems where the neutral wire and ground are combined and performed as a single line, they are designated as PEN. In terms of color, the combined PEN conductor has a combination of blue and yellow-green insulation.

Rice. 2: Ground wire color options

It should be noted that the above color marking procedure does not apply to tires, since in them yellow indicates phase A, green - phase B, red - C. A zero tire may have no color at all and be used in its natural form. The PE busbar is painted black and the overlays are organized as bare metal.

Ground wire cross section

Since the effectiveness of the protective device and ensuring human safety directly depends on such a parameter as ohmic resistance, the ground wire must have an appropriate cross section that meets the operating parameters of the laid line or electrical installation. Due to the fact that, unlike the phase and neutral bus, protective grounding should not withstand the load for a long time, its cross section can be performed with excellent parameters.

Figure 3: Example of a cable with a smaller PEN core

So the cross section of the PE conductor is determined in accordance with clause 1.7.126 of the PUE, the simplest option is to calculate the value based on the area of ​​the phase conductors:

• For a phase wire up to 16mm 2, the grounding section must be the same;
• For models from 16 to 35mm2, grounding can be at least 16mm2.
• For lines with a phase wire cross section of 35 mm 2 or more, the ground wire must be selected with an area of ​​at least half of the phase wire.

This option is the simplest, but it is far from always advisable to install a large-section conductor to ground, as this affects the total cost of cable and wire products. In such cases, it is allowed to determine the cross section by calculation:

• S is the area of ​​the ground wire;
• I is the value ;
• t is the response time of protective devices;
• k - coefficient determined by the materials of current-carrying and insulating elements, temperature.

Connection

Before connecting, it is necessary to designate the main conclusions of five or three-wire wires. If you are just doing installation work, you will be able to independently determine which wire to connect where, otherwise you will have to understand the existing wiring. In practice, to determine the location of all types of wires in the connection diagram, use their color designation:

• Phase conductors - have the most diverse spectrum (brown, red, gray, purple, etc.);
• Grounding conductors - are made in yellow-green color, some manufacturers use only bright green color;
• Zero conductor - blue or blue.

Rice. 4: wire color matching

However, note that not all installers follow the standard procedure, or the wire itself may not match the power circuit, so before using the ground or phase wire, you should first ring them.

The connection itself is made in such a way as to provide the most reliable contact with zero or close to that transition resistance. Therefore, the most acceptable is soldering, crimping or tightening under a nut or lug.

It is strictly forbidden to make an electrical connection of the ground wire by twisting and other non-standard methods. If a copper and aluminum conductor is connected, a brass gasket must be installed between them or they are crimped into a sleeve. Next, the ground wire is connected from the circuit to the equipment case, metal elements for potential equalization or to the corresponding socket contact.

Video in the development of the topic