Insulation between reinforcement in a reinforced belt. Insulation of a monolithic armored belt for a house made of gas silicate blocks. Brick armored belt

Under " grounding"is understood as the electrical connection of equipment, devices to a grounding device, which in turn is connected to the ground (earth). The purpose of grounding is to equalize the potential of equipment, circuits and the potential of the earth. Grounding required for use at all power facilities to ensure the safety of workers and equipment from the action of short circuit currents. In the event of a breakdown, the short-circuit current flows through the grounding device circuit to the ground. The current passage time is limited by the action of relay protection and automation. This ensures the safety of equipment, as well as the safety of workers in terms of damage. electric shock.

To protect electronic equipment from electrostatic potentials and to limit the magnitude of the voltage of the equipment case for the safety of maintenance personnel, the resistance of an ideal grounding circuit should tend to zero. However, in practice this is not feasible. Considering this circumstance, in modern safety standards, sufficiently low permissible values ​​\u200b\u200bof the resistance of ground circuits are set.

Grounding device resistance

The impedance of the grounding device is composed of:

• The resistance of the metal of the electrode and the resistance at the point of contact between the ground conductor and the ground electrode.
• Resistance in the area of ​​contact between the electrode and soil.
• The resistance of the earth in relation to the flowing currents.

On Fig. 1 shows the layout of the ground electrode (pin) in the ground.

As a rule, a grounding pin is made of a metal that conducts electric current (steel or copper) and is marked with an appropriate terminal. Therefore, for practical calculations, one can neglect the resistance value of the grounding pin and the point of contact with the conductor. Based on the results of the studies, it was found that, if the technology of mounting the grounding device is observed (tight contact of the electrode with the ground and the absence of impurities in the form of paint, oil, etc. on the electrode surface), due to the small value, it is possible to ignore the resistance at the point of contact of the grounding electrode with earth.

The ground surface resistance is the only component of the grounding device impedance, which is calculated during the design and installation of grounding devices. In practice, it is believed that the grounding electrode is located among the same layers of soil, arranged in the form of concentric surfaces. The closest layer has the smallest radius and therefore the smallest surface area and the highest resistance.

As you move away from the ground electrode, each subsequent layer increases the surface and decreases the resistance. At some distance from the electrode, the resistance of the soil layers becomes so small that its value is not taken for calculations. The region of the ground beyond which the resistance is negligible is called the effective resistance region. The size of this area is directly dependent on the depth of immersion in the ground of the ground electrode.

The theoretical value of soil resistance is calculated by the general formula:

where ρ is the soil resistivity value, Ohm*cm.
L is the thickness of the soil layer, cm.
A is the area of ​​the concentric soil surface, cm2.

This formula clearly explains why the resistance of each layer of soil decreases with distance from the ground electrode. When calculating soil resistance, its resistivity is taken as a constant value, however, in practice, the resistivity value varies within certain limits and depends on specific conditions. Formulas for finding ground resistance at large numbers ground electrodes are complex and allow you to find only an approximate value.

Most often, the grounding resistance of a pin is determined by the classical formula:

where ρ is the average value of soil resistivity, Ohm*cm.
R is the electrode grounding resistance, Ohm.
L is the depth of the ground electrode, see
r is the radius of the ground electrode, see

Influence of the dimensions of the grounding electrode and the depth of its grounding on the value of the grounding resistance

The transverse dimensions of the grounding electrode have little effect on the grounding resistance. With an increase in the diameter of the ground pin, a slight decrease in the ground resistance is noted. For example, if the electrode diameter is increased by 2 times (Fig. 2), then the grounding resistance will decrease by less than ten percent.

Rice. 2. The dependence of the resistance of the grounding pin on the diameter of its section, measured in inches

With an increase in the depth of the ground electrode, the ground resistance decreases. It has been theoretically proven that doubling the depth can reduce drag by as much as 40%. The NEC standard (1987, 250-83-3) requires the pin to be immersed to a depth of at least 2.4 meters to ensure reliable ground contact (Fig. 3). In many cases, a three meter grounded pin will fully comply with current NEC standards.

According to NEC standards (1987, 250-83-2), the minimum acceptable diameter for a steel ground electrode is 5/8"" (1.58 cm), a copper-clad steel electrode or a copper electrode is 1/2"" (1.27 cm).

In practice, the following transverse dimensions of the grounding pin are used with its total length equal to 3 meters:

• Normal primer - 1/2 "" (1.27 cm).
• Wet soil - 5/8 "" (1.58 cm).
• Hard ground - 3/4 "" (1.90 cm).
• With a pin length of more than 3 meters - 3/4 "" (1.91 cm).

Rice. 3. Dependence of the resistance of the grounding device on the depth of grounding (vertically - the value of the resistance of the electrode (Ohm), horizontally - the depth of grounding in feet)

Influence of soil resistivity on the value of electrode grounding resistance

The above formula shows that the value of ground resistance depends on the depth and surface area of ​​the ground electrode, as well as on the value of soil resistivity. The latter value is the main factor that determines the grounding resistance and the depth of the electrode grounding required to ensure the minimum resistance. Soil resistivity depends on the time of year and point on the globe. The presence of electrolytes in the soil in the form aqueous solutions salts and electrically conductive minerals to a large extent affects the resistance of the soil. In a dry soil that does not contain soluble salts, the resistance will be quite high (Fig. 4).

Rice. 4. Dependence of soil resistivity (minimum, maximum and average) on the type of soil

Factors affecting soil resistivity

At an extremely low moisture content (close to zero), sandy loam and ordinary earth have a resistivity of over 109 Ohm * cm, which makes it possible to classify such soils as insulators. An increase in soil moisture up to 20 ... 30% contributes to a sharp decrease in resistivity (Fig. 5).

Rice. 5. Dependence of soil resistivity on moisture content

Soil resistivity depends not only on the moisture content, but also on its temperature. On Fig. Figure 6 shows the change in the resistivity of sandy loam with a moisture content of 12.5% ​​in the temperature range of +20 °C to –15 °C. The soil resistivity increases to 330,000 ohm*cm when the temperature drops to -15°C.

Rice. 6. Dependence of soil resistivity on its temperature

On Fig. 7 shows changes in soil resistivity depending on the time of year. At considerable depths from the surface of the earth, the temperature and humidity of the soil are quite stable and less dependent on the season. Therefore, a grounding system in which the pin is located at a greater depth will be more effective at any time of the year. Excellent results are achieved when the ground electrode reaches the groundwater level.

Rice. 7. Change in ground resistance during the year.

Taken as a grounding device water pipe(¾""), located in rocky ground. Curve 1 (Curve 1) shows the change in soil resistance at a depth of 0.9 meters, curve 2 (Curve 2) - at a depth of 3 meters.

In some cases, an extremely high value of soil resistivity is noted, which requires the creation of complex and expensive protective grounding systems. In this case, it is necessary to install a small grounding pin, and to reduce the grounding resistance, periodically add soluble salts to the surrounding soil. On Fig. 8 shows a significant decrease in soil resistance (sandy loam) with an increase in the concentration of salts contained.

Rice. 8. Relationship between soil resistance and salt content (sandy loam with a moisture content of 15% and a temperature of +17 ° C)

On fig. 9 shows the relationship between the resistivity of a soil saturated with salt solution and its temperature. When using a grounding device in such soils, the grounding pin must be protected from the effects of chemical corrosion.

Rice. Fig. 9. Influence of the temperature of soil impregnated with salt on its resistivity (sandy loam - salt content 5%, water 20%)

Dependence of the resistance value of the grounding device on the depth of electrode greening

A grounding nomogram (Figure 10) will be helpful in determining the required depth of the ground electrode.
For example, to obtain a ground value of 20 ohms in soil having a resistivity of 10,000 ohm*cm, a metal pin with a diameter of 5/8"" buried 6 meters must be used.

Practical use of the nomogram:

• Set the desired resistance of the grounded pin on the R scale.
• Mark on the P scale the point of the actual resistivity of the soil.
• Draw a straight line to the scale K through given points on the R and R scale.
• Mark a dot at the intersection with the K scale.
• Select the required ground pin size from the DIA scale.
• Draw a straight line through the points on the K scale and on the DIA scale until the intersection of the D scale.
• The intersection of this straight line with the scale D will give the desired value of the pin depth.

Rice. 10. Nomogram for calculating the grounding device

Measurement of soil resistivity with TERCA2

Available land plot large area.
The task is to find a place with minimal resistance and estimate the depth of the soil layer with the lowest resistivity. Among various kinds soil found in this area, the minimum resistance will be in moist loam.
After a detailed survey of the site, the search area narrows to 20 m2. Based on the requirements for the grounding system, it is necessary to determine the soil resistance at a depth of 3 m (300 cm). The distance between the outermost earth pins will be equal to the depth for which the average resistivity is being measured (in this case 300 cm).

To use the simplified Wenner formula

the ground electrode should be at a depth of about 1/20 of the distance between the electrodes (15 cm).

The installation of electrodes is carried out according to a special scheme shown in Fig. eleven.
An example of connecting the earth tester (Mod. 4500) is shown in Fig. 2. 12.

Rice. 11. Installation of ground electrodes on the grid

1. Remove the jumper that closes the terminals X and X V (C1 and P1) of the measuring device.
2. Connect a tester to each of the 4 pins (Fig. 11).

Example.
The tester showed resistance R = 10 ohms.
The distance between the electrodes A = 300 cm.
Resistivity is determined by the formula ρ = 2 π *R*A

Substituting the initial data, we get:

ρ \u003d 2 π * 10 * 300 \u003d 18 850 ohm cm.

Rice. 12. Tester connection diagram

Touch voltage measurement

The most important reason for carrying out touch voltage measurements is to obtain a reliable assessment of the safety of substation personnel and the protection of equipment from the effects of high voltage currents. In some cases, the degree of electrical safety is assessed according to other criteria.

Grounding devices in the form of a separate pin or array of electrodes require periodic inspection and verification of resistance measurement, which is performed in the following cases:

• The grounding device is compact and can be temporarily disconnected.
• When there is a threat of electrochemical corrosion of the ground electrode caused by low soil resistivity and constant galvanic processes.
• When there is a low probability of a ground fault close to the grounding device being tested.

As an alternative way to define security technological equipment substation uses touch voltage measurement. This method recommended in the following cases:

• If it is impossible to disconnect the grounding device for measuring the grounding resistance.
• In the event of a threat of ground faults in the vicinity of the tested grounding system or in the vicinity of equipment connected to the tested grounding system.
• When the circuit of the equipment in contact with the ground is comparable in area to the size of the earthing device to be tested.

It should be noted that the measurement of ground resistance using the potential drop method or touch voltage measurements do not allow a reliable conclusion about the ability of the ground conductor to withstand significant currents when current flows from the phase to the ground conductor. For this purpose, a different method is needed, in which a test current of a significant magnitude is used. The touch voltage measurement is carried out using a four-point earth tester.

In the process of measuring the touch voltage, the device creates a small voltage in the ground, which simulates the voltage during a fault. electrical network close to the test point. The tester shows the value of voltage in volts per 1 A of current flowing in the ground circuit. To determine the highest touch voltage that can occur in an extreme case, multiply the resulting value by the maximum possible current.

For example, when testing a grounding system with the highest possible fault current of 3000 A, the tester returned a value of 0.200.

Therefore, the contact voltage will be

U \u003d 3000 A * 0.200 \u003d 600 V.

Measuring the touch voltage is in many ways similar to the potential drop method: in each case, auxiliary earth electrodes must be installed in the ground. However, the distance between the electrodes will differ (Fig. 22).

Rice. 13. Ground conductor diagram (general case for industrial power supply)

Let's consider a typical case. Near the substation underground cable damaged insulation. Through this place, currents will flow into the ground, which will be directed to the substation grounding system, where they will create a high potential difference. High leakage voltage can pose a significant threat to the health and life of substation personnel located in a hazardous area.

To measure the approximate value of the touch voltage that occurs in this case, you should perform a series of actions:

• Connect cables between metal fence electrical substation and points P1 and C1 of the four-point ground tester.
• Install a ground electrode in the ground in the place where the cable breakdown is most likely.
• Connect the electrode to input C2 of the tester.
• On a straight line between the first electrode and the connection to the fence, install an additional electrode into the ground. The recommended distance from the point of installation of this electrode to the point of connection to the fence is one meter.
• Connect this electrode to point P2 of the tester.
• Turn on the tester, select the range of 10 mA, record the readings of the device.
• To obtain the value of the touch voltage, multiply the tester readings by the maximum current value.

To obtain a voltage potential propagation map, it is necessary to install an electrode (of course, connected to the P2 terminal of the tester) in various places near the fence, located next to the faulty line.

Measurement of ground resistance with the device "S.A. 6415" using current clamps

The measurement of earth resistance with current clamps is a new, very effective method, which allows measurements to be taken with the grounding system switched on. Also, this method provides a unique opportunity to measure the total resistance of the earthing device, including the determination of the resistance of connections in the current system grounding.

The principle of operation of the device S.A. 6415

Rice. 14. Ground conductor diagram (general case for an industrial power supply)

Rice. 15. The principle of operation of the grounding conductor

A classic grounding device for an industrial electrical network can be represented as circuit diagram(Fig. 23) or in the form of a simplified diagram of the operation of the grounding conductor (Fig. 24).

If a voltage E is applied to one of the sections of the circuit with resistance RX using a transformer, then an electric current I will flow through this circuit.

These quantities are interconnected by the relation:

By measuring the current I at a known constant voltage value E, we can determine the resistance RX.

In the diagrams shown (Fig. 23 and 24), a special transformer is used to generate current, connected to a voltage source through a power amplifier (frequency 1.6 kHz, constant amplitude). The resulting current is recorded by a synchronous detector in the resulting circuit, then amplified using a selective amplifier and, after conversion through an analog-to-digital device, is displayed on the instrument's display.

Typical examples of earth resistance measurement in real conditions

1. Measurement of the grounding resistance of a transformer installed on a power line pole

Measurement procedure:

• Remove the protective cover from the ground conductor.
• Provide adequate space for the current clamp to freely wrap around the conductor or earth spike.
• The clamps must be connected in the current path from the neutral or earth wire to the earth pin (stud system).
• On the device, select the measurement of current "A".
• Grab the ground conductor with a current clamp.
• Determine the current values ​​in the conductor (the maximum allowable current is 30 A).
• If this value is exceeded, stop measuring the resistance.
• Disconnect the device from this point and take measurements at other points.
• If the current value does not exceed 30 A, you should select the mode "?".
• The display of the device will show the result of measurements in Ohms.

The resulting value includes the total resistance of the earthing system, which includes: the contact resistance of the neutral wire with the earth pin, as well as the local resistances of all connections between the pin and neutral.

Rice. 16. Measurement of ground resistance on a power line pole

Rice. 17. Measuring the grounding of a transformer installed on a power line tower (grounding in the form of a group of pins)

Rice. 18. Measuring the grounding of a transformer installed on a power line tower (a metal pipe is used for grounding)

According to the diagram shown in Fig. 25, the end of the pole and the pin located in the ground are used for grounding. For a correct measurement of the total earth resistance, the current clamp should be connected at a point located above the junction of the earth conductors laid from the earth pin and the end of the pole.

The reason for the increased value of the ground resistance may be:

• Poor grounding pin.
• Disconnected ground conductor
• High resistance values ​​at the conductor contacts or at the splice point of the ground wire.
• The current clamps and the connections at the end of the pin should be carefully inspected for the absence of significant cracks in the joints.

2. Earth resistance measurement at the junction box or electricity meter

The technique for carrying out grounding measurements on the junction box and on the electric meter is similar to that considered when measuring the grounding of a transformer. The grounding circuit may consist of a group of pins (Fig. 26) or a metal water pipe in contact with the ground may be used as a grounding conductor (Fig. 27). When measuring resistance grounding, you can use both types of grounding at the same time. To do this, it is necessary to select the optimal point on the neutral in order to obtain the correct value of the total resistance of the earthing system.

3. Measurement of earth resistance at the transformer installed on the site

When carrying out grounding measurements at a transformer substation, you must remember:

• At this power facility there is always a high voltage that is dangerous to human life.
• Do not open the transformer guard.
• All work may only be carried out by qualified personnel.
• When carrying out measurements, the requirements of safety and labor protection measures should be observed.

Rice. 19. Measurement of the value of grounding on a transformer located on a special site

Measurement procedure:

• Decide on the number of grounding pins.
• When the ground pins are located inside the fence, measurements should be made according to the scheme shown in Fig. 28.
• When the grounding pins are located outside the fence zone, use the diagram shown in Fig. 29.
• If there is only one ground spike inside the enclosure, you must connect to the ground conductor at a point located after that conductor contacts the ground spike.
• Use of current clamp mod. The 3730 and 3710 connected directly to the ground pin will provide the best measurement results in most cases.
• In many cases, several conductors are connected to the terminal on the pin, leading to the neutral or inside the fence.
• The current clamp should be connected at a point where there is only one path for current to flow into the neutral conductor.

When low resistance values ​​are obtained, the measuring point should be moved as close as possible to the ground pin. On fig. 29 shows the ground pin outside the barrier area. To ensure correct measurements, it is necessary to select the current clamp connection point in accordance with the diagram shown in Fig. 29. If there are several grounding rods inside the fence, you should decide on their connection in order to select the optimal point for measurements.

Rice. 20. Choosing the right point for earth measurement

4. Transfer racks

When making earth measurements on transmission racks, it should be remembered that there are many different configurations of earthing devices, which introduces certain difficulties in assessing the earth conductors. On Fig. 30 shows the grounding diagram of a single rack on a concrete foundation with an external ground conductor.

The current clamp connection point is selected above the connection point of the grounding elements, which may have a structure in the form of a group of plates, pins, or be structural elements rack foundation.

Figure 21. Measuring the earth resistance of a transmission rack

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 - 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 difficult 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, it is necessary more vertical electrodes - 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 you can only measure ground resistance 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 right 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 starts 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 section 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 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 when TN-C-S system to protect against electric shock, it is necessary to install an RCD and difavtomatov. Without them, there is no protection.

Also, to ensure protection, it is required to connect to the earth bus with separate wires (inseparable) all systems that are made of conductive materials - 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 case 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 neutral 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 ground 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.

Modular grounding- this is a project created specifically for the installation of grounding conductors at residential facilities, for example, such as suburban private houses, country houses, as well as for industrial and administrative facilities.

The practice of mounting a modular ground loop.

The modular earthing switch is a prefabricated structure consisting of steel pins specially treated with copper, each 1.5 meters long. These pins are combined into a single grounding object ground loop.

The length of the prefabricated grounding rod can reach a depth of about 30 - 40 meters. Grounding 1.5 meter rods have a thread at the ends, through which the couplings between them, it becomes possible, as the prefabricated grounding rod moves in depth, to build it up with the next rod, etc.

Installation of a vertical grounding rod in depth is done as follows. The first pin is equipped with a steel tip from below, and a mounting sleeve with a nozzle for a vibrating hammer is screwed onto its upper part. A hammer or punch is used to strike the nozzle, and a special clamp is used to hold the pin in a vertical position.

When the first pin enters the ground for a length of approximately 1.3 - 1.4 meters, the mounting sleeve with a nozzle for the vibratory hammer is removed, and instead of them, the second pin is screwed through the coupling. The special clamp for holding the pin in a vertical position moves up along the newly mounted structure, and its top is again equipped with a mounting sleeve and a hammer head, and the process of driving the ground pin continues.

The scheme of the modular earthing rod is shown in the diagram below, where:

1. Nozzle for hammer or vibratory hammer.

2. Mounting coupling.

3. Clamp to hold the ground rod in a vertical position.

4. Coupling.

5. Grounding rod.

6. Steel tip.

There are several such modular grounding switches for the grounding loop (according to the project), and then they are connected to each other, using a copper strip or wire using clamps, into a single ground loop. When installing the clamps, these places are pre-treated with conductive paste, and after the complete installation of the entire ground loop, it is subjected to anti-corrosion painting.

Measurement of the resistance of the mounted vertical pin is possible at the stage of installation of each newly screwed 1.5 meter pin, and the service life of such a modular ground loop is approximately 30 years.

Advantages of modular grounding.