How to connect ground. Protective grounding: how to properly build and connect a reliable protective circuit

The 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 wet hands touch the body of the washing machine, 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. So 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 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, 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 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.

According to the electrical standards of the last century, the construction of protective grounding in private property was considered an optional matter. The load was small, steel pipelines coped tolerably with the tasks of diverting electrical leaks. Time runs. Steel and cast iron communications replaced plastic and composites. Country property filled with numerous household appliances. Water and heat are supplied by powerful pumps, heating devices are working. It's time to protect yourself and the units from the vagaries of a useful, but wayward electric current. Let's do grounding with our own hands! The work is not difficult, the skilled owner will not have problems with the implementation.

The task and device of protective earthing

The purpose of grounding is to divert electrical current that has found a loophole in the insulation to reach the surface. This surface is metal cases and fasteners of washing machines, computers, microwave ovens, electric heating equipment. According to their functional duties, they should not conduct current, but they are always ready to substitute their metal “barrel” for leakage and short circuit current. This warm welcome is often felt by the owners of leaky or overly loaded equipment in the form of light blows, pinches and tingling.

Breakdowns on the body of household units rarely cause serious concern. Well, it shied away a little: it kind of cheered up. However, the apparent absence of serious risks is no reason to relax. The stray currents that have escaped to the outside contribute to discomfort and an unreasonable feeling of anxiety. In addition, ungrounded equipment makes noise, interference occurs in it, which reduces the speed and quality of receiving, processing and transmitting a signal. Such troubles will not disable the equipment instantly, but will significantly help to reduce its working life.

So, a ground loop is needed:

• to protect the owners from electromagnetic radiation, negative mood and ailments;
• to eliminate interference in the electrical network;
• to maintain the performance of the equipment.

Protective grounding will eliminate the above problems by providing the most attractive paths for the current to exit. By the principle of movement, electricity is very similar to water. It flows where there are no barriers, where there is less resistance and where it is easier for it to pass. Those. in order for people and units not to suffer, it is necessary to lay an unobstructed path “to the left” for the electric current, in the case of grounding, by definition, into the ground.

The resistance of the constructed path must be less than that of a person and equipment connected to protective grounding. That's when most of the electricity that has broken through will flow along the intended path with the smallest barriers, go beyond the building and dissipate in the ground. And the owner and equipment will get only the normative minimum.

The grounding system is a closed or linear circuit, which includes:

• two or more metal ground rods, strictly vertically immersed in the ground;
• a horizontal grounding conductor that combines the electrode rods into a common circuit;
• a bus that provides entry to the house and grounding connection to protected units.

An autonomous building may have several grounding systems, but one of them must be connected to the main grounding bus or to the main element - to the switchboard with the formation of a metal connection between the shield and the grounding conductor brought to it.

The choice of geometric shape for the earthing system

The most common configuration, according to which it is easiest to build a protective earth loop with your own hands, is an equilateral triangle. The contour triangular in plan is formed by three metal rods driven into the ground with a sledgehammer, the distance between a pair of which should be equal. In addition to triangles, grounding systems are constructed in the form of squares, straight or rounded lines, or other geometric shapes. Compliance with equal distances between ground electrodes is a mandatory condition, a clear geometry is desirable, but not essential.

Often, autonomous buildings filled with all kinds of equipment are simply surrounded by a ground loop. An excellent, effective option, if there are funds for this and enough free space on the site. More precisely, special money is not needed for an independent organization of grounding, but the choice of the shape of the contour is most often dictated by the site planned for the grounding device. However, one should not forget that when earthing switches are connected in parallel in one row, the efficiency of the system will be reduced due to the influence of the electrodes on each other. Closed loops are preferred.

There are three or more grounding electrodes in the protective earthing complex. A working ground, created to optimize the signal supplied to the instruments, can have two ground rods. Because the ground is a non-linear conductor, there must be at least two ground electrodes. So it is necessary that a potential surface is formed in the space between them, contributing to the spreading of the current. A single rod is not enough for this.

The working potential of a grounding system is affected by the distance between the vertical electrodes. The more often they are installed, the more effective the grounding. Recommended distance minimum 1.0m, maximum 2.0m. With an increase in the maximum limit between the metal rods, a gap in the potential surface is formed, it will nullify all the arrangement efforts.

The distance between the extreme grounding point and the foundation must be more than 1.0 m. The system will work flawlessly at a distance of 4-6m from home. It is pointless to arrange grounding further than 10m from the building.

Details about the components of the contour

It was mentioned above that grounding consists of horizontal and vertical components. By analogy, ready-made kits are produced for the operational device of ground loops. Following the attached instructions, building grounding from factory elements is easy and pleasant, but expensive.

Vertical ground conductors

As grounding vertical rods for self-made grounding, any long products made of black rolled metal without galvanization can be used. This treatment is not necessary for parts located in the ground, it reduces the potential. Reinforcing bar with ribs is undesirable, it is difficult to drive it into the ground. A square, a strip, a channel and its I-beam counterpart will do. Rolled metal with a complex profile is applicable if it is planned to drill wells for laying vertical electrodes before installing the system.

Advice. In order for the process of driving ground electrodes into the ground not to be unnecessarily laborious, it is better to purchase rolled metal with a smooth surface. Before work, its lower edge must be sharpened with a grinder. In the process of work, the earth around the rod must be periodically “irrigated” with water. This will make it easier to score.

Common materials for the manufacture of vertical conductors are:

• pipe with a wall thickness of at least 3.0 mm, the recommended diameter is 32 mm;
• corner with equal or different shelves with a preferred thickness of 5mm;
• circle with a diameter of 10mm.

The optimal cross-sectional area of ​​the vertical electrode is 1.6 cm². Based on this size, you should select the material. The length of the earth electrode is determined according to the local geological situation. It is necessary to go deep at least half a meter below the level of seasonal freezing.

The second condition affecting the length of metal rods is the water saturation of the host rocks. Simply put, the lower the groundwater, the longer the electrodes are needed.

In order not to suffer with geological characteristics and calculations, information about the depth of laying the ground electrodes must be obtained from the local energy department from the electricians on duty. Indicative data will help in any case, because. they have some estimated efficiency margin.

The average standard for the length of the ground electrode varies from 2 to 3 meters with half-meter variations. A favorable environment for the construction of grounding are loams, peat, water-saturated sands, sandy loam, fractured flooded clays. It is unrealistic to arrange grounding in rocks on your own, but there are ways to create electrical protection. Before the construction of the circuit, wells of the required depth are drilled. The rods are installed in them, and the free space is filled with sand or sandy loam mixed with salt or pre-filled with saline. Approximately half a pack per bucket.

With insufficient electrical conductivity of the soils on the site, it is better to use pipes as vertical ground electrodes. In the lower part of them, you need to arbitrarily drill several technological holes. Brine can be periodically poured through pipes with holes to reduce resistance. Salt, of course, will help to destroy the electrodes from corrosion, but grounding will work flawlessly for a long time. Then you just need to replace the rods.

Independent craftsmen for the manufacture of electrodes most often use black steel rolled metal. After all, economy is at the head of one's own efforts. An excellent, but expensive material for vertical electrodes is steel with an electrochemical copper coating or copper. Grounding elements embedded in the ground must not be painted, paint will worsen the electrochemical contact of the metal with soils.

Grounding metal connection - horizontal conductor

The horizontal grounding element that unites the system and brings it to the shield is most often made of a strip 40 mm wide, strip thickness 4 mm. Round steel is also used, less often a corner or corrugated reinforcement. The strip is welded to the upper edge of the vertical ground electrodes or fastened with bolts. Advantages of welding, it is more reliable. Places of welded and bolted joints are generously treated with anti-corrosion bituminous mastic or simply bitumen. It is impossible to crimp the underground grounding elements!

For the construction of a horizontal component located underground, it is undesirable to change the material so that, with inevitable moisture, a galvanic couple with its traditional corrosive consequences is not formed. An aluminum, copper or steel conductor can be connected to the horizontal grounding component brought out of the ground. Further, the entire system is connected to the busbar through a welded bolt, and from it it is fed to each of the grounded devices separately.

Triangular contour device algorithm

Work order:

• On the site chosen for the device of the grounding system, we mark the points for laying vertical conductors. These are the vertices of a triangle with sides approximately 1.2-1.4m.
• We outlined the outline of the future trench. It will be triangular with a "sprout" for bringing ground to the entry point to the house or to the outer shield. The choice of the minimum distance from the contour to the shield will save materials. The width of the trench is arbitrary, but taking into account the need for welding work in it. Depth depends on local conditions. 20 cm must be added to the installation level of the horizontal conductor recommended by electricians. For example, if the depth of the horizontal metal connection is 0.8 m, the trench must be deepened by 1.0 m.
• We drive the pre-pointed rods into the points of their installation, periodically wetting the soil around the point of driving with water. The vertical grounding conductor must be almost completely immersed in the ground, with the exception of the extreme 20 cm.
• We weld a horizontal connecting bar to the pieces of electrodes sticking out of the ground.
• From the point closest to the grounded structure, we lead the bar along the section of the trench dug to the power cabinet. We put it on the wall.
• At a convenient point for connecting the bar connected to the cabinet, we weld a steel bolt with the thread outward. Those. a bolt head will be welded to the bar, from which it is necessary to clean off rust and galvanization, if any. To connect the ground to the shield located inside the house, you will need to drill a hole in the wall through which the ground cable will be passed.
• We attach a ground wire to the welded bolt, fasten it with a nut.
• Then we thickly process the welded seams of underground joints with bitumen, fill the outer side joints with automotive silicone sealant.
• We call an electrician with an ohmmeter and check the operation of the created grounding system. The test is carried out in dry weather so that atmospheric moisture does not make adjustments to the readings. According to the standards, the loop resistance should not exceed 4 ohms. If the device confirmed the excess of resistance, the grounding will have to be finalized: install an additional vertical grounding switch and turn the triangle into a rhombus.
• If the readings of the device satisfy the requirements of PUE-7 and confirm the formation of a circuit with a sufficiently low resistance, we bury the trench, the equipment is connected to the ground not in parallel, but separately for each technical unit.

All. The grounding construction process can be considered completed.

A home master who knows how to properly make and correctly connect the ground will spend no more than 2-3 days on work.

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 system, the zero 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 neutral grounding conductor 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 in case of 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

General requirements

Grounding is one of the main measures to protect against electric shock.

This article provides detailed, step-by-step instructions on how to make grounding in a private house with your own hands.

To begin with, let's define what is grounding?

According to the PUE grounding- this is an intentional electrical connection of any point of the network, electrical installation or equipment with a grounding device. (clause 1.7.28.)

As a grounding device use metal rods or angles that are driven vertically into the ground (so-called vertical earthing switches) and metal rods or metal strips that, by welding, connect vertical ground electrodes (the so-called horizontal earthing switches).

Vertical and horizontal grounding together form ground loop, this contour can be closed (Figure 1) or linear (Figure 2):

The ground loop must be connected to the main ground bus in the introductory electrical panel of the house using ground conductor which, as a rule, uses the same metal strip or rod that is used as a horizontal ground electrode.

The protective grounding of a private house will have the following general form:

In turn, the combination of the ground loop and the ground conductor is called grounding device.

A closed ground loop is usually made in the form of a triangle with sides from 2 to 3 meters (depending on the length of the vertical ground electrodes); it is important that the distance between the vertical ground electrodes is not less than their length (see Fig. 1). A closed contour can also be made in other shapes, such as an oval, a square, etc. In turn, the linear circuit is a series of vertical earthing switches in the amount of 3-4 pieces lined up in a line, while, as in the case of a closed circuit, the distance between them in the linear circuit must be at least their length, i.e. from 2 to 3 meters (see Fig. 2).

Note: A closed ground loop is considered more reliable, because. even if one of the horizontal grounding conductors is damaged, this circuit remains operational.

Horizontal and vertical earthing switches must be made of black or galvanized steel or from copper (clause 1.7.111. PUE). Due to their high cost, copper ground electrodes, as a rule, are not used. Same way earthing conductors from reinforcement should not be made - the outer layer of the reinforcement is hardened, which disrupts the distribution of current over its cross section, in addition, it is more susceptible to corrosion.

Vertical earthing switches are made of:

• round steel rods with a minimum diameter of 16mm (recommended: 20-22mm)
• steel corners with dimensions of at least 4x40x40 (recommended: 5x50x50)

Length of vertical grounding should be 2-3 meters(recommended at least 2.5 m)

Horizontal earthing switches are made of:

• round steel rods with a minimum diameter of 10mm (recommended: 16-20mm)
• steel strip dimensions 4x40

The ground conductor is made of:

• round steel rod with a minimum diameter of 10mm
• steel strip with dimensions of at least 4x25 (recommended 4x40)

2. Grounding installation procedure:

STEP 1- Choose a place for installation

The place for installation is chosen as close as possible to the main electrical panel (introductory panel) of the house in which the main ground bus (GZSH) is located, it is also a PE bus.

If the input switchboard is located inside the house or on its outer wall, the ground loop is mounted near the wall on which the switchboard is located, at a distance of about 1-2 meters from the foundation of the house. If the electrical panel is located on an overhead power line support or on an outrigger stand, the ground loop can be mounted directly below it.

At the same time, ground electrodes should not be located (used) in places where the earth dries out under the influence of heat from pipelines, etc. (p. 1.7.112 PUE)

STEP 2- Excavation

We dig a trench in the shape of a triangle - for mounting a closed ground loop, or a straight line - for a linear one:

trench depth should be 0.8 - 1 meters

trench width should be 0.5 - 0.7 meters(for the convenience of welding in the future)

trench length- depending on the selected number of vertical ground electrodes and the distances between them. (For a triangle, 3 vertical earth electrodes are used, for a linear circuit, as a rule, 3 or 4 vertical earth electrodes)

STEP 3— Installation of vertical grounding

We place vertical ground electrodes in trenches at the required distance from each other (1.5-2 meters), after which we drive them into the ground using a perforator with a special nozzle or an ordinary sledgehammer:

Beforehand, the ends of the ground electrodes must be sharpened for easier entry into the ground:

As already mentioned above, the length of the vertical ground electrodes should be approximately 2-3 meters (at least 2.5 meters is recommended), while it is necessary to drive them into the ground for the entire length, so that the upper part of the earth electrode protrudes 20-25 cm above the bottom of the trench :

When all vertical ground electrodes are hammered into the ground, you can proceed to the next step.

STEP 4— Installation of horizontal grounding switches and grounding conductor:

At this stage, it is necessary to connect all vertical grounding conductors to each other using horizontal grounding conductors and weld a grounding conductor to the resulting ground loop, which will come out of the ground to the surface and is designed to connect the ground loop to the main grounding bus of the input electrical panel.

Horizontal and vertical grounding conductors are interconnected by welding, while the junction must be welded on all sides for better contact.

IMPORTANT! Bolted connections are not allowed! Vertical and horizontal grounding conductors forming a grounding loop, as well as a grounding conductor at the point of its connection to the grounding loop, must be connected by welding.

Welds must be protected from corrosion, for which the welding points can be treated with bituminous mastic.

IMPORTANT! Myself the ground loop must not be painted!(clause 1.7.111. PUE)

The result should be something like this:

STEP 5- We fill the trench with soil.

Everything is simple here, we fill up the trench with the ground loop mounted, so that there is at least 50 cm of soil above the loop, as already mentioned above.

However, there are some subtleties here:

IMPORTANT! The trenches for horizontal grounding conductors must be filled with homogeneous soil that does not contain crushed stone and construction debris (clause 1.7.112. PUE).

STEP 6- Connecting the grounding conductor to the GZSH of the input switchboard (input device).

Finally, we have come to the final stage - grounding the electrical panel at home, for this we perform the following work:

We bring the ground conductor to the electrical panel, so that about 1 meter remains before the electrical panel, if the input shield is in the house, it is advisable to bring the ground conductor into the building. At the same time, the following identification mark should be provided at the places where grounding conductors are entered into buildings (clause 1.7.118. PUE):

The grounding conductor itself, located above the ground, must be painted, it must have a color designation with alternating longitudinal or transverse stripes of the same width (from 15 to 100 mm) of yellow and green colors. (clause 1.1.29. PUE).

We weld a bolt to the end of the grounding conductor from the side of the electrical panel, to which we connect a flexible copper wire with a cross section of at least 10 mm 2, which should also have a yellow-green color. We connect the second end of this wire to the main ground bus, which should be used as a bus inside the input device (input switchboard at home). RE(clause 1.7.119. PUE).

IMPORTANT! The main ground bus should usually be copper. It is allowed to use the main earthing bar made of steel. The use of aluminum tires is not allowed. (clause 1.7.119. PUE).

As a result, the grounding circuit of the shield at home should look like this: