Wire for grounding what section, quality and type to choose for an apartment and a house. How to connect the ground wire

In this article, we will deal with you how to connect ground. This topic is quite extensive and has many nuances, and it’s not so easy to say here - do it this way or connect it here. Therefore, in order for you to understand me, and it would be easier for me to explain to you, there will be both theory and practice.

Grounding in our modern life is an integral part. Of course, you can do without grounding, because how long have we lived without it. But, with the advent of modern household appliances, grounding is simply a prerequisite for protecting a person from electric shock.

General concepts.

grounding- intentional electrical connection of any point of the network, electrical installation or equipment with a grounding device.

Grounding is for removal of leakage currents arising on the body of electrical equipment during emergency operation of this equipment, and provision of conditions to immediate disconnection of voltage from the damaged section of the network by triggering protective and automatic shutdown devices.

For example: there was an insulation breakdown between the phase and the electrical equipment case - a certain phase potential appeared on the case. If the equipment is grounded, then this voltage will flow through the low-resistance protective ground, and even if the residual current device does not work, then when a person touches the case, the current that remains on the case will not be dangerous to humans. If the equipment is not grounded, all the current will flow through the person.

Grounding consists of ground electrode and ground conductor connecting grounding device with grounded part.

ground electrode is a metal rod, most often steel, or another metal object that has contact with the ground directly or through an intermediate conductive medium.

Ground conductor- this is a wire connecting the grounded part (equipment case) to the ground electrode.

Grounding device- this is a combination of a grounding conductor and grounding conductors.

A bit of theory.

All of you have seen small brick structures in the yards, into which power cables enter and exit - this transformer substations(electrical installations). Transformer substations are used to receive, convert and distribute electrical energy. Any substation has a power transformer used for voltage conversion, switchgear and automatic control and protection devices.

Accepting high voltage network 6 – 10 kV(kilovolt) substation converts it and transfers it to the consumer - that is, to us. Reception and conversion of voltage is provided by a power transformer, from the output of which a three-phase alternating voltage goes to the consumer 0.4kV or 400 volts.

One of three phases is used to power home single-phase equipment (TV, refrigerator, iron, computer, etc.) L1; L2; L3 and zero worker conductor " N».

This is a standard scheme for providing consumers with electrical energy, on the basis of which additional schemes were developed that differ in the method of connecting protective grounding, connecting and protecting electrical equipment, as well as the measures taken to protect people from electric shock.

The transformer substation has its own ground loop, to which all metal cases of substation equipment are connected. The ground loop is a metal rod driven into the ground, interconnected by a metal bus by welding. This tire is called ground bus.

The ground bus is brought into the substation building and laid along the perimeter of the building. Bolts are welded to it, to which already through ground conductors all substation equipment is connected.

According to the PUE (Electrical Installation Rules), a grounding conductor ( zero protective) on electrical diagrams has the letter designation “ RE» and color marking with alternating transverse or longitudinal stripes of yellow and green.

Grounding systems.

Earthing systems differ in the way they are grounded zero worker"N" conductor on the secondary winding of the power transformer and consumers of electrical energy (motor, TV, refrigerator, computer, etc.) powered by this transformer.

Consider the example of a transformer substation.
The secondary winding of the power transformer of the substation has three coils connected " star”, where the beginnings of the coils are connected to a common point, called neutral « N", which is directly connected to grounding device.

The free ends of the coils are connected to the wires of a three-phase network that goes to consumers of three-phase or single-phase electrical energy. This neutral connection is called deaf-earthed and is used in grounding systems such as TN.

Here is neutral N", or it is also called working zero, performs two functions:

1. Together with one of the three phases, it forms a voltage of 220 volts.
2. Performs a protective function, as it has direct contact with the ground.

At the moment there are 3 types of grounding systems:

1. TN– a system in which the transformer neutral is earthed and exposed conductive parts are connected to the neutral;
2. TT— a system in which the transformer neutral is earthed and the exposed conductive parts are earthed by means of an earthed device electrically independent of the earthed transformer neutral;
3. IT- a system in which the transformer neutral is isolated from earth or earthed through high resistance devices and the exposed conductive parts are earthed.

All three earthing systems are designed to protect people and electrical equipment from electrical current. These grounding systems are considered equivalent for the protection of people, but they are not equivalent in terms of the method of ensuring the reliability (reliability, maintainability) of the power supply to consumers of electrical energy.

Grounding systems are designated by two letters.
The first letter defines the connection of the transformer neutral to earth:

T– the neutral is grounded;
I– the neutral is isolated from the ground.

The second letter defines the connection of exposed conductive parts to ground:

T– exposed conductive parts are directly earthed;
N– exposed conductive parts are connected to the dead-earthed neutral of the transformer.

Now consider all systems in order.

1. TN grounding system.

System " TN" is a system in which neutral transformer grounded, and exposed conductive parts are connected to neutral through zero protective conductors.

exposed conductive part– a conductive part of the electrical installation accessible to the touch (for example: housing of household appliances), which in the normal operation of the electrical installation not energized, but maybe be under stress in case of insulation failure.

As a rule, insulation damage can be caused by many factors: equipment aging, mechanical damage, long-term operation at maximum loads, dust accumulation between the equipment case and current-carrying parts, moisture formation on a dusty surface located next to current-carrying parts, climatic effects, factory marriage, etc.

So, in turn, the system TN is further divided into three subsystems:

1. TN-C- a system in which the zero protective "PE" and zero working "N" conductors are combined in one conductor "PEN" throughout the system;
2. TN-S- a system in which the zero protective "PE" and zero working "N" conductors are separated throughout the system;
3. TN-C-S- a system in which the functions of the zero protective "PE" and zero working "N" conductors are combined in one conductor in some part of it, starting from the power transformer.

TN-C system.

System TN-C- this is one of the first grounding systems, which is still found in the old housing stock built before the mid-90s, but, despite this, it still exists and operates. This system is being laid four-wire cable containing 3 phase wires and 1 null.

Here zero protective " RE"and zero worker" N» conductors are combined in one conductor throughout the system. That is, one " PEN"conductor, and this is by far the main drawback of the system TN-C.

At that time, there was practically no electrical equipment requiring a three-wire connection, and therefore no special requirements were attached to protective grounding, and such a system was considered reliable. But with the advent of modern three-wire equipment in our everyday life, where a “PE” grounding conductor is provided, the TN-C system has ceased to provide the required level of electrical safety.

Today, almost all modern equipment is powered through switching power supplies that do not have galvanic isolation with a network of 220 Volts.

This is due to the fact that switching power supplies have noise filters, which are designed to suppress high-frequency interference of the 220 V supply network, and which are connected to the equipment case through decoupling capacitors.

High-frequency interference from the supply network flows through decoupling capacitors, protective earth wire "PE", three-pole plug and socket to "ground". That is why there is a danger of phase voltage appearing on the equipment case in case of insulation breakdown between the phase and the case or the disappearance of the working zero “N” when powering modern equipment using the TN-C grounding system that does not have a separate protective grounding conductor “PE”.

For example: if your working zero “N” breaks off or burns out between the floor and apartment shields, then there is a danger of phase voltage appearing on the case of the currently operating household equipment. And if it is not grounded, then when you touch the metal unpainted case with your bare hand, current will flow through you and you will receive a charge.

Although, thanks to switching power supplies, modern technology has become smaller, cheaper and lighter, but, of course, the requirements for the level of electrical safety have become higher.

But, as they say, the salvation of the drowning is the work of the drowning themselves, and therefore some craftsmen, in order to protect themselves, pull the ground on their own. Some sit on central heating batteries, others connect to the floor shield body, put a jumper in the socket, install an RCD, and some even make their own ground loop.

For example: You have connected with the third conductor to the body of the floor shield and think that you have grounded. This is a big misconception. you did nulling— and no more.

Protective zeroing- this is a deliberate electrical connection of open conductive parts of an electrical installation (for example, an equipment case) with a solidly grounded neutral of a generator or power transformer, performed for electrical safety purposes.

Solidly grounded neutral is the transformer neutral connected directly to the grounding device.

So here it is nulling on the case of the floor shield is dangerous because in the event of a break in your working zero"N" the power of household appliances that are currently plugged into the socket will pass through the protective conductor "PE".

And this is already wrong power circuit for household appliances, which will lead to short circuit and breakdown of all equipment. The circuit breaker will work, but only from the short circuit current that your already burned equipment will create. And if at this moment you take hold of the unpainted metal body, then in addition, for a moment, you will get a charge of vivacity.

Although in PUE No. 7, zeroing is allowed and is considered an additional measure of protection. But again the question arises: where to do the zeroing. Here you decide.

Another example.
You are connected to central heating battery, trying in this way to deceive the counter or to ground. On your riser, a neighbor from below is doing repairs and replacing old rusty pipes with plastic ones. As a result, you were cut off from your imaginary land. Now you and the neighbors from above will be in constant danger.

Or another example.
You took into account all the nuances and decided to ground yourself in a different way. They dug a hole in the basement of the house or near the house, drove in the pins, did it according to all the rules ground loop, and the grounding conductor "PE" was led to his apartment. Everything is done, and now you can sleep peacefully. And here it is not.

Suddenly, your neighbor decided to play a trick on you out of spite or just out of envy that you have grounding, but he does not. Take and cut off the grounding conductor. Or the person responsible for the house will see the wire that is not laid down according to the project and remove it, and you live and don’t know that you were left without grounding. In addition, grounding should be periodically checked with special devices. Will you do it? Do you have such devices?

As a protection option, you installed in a two-wire line RCD. In principle, this is not such a bad option, but it also has its own nuances.

The RCD operates on leakage currents of 10 mA, 30 mA and 300 mA, but for this it needs protective conductor"PE", relative to which the RCD sees these currents. In system TN-C protective conductor "PE" No, but it is in the system TN-S for which the RCD was developed. On a two-wire line, the RCD will also work, but through the leakage current that you create with your body.

Let's take, for example, the same breakdown of insulation on the body, and at the same time, a simultaneous touch on a bare central heating battery.

In system TN-S the leakage current that has arisen on the case will immediately go through the protective conductor " RE”, and if its threshold exceeds the RCD setting, it will trip and turn off the power. And even when the threshold for the RCD is small and it does not work, you will not feel anything, or you will just be pinched a little.

In system TN-C another case. At simultaneous touching the body and the exposed central heating battery, current will flow through you to the battery. If there is an ordinary machine, then you, depending on current strength, and you will remain hanging between two fires, as the passing through you current will not be short circuit current. If it will stand RCD, then upon reaching the setpoint threshold, it will operate and turn off the power.

And here comes the moment of truth: RCD, in the TN-C system, will not save you from electric shock. You will receive your charge of vivacity. The question is only time spent under the influence of electric current.

In PUE No. 7 regarding the installation of an RCD in the TN-C system, it is said:

1.7.80. It is not allowed to use RCDs that respond to differential current in four-wire, three-phase circuits (TN-C system). If it is necessary to use an RCD to protect individual electrical receivers powered by the TN-C system, the protective PE conductor of the electrical receiver must be connected to the PEN conductor of the circuit supplying the electrical receiver to the protective switching device.

Again the question arises: where to pull the protective conductor. So, here again, it's up to you.

Therefore, if you live in houses of old construction and you have a two-wire network, then by securing your apartment with grounding, as it seems to you, the problem will not be solved, but will only worsen for you or your neighbors. The problem of a two-wire network must be solved collectively - by the whole house:

1. Alteration or change in the power system of the house from a four-wire to a five-wire line.
2. Replacement of old floor boards with new ones designed for a five-wire line.

But do not think that everything is so scary. In this part of the article, I talked about the possible situations that may arise with us if we incorrectly connect and use protective grounding. In the article, we will continue to deal with the remaining grounding systems.
Good luck!

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

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

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

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

Dependence of the connection scheme on the type of grounding system

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

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

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

TN-S earthing system

Figure 1. TN-S system

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

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

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

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

Figure 2. TN-S system

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

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

Grounding connection according to the TN-C-S system

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

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

Figure 3. Schematic of the main switchboard

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

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

Figure 5. TN-C-S ground connection diagram

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

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

TT earth connection

Figure 6. TT system

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

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

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

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

Figure 7. TT earth connection diagram

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

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

Conclusion

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

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

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

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

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

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

The electricity carried into our homes is an impressive force that can easily kill a person. Therefore, when installing electrical wiring, first of all, it is necessary to take care of the safety of users.

In electrical engineering, the word "grounding" can rightfully be considered synonymous with the word "safety".

In this article we will talk about what a ground wire is for and what requirements it must meet.

Under normal conditions, the current-carrying parts of electrical equipment are separated from all other parts by insulation, so touching, say, the case to the user does not threaten anything.

But as a result of an accident, aging of the material or damage by rodents, the insulation can be broken, as a result of which the case or other element is energized. It is worth touching it now, as an electric shock will immediately follow.

Ground wire

In order to weaken or even completely prevent (when connected through an RCD) the impact of current on the user in such a situation, all parts of the equipment that may be energized are connected with a separate wire to a ground loop immersed in the ground. Now, upon contact, the charge will only partially go through the user, since some of it will go into the ground.

If the device is connected through an RCD (residual current device), then, as already mentioned, electrical injury can be avoided altogether: the device will detect the current leakage in the circuit and immediately disconnect it.

A grounding system in a residential or industrial building must be present - this is a requirement of the PUE and other regulatory documents. Moreover, a special act must be drawn up on this account.

Marking

You need to know what color the ground wire is.

Usually, a ground wire in the form of a separate core is part of a stranded wire that feeds an electrical appliance or outlet.

Thus, in a 1-phase network, it will be the 3rd residential, and in a 3-phase network it will be the 5th.

In this case, a special marking is provided for the ground wire, which allows it to be distinguished from the phase or neutral conductor and thus prevents confusion when connecting:

1. Letter. The PUE is prescribed to apply the letter "PE" to the ground wire insulation. The same designation is provided for by international standards. The indication of the cross-sectional area, grade and material is optional.
2. Color. Domestic and foreign standards assign a combination of yellow and green colors to the ground wire. Some foreign manufacturers of cable products designate such a core only in yellow or only in green.

In addition to grounding, combined conductors are used, which simultaneously perform the function of zero working and zero protective. They are designated by the letters "PEN" and a combination of blue with yellow or green. One color of the ground wire is the main one, the second is applied in the form of stripes at the ends.

Ground wire installation

Thus, it is quite simple to distinguish the ground wire from the zero wire, to which the blue color and the letter “N” are assigned, and from the phase wire (has brown, black or white insulation, denoted by the letter “L”). Color coding has made it easier not only to install electrical systems, but also to find and replace burnt, broken or overloaded wires.

Some manufacturers paint the phase conductor in other colors: gray, purple, red, turquoise, pink, orange.

Please note that the color coding cannot tell if the network is 1-phase or 3-phase, and whether AC or DC is supplied to it. Thus, the cores and buses of DC networks (used in construction, electric transport, substations, etc.) are also painted in red ("+"), blue ("-") and blue (zero bus) colors. In 3-phase networks, phases A, B and C are usually denoted, respectively, in yellow, green and red.

The designation of cores in different colors is not used in all wires. So, in a 3-core cable of the PPV brand, which seems attractive due to its relatively low cost, you will not find yellow-green insulation, so it is very easy to mix up the cores when connecting.

Working ground

If the marking is not visible or absent, you can determine the ground wire in the wire connected to the network using a voltmeter: the voltage is measured between the phase wire (it is determined by the phase indicator) and each of the two remaining ones. When the probe contacts the "ground", the value on the instrument panel will be higher than when it contacts "zero".

It is also possible to measure the voltage between the conductors being tested and any grounded device, for example, an electrical panel housing or a heating battery. If the core is zero, the device will show some small value; if "ground" - the scoreboard will display zero.

The phase indicator, with the help of which the core connected to the phase is determined, looks like a screwdriver, only there is a diode light bulb and a special contact on the handle (usually in the form of a ring under the light bulb). To determine the phase, you need to attach your finger to this contact and at the same time the tip of the screwdriver to the conductor under test. If it is energized, the light will turn on.

It should be understood that connecting the consumer to the ground wire is not yet a sufficient condition for safety. The wire itself on the other side must be connected to the ground loop.

It is enough for a resident of an apartment in a city high-rise building to find the appropriate contact in the switchboard, but the owner of a private house will have to create such a circuit himself.

Usually it is metal pins driven into the ground (in the form of an isosceles triangle), connected by reinforcement.

Wire cross section for grounding

This parameter is primarily determined by the power of the protected equipment. Regulated by the following documents:

1. Chapter 1.7 of the PUE ("Grounding and protective measures for safety").
2. Chapter 54 in part 5 of GOST R 50571.10-96 "Electrical installations of buildings" (repeats the international standard IEC 364-5-54-80).
3. Appendix RD 34.21.122-87 "Instructions for the installation of lightning protection of buildings and structures."

Yellow-green color for ground terminals

The main task in selecting the cross section of the ground wire is to exclude its heating during the flow of maximum current (single-phase short circuit) above a temperature of 400 0 C. The maximum cross section for a copper wire is 25 square meters. mm, aluminum - 35 sq. mm, steel - 120 sq. mm. It does not make sense to use wires with a larger cross section than indicated.

When installing a household electrical network for grounding, it is enough to use a wire of the same cross section as the cores of the supply wire.

Popular brands

A separate core for grounding contains wires of the following brands:

NYM

It is used to connect stationary installations and is designed for voltage up to 660 V. It can be used in explosive areas: class B1 b, V1 g, VPa - in power and lighting networks; class B1 a - only in lighting.

NYM cable

Specifications of NYM ground cable:

• core material: copper;
• core type: single-wire;
• there is an intermediate shell;
• cores are color-coded as standard.

Cutting and installation are very easy.

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VVG

Common for cables of this brand is the following:

• core material: copper;
• core type: stranded (twisting class - I or II);
• insulation and sheath material: PVC (color-coded);
• there are two steel tapes that act as armor;
• outside the cable is wrapped with fiberglass and coated with bituminous composition.

The outer cover of the VVG cable does not spread combustion and is not destroyed under the influence of ultraviolet radiation. Versions are produced with the number of cores from 1 to 5.

If the wiring is already laid with a 2-wire or 4-wire cable, the ground wire can be laid separately.

The following cable brands are suitable for this:

PV-3

Multi-wire single-core copper cable. Insulation - single layer, PVC. During installation, it should be easily removed from the core. If the insulation sticks to the copper, then violations were made during production or storage.

The PV-3 cable is produced with a cross section from 0.5 to 240 sq. mm.

PV-6-ZP

This cable is used for portable grounding.

Like the previous one, it is a copper stranded single-core, but it also has some differences:

• the core class is higher (No. 6 versus No. 2, 3 and 4 for PV-3);
• the insulation is made of a transparent variety of PVC, which allows you to visually monitor the condition of the core;
• withstands temperatures from -40C to +50C;

PV6-3P is not afraid of alternating bends (at an angle of up to 180 degrees and a bend radius of at least 50 mm).

ESUY

This cable is manufactured in Germany. Designed for use as a ground wire in short circuit protection systems. Able to withstand high temperatures and has a particularly strong and chemical resistant shell.

Since the ESUY cable was originally designed for grounding, the rated voltage for it is not standardized.

Related video

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

Briefly about terms

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

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

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

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

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

Ground wire cross section

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

The cross section of the ground wire must be:

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

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

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

Brand and requirements for conductors

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

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

The ground conductor can be:

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

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

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

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

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

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

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

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

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

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

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

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 the 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: