What is an electric zero? About grounding and grounding for dummies

My bitter experience as an electrician allows me to say: If your “grounding” is done correctly - that is, in the panel there is a place for connecting "grounding" conductors, and all plugs and sockets have "grounding" contacts - I envy you, and you have nothing to worry about worry.

Grounding connection rules

What is the problem, why can’t you connect the ground wire to heating or water supply pipes?

In reality, in urban conditions, stray currents and other interfering factors are so great that anything can end up on the heating radiator. However, the main problem is that the tripping current of the circuit breakers is quite high. Accordingly, one of the options for a possible accident is a short-circuit breakdown of a phase to the housing with a leakage current just somewhere on the border of the machine’s operation, that is, at best 16 amperes. Total, we divide 220V by 16A - we get 15 ohms. Just some thirty meters of pipes, and you get 15 ohms. And the current flowed somewhere, towards the uncut forest. But that doesn't matter anymore. The important thing is that in the neighboring apartment (which is 3 meters away, not 30, the voltage on the tap is almost the same 220), but on, say, a sewer pipe there is a real zero, or so.

And now the question is - what will happen to the neighbor if he, sitting in the bathroom (connected to the sewer by opening the plug) touches the tap? Did you guess it?

The prize is prison. Under an article about violation of electrical safety rules resulting in casualties.

We must not forget that you cannot imitate a “grounding” circuit by connecting the “zero working” and “zero protective” conductors in a European socket, as some “craftsmen” sometimes practice. Such a replacement is extremely dangerous. It is not uncommon for the “working zero” in the shield to burn out. After this, on the body of your refrigerator, computer, etc. 220V is placed very firmly.

The consequences will be approximately the same as with a neighbor, with the difference that no one will be held responsible for this except the one who made such a connection. But as practice shows, this is done by the owners themselves, because... They consider themselves sufficient specialists not to call electricians.

"Grounding" and "grounding"

One of the options for “grounding” is. But not as in the case described above. The fact is that there is a zero potential on the switchboard body on your floor, or more precisely, the neutral wire passing through this very switchboard simply has contact with the switchboard body through a bolted connection. Neutral conductors from the apartments located on this floor are also connected to the shield body. Let's take a closer look at this point. What we see is that each of these ends is threaded under its own bolt (in practice, however, these ends are often connected in pairs). This is where we need to connect our newly made conductor, which will later be called “grounding”.

This situation also has its own nuances. What prevents the “zero” from burning out at the entrance to the house. Actually, nothing. We can only hope that there are fewer houses in the city than apartments, and therefore the percentage of occurrence of such a problem is much lower. But this is again a Russian “maybe”, which does not solve the problem.

The only correct decision in this situation. Take a metal corner 40x40 or 50x50, 3 meters long, hammer it into the ground so that they don’t stumble over it, namely, dig a hole two shovel bayonets deep and drive our corner there as much as possible, and from it draw a PV-3 wire (flexible , stranded), with a cross-section of at least 6 mm. sq. to your switchboard.

Ideally, it should consist of 3 - 4 corners, which are welded with a metal strip of the same width. The distance between the corners should be 2 m.

Just don’t drill a hole in the ground with a meter-long drill and lower the pin there. It is not right. And the efficiency of such grounding is close to zero.

But, as with any method, there are downsides. You are, of course, lucky if you live in a private house, or at least on the first floor. But what about those who live on the 7th-8th floor? Should you stock up on 30-meter wire?

So how to find a way out of this situation? I’m afraid that even the most experienced electricians will not give you the answer to this question.

What is required for house wiring

For wiring around the house, you will need a copper grounding wire of appropriate length and a cross-section of at least 1.5 mm. sq. and, of course, a socket with a “grounding” contact. Box, plinth, bracket - a matter of aesthetics. The ideal option is when you are doing renovations. In this case, I recommend choosing a cable with three cores in double insulation, preferably VVG. One end of the wire goes under the free bolt of the distribution board bus connected to the panel body, and the other end goes to the “grounding” contact of the socket. If there is an RCD in the panel, the grounding conductor should not have contact with the N conductor anywhere on the line (otherwise the RCD will trip).

We must also not forget that the “earth” has no right to be broken by means of any switches.

First of all, you need to understand what it is phase, So what zero, and only after that - how to find them.

On an industrial scale and in everyday life, different currents are produced, these are three-phase alternating and single-phase, respectively. A three-phase network is characterized by the fact that alternating current flows through three wires and returns back through one. But single-phase differs in that our apartment wiring connects to only one of three-phase wires, this process is shown schematically in Figure 1.

To calculate the conductor resistance, you can use the conductor resistance calculator.

It is important to understand that the occurrence of electric current is possible only in the presence of a closed electrical network (Figure 2). Such a network consists of the following elements:

• winding - Lt,
• substation transformer - 1,
• connecting line - 2,
• electrical wiring of the apartment - 3.

In this scheme phase designated as L, zero- N.

In order for current to flow in a closed network, it is important to ensure that at least one energy consumer is connected to it - Rн, otherwise there will be no current, but the voltage in the phase will remain.

The Lt winding has two ends: one of them has contact with the ground, that is, it is grounded (Zml) and goes from this grounding point, it is called zero. The other end is called the phase end.

How to determine phase and zero.

Here we can conclude that the voltage between zero and phase (220 Volts) values ​​will be approximately zero, this fact is determined by the grounding resistance.

For example, for some reason, a contact situation may arise between the phase and the metal body of the electrical appliance, which is conductive, as a result of which tension will appear. To avoid electric shock in such a situation, a residual current device is needed that can provide protection.

If a person touches the tense body of this electrical device, an electric current may occur that will flow through the body, the reason for this is the presence of electronic contact between the body and the “ground” (Figure 4). The degree of danger that a person faces depends on the resistance value of this contact; this can be influenced by the following factors: for example, a wet or metal floor, contact of a building structure with natural grounding conductors (batteries, water pipes) and others. And, accordingly, the lower the contact resistance, the greater the danger.

In such a situation, grounding the chassis will be a solution to the problem (Figure 5).

In practice, this method of protection is implemented as follows: it is necessary to lay a separate grounding conductor PE, which is then grounded in one way or another (Figure 6).

There are various methods of grounding, each has its own advantages and disadvantages, but this is a topic for a separate article; we will not dwell on this now.

Let us now move on to consider several important practical issues.

How to determine phase and zero.

When connecting any electrical appliance, a natural question arises: where phase and where zero?

First, let's try to figure out how to find the phase. The easiest way that currently exists is to use an indicator screwdriver (Figure 7). It consists of the following elements:

• conductive tip - 1,
• indicator - 2,
• contact pad - 3.

The mechanism for using such a screwdriver is quite simple: we touch the controlled section of the electrical circuit with a conductive tip, and touch the contact pad with our finger; if the indicator lights up, this indicates the presence of a phase.

Another way to check the phase is to use a multimeter, or also called a tester. However, this method is more labor-intensive. The multimeter can operate in various modes; in our case, it is necessary to select the AC voltage measurement mode and set the limit to more than 220 Volts. We take one multimeter probe, it doesn’t matter which one, and touch it to the section of the circuit being measured, and with the other probe we touch a natural ground electrode, which can be a heating battery or metal water pipes. An indicator that a given section of the circuit contains phase, there will be multimeter readings corresponding to the network voltage, that is, about 220 V (Figure 8).

If you have taken measurements and they show a lack of phase, state that this is zero it is forbidden. An example can be seen in Figure 9:

• a) At the moment there is no phase at point 1,
• b) When switch S is closed phase appears.

Therefore, it is very important to check all possible options. I would also like to note one point: if in electrical wiring there is a grounding cable, using electrical measurements to distinguish it from neutral conductor impossible. Typically, grounding is performed using a yellow-green wire, but this cannot provide a complete guarantee. Therefore, the easiest way is to look at which wire is connected to the ground contacts under the outlet cover.

Which is called electric current, provides a comfortable existence for modern man. Without it, production and construction facilities do not operate, medical devices in hospitals do not operate, there is no comfort in the home, and city and intercity transport is idle. But electricity is a servant of man only in case of complete control; if charged electrons can find another path, then the consequences will be disastrous. To prevent unpredictable situations, special measures are used, the main thing is to understand what the difference is. Grounding and grounding protect a person from electric shock.

The directional movement of electrons follows the path of least resistance. To avoid the passage of current through the human body, it is offered another direction with the least loss, which provides grounding or grounding. What is the difference between them remains to be seen.

Grounding

Grounding is a single conductor or a group made up of them in contact with the ground. With its help, the voltage supplied to the metal body of the units is reset along the path of zero resistance, i.e. to the ground.

Such electrical grounding and grounding of electrical equipment in industry is also relevant for household appliances with steel external parts. A person touching the body of a refrigerator or washing machine that is energized will not cause electric shock. For this purpose, special sockets with a grounding contact are used.

Operating principle of RCD

For the safe operation of industrial and household equipment, automatic differential switches are used. Their work is based on comparing the electric current entering through the phase wire and leaving the apartment through the neutral conductor.

The normal operating mode of an electrical circuit shows the same current values ​​in the named sections, the flows are directed in opposite directions. In order for them to continue to balance their actions, ensure balanced operation of the devices, they carry out the installation and installation of grounding and grounding.

A breakdown in any section of the insulation leads to the flow of current directed to the ground through the damaged area, bypassing the working neutral conductor. The RCD shows an imbalance of current, the device automatically turns off the contacts and the voltage disappears in the entire operating circuit.

For each individual operating condition, different settings are provided for turning off the RCD, usually the setting range is from 10 to 300 milliamps. The device operates quickly, the shutdown time is seconds.

Operation of the grounding device

To connect to the housing of household or industrial equipment, a PE conductor is used, which is output from the panel along a separate line with a special output. The design provides a connection between the housing and the ground, which is the purpose of grounding. The difference between grounding and grounding is that at the initial moment when connecting the plug to the socket, the working zero and phase are not switched in the equipment. The interaction disappears at the last minute when the contact opens. Thus, the chassis grounding has a reliable and permanent effect.

Two ways of grounding device

Protection and voltage removal systems are divided into:

• artificial:
• natural.

Artificial groundings are intended directly to protect equipment and people. Their installation requires horizontal and vertical steel metal longitudinal elements (pipes with a diameter of up to 5 cm or angles No. 40 or No. 60 with a length of 2.5 to 5 m are often used). This makes the difference between grounding and grounding. The difference is that a specialist is required to perform high-quality zeroing.

Natural grounding electrodes are used if they are located closest to an object or residential building. Pipelines in the ground made of metal serve as protection. It is impossible to use pipelines with flammable gases, liquids and those pipelines whose outer walls are treated with an anti-corrosion coating for protective purposes.

Natural objects not only serve to protect electrical appliances, but also fulfill their main purpose. The disadvantages of such a connection include access to pipelines for a fairly wide range of people from neighboring services and departments, which creates the risk of violating the integrity of the connection.

Zeroing

In addition to grounding, in some cases grounding is used; you need to distinguish what the difference is. Grounding and zeroing remove voltage, but they do it in different ways. The second method is the electrical connection of the housing, which is not normally energized, and the output of a single-phase source of electricity, the neutral wire of a generator or transformer, a direct current source at its midpoint. When zeroed, the voltage from the housing is reset to a special distribution panel or transformer box.

Grounding is used in cases of unexpected voltage surges or breakdown of the insulation of the housing of industrial or household appliances. A short circuit occurs, leading to blown fuses and instantaneous automatic shutdown, this is the difference between grounding and neutralizing.

Zeroing principle

Variable three-phase circuits use the neutral conductor for various purposes. To ensure electrical safety, it is used to obtain the effect of a short circuit and voltage generated on the housing with phase potential in critical situations. In this case, a current appears that exceeds the rated value of the circuit breaker and the contact stops.

Zeroing device

The difference between grounding and grounding can be seen in the connection example. The housing is connected with a separate wire to zero. To do this, connect the third core of the electrical cable in the socket to the terminal provided for this in the socket. This method has the disadvantage that automatic shutdown requires a current greater than the specified settings. If in normal mode the disconnecting device ensures operation of the device with a current of 16 Amps, then small current breakdowns continue to flow without shutting down.

After this, it becomes clear what the difference is between grounding and neutralizing. The human body, when exposed to a current of 50 milliamps, may not be able to withstand it and cardiac arrest will occur. Zeroing may not protect against such current indicators, since its function is to create loads sufficient to disconnect the contacts.

Grounding and zeroing, what is the difference?

There are differences between these two methods:

• when grounding, excess current and voltage generated on the housing are diverted directly into the ground, and when grounded, they are reset to zero in the panel;
• grounding is a more effective way to protect people from electric shock;
• when using grounding, safety is achieved due to a sharp decrease in voltage, and the use of grounding ensures that the section of the line in which a breakdown occurred on the housing is switched off;
• When performing grounding, in order to correctly determine the zero points and choose a protection method, you will need the help of a specialist electrician, and any home craftsman can make grounding, assemble a circuit and deepen it into the ground.

Grounding is a system for removing voltage through a triangle located in the ground made of a metal profile welded at the joints. A properly constructed circuit provides reliable protection, but all rules must be followed. Depending on the required effect, grounding and grounding of electrical installations are selected. The difference between grounding is that all elements of the device that are not under current in normal mode are connected to the neutral wire. Accidental contact of a phase with zeroed parts of the device leads to a sharp jump in current and shutdown of the equipment.

The resistance of the neutral neutral wire is in any case less than the same value of the circuit in the ground, therefore, when grounding, a short circuit occurs, which is, in principle, impossible when using an earth triangle. After comparing the operation of the two systems, it becomes clear what the difference is. Grounding and grounding differ in the method of protection, since there is a high probability of the neutral wire burning out over time, which must be constantly monitored. Grounding is used very often in multi-storey buildings, since it is not always possible to arrange reliable and complete grounding.

Grounding does not depend on the phase phase of the devices, while the grounding device requires certain connection conditions. In most cases, the first method prevails in enterprises where safety requirements require increased safety. But even in everyday life, recently a circuit has often been installed to discharge the excess voltage that arises directly into the ground; this is a safer method.

Grounding protection directly concerns the electrical circuit; after an insulation breakdown, due to the flow of current into the ground, the voltage is significantly reduced, but the network continues to operate. When zeroed, a section of the line is completely switched off.

Grounding in most cases is used in lines with an insulated neutral in IT and TT systems in three-phase networks with voltages up to 1 thousand volts or above this figure for systems with a neutral in any mode. The use of grounding is recommended for lines with a solidly grounded neutral wire in networks TN-C-S, TN-C, TN-S with available N, PE, PEN conductors, this shows what the difference is. Grounding and grounding, despite their differences, are systems for protecting people and devices.

Useful Electrical Engineering Terms

To understand some of the principles by which protective grounding, grounding and disconnection are performed, you should know the definitions:

A solidly grounded neutral is a neutral wire from a generator or transformer, directly connected to the ground loop.

It can serve as the output from an AC source in a single-phase network or the pole point of a DC source in two-phase mains, as well as the average output in three-phase DC networks.

An insulated neutral is the neutral wire of a generator or transformer that is not connected to the ground loop or is in contact with it through a strong resistance field from alarm devices, protective devices, measuring relays and other devices.

Accepted notations on the network

All electrical installations with grounding and neutral conductors present in them must be marked. Designations are applied to tires in the form of the letter PE with alternating transverse or longitudinal identical stripes of green or yellow color. Neutral neutral conductors are marked with the blue letter N, which indicates grounding and grounding. The description for the protective and working zero consists of putting down the letter designation PEN and painting it blue throughout its entire length with green-yellow tips.

Letter designations

The first letters in the explanation of the system indicate the selected nature of the grounding device:

• T - connection of the power source directly to ground;
• I - all live parts are isolated from the ground.

The second letter serves to describe the conductive parts regarding the connection to earth:

• T speaks about the mandatory grounding of all exposed live parts, regardless of the type of connection to the ground;
• N - means that protection of exposed parts under current is carried out through a solidly grounded neutral from the power source directly.

The letters separated by a dash from N indicate the nature of this connection and determine the method of arranging the neutral protective and working conductors:

• S - PE protection of the neutral and N-working conductors is made by separate wires;
• C - one wire is used for the protective and working zero.

Types of protective systems

The classification of systems is the main characteristic according to which protective grounding and grounding are arranged. General technical information is described in the third part of GOST R 50571.2-94. In accordance with it, grounding is carried out according to the IT, TN-C-S, TN-C, TN-S schemes.

The TN-C system was developed in Germany at the beginning of the 20th century. It provides for the combination of a working neutral wire and a PE conductor in one cable. The disadvantage is that when a zero burns out or another connection failure occurs, voltage appears on the equipment housings. Despite this, the system is used in some electrical installations to this day.

The TN-C-S and TN-S systems are designed to replace the unsuccessful TN-C grounding scheme. In the second protection scheme, two types of neutral wires were separated directly from the shield, and the circuit was a complex metal structure. This scheme turned out to be successful, since when the neutral wire was disconnected, no linear voltage appeared on the casing of the electrical installation.

The TN-C-S system differs in that the separation of the neutral wires is not carried out immediately from the transformer, but approximately in the middle of the line. This was not a good solution, since if a zero break occurs before the separation point, then the electric current on the housing will pose a threat to life.

The connection scheme according to the TT system provides direct connection of live parts with the ground, while all open parts of the electrical installation with the presence of current are connected to the ground circuit through a ground electrode, which does not depend on the neutral wire of the generator or transformer.

The IT system protects the unit, arranges grounding and grounding. What is the difference between this connection and the previous diagram? In this case, the transfer of excess voltage from the housing and open parts occurs to the ground, and the source neutral, isolated from the ground, is grounded using devices with high resistance. This circuit is installed in special electrical equipment that must have increased safety and stability, for example, in medical institutions.

Types of zeroing systems

The PNG grounding system is simple in design; in it, the neutral and protective conductors are combined along their entire length. It is for the combined wire that the indicated abbreviation is used. The disadvantages include increased requirements for the coordinated interaction of potentials and conductor cross-section. The system is successfully used for zeroing asynchronous units.

It is not allowed to perform protection according to this scheme in group single-phase and distribution networks. It is prohibited to combine or replace the functions of neutral and protective cables in a single-phase DC circuit. They use an additional one marked PUE-7.

There is a more advanced grounding system for electrical installations powered by a single-phase network. In it, a combined common conductor PEN is connected to a current source. The separation into N and PE conductors occurs at the point where the main line branches into single-phase consumers, for example, in the access panel of an apartment building.

In conclusion, it should be noted that protecting consumers from electric shock and damage to electrical household appliances during voltage surges is the main task of energy supply. The difference between grounding and grounding is explained simply; the concept does not require special knowledge. But in any case, measures to maintain the safety of household electrical appliances or industrial equipment must be carried out constantly and at the proper level.

Source of electrical energy serves as a generator, which consists of three windings or poles connected in a three-rayed star, the central point is connected to the ground or grounded. See how it happens.

As seen according to the scheme to the three ends of the star the wires that lead out the phases are connected, and the central point will be zero, as I said, it is grounded, because the 380-volt power supply is a system with a solidly grounded neutral. Without grounding the neutral of the transformer at the transformer substation, the power supply will not work normally.

Three phases, zero and an additional grounding conductor (also connected to the ground) - a total of five wires that come from the substation to the electrical panel of the house, but only one phase, zero and ground come to each apartment from the floor panel. But only phase and zero are involved in the transmission of electric current. And electric current does not flow through the fifth grounding conductor; it has another protective function, which is that when a phase comes into contact with the metal body of household appliances (connected to the grounding conductor), the machine or RCD is switched off if there is a current leak.

Electric Energy is transmitted in phase, and on the neutral conductor the voltage is zero, but not always with electrical appliances connected to it - read on.

The voltage between zero (ground) and any phase is equal to 220 V, and between opposite phases 380 Volts - and this voltage is used where there are large loads or large power consumption. And this does not apply to the apartment! In addition, 380 Volts are many times more dangerous for humans.

In the water electrical panel At home, zero and earth are connected together and additionally with a ground electrode, which is buried in the ground. And then they go separately along the floor panels of the house, that is, they are isolated from each other, besides, the grounding conductor is connected directly to the electrical panel housing, and the zero lands on an insulated block!

Electric alternating current flows between two wires, phase and neutral, and at its frequency in our electrical network of 50 Hz, it changes its direction (from zero or to zero) 50 times per second.

But it doesn’t just flow, it flows through an electrical consumer connected directly to an outlet or to an electrical cable!

The third conductor is protective it does not participate in the transmission of electricity, but serves one purpose - to protect us from electric shock in emergency situations when a phase appears on the metal body of electrical appliances! Therefore, it is connected through the grounding contacts of the socket to the metal housings of the washing machine, refrigerator, microwave oven, etc. And in addition, grounding significantly reduces harmful electromagnetic radiation from household appliances.

Beats when touched current only phase. If you are not well insulated from the ground, i.e. you are not wearing rubber slippers or are not standing on a wooden chair without touching the floor or wall with your other hand, then when you touch a bare phase wire you will feel the flow of electric current through you from the phase to land.

Attention, it is not uncommon for people to die in everyday life as a result of prolonged exposure to or the passage of electric current through the human heart. Be careful!

In some rare cases may beat zero when an electrical appliance with a switching power supply is connected to it - a computer, household appliances, etc. But, as a rule, the tension there is not great and it is safe, it will only tickle you!

You can always take the grounding conductor and not be afraid, except in cases of its break in the electrical wiring or in the panel!

How to find phase, zero and ground?

To determine the phase wire, you need to purchase an inexpensive indicator screwdriver, which lights up when you touch the protected phase wire. I recommend reading ours. Usually the phase wire is red, brown, white or black.

Zero connects in a lamp or socket together with the phase to the supply contact, and when touched by the indicator, it does not light up. A blue wire or with a blue stripe is used under it!

Protective conductor connects to the grounding contacts of the socket, the metal body of a lamp or electrical appliance. According to generally accepted standards, the grounding conductor is made with a yellow-green wire or with a stripe of these colors.

Similar materials.

The neutral working conductor is also called neutral. Most household appliances are powered by an alternating 220 V network. In order to supply this voltage to them, one phase wire is used, and the second is neutral. The phase has a potential of 220 V, and the neutral wire has a potential of 0 relative to the power source and the phase wire.

Zero is designated as N, and its insulation should be blue or white-blue, in accordance with. Often the functions of the neutral working wire and the protective wire are combined (for). This joint conductor is designated PEN and has yellow-green insulation with blue markers (tags) at the ends. Similar color designations are used in Europe. In the US, the neutral working wire may be designated white or gray.

Different networks can use different neutrals (isolated, solidly grounded, effectively grounded). The choice of one option or another is determined by the functional purpose of the network.

At the moment, almost all residential buildings in Russia have grounding systems with a solidly grounded neutral. In this case, electricity is supplied from three-phase generators in 3 phases with potential, and also a fourth wire comes from the generator - neutral (working zero). The three phases at the end of the line are connected in a star: this creates the end of the neutral, which is connected to the neutral of the supply generator. The wire connecting these two neutrals is called the working neutral conductor of the network.

In the case of a symmetrical load on all phases, there is no working zero. If the load is distributed unevenly, then an unbalance flows along the zero working conductor. The use of such a scheme makes it possible to achieve self-regulation of all three phases, while they are almost equal to each other.

To increase safety, the working zero is at the end of the line, and additional grounding is often used: at the beginning of the line and at its different points. In houses, the neutral working wire is supplied to a switchgear, from which separate neutral conductors already go to direct consumers of electricity (for example, to apartments).

In addition to networks with a solidly grounded neutral, they are also used with an isolated neutral. In such networks there is no neutral working wire. Instead, if necessary, a neutral grounded wire can be used.

When using three-phase power lines in a building, the cross-section of the neutral working conductor must be no less than the cross-section of the phase conductors, with sizes of the latter up to 25 mm2 (aluminum). If the cross-section of the phase conductors is more than 25 mm2, then the cross-sectional area of ​​the working zero must be at least 50% of their cross-section. If the network uses a grounding working zero, then when connecting the wire to the main grounding bus, the identification sign “ground” must be present.

Even if the protective and working zeros are connected at the switchgear, their further combination at consumers is not allowed. That is, further through the apartments two separate wires PE and N are run. They cannot be connected because when the phase is closed to the neutral working conductor, and all devices connected to the protective conductor PE (in the case of combining PE and N) will be under the phase conductor voltage, which creates a high probability of electric shock to a person.