What is the difference between zero and ground. What is the difference between grounding and grounding. Mandatory use of additional protective devices

The function of grounding and grounding is one - protecting a person from damage electric shock. The current-carrying core was exposed, there was a leakage of current to the body of the electrical appliance, the body of the socket was damaged - such a problem can lead to backfire. The considered protective devices, which are designed to neutralize dangerous factor to ensure the safety of a person and his property. In the article we will talk about grounding and zeroing, what is the difference and similarity, consider their purpose and installation schemes.

What is the difference between grounding and grounding

Grounding scheme indicating splitting into N and PE on the terminal block of the shield

It is most convenient to consider the difference between grounding and grounding using the example of connecting household electrical appliances. modern houses equipped with a three-wire electrical wiring, where the PE conductor is grounding and does not depend on the conductor of the working zero N. Thus, the body of the electrical appliance connected to the PE conductor receives a reliable connection to the ground - grounding.

Old buildings have a two-wire power supply, consisting of a conductor L - phase, N - working zero. N is derived from the ground bus in the general house or access electrical panel. Initially, it is called a PEN conductor and can be split into N and PE.

Splitting must be done before entering the apartment switchboard, or directly in the switchboard. Further, the PE wire is connected to the body of the electrical appliance in the same way as in the first embodiment, but such a circuit will be called zeroing, since the connection with the ground is not direct, but is carried out through a neutral conductor. Read also the article: → "".

Which system is more reliable

For comparison, here are a few points:

As practice shows, there are frequent cases of a break or burnout of the neutral wire in the electrical panel, which makes the zeroing protection system inoperative. In this case, there is a real threat of electric shock to a person. To avoid such a problem, the switching points must be periodically inspected, which creates certain inconveniences.

The burnt neutral wire in the switchboard is close to a complete break

The grounding system is free from these disadvantages, since the PE conductor is not involved in common work wiring and is activated only when a leak occurs to divert current to earth.
The zeroing device requires certain knowledge and skills in working with electrical circuits, which, if they are not available, also causes some inconvenience associated with the need to call an electrician.

Taking into account the above, we can conclude that the grounding system is more reliable and safe, so it is better to use it. However, if this is not possible, one can resort to alternative. It is forbidden to ground directly in the socket by installing a jumper between the zero connector and the grounding bracket. This poses a danger to humans (electric shock) and to household appliances.

The device of protective current taps when working with three-phase electrical equipment

The switching of three-phase consumers of electricity differs from the connection of conventional household electrical equipment, so the installation of protective systems is carried out in a different way. In this case, one should not confuse the neutral or ground wire participating in the control system, that is, involved in the starting and stopping circuit of the unit, with a protective conductor designed to discharge a dangerous discharge to the ground.

Design, wiring, connection of electrical equipment

The work is carried out in several stages:

Equipped around the perimeter of the room separate line(route), made of a narrow metal strip 40x3 mm or copper wire with a cross section of 16 mm.kv.
On her in hidden place a busbar is mounted (preferably copper) with contact devices (studs or holes for bolted connections). It is allowed to use a metal tire, but in this case, welding the studs is a prerequisite.
This line is connected to the ground or ground loop, brought out by a separate wire from switchboard and having a reliable connection with the ground either directly or through a working zero
Housings of all consumers (three-phase electric motors) through copper wire connected to the described bus.

In the event of a short circuit from voltage leakage due to a violation of the insulation or “breakthrough” of one of the phases on the body of grounded electrical equipment, the current will immediately go to the ground along the path of least resistance, that is, through a core connected to working zero or ground. This will save a person from electric shock when touching the body of the device. Read also the article: → « ».

A zeroing device is allowed only if there is no possibility of switching with an earth circuit. In all other cases, only protective earth.

The unit is connected via a copper wire to a busbar mounted from a grounding track

Mandatory use of additional protective devices

The described grounding and zeroing systems are effective in the event of significant leaks or short circuits on the body of electrical appliances. However, to achieve complete safety when servicing equipment, it is necessary to use additional funds break protection electrical circuit in case of violations of their work.

On the manufacturing enterprises these can be automation units (insulation control of BKI or maximum current protection). But the most common means, both in production and in everyday life, are circuit breakers and devices protective shutdown, which:

ensure the de-energization of the electrical circuit in the event of a malfunction;
protect the user from electric shock;
protect equipment from fire.

Such devices can be designed for single-phase or three-phase systems. They are:

single-pole - installed on one of the lines (zero, phase);
bipolar - are installed on both wires of the electrical wiring;
multi-pole (three or more) - used with three-phase voltage.

Household wiring diagram with PE ground conductor and VA and RCD protection

The circuit breaker trips when the current load exceeds the nominal value indicated on the device case. The RCD monitors the state of the electrical network and is triggered when the smallest current leaks occur.

Possible malfunctions of the electrical network and the action of protective devices when they occur

Users are presented with a description of the most common problems that occur during the operation of electrical appliances. For the convenience of considering this issue, the information is summarized in the table:

No. p / p	Faults	Protection
1.	Violation of the insulation of electrical wiring in the wall or ceiling	Grounding (zeroing) RCD
2.	Current leakage to the housing due to moisture, contact failure, chafing of the wire	-/-/-, RCD
3.	Short circuit	-/-/-, Automatic switch
4.	Failure of the heating element, engine (breakdown of the phase on the body, including through water)	-/-/-, VA
5.	Action through the body of the current device from the capacitors of the electronics system	-/-/-, RCD

At correct device protective grounding (grounding) and the use of additional protective equipment, these factors will not be able to cause significant harm to property or human health. Read also the article: → "".

Errors during installation

The most common errors in the design of security systems are as follows:

In the absence of special education or skills in working with electrical appliances, it is better to entrust the installation of protective systems to experienced professionals.

Issues that arise when designing protection systems

Question number 1. Is it possible to make a ground loop under the windows high-rise building and lay the wire in the apartment?

Theoretically it is possible, but provided that there is permission for this management company, the ground resistance does not exceed 4 ohms, as evidenced by a certificate from the standardization department, as well as confirmation from the meteorological department that the device does not violate the lightning protection of the building.

It is possible to ground an apartment in a high-rise building, but it is difficult to document it

Question number 2. Is it possible to use a water pipeline for temporary grounding until the main one is arranged?

Definitely no one can answer this question. It is better not to connect the device at all for some time until grounding or zeroing is done, but as a temporary measure, you should not endanger yourself and your neighbors.

Question number 3. Is it allowed to bury a metal grounding strip with a plinth or lay it in cable channels?

Can. This will hide the unsightly view and decorate the interior of the room.

Question number 4. Is an electrician from a service organization obliged, at the request of residents, to ground in apartments of old housing constructions where there is no grounding?

This is not his direct responsibility, but if you approach the issue productively and try to hire him as a specialist, then hardly anyone will refuse additional earnings.

Question number 5. In the entrance shield, the working zero is removed from the terminal block connected to the common zero coming from the general house switchboard. Is it possible to remove the neutral wire from the free terminal?

Of course you can. This will be the same splitting that was mentioned in the article. And in this case, it will be done absolutely right. You just need to make good contact and lay the wire very carefully.

In conclusion, we can conclude: You can create a protective system in any case, under any circumstances. The main thing is that it should be competently and reliably arranged and that the functions entrusted to it be effectively carried out in full.

The main requirement for any electrical household appliance is safety of operation. This is especially true for equipment that comes into contact with water. In the absence of additional protection, even a small problem with the wiring (burning through the insulating layer, punching between the turns of the motor) is dangerous. On the body of the faulty device appears electric potential. In this case, a person or animal that touches the body may be electrocuted. To avoid this, such protection methods as zeroing and grounding have been developed.

Grounding tasks

The artificially created contact between the electrical installation and the ground is called grounding. Its task is to lower the voltage on the device case to a level that is safe for living beings. In this case, most of the current is diverted to the ground. For the grounding system to work effectively, its resistance must be significantly lower than in the rest of the circuit. This requirement is based on the property of electric current to always choose the least resistance in its path.

Note! Grounding is used exclusively in electrical networks with isolated neutral.

The fault current is sometimes not enough when using an earth electrode with a relatively high reaction protective devices resistance. Therefore, another task of the grounding system is the growth of the emergency fault current.

Types of grounding devices:

Lightning protection. They divert impulse currents entering the system as a result of lightning strikes. Used in lightning rods and arresters.
Workers. Designed to maintain the normal operation of electrical installations. Used in both normal and emergency situations.
Protective. They protect people and animals from electric shock passing through metal objects in case of breakdown of phase conductors.

Grounding devices are natural and artificial:

The natural ones are hardware, whose main function is not to drain current to the ground. These grounding conductors include pipelines, reinforced concrete elements buildings, casing lines, etc.
Artificial grounding - systems designed specifically for the removal of current. These are steel strips, pipes, corners and other metal elements.

For the grounding system, pipes intended for the transport of combustible substances (both gases and liquids), aluminum parts, cable sheaths cannot be used. Also not suitable for this purpose are items covered with an anti-corrosion insulating layer. It is forbidden to use water pipes and heating pipes as grounding conductors.

Technical execution of grounding systems

There are several connection schemes with different composition of protective and working conductors:

TN-C;
TN-C-S;

The type of grounding is indicated by the first letter in the designation:

I - current-carrying elements do not touch the ground;
T - the neutral of the power supply is grounded.

The method of grounding open conductors is determined by the second letter:

N - direct contact between the grounding point and the power source;
T - direct connection with the ground.

After the hyphen, there are letters indicating the method of operation of the protective PE and the working N of the neutral conductors:

S - the operation of the conductors is provided by a single PEN conductor;

C - there are several conductors.

TN system

Grounding of the TN variety includes the TN-C, TN-S, TN-C-S subsystems. The oldest of these subsystems - TN-C - is used in 3-phase four-wire and 1-phase two-wire power networks. Such networks are usually found in old buildings. For all its simplicity and relatively low cost, the system does not provide a sufficient level of security, and therefore is not used in new buildings.

The TN-C-S subsystem is used in the renovation of old buildings. It is relevant where the working and protective conductors are combined at the input. The use of TN-C-S is necessary for system refurbishment when computer or telecommunications equipment is installed in the old building. This grounding is a transitional type between TN-C and the most modern subsystem - TN-S. TN-C-S is a relatively safe and financially affordable grounding scheme.

The difference between the TN-S subsystem and other types of such equipment is the location of the working and neutral conductors. They are installed separately, while the neutral protective PE conductor connects all the current-carrying elements of the electrical installation. To avoid duplication, a transformer substation is created, equipped with a main ground. Additional advantage substation is the ability to reduce the length of the conductor from the cable entry into the equipment to the ground electrode.

TT system

In this grounding system, current-carrying open elements directly in contact with the ground. In this case, the electrodes do not depend on the grounding device of the neutral of the substation. TT applies when technical reasons you can't build a TN system.

IT system

In this system, the neutral of the power supply does not touch earth or is earthed by an electrical installation with increased resistance. The circuit is popular in situations where it is necessary to connect sensitive equipment (hospitals, laboratories, etc.).

Zeroing

The zeroing process consists in combining metal elements, not energized with a grounded neutral of a step-down source of 3-phase current. Also use the grounded output of the 1-phase current generator. Zeroing is used to provoke a short circuit in the event of a breakdown of the insulating layer or the penetration of current into a non-current-carrying element of the equipment. The meaning of the occurrence of a short circuit is that after that the circuit breaker is triggered, the fuses blow, or others turn on. protective equipment. Zeroing is used in electrical installations with earthed neutral.

If you install a residual current device on the line, it will operate due to the difference in current strengths in phase and zero. The circuit breaker installed in addition to the RCD will allow both devices to operate in the event of a breakdown, or to connect the fastest connecting protection element.

When installing the zeroing, it should be borne in mind that a short circuit should lead to the fuse melting or turning off the circuit breaker. If this does not happen, the free flow of the fault current through the electrical circuit will cause voltage to appear on all zeroed objects, and not just at the breakdown site. The voltage indicator is the product of the zero resistance and the fault current, which is very dangerous when a living being is struck by a current.

It is necessary to carefully monitor the good condition of the neutral conductor. When it breaks, voltage appears on all zeroed elements, since they automatically come into contact with the phase. For this reason, it is forbidden to install any protective devices on the neutral conductor (in addition to switches and fuses), due to which a break occurs when triggered.

To reduce the risk of electric shock when the neutral conductor breaks, additional groundings are created every 200 meters of the line, as well as on the end and input supports. The resistance level on each new ground electrode must not exceed 30 ohms.

Grounding difference from zero

The main difference between grounding and grounding is the purpose of the systems. Grounding is needed to quickly lower the voltage to an acceptable level. The task of zeroing is to completely turn off the current in the area where a breakdown occurred on the case or other non-current-carrying element. Zeroing is associated with a decrease in the potential of the case in the period between the short circuit and the power outage.

Zeroing is not used in new buildings. In new buildings, lay a 3-wire cable with phase, zero and earth (1-phase system) or a 5-wire cable (three phases, zero and earth) in a 3-phase system. The most commonly used scheme is TN-S, but TN-C-S is also found.

Do I need to do zeroing in the apartment

It is not worth using zeroing in order to protect residents and electrical installations in the apartment - there are situations when the refrigerator (or other device) is zeroed, and a current breakdown occurs. Also, incorrectly performed wiring is often encountered (after all, an electrician could have mixed up the wires and connected a phase instead of zero). In such cases, household appliances fail even before the circuit breaker operates.

Installing a residual current device, differential automaton or a circuit breaker is only needed together with zeroing.

Requirements for grounding and grounding

All electrical installations and circuits equipped with neutral wire insulation require the installation of a protective system (zeroing or grounding).

There are several rules that should be followed when creating a protective system:

Zeroing must be done for installations with a solidly grounded conductor with a power of up to 1000 volts. Grounding in such systems is not done.
Zeroing should be provided with a 380 volt transformer. In a zeroed system, the secondary voltage should not exceed 380 volts, and the step-down voltage should not exceed 42 volts.
When zeroing, it is allowed to connect from a separating transformer to only one consumer of electricity. The current rating of the protective device is up to 15 amperes. Zeroing or grounding of the secondary winding is not allowed.
When grounding zero in a 3-phase electrical circuit, it is necessary to set protection against current breakdown. Mount it in the neutral conductor or phase from the lower voltage.
Protective grounding or grounding must be created at outdoor installations, as well as in special hazardous conditions work. The voltage rating is 42 volts (alternating current) or 110 volts (direct current).
For voltages above 380 volts (DC) and 440 volts (AC), protection is required regardless of other conditions.

Grounding is subject to:

cases of electrical installations;
equipment drives;
frame parts and metal structures of distribution cabinets and shields;
secondary transformer windings;
steel cable sheaths;
busbars;
cables;
metal pipes for wiring;
electrical equipment mounted on moving elements.

As for housing, grounding and grounding is necessary for electrical household appliances with a power of more than 1300 watts. Metal products such as bathtubs and shower trays, suspended ceilings are subject to grounding for potential equalization.

To ground air conditioners, electric stoves or similar consumers of electricity with a power of over 1300 watts, use a dedicated conductor. It should be connected to the zero of the mains.

Note! The cross sections of the phase and neutral conductors must be the same.

A detailed list of electrical installations that require protection by grounding or zeroing is indicated in the Electrical Installation Rules. PUE is an official document, it contains all the standards. The document also establishes a list of equipment for which protection is optional.

The creation of a grounding and grounding system is extremely important; the safety of people and the preservation of property depend on it. Therefore, the cost of a mistake is high. It is recommended to entrust this work only to qualified personnel.

Electricity has been making our lives more comfortable, convenient and interesting for several hundred years. A great many different machines, devices and devices powered by electricity have been invented and made, creating material benefits for us, or such as the infamous electric chair. But, unfortunately, electricity can kill not only in the electric chair by court order. The flow of tiny electrons is a formidable and powerful force, which should be treated with due respect. Naturally, man-made a large number of various methods of protection against electric shock. What is the difference? Grounding and grounding will be discussed further as an example. These are two ways to help protect yourself from electric current by diverting its flow to the side. Both methods work on the same principle, but at the same time differ from each other.

What is electricity

In order to understand for ourselves what electrical safety, protective grounding, zeroing are, how it all works, we recall the essence of the phenomenon of electric current.

All bodies in the Universe consist of atoms, the structure of which is known to every schoolchild: a positively charged nucleus inside and negative electrons rotating around the nucleus. There are a number chemical elements- metals, in which several electrons located in the orbits farthest from the nucleus can easily be torn off (attracted by a strong positive charge).

Thus, if you take a metal wire, attach opposite ends to its ends. electric charges, then the electrons, breaking away from their atoms, will begin to move towards a positive charge.

However, when moving in the thickness of the metal, electrons constantly "stumble" on atoms, causing them to vibrate slightly at the nodes of the crystal lattices. This results in the release of heat. Moreover, the heating can be so strong that the metal is able to heat up to thousands of degrees (like a spiral of an incandescent lamp). In some cases, the metal can even melt and even evaporate.

How electric current affects the human body

The human body is three-quarters water. Water is a good conductor of electric current (however, the conductor mechanism is somewhat different than that of metals - ionic). The passage of electric current through the human body is accompanied by a number of unpleasant phenomena. Huge, enterprise-wide funds are sometimes spent on grounding and zeroing of electrical installations to prevent this action.

Electrons, moving through living tissues, cause them to heat up, the liquid contained in the cells instantly boils. In addition, the electric current, acting on the neuron endings, causes convulsive spasmodic contraction of all muscles. A spasm leads to cardiac arrest, to blocking of breathing.

For a person, an electric current passing through the body from 0.1 A is dangerous. But what value it reaches depends on a number of factors: on dryness skin, quality of contact, voltage, location of the "entry" and "exit" points of electrons.

The most dangerous "routes" are the following:

Hand - hand;

Right leg - left hand or vice versa;

The head is any part of the body.

Types of protection against electric shock

Ways to protect yourself from damaging current factors are divided into active and passive. Active methods assume the presence of protective automation. The fact is that the human body has a certain electrical resistance and capacity, and, touching the bare wire, we, as it were, “plug in” to the network additional element. Smart appliances able to fix such a change and de-energize the circuit in a split second.

Other measures are aimed at preventing direct contact of the body with sources: the use of protective gloves, dielectric shoes, special rugs.

Even standing on a stool made of dry wood during the electrical work, a person greatly reduces the risk of receiving a fatal blow.

And there are other methods, such as protective grounding and zeroing. The essence of their action, to put it simply, is to provide the electric current with an easier and “attractive” route compared to the human body.

Why are electrical appliances dangerous?

How do these measures work and what is the difference? Grounding and grounding are protective measures that receive a lot of attention at the design stage. electrical machines and productions.

Let's imagine that in any household or industrial device there was a phase short circuit on the case. What happens if a person touches a car with their bare hand?

Given that the planet Earth is an excellent receiver of electric current, electrons will rush through the human body into the ground.

How does grounding work?

So, how will grounding protect a person? Everyone paid attention to the third contact of household electrical plugs, which appeared in our country at the end of the last century. Two familiar contacts are “zero” and “phase”, where does the third lead? And he is the grounding and leads, as the name implies, to the ground.

What happens if a person touches a conventional or grounded device, what is the difference? Grounding and zeroing, as it were, create a second parallel route for the electron flow. In the case of grounding from the instrument case, a electrical wire With good section and low resistance, connected to metal pins or other elements specially buried in the ground (and always below the freezing point - ice is a poor conductor).

If you explain the principle of operation of grounding plain language: electrons, following the path of least resistance, mainly move to the ground along the ground wire, while the flow going through the human body is significantly weakened due to this.

How does zeroing protect

And here is another, similar method of protection against electric shock. What is the difference between grounding and grounding? If grounding connects open parts of electrical machines to the soil, then grounding connects to the neutral wire.

The electric current here again chooses an easier path for itself, due to which the electric shock received by a person is significantly weakened. But there is another significant difference between grounding and zeroing. When touching the phase ground wire, the system is actually short-circuited. And this almost always results in automatic protection and shuts down the system. Thus, an accident is prevented in advance.

Technical features of both systems

Why in different conditions apply various methods protection, what is the difference between grounding and zeroing in operation?

Grounding also provides for the possibility of lightning protection (although experts do not recommend doing this), grounding is not intended for this;

Zeroing involves the mandatory use of circuit breakers; without them, the zeroing device is prohibited;

Zeroing is not always applicable in technology due to the de-energization of certain sections of the wiring when triggered.

Where is grounding applied?

In everyday life, in order to protect against electric shock, grounding is more often used. Natural structures, such as metal pipelines or fittings buried in the ground, can work perfectly as ground electrodes. reinforced concrete structures. But more often a special grounding circuit is made of pins driven into the ground connected together.

What is the difference? Grounding and grounding are designed to ensure electrical safety, while when the phase wire is closed to the ground loop, it itself becomes a source of danger. If in your house, for example, a neighbor grounded his washing machine to the heating system, then in the event of a “breakthrough” of electricity on the building, it is better not to touch the elements of the heating system for all residents of the building.

When using a special grounding circuit, the tenants are not in danger. When installing individual grounding systems in private construction, they are often combined with lightning protection systems. Experts do not recommend doing this in any case, since in the event of a lightning strike, all wiring in the house becomes a factor of increased danger, and many electrical appliances simply fail.

Where is the nulling done

Grounding is used mainly in the housing stock. In industry, protective grounding and zeroing of electrical installations in the complex are most often used. Here it is taken into account that when voltage hits the case of a device, a unit operating from a network with a voltage much higher than household voltage, the danger to a person increases many times over.

In addition, expensive equipment is at risk. Therefore, in this case it is better if the circuit section is instantly de-energized by protective automation.

When using electrical machines and units with a voltage of 380V and above for alternating current or 440V and above for direct current, the installation of a grounding system is mandatory.

Electricity Safety Precautions

There are simple rules that, when using household and industrial electrical appliances, will help to avoid trouble.

The plug from the socket is not pulled out by the cord, it must be removed from the socket, tightly grasping it with your fingers;

Turn on/off electrical appliances or lighting (with a socket in a plug or by means of a switch) in no case should you stand with wet hands;

It is not necessary to use lamps of higher power in lamps than indicated in the instructions for this lighting device;

If the device sparks, or a characteristic crackling of a short circuit is heard during its operation, it is possible to carry out any actions with it only after unplugging it from the outlet;

It is useful to know where and how all the electrical wiring in the house is de-energized, sometimes it can save lives and property;

If the manual for the device does not indicate that it refers to equipment that can be left unattended, then this should never be done.

For the safety of using electrical installations in modern electricians, various protective equipment and structures are used, due to which overloads, short circuits or the contact of the working part of the equipment with voltage do not harm a person. The main protection when working with electrified equipment is grounding and grounding. These two options differ from each other in the way of installation, and are also used for different types electrical equipment. To find out what the difference between zeroing and grounding is, you need to familiarize yourself with their principle of operation and installation features.

Grounding and zeroing have different ways installation, but serve one purpose - ensuring electrical safety

Why do we need grounding and grounding

Today there are a large number various devices and tools, the main task of which is to ensure safety when working with electrical installations. If any problems occur, the most dangerous consequence malfunction may be voltage on metal parts or the equipment case.

Depending on the strength of the current, a person can receive injuries of varying severity. For example, at 25 mA, muscle paralysis may occur, which will prevent an attempt to break contact with a energized surface. If the current flowing through the insulation is between 50 and 100 mA, then contact with it will cause serious damage, such as impaired blood circulation in the body, or even death.

To avoid the situations described above, when working with electrical installations, use various fixtures complying with the generally accepted safety regulations.

A prerequisite for the operation of electrical equipment is protective grounding and grounding of electrical installations, which prevent electric shock in case of violation of the insulation of the installation.

To understand the difference between these devices, you need to know what each of them is.

The concept of grounding includes structures that connect installations that use electricity to the ground. Due to this, when touching a live surface, the charge received by a person is minimized.

use this method only in electrical equipment with isolated neutral. Due to the connection of the earth to the body of the installation, if the insulation is damaged, the current must go through the grounding part due to the lower resistance.

Grounding a private house

Another function performed by grounding is to increase the emergency fault current. This is necessary so that the protective electrical device worked when non-current-carrying parts were energized. This is due to the fact that the installation of grounding, which has enough high level resistance, there may not be enough fault current. This situation is dangerous because, despite emergency state equipment, the protection does not work and the risk of injury to operating personnel remains high.

The grounding device in its structure is one or a whole group of conductors that connect current-carrying elements to the ground. There are several main types of grounding:

Working type. The main purpose is to provide uninterrupted operation electrical equipment both in normal operation and in emergency.
Protective type. Designed to ensure safety when working with electrical installations. main reason the occurrence of danger in the equipment is a breakdown of the current-carrying wire on work surface or body.
Lightning protection type. The main purpose is to remove a lightning discharge that has fallen into a lightning arrester or lightning rod.

In addition to the division into types, grounding devices differ in the following:

Artificial grounding. This type structures are manufactured specifically to provide voltage protection. They consist of such elements as metal wires and rods, pipes of substandard type, steel corner fixtures.
natural grounding. This category includes structures made of metal, but not originally designed to provide voltage protection. Usually used as a natural ground casing, pipeline, reinforced concrete structures.

Grounding identification mark

It should be noted that the natural type of grounding is used subject to certain rules. The main one is a ban on the operation of structures that are designed to transfer flammable liquids or gases. Also, conductors made of aluminum or pipes, the surface of which is covered with an anti-corrosion layer of insulation, are not suitable for the above purpose.

Zeroing differs from grounding both in purpose and in the principle of installation. Connect this system protection to metal parts or housing instead of ground, which do not conduct electricity during normal operation. Connect the neutral to the neutral used by the low voltage source. three-phase voltage. It can also be mounted using a single-phase voltage generator, namely, it is connected to a grounded terminal.

Zeroing is one of the options for protection against electric shock

The main task of zeroing is the protection of working personnel due to the timely operation of switching automatic equipment. The principle of operation is to create an artificial short circuit during the breakdown of insulation and current flow to working part equipment . Due to the resulting short circuit, the following protection devices are triggered:

fuse;
modern systems of protection against short circuit.

The difference between grounding and grounding, as a rule, is installation and use instead of a simpler and more reliable method when operating equipment in which there is a deadly grounded neutral. But before proceeding to mount this device protection, it must be taken into account that the short-circuit current that will be created using the neutral wire must be high enough for the protective device to work with 100% probability.

If it is not enough to operate the circuit breaker or break the fusible link, then this will lead to voltage on all other parts of the electrical equipment that were not previously energized. This situation can lead to a great danger to the life of the operating personnel and affect the production process.

Connecting zeroing to the machine

For the installation of zeroing, it is necessary to follow some rules that ensure uninterrupted and safe work electrical installations. For example, it is strictly forbidden to install any switching equipment in the neutral wire, since its break can lead to the appearance of current in places with grounding.

How is the grounding of electrical equipment

Next, we will talk about where the protective zeroing comes from in our house, and consider its path from transformer substation and is it safe to perform zeroing in the apartment. Such zeroing begins with a dead-earthed neutral - a power transformer neutral connected to the grounding device.

The neutral, together with the three-phase line, first enters the inlet cabinet. From there, it is distributed to the electrical panels located on the floors.

A working zero is taken from it, which together with the phase forms the phase voltage familiar to us. The name "working zero" is due to the fact that it is used to operate electrical installations or electrical appliances.

Taken from the electrical panel with a protective separate zero, having electrical connection with solidly grounded neutral, and protective zeroing is formed. It is necessary to know that in the circuit protective earthing conductors there should not be any switching devices (machines, knife switches, etc.), as well as fuses.

Scope of protective zeroing

Protective earth is used in electrical installations with voltage up to 1 kV:

- in direct current networks with a grounded midpoint of the source;
- in single-phase AC power networks with a grounded output;
- in three-phase AC power networks with grounded zero (TN-S system; as a rule, these are 660/380, 380/220, 220/127 V networks);

The formation of a current circuit of a single-phase short circuit (i.e., a short circuit between the neutral and phase protective conductors) occurs in the event of a phase wire shorting to the zeroed housing of the electrical consumer. A damaged electrical installation is disconnected from the mains due to the operation of the protection caused by the current of a single-phase short circuit.

To quickly turn off the electrical installation located, circuit breakers and fuses installed to protect against short-circuit currents can be used. Also for this purpose, magnetic starters with built-in thermal protection are used, contactors with thermal relays, which provide overload protection, etc.

The principle of operation of protective zeroing

A short circuit occurs when a phase wire (voltage) enters the metal body device connected to the neutral conductor. At the same time, an increase in the current strength in the circuit to huge values is recorded, as a result of which protective devices are triggered, which turn off the line supplying the faulty device.

The shutdown time in automatic mode for a damaged power line for a phase voltage of a network of 380/220 V, in accordance with the PUE, should not exceed 0.4 seconds.

To carry out grounding, specially designed conductors are used, for example, the third core of a cable or wire in the case of single-phase wiring.

The phase-zero loop should have little resistance, because only in this case the protective device is turned off at the time specified by the rules. Therefore, effective zeroing can only be achieved with high quality all connections and network installation.

Zeroing allows you to provide not only a quick disconnection from the electricity of a faulty line, but also, thanks to the grounding of the neutral, a low touch voltage on the body of the electrical device. Due to this, the probability of injury human body electrical current is excluded. A grounded neutral gives reason to call grounding a certain type of grounding.

Therefore, as a basis operating principle protective zeroing the transformation of the short circuit to the case into a single-phase short circuit acts. to call a tripping high current protection, the ultimate goal of which is to disconnect the damaged electrical installation from the network.

What is dangerous zeroing in the apartment

Zeroing is significantly different from grounding. Let's try to consider this difference in more detail. In accordance with the PUE, the use of such deliberate protection as zeroing at the household level is prohibited due to its unsafety.

But, despite the fact that such a system should be practiced only in industrial production, many put it in their apartments. This far from perfect protection is resorted to, in particular, due to the absence of another option or due to a lack of knowledge in this area.

Indeed, it can be done, but the consequences of this will not be the best. Further, using examples, we will consider some situations that may arise if zeroing is performed in the apartment.

1) Zeroing in sockets

Sometimes it is proposed to “ground” electrical appliances by jumpering the operating zero terminal in the outlet to a protective contact. This method of "grounding" does not meet the requirements of paragraph 1.7.132 of the PUE, because it involves the use of the neutral conductor of a two-wire network as a protective and working zero at the same time.

In addition, at the entrance to the apartment there is usually a device designed to switch both phase and zero, for example, a packet or a two-pole device. But it is forbidden to switch the neutral conductor, which is used as a protective one. That is, it cannot be used as a protective conductor, the circuit of which has a switching device.

The danger of "grounding" with a jumper in the outlet lies in the fact that the cases of electrical appliances, if the integrity of zero is violated, will be under phase voltage anywhere. When the neutral wire breaks, the operation of the electrical receiver is interrupted, and then such a wire looks like a de-energized, that is, safe, which, of course, aggravates the situation.

One can only imagine how much trouble such an outlet will do if a washing machine is included in it. In this case, you can see the jumper that connects the "zero" contact to the protective one. And, if “zero” burned out, then such washing machine would turn into a killer.

If, while taking a soul, a zero “snot” falls out in the outlet to which the boiler is connected, such a person will simply be “flashed” with current. Therefore, such zeroing in the apartment is extremely dangerous and it is forbidden to perform it.

2) Phase and zero reversed

Considering the following example, you can clearly see the most likely danger in a two-wire riser. Often, when carrying out any repair work in the house electrical system, the zero "N" is erroneously interchanged with the phase "L".

The cores of the wires in the electrical panel in houses with two wires do not have a distinctive color, and when performing any work in the shield, any electrician can switch zero and phase in places - in this case, the electrical appliance cases will also be under phase voltage.

Be sure to remember the high risk of performing protective neutral in a two-wire system. Therefore, in accordance with the rules, it is forbidden to do this!

3) Zero burnout

What is “zero burnout”, or zero break, every electrician knows, but not every consumer of electricity. Let's try to understand the meaning of this phrase, and find out what is the danger of zero burnout?

Very often, a "zero" break is recorded in houses with old wiring, the basis for the design of which was the calculation of approximately 2 kW per apartment. Of course, the current equipment of apartments with all kinds of electrical appliances increases these figures by an order of magnitude.

In the event of a “zero” break, phase imbalance can occur at the transformer substation, from which the multi-storey building, in the general electrical panel or in the shield on landing this house, in the power line located after this break. The result may be the entry of low voltage into one part of the apartments, and increased voltage into the other.

Reduced voltage is dangerous for refrigerators, air conditioners, split systems, hoods, fans and other equipment with electric motors. As for the increased voltage, any household appliance can fail with it.