What is the difference between grounding and grounding: concepts, diagrams, advantages and disadvantages

When installing electrical networks in premises for various purposes, protection must be provided to prevent possible electric shock to a person. And for this purpose grounding and grounding are used. Moreover, not everyone knows what their difference is. After all, both of them ensure the safety of using electrical appliances.

In fact, these two concepts are similar in many ways, which is why they are often confused, but they perform their functions in different ways. Therefore, we will try to figure out what they have in common and how they differ.

Zeroing - what is it?

This electrical connection is connected to metal components of electrical installations without electrical voltage.
In this case, a single-phase wire is used. Simply put, during voltage surges, with the help of grounding, the surges are taken to the panel or transformer booth. This method is used if electric current enters a de-energized part of the device or the insulation is damaged. This prevents short circuits and overheating of the fuses. The damaged system is shut down, the circuit is interrupted, but the main equipment does not fail.

Distinctive features

As it becomes clear, in essence, grounding and grounding perform the same function - they remove residual electricity from the metal parts of any device that consumes current. But they have significant differences. The first technique directs excess current from electrical installations to the ground, and the second - to the transformer. Grounding is most often made of metal rods and is used to relieve excess voltage. Its quality directly depends on how the grounding mechanism circuit is made.

When grounding occurs, the neutral wire is connected to the electrical installation housing. If the housing or ground touches a phase, a sharp increase in current will occur, that is, a short circuit. As a result, the installation is switched off in a timely manner, which is impossible when using a grounding mechanism. Of course, such a remedy is not always effective, and there is a risk that the neutral wire will burn out. To prevent this from happening, regular monitoring of its condition is required. Now it is clear how grounding differs from grounding. Let's look at the advantages of the basic method that is used everywhere today.

Types of grounding systems

Have you noticed that the neutral wire in a three-phase cable has a smaller cross-section than the rest? This is understandable, because it does not bear the entire load, but only the current difference between the phases. There must be at least one grounding loop in the network, and it is usually located next to the current source: a transformer at a substation. Here the system requires mandatory grounding, but at the same time the neutral conductor ceases to be protective: what happens if a “zero burns out” in a transformer transformer is familiar to many. For this reason, there may be several grounding loops along the entire length of the power line, and this is usually the case.

Of course, repeated grounding, unlike grounding, is not at all necessary, but is often extremely useful. Depending on where the general and repeated grounding of the three-phase network is performed, several types of systems are distinguished.

Difference between grounding and neutralizing

In systems called IT or TT, the protective conductor is always taken regardless of the source. To do this, the consumer arranges his own circuit. Even if the source has its own grounding point to which the neutral conductor is connected, the latter does not have a protective function. It does not contact the consumer’s protective circuit in any way.

Systems without grounding on the consumer side are more common. In them, the protective conductor is transferred from the source to the consumer, including through the neutral wire. Such schemes are designated by the prefix TN and one of three postfixes:

TN-C: the protective and neutral conductors are combined, all grounding contacts on the sockets are connected to the neutral wire.
TN-S: The protective and neutral conductors do not contact anywhere, but can be connected to the same circuit.
TN-CS: the protective conductor follows from the current source itself, but is still connected there to the neutral wire.

Key points of electrical installation

So how can all this information be useful in practice? Schemes with the consumer’s own grounding are naturally preferable, but sometimes they are technically impossible to implement. For example, in high-rise apartments or on rocky ground. You should be aware that when combining neutral and protective conductors in one wire (called PEN), the safety of people is not a priority. Therefore, equipment with which people come into contact must have differential protection.

And here, novice installers make a whole bunch of mistakes. Incorrectly determining the type of grounding/zeroing system and, accordingly, incorrectly connecting the RCD. In systems with a combined conductor, the RCD can be installed at any point, but always after the point of combination. This error often occurs when working with TN-C and TN-CS systems. And especially often if in such systems the neutral and protective conductors do not have appropriate markings.

Difference between grounding and neutralizing

Therefore, never use yellow-green wires where it is not necessary. Always ground metal cabinets and equipment housings, but not with a combined PEN conductor. When the zero breaks, a dangerous potential arises on it. This must be done with a PE protective conductor, which is connected to its own circuit.

By the way, if you have your own circuit, performing unprotected zeroing on it is very, very not recommended. Unless it's your own substation or generator circuit. The fact is that if the zero is broken, the entire difference in the asynchronous load in the citywide network will flow into the ground through your circuit, heating up the connecting wire.

Protective grounding. What are the dangers of doing grounding yourself?

The operating principle of grounding for buildings according to the TN-C, TN-S and TN-CS systems.

Grounding the house. Installation of the ground loop!

Ground loop. Grounding and zeroing at objects.

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Circuit design

Components

The previously mentioned grounding resistance (Rз) of the circuit is the main parameter controlled at all stages of its operation and determines the effectiveness of its use. This value must be so small as to provide a free path for the emergency current tending to flow into the ground.

Note! The most important factor that has a decisive influence on the value of grounding resistance is the quality and condition of the soil at the site of the installation. Based on this, the charger in question or the ground loop of the charge circuit (which in our case is the same thing) must have a design that meets the following requirements:

Based on this, the charger in question or the ground loop of the charge circuit (which in our case is the same thing) must have a design that meets the following requirements:

It must include a set of metal rods or pins with a length of at least 2 meters and a diameter of 10 to 25 millimeters;
They are connected to each other (necessarily for welding) by plates of the same metal into a structure of a certain shape, forming a so-called “grounding conductor”;
In addition, the device includes a supply copper busbar (also called electrical) with a cross-section determined by the type of equipment being protected and the magnitude of the drain current (see the table in the figure below).

Tire Section Table

These component devices are necessary to connect the elements of the protected equipment with the descent (copper busbar).

Differences in device location

According to the provisions of the PUE, the protective circuit can have both external and internal design, and each of them is subject to special requirements. The latter establishes not only the permissible resistance of the ground loop, but also stipulates the conditions for measuring this parameter in each particular case (outside and inside the object).

When dividing grounding systems according to their location, it should be remembered that only for external structures the question of how the grounding resistance is normalized is correct, since it is usually absent indoors. Internal structures are characterized by wiring of electrical busbars along the entire perimeter of the premises, to which grounded parts of equipment and devices are connected through flexible copper conductors.

For structural elements grounded outside the facility, the concept of re-grounding resistance is introduced, which appeared as a result of the special organization of protection at the substation. The fact is that when forming a neutral protective conductor or a working conductor combined with it at the supply station, the neutral point of the equipment (step-down transformer, in particular) is already grounded once.

Therefore, when another local grounding is made at the opposite end of the same wire (usually a PEN or PE bus connected directly to the consumer panel), it can rightfully be called repeated. The organization of this type of protection is shown in the figure below.

Re-grounding

Important! The presence of local or repeated grounding allows you to insure yourself in case of damage to the protective neutral wire PEN (PE - in the TN-CS power supply system). Such a malfunction is usually found in technical literature under the name “zero burnout”

Such a malfunction is usually found in technical literature under the name “zero burnout.”

Systems with solidly grounded neutral TN grounding system

Such systems include:

TN-C;
TN-S;
TNC-S;
TT.

According to clause 1.7.3 of the PUE, a TN system is a system in which the neutral of the power source is solidly grounded, and the open conductive parts of the electrical installation are connected to the solidly grounded neutral of the source through neutral protective conductors.

TN includes elements such as:

grounding electrode of the middle point, which relates to the power source;
external conductive parts of the device;
neutral type conductor;
combined conductors.

The source neutral is solidly grounded, and the external conductors of the installation are connected to the solidly grounded midpoint of the source using protective type conductors.

It is possible to make a grounding loop only in electrical installations whose power does not exceed 1 kV.

TN-C system

In this system, the neutral protective and neutral working conductors are combined into one PEN conductor. They are combined throughout the system. The full name is Terre-Neutre-Combine.

Among the advantages of TN-C, one can highlight only the easy installation of the system, which does not require much effort and money. Installation does not require improvement of already installed cable and overhead power lines, which have only 4 conducting devices.

Flaws:

the likelihood of receiving an electric shock increases;
it is possible that line voltage may appear on the body of the electrical installation during an electrical circuit break;
high probability of loss of the grounding circuit in case of damage to the conductive device;
This system only protects against short circuits.

TN-S system

The peculiarity of the system is that electricity is supplied to consumers through 5 conductors in a three-phase network and through 3 conductors in a single-phase network.

In total, 5 conductive sources leave the network, 3 of which serve as the power phase, and the remaining 2 are neutral conductors connected to the zero point.

Design:

PN is a neutral mechanism that is involved in the circuit of electrical equipment.
PE is a solidly grounded conductor that performs a protective function.

Advantages:

ease of installation;
low cost of purchasing and maintaining the system;
high degree of electrical safety;
no contour creation required;
the ability to use the system as a current leakage protection device.

TN-CS system

The TN-CS system involves dividing the PEN conductor into PE and N in some part of the circuit. Usually the separation occurs in the panel in the house, and before that they are combined.

Advantages:

simple design of a protective mechanism against lightning strikes;
availability of short circuit protection.

Disadvantages of use:

poor level of protection against burning of the neutral conductor;
possibility of phase voltage occurrence;
high cost of installation and maintenance;
the voltage cannot be turned off automatically;
There is no protection against current in the open air.

TT system

TT is designed to provide a high level of safety. Installed in power plants with a low level of technical condition, for example, where bare wires are used, electrical installations that are located in the open air or mounted on supports.

TT is mounted according to a four-conductor circuit:

The 3 phases supplying voltage are shifted at an angle of 120° to each other;
1 common zero performs the combined functions of a working and protective conductor.

TT advantages:

high level of resistance to deformation of the wire leading to the consumer;
short circuit protection;
Possibility of use on high voltage electrical installations.

Flaws:

complex lightning protection device;
inability to track the phases of a short circuit in an electrical circuit.

Distribution transformer - phase, zero (neutral)

To begin with, it is worth briefly familiarizing yourself with the path and methods of supplying voltage to the outlets in your home. The last intermediate link from which electricity enters your home is the distribution transformer.

Having received three phases from the generators at the power plant, the transformer reduces the voltage and transfers power from the secondary winding to the consumer through the phase and combined working and protective neutral (PEN) conductor.

Zero acts as a neutral, a beginning, and serves as the starting point for measuring voltage characteristics. It connects the phase windings in a star connection diagram. The potential at this point is zero. And the potential difference between phase and neutral corresponds to a phase voltage of 230 Volts.

What is grounding of electrical appliances: application possibilities

Protective grounding of electrical appliances is used if it is impossible to install grounding. This situation may arise if an apartment building was built in Soviet times. Such houses do not have their own outline, and it will not be possible to arrange one on your own.

Protective grounding is a system that performs a different job from grounding. If the second is designed to divert the voltage to the ground, eliminating the possibility of electric shock, then the first is performed with the aim of creating (in the event of an insulation breakdown and voltage entering the housing) a short circuit. In this case, the automation is triggered and the electricity is turned off.

Any ungrounded electrical appliance can become a source of danger.

Protective grounding requires proper installation. You should not think that it is enough to throw a jumper from the zero contact inside the socket to the ground one. This is strictly prohibited. Let's consider a situation when an already “burnt” zero is subjected to a short circuit load, and the machine has not yet had time to operate. The zero burns out, eliminating the short circuit, but the device remains energized. A person, hoping for the absence of electricity (after all, there is no light, the zero has burned out), moves towards the exit by touch and leans his elbows on the body of a household appliance that is energized. The outcome is clear, isn't it?

Properly performed grounding, coupled with automatic protective equipment, is the key to peace of mind for those living in a house or apartment.

The role of the neutral wire in three-phase networks

If the loads in different phases are equal, then such a load is called symmetrical. A symmetrical load, for example, is a three-phase electric motor. With a symmetrical load, equal currents in the neutral when added together give zero.

That is, with a symmetrical load there is no current in the neutral. The neutral wire can be removed altogether. When the loads are unbalanced, a so-called phase imbalance occurs, and the potential of the neutral point on the load shifts. The voltages across the loads in different phases in the absence of a neutral wire become different. If the neutral points of the load and the generator are connected, the voltages across the loads remain equal, but a compensating current begins to flow in the neutral.

Main differences

First of all, it should be noted that grounding and grounding have completely different purposes and actions. The main difference between these protective measures is their purpose. Grounding is a more effective and reliable way to protect a residential building from a power surge than the grounding method. The difference in their purpose allows you to choose from them the method of protection that is more suitable in a particular situation. You can immediately install both protection options in a residential building. However, it should be noted that usually preference is given to grounding, considering that this method is necessary in any case.

Grounding allows you to create network protection and quickly reduce the AC voltage in the network to a normal stable value. Whereas grounding will facilitate a faster shutdown of the circuit that was energized, where the fault actually occurred on the line. Also a big difference is the fact that the methods of their installation have varying degrees of complexity.

Creating a grounding connection in a residential building and connecting special equipment requires deeper knowledge of electrical engineering. For this protection method to work correctly, you need to do everything right

Determining the zeroing point is very important, since otherwise there may be negative consequences. When installing protective ground loops, it is enough to follow clear instructions or instructions

Their design is quite simple.

The grounding method does not depend on the phase pattern of electrical appliances and various devices, since they have the same installation diagram. Also, grounding schemes have a greater variety, in contrast to grounding, which allows you to choose a more suitable option in a particular situation. Another difference between them is that directional grounding ensures equalization of potentials, and grounding reacts to such a change by de-energizing the network.

Requirements for grounding and grounding

In protective grounding, there is a gap between the ground and the grounding contact of the electrical appliance.
The main requirement is correct implementation, which will ensure complete safety and protection of a person from electric shock in the event of emergency or emergency situations.

The main requirements for grounding are the removal of voltage into the soil layers. The earth absorbs the electric current, preventing damage to human health.

Requirements for grounding - turning off the protective automatic equipment if there is a contact of current-carrying elements or bare wires with the surfaces of metal cases of electrical parts and household appliances, where there should not be voltage.

Electric shock protection

What Richman did to capture atmospheric charges is very reminiscent of a modern lightning rod (lightning rod). Only atmospheric charges/discharges are now considered good to immediately send deeper into the ground, without waiting for them to send someone... to the same place as Richman. And it turned out that it is quite reliable and safe - the Earth accepts everything. Well, it is best to isolate a person from this process well.

This is how grounding came about - the removal of excess, unnecessary, dangerous charges into the ground. And since stray charges from the atmosphere, especially lightning, can carry colossal electrical energy, it is necessary to provide metal conductors of substantial cross-section for the movement of this flow. So that nothing melts and unhinderedly diverts energy from sin further into the depths of the earth.

And so they started installing these same lightning rods everywhere on buildings and towers.

And then soon systems for generating electrical energy were invented. And transmitting electrical signals over a distance using wires. Well, soon the transfer of energy will do the same. And they noticed that metal transmission lines attract this same atmospheric electricity. And we don’t even have to wait for the electricity to come “to visit us.” That’s why we immediately thought about protecting the network from it first and foremost.

Requirements for grounding and grounding

The main requirement is correct implementation, which will ensure complete safety and protection of people from electric shock in the event of emergency or emergency situations.

The main requirements for grounding are the removal of voltage into the soil layers. The earth absorbs the electric current, preventing damage to human health.

Grounding and grounding: what is it, what is the difference?

To protect electrical wiring and electrical appliances from short circuits (short circuits) in the house, automatic machines and various other protective devices are designed. But what to do in case of current leakage, for example, on the body of an electrical appliance. If this happens, an electric current will shock anyone who touches a metal part of the washing machine or water heater.

Often, due to a damaged shell of the heating element or cable insulation, various problems arise: the water in the bath receives an electric current, or the taps begin to tingle unpleasantly. It goes without saying that no machines on the electric meter will help solve this problem; for these purposes, there is grounding that will prevent electric current from passing through your body.

So, grounding is the intentional connection of metal parts of electrical appliances and electrical equipment to the ground. For these purposes, special metal pins are driven into the ground, which, in the event of a current leakage onto the body of the electrical appliance, drain the electric current into the ground. If there is no grounding, it will not be possible to avoid electric shock when touching the metal casing of electrical equipment.

Grounding works on a slightly different principle than grounding. So, for example, if the body of an electrical appliance suddenly becomes energized, this will lead to a short circuit, to which the protective devices must react, automatically turning off the power to the electrical appliance from the mains. As you can see, the difference between grounding and grounding is that the electric current does not go into the ground during a leak, as is the case with protective grounding.

Consequently, grounding can provide protection against electric shock by reducing it, and grounding can provide protection from electric shock by disconnecting the power to the electrical appliance from the electrical network.

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

Switching three-phase electricity consumers differs from connecting conventional household electrical equipment, therefore the installation of protective systems is carried out in a different way. In this case, you should not confuse the neutral or ground wire involved in the control system, that is, involved in the start-up and stop circuit of the unit, with the protective conductor designed to divert a dangerous discharge to the ground.

Design, wiring, connection of electrical equipment

The work is carried out in several stages:

A separate line (route) is installed along the perimeter of the room, made of a narrow metal strip 40x3 mm or copper wire with a cross-section of 16 mm2.
A busbar (preferably copper) with contact devices (studs or holes for bolted connections) is mounted on it in a hidden place. It is possible to use a metal bus, but in this case welding the studs is a prerequisite.
This line is connected to a grounding or grounding circuit, which is led out by a separate wire from the switchboard and has a reliable connection to the ground either directly or through a working zero
The housings of all consumers (three-phase electric motors) are connected via a copper wire to the described bus.

If a short circuit occurs from a voltage leak due to an insulation failure or a “breakthrough” of one of the phases onto the body of grounded electrical equipment, the current will immediately flow into the ground along the path of least resistance, that is, through the conductor connected to the working zero or ground. This will protect a person from electric shock when touching the body of the device.

A grounding device is allowed only if it is not possible to switch with the ground loop. In all other cases, only protective grounding is considered correct.

The unit is connected through a copper wire to a bus mounted from the grounding path

Mandatory use of additional protective devices

The described grounding and neutralizing systems are effective when significant leaks or short circuits occur on the housing of electrical appliances. However, to achieve complete safety when servicing equipment, it is necessary to use additional means of protection to ensure that the electrical circuit is broken when malfunctions occur.

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

will ensure that the electrical circuit is de-energized in case of problems;
protect the user from electric shock;
will 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 - installed on both wires of the electrical wiring;
multi-pole (three or more) – used for three-phase voltage.

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

The circuit breaker switches off when the current load exceeds the rated value indicated on the device body. The RCD monitors the state of the electrical network and is triggered when the slightest current leakage occurs.

Where is zeroing done?

Grounding is used mainly in residential buildings. In industry, protective grounding and grounding of electrical installations in combination are most often used. Here it is taken into account that when voltage comes into contact with the body of a particular device, a unit operating from a network with a voltage much higher than household voltage, the danger to humans increases many times over.

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

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

Basic requirements of the PUE: excerpts from articles

Let's start with the fact that the definitions of grounding and grounding are clearly stated in the rules for electrical installations (PUE) and GOST. Let's try to identify some.

PUE 7. Clause 1.7.28 - intentional electrical connection of any point in the network, electrical installation or equipment with a grounding device,
PUE 7. Clause 1.7.31 - protective grounding in electrical installations with voltage up to 1 kV - intentional connection of open conductive parts with a solidly grounded neutral of a generator or transformer in three-phase current networks, with a solidly grounded output of a single-phase current source, with a grounded source point in direct current networks, carried out for the purpose electrical safety,
GOST 12.1.009-76. Grounding (protective grounding) is a deliberate electrical connection to the neutral protective conductor of metal non-current-carrying parts that may be energized.

This is not difficult for an electrician to understand, but for a novice master, everything written will seem like a bunch of words. Today we will “translate” everything into simple language and everything will immediately fall into place.

Grounding concept

Before answering the question of how grounding differs from grounding, let’s consider each concept separately. Grounding is a special connection of electrical installations to the ground. The purpose of this connection is to reduce sudden voltage surges in the electrical network. It is used in the circuit where the neutral will be isolated. When suitable grounding equipment is installed, the excess current that enters the network will flow into the ground through the outlet contacts. The resistance of this part must be relatively low so that the current is completely absorbed.

Also, the function of protective grounding of electrical installations allows you to increase the volume of emergency fault current, despite the fact that this contradicts its purpose. A grounding electrode with high resistance may not be able to withstand a weak fault current, only with special protective devices. In this case, when there is an emergency, the installation will be energized, which can pose a great danger to human health in this room. The purpose of protective electrical installations is also designed to remove stray current in the electrical network.

The ground electrode is a special conductor that may consist of one or more elements. They are usually connected to each other by electrically conductive material and are embedded in the ground, which absorbs the passing charge. Steel and copper can be used as grounding conductors. According to the PUE standards, this protective measure must be taken in modern residential buildings, as well as work premises, factories, public institutions and other buildings for various purposes.

Most modern homes have grounding circuits installed. However, they may not be present in older buildings. In such a situation, experts recommend replacing the wiring with a three-core cable with a grounding wire, connecting a protective electrical installation. There are situations when it is not possible to install a complete grounding loop. In modern electrical engineering, special portable equipment can be used - a portable grounding pin (bus). Their action corresponds to the standard grounding device of residential buildings or taps. Such a device has good practical value, is easy to install, carry, repair, and also has a wide range of functionality.

The grounding function can be performed by several independent groups of protective equipment. Lightning protection. They serve to quickly remove high pulsed charge from lightning. Often their use is necessary in arresters and modern lightning rods. Workers. This group allows you to maintain the required operation of all electrical installations under different conditions (normal and emergency).

Protective. This group of equipment is needed to prevent direct contact of people and animals with an electrical charge that occurs as a result of mechanical damage to a phase in the wire. They prevent many accidents that could occur if problems with the power line were not noticed in a timely manner.

Grounding electrodes are conventionally divided into artificial and natural. Artificial electrical installations are special structures that I make specifically in order to divert excess network current into the ground, providing protection for my home. They can be produced in a factory or made independently using steel elements. Natural grounding conductors are the soil, the foundation under a building, or a tree near the house.

Practical advice

When building a private house, grounding is a prerequisite.
When completely or partially replacing, modernizing or repairing wiring in an apartment or country house, it is important not to neglect the rules of personal safety. Some practical tips:

If a two-wire electrical network is installed, when installing a three-wire socket, you cannot connect the ground loop and the working zero. This is a violation of one of the basic safety rules. If you neglect it, the body of a household appliance connected to the network will always be energized, which negatively affects performance and service life, and also poses a danger to the life and health of humans and pets.
During the construction of a summer house or country house, installation of grounding is a prerequisite for the operation of electricity. An inexpensive grounding system with a simple design will protect people’s health and the integrity of all expensive household appliances and electrical devices.
To provide electricity to powerful household appliances, for example, a washing machine, dishwasher, boiler, it is recommended to install a separate electrical wiring line in the room. This is due to the fact that when these devices are started simultaneously, RCD sensors (residual current devices) and safety sensors will often trip, completely cutting off the supply of resources to the apartment or house.

A safety circuit breaker and an RCD are two completely different electrical devices. Each of them has its own design features and performs certain functions.

The residual current device is a protection for humans and pets, a quick response device. A machine is an electrical device that detects changes in the parameters of the electrical network, in particular its overload. Its main drawback is that it may not work immediately, but after a certain time. In order to combine the capabilities of two protective devices and level out their shortcomings, a hybrid device was developed - a difavtomat.

Difference in comparison

You don't have to be an electrician to understand the differences between these devices. It is enough to understand the essence of their purpose. If one diverts dangerous voltage into the ground, then the other equalizes it to safe levels.

Proper connection of electrical equipment and electrical appliances prevents electric shock. In an extreme situation, a short circuit occurs on the housing. The protection is triggered and disconnects the electrical circuit. In this case, grounding works. The earth is used as a conductor.

There was voltage in the house, on the heating device. A dangerous situation must be prevented by grounding. But the pipes between the apartment and the basement were changed: plastic ones were installed instead of steel ones. They disconnected the conductor. Grounding didn't work. The SUP eliminated the electrical potential difference using conductors. The danger has been eliminated.

Comparing these devices helps to understand the differences between them:

SUP is the electrical connection of metal structures with each other and the ground. They have equal potential.
Grounding - connection of all metal parts with a ground electrode.
The potential equation concerns only structures that may be energized among themselves.
Grounding concerns only the drainage of currents into the ground.
The purpose of the control system is to equalize the potentials of the conductive parts among themselves: to make them safe for the lives of people and animals.
The purpose of grounding is to equalize the potentials of grounded parts of equipment with the ground potential.

They can be called comprehensive protection against electric charge. But before installing a potential equalization system in your house, call an electrician, read the PUE, look at the house construction project. What grounding system is it built with?

For example, with TN-C and a combined PEN conductor, DSUP is prohibited. Reconstruction with transition to the TN-CS system is required.

How to calculate a system of grounding elements

Getting acquainted with the procedure for calculating grounding should begin with finding out what value to take as the defining indicator and for what purpose the procedure itself is used. This parameter is the resistance of the protective circuit, which depends on such technical indicators as:

Dimensions and shape of the grounding system.
The depth of its immersion into the ground.
Condition of the soil in the area.

Important: A large “contribution” to the formation of the conductivity of the current flow chain is made by the contact resistance of the contacts in the design of the charger itself.

It is known that an artificial grounding loop consists of a set of vertical and horizontal metal elements and a copper busbar connecting them. In order to ensure minimal resistance to current flow into the ground, it is necessary:

use grounding systems with a large area of contact with the ground (if necessary, increase the number of vertical pins and their pitch);
constantly monitor the condition of the soil at the location of the device and be able to determine the soil resistivity;
control the reliability of welded joints.

To assess the real performance indicators of the charger, it is necessary to familiarize yourself with the existing methods for measuring the conductivity of the grounding system.

Grounding and grounding in alternating current circuits

Essentially, zero is a blue wire marked N. Grounding is a deliberate connection of either the midpoint in the winding of a 3-phase generator, or a connection in the load to the operating zero. Zeroing has two main functions: 1 – working function and 2 – protective function. The operating function is most clearly manifested in the electrical distribution diagram in an apartment building. Initially, electricity is supplied only using three-phase current, which is evenly distributed throughout the apartment. As an example, let's say that there are 36 apartments in one specific entrance. Therefore, the load distribution should be done as balanced and evenly as possible: we connect 12 apartments to phase A, 12 apartments to phase B, and, naturally, the remaining 12 apartments to phase C. No matter how hard designers try to balance the consumption pattern, practice clearly shows that it is never possible to achieve balance and load uniformity 100% - some spend more electricity, and some less. That's why line N was invented - working zero. The main purpose of the working zero is to restore the voltage balance across phases, that is, to prevent voltage imbalances from occurring. By the way, it is the sudden disconnection of the neutral conductor that can lead to the fact that in some apartments there will be a lightning-fast surge in operating voltage up to 380 V. In the jargon of electricians, this phenomenon is called burnout or zero drop.

A three-phase system requires grounding and grounding of the midpoint of the working windings connected in a star configuration. To clearly understand the difference between grounding and grounding, let's turn to the standard diagram for connecting a load to a three-phase power source using a Y (star) circuit. If we consider a three-phase transformer, a three-phase asynchronous electric motor, a three-phase furnace as a load, then the system will function when connected using three wires with phases A, B, C and a neutral wire N. In fact, if we consider electrical installations in production, then the presence of a fourth conductor performs purely protective functions. When the insulation of the windings of a three-phase electric motor breaks down, a high potential rushes to the body of the device, which is in direct galvanic connection with wire N, that is, the working zero. Consequently, with such a connection, a short circuit will occur, which will cause the three-phase circuit breaker to turn off.

Two connection schemes in three-phase networks

On the rotor of a three-phase generator there are no longer two, but three windings, shifted by a third of a turn or 120 degrees. Accordingly, the phases of currents in a three-phase network are shifted by 120 degrees.

In a three-phase network, there are two connection diagrams for the generator and the load; when switched on by a star, the ends of the phase windings are connected to one common point - the neutral. The ends of the loads are also connected to a common point.

The wire that connects the common points of the load and the generator is called the neutral. The wires connecting the other ends of the phase windings to the load are called linear.

The voltage at the terminals of the phase coils (phase voltage) is 220 V. The voltage between linear wires is called linear. In a three-phase network it is equal to 380 V. When connected by a star, the loads are under phase voltage.

In a delta connection circuit, loads are connected between the ends of the phase windings. In a delta circuit there is no neutral, and the line voltage is equal to the phase voltage.

What's better?

In order for you to fully understand the material, we will first provide the differences in the use of each system, on the basis of which we will draw our own conclusion.

Grounding a house can easily be done with your own hands, having a welding machine and some metal on hand. At the same time, creating a grounding requires certain knowledge related to calculations and selection of the optimal point for connecting the wire to the neutral. If the neutral wire in the distribution panel breaks, the neutralizing system will not work and you may become a victim of electric shock. In this regard, it is easier with a protective grounding system, because Unlike zero, the PE wire does not burn out and practically does not fall off if the terminal is tightened at least once a year. Although we can say about this that the “ground” circuit, due to the fact that it is located on the street, can also be damaged over time, especially in the places where the electrodes are welded. Again, if you do an annual audit, there will be no problems.

Based on this, we can draw the following conclusion: proper grounding in a private house is not difficult to do with your own hands, and besides, such a system is more durable, and therefore safer. As for grounding, to create it you need to call a specialist and, at the same time, more frequently inspect the integrity of the neutral wire, which is a huge disadvantage when comparing the differences. This option is not recommended; it is better to connect an RCD for protection. We hope that now you understand the difference between grounding and grounding, how both systems work and which is more effective for a house or apartment.

Distinctive features - part 1

Distinctive features - part 2

Basic methods of grounding

When constructing a grounding system, vertical metal rods are usually used as a grounding conductor. This is due to the fact that horizontal electrodes, due to their shallow depth, have increased electrical resistance. Steel pipes, rods, angles and other rolled metal products with a length exceeding 1 meter and having a relatively small cross-section are almost always used as vertical electrodes.

Grounding diagram in a private house

There are two main methods for installing vertical ground electrodes.

Related article:

Electricity can not only create comfortable living conditions, but also carries a certain danger. To reduce the likelihood of this danger occurring, do-it-yourself 220V grounding in a private house . How to make it - read the publication.

Several short electrodes

This option uses several steel angles or rods 2-3 meters long, which are connected together using a metal strip and welding. The connection is made at the surface of the earth. Installation of the ground electrode occurs by simply driving the electrode into the ground using a sledgehammer. This method is better known as “corner and sledgehammer”.

Using reinforcement as a grounding conductor

The minimum permitted cross-section of grounding electrodes is given in the PUE, but most often the corrected and supplemented values are from technical circular No. 11 of RusElectroMontazh. In particular:

for corners and strips made of black steel with a cross-section of at least 150 mm2 and a wall thickness of 5 mm;
for steel rod with a diameter of at least 18 mm;
for steel pipes with a wall thickness of 3.5 mm and a diameter of at least 32 mm.

The advantages of this method are simplicity, low cost and availability of materials and installation.

Single electrode

In this case, an electrode in the form of a steel pipe (usually single) is used as a grounding electrode, which is placed in a deep hole drilled in the ground. Drilling the soil and installing the electrode requires the use of special equipment.

Single ground electrode mounted in a drilled hole

An increase in the contact area of the ground electrode with the ground is ensured by a greater depth of installation of the electrode. Moreover, this method is more effective in comparison with the previous option, with the same total length of the electrodes, due to reaching deep layers of soil, which usually have low electrical resistivity.

The advantages of this method include high efficiency, compactness and seasonal “independence”, i.e. Due to winter freezing of the soil, the resistivity of the ground electrode practically does not change.

Another way is to lay a grounding conductor in a trench. However, this option requires greater physical and material costs (more material, digging a trench, etc.).

This method requires a lot of physical effort.

Having figured out how grounding works and why it is needed, we now face the second question of our article, namely, what constitutes grounding, why it is needed and how it differs from grounding.

Zeroing: purpose and characteristics

Grounding instead of grounding is often used in apartments where there is no traditional grounding system or it has an outdated appearance. This type of protection involves connecting metal parts that do not conduct current with a solidly grounded neutral conductor. This mechanism is designed so that when the insulation is damaged and current exits to the device body, a short circuit occurs, as a result of which circuit breakers and RCDs are triggered.

Important! When practicing grounding instead of grounding, be sure to install automatic circuit breakers and residual current devices. You should carefully and regularly check the neutral wire, since in the event of a high current output, all devices that are grounded are energized

This situation is explained by the automatic switching of zeroed devices to phase. Therefore, for safety reasons, it is not recommended to connect automatic devices and other protective equipment to zero. However, you can completely protect yourself from electric shock only by installing repeated grounding conductors for every 200 m of the electrical network

You should carefully and regularly check the neutral wire, since in the event of a high current output, all devices that have been grounded are energized. This situation is explained by the automatic switching of zeroed devices to phase. Therefore, for safety reasons, it is not recommended to connect automatic devices and other protective equipment to zero. However, you can completely protect yourself from electric shock only by installing repeated grounding conductors for every 200 m of the electrical network.

Scheme of work

As mentioned above, grounding is based on provoking a short circuit after a phase hits the metal body of the electrical installation connected to zero. As the current increases, a protective mechanism is activated that cuts off the power supply.

According to the standards of the Electrical Installation Rules, in the event of a violation of the integrity of the line, it must be turned off automatically. The shutdown time is regulated - 0.4 seconds (for 380/220V networks). To disconnect, special conductors are used. For example, in the case of single-phase wiring, the third core of the cable is used.

For correct zeroing, it is important that the phase-zero loop has low resistance. This ensures that the protection is activated within the required period of time.

Organization of grounding requires high qualifications, therefore such work should be performed only by qualified electricians.

The diagram below shows how the system works:

In what cases is protection required?

When there is physical (more precisely, electrical) contact with the body of a phase conductor, or a circuit element to which voltage is currently applied, two dangers arise:

Electric shock. In case of accidental or intentional (occurring during operation of the installation) touch, electric current will flow through your body. A potential difference arises between the phase and the “ground” (in the literal sense of the word), and you act as a conductor. The resistance of the human body is not so great, especially if the skin is moistened by sweat. Therefore, the strength of the current flowing through you is sufficient to cause damage to health, and in some cases leads to death;

Short circuit through electrical installation components. If voltage appears in an unauthorized area of the circuit, at a minimum, the electrical appliance may suffer. Restoring is sometimes more expensive than buying a new one. If the integrity of the wiring is damaged, a fire often occurs. The current flowing through wires with low resistance reaches a value that can ignite the insulation and other elements of the circuit.

The system of grounding and grounding of electrical equipment provides protection against the considered hazards, or at least minimizes the consequences. Many inexperienced home-grown electricians confuse these two concepts. Or they deliberately use the working zero when organizing grounding.

This is especially true in old high-rise buildings, where a separate grounding loop is not provided. If the power supply lines are fully operational, this is not so dangerous. However, if the neutral wire on the main line is damaged, or the contact at the terminal connections deteriorates, the working zero loses electrical connection with the real “ground”.

You rely on phase protection and work with an electrical appliance without fear. At a critical moment, the protection does not work, and in the best case, equipment damage occurs, and in the worst case, a fire or electric shock occurs.

Important! Using a working zero to protect users is prohibited!

Protective grounding and grounding are fundamentally different in the way they are connected to the physical ground. If you use zero as grounding, troubles can happen:

For example, you grounded the boiler to working zero. In the event of a phase breakdown on the housing, the residual current device (RCD) may not operate. Through water, from a hot tap, tension is transferred to you. If you are in the bathroom, you will be exposed to a life-threatening electrical current;
You are using an electric stove located next to the radiator. The hot water supply system is laid in the ground and has reliable contact with the ground. If the electric stove is not grounded or is grounded to zero, if the neutral wire is damaged, a phase may appear on the body. If your hands touch the live housing and the grounded battery at the same time, electric shock is guaranteed.

Errors in the implementation of zeroing [edit | edit code]

It is sometimes believed that grounding to a separate circuit not connected to the neutral wire of the network is better, because in this case there is no resistance of a long PEN conductor from the consumer's electrical installation to the ground electrode of the KTP (complete transformer substation). This opinion is erroneous, because the grounding resistance, especially a homemade one, is much greater than the resistance of even a long wire. And when a phase is shorted to the body of an electrical appliance grounded in this way, the circuit current, due to the high resistance of the local grounding, may be insufficient to trigger the circuit breaker (circuit breaker) or the fuse protecting this line. In this case, the device body will be at dangerous potential. In addition, even if you use a small rated AV, triggered by a ground fault current, it is still practically impossible to ensure the time required by the PUE for automatic shutdown of the damaged line.

Therefore, earlier, before the widespread use of RCDs, grounding the housings of electrical receivers without grounding them (that is, grounding according to the TT system) was not allowed at all. Clause 1.7.39 PUE -6:

The directed movement of charged particles, 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.

IT isolated neutral system

In IT, the neutral does not physically have contact with the ground or does, but through devices with high resistance, and the current-carrying elements of the system are grounded.

IT stands for:

I – (from English isolation) isolated neutral;

T – indicates the presence of local (local) grounding of parts of electrical installations;

In such systems, the leakage current to the frame or ground will be quite low and will not affect the operation of the equipment.

IT is used in special-purpose installations with increased requirements for reliability and safety (for example, in hospitals for emergency power supply).

How to determine the resistance of a phase-zero loop

The requirements contained in the PTEEP rules require constant monitoring of the condition of the chargers, ensuring the safe operation of household and industrial electrical equipment. According to these standards, in systems up to 1000 Volts with a tightly grounded neutral, they must be checked for a single phase fault. The testing methods used are, first of all, based on the technical base represented by samples of special-purpose measuring instruments.

Measuring equipment

To check the resistance of the “phase zero” circuit circuit, electronic devices are traditionally used, characterized by a small measurement error. The most famous examples of measuring equipment of this class include:

Meters of the M 417 and MSC 300 brands, allowing to determine the conductivity of controlled circuits (based on the results obtained, short-circuit currents into the ground are calculated using special formulas).
The EKO-200 device is intended exclusively for determining short-circuit currents. The EKZ-01 device is used in exactly the same way as the EKO-200.
Measuring device brand IFN-200.

M417 can be used when organizing and carrying out measurements in three-phase circuits with a tightly grounded zero (in this case, removing the supply voltage is not required). During the tests, the voltage drop method is used when the controlled circuit is opened for a time of about 0.3 seconds. The inconveniences of working with this device include the requirement to calibrate it before starting each new measurement.

Phase-zero circuit resistance meter brand M 417

The MSC300 product is a more advanced technical device, equipped with complex electronic filling in the form of modern microprocessor chips. When working with this device, the method of reducing the potential is used by including a resistance of 10 ohms in the measured circuit. The operating voltage varies from 180 to 250 Volts, and the measurement time of the desired parameter is about 0.03 seconds. When taking measurements, it is connected to the monitored line at the most remote point, and to start working with it you will need to press the “Start” button. The measurement results can be viewed after they are displayed on the built-in digital display.

MZC-300 meter for parameters of power supply networks of buildings and structures

In a situation where the user does not have a single sample of special measuring equipment at his disposal, a standard voltmeter and ammeter can be used to practically determine the resistance of the phase-zero loop. The required result is found using the simplest formula, familiar to many from the school physics course.