Potential equalization systems - main (osup) and additional (dsup). grounding

I’m sure many of you have heard about the potential equalization system (abbreviated as EPS), but few people understand what it is and why it is needed. This article aims to clear up this misunderstanding.

What is a potential equalization system?

The SUP is designed to equalize the potential of all conductive parts of the building:

  • building elements;
  • building structures;
  • engineering networks and communications;
  • lightning protection systems.

The connection of all current-carrying parts of the building is carried out with PE protective conductors, which are laid separately or can be part of the power supply lines. These conductors form the so-called “grid” in the building and must connect all of its above-mentioned parts to the grounding device and grounding conductors.

In the event of damage to the electrical installation and potential (voltage) contacting the conductive parts of the building, a short circuit current or large leakage currents occurs, which lead to the disconnection of the damaged section of the circuit from the power source by triggering circuit breakers or RCD.

In previous articles, we talked about the TN-C-S, TN-S grounding systems, where, according to the requirements of PUE-7, electrical wiring of residential, domestic and administrative buildings is prohibited without the use of protective conductors, i.e. PE conductors. This primarily has a positive effect on electrical safety.

There are 2 types of potential equalization system (PES):

  • basic potential equalization system (BPES);
  • additional system potential equalization (DSUP).

Basic system (BPCS)

Comprises:

  • ground loop (grounding device);
  • main ground bus (GZSh);
  • “grids” of protective conductors PE;

The main grounding bus (GZSh), also known as the PE bus, is installed in the input switchgear(VRU) buildings. A steel strip coming from the ground loop (grounding device) is connected to the GZSh.

The following is connected to the same main bus:

  • PEN-conductor of input lines (cable) in the TN-C-S grounding system;
  • PE conductor of the input line (cable) in the TN-S grounding system.

1. It is prohibited to install a potential equalization system in houses with a TN-C grounding system.
2. It is prohibited to connect protective PE conductors with zero working N conductors starting from the main ground bus (GZSh).
3. The connection diagram to grounded structures, elements and utility networks of the building must be radial. The radial scheme is carried out as follows: each grounded part of the building has its own potential equalization conductor. Connecting PE potential equalization conductors with a loop is strictly prohibited!
4. It is prohibited to install various protection switching devices in the circuits of protective PE conductors. Continuity of protective conductors is the most important and basic requirement.

Additional system (DSUP)

We have figured out the basic potential equalization system (EPS). Now let's look at what an additional potential equalization system is. DSUP is necessary to provide additional electrical safety in areas with increased danger, for example, a bathroom or shower room.

It consists of:

  • potential equalization boxes, abbreviated as PCB;
  • potential equalization conductors.

How is the DSUP installed?

  1. First of all, you need to decide on the installation location of the potential equalization box (PEC).
  2. Next, you need to connect the PE bus of the input electrical panel (apartment, dacha) with the PE bus located in the potential equalization box (PEC). This is done with copper wire with a cross section of 6 sq. mm.
  3. The third step, according to, will be the connection of all metal structures of the bathroom:
    • heating;
    • cold water supply;
    • hot water supply;
    • bath or shower.
  4. We lay protective potential equalization conductors from grounded structures and connect them to the PE bus in the potential equalization box (PEC). The protective potential equalization conductors can be secured to the pipes using metal clamps.
  5. All sockets installed in the bathroom are also subject to additional grounding.

Quality control

The cross-section of the protective potential equalization conductors is made of copper wire with a cross-section of 2.5 - 6 square meters. mm.

After electrical installation of the potential equalization system, it is necessary to invite specialists from the electrical laboratory to carry out the following electrical measurements:

  • grounding resistance measurement;
  • checking the presence of a circuit between the grounded structures and the PE grounding bus in the box (KUP).

This was introductory information about the potential equalization system. If you have any clarifying questions, ask them in the comments.

In our apartments and houses, production premises and the offices where we work are full of metal cases and structures, during simultaneous touching of which a person can fall into the zone of potential difference. To prevent this from happening, the potentials must be equalized. How to do this practically? Connect all current-carrying elements in the building. This potential equalization system (EPS) creates a safe environment for humans. One of the elements of the control system is a potential equalization box (PEC).

We’ll talk about these SUP and PMC in more detail, but first we’ll look at practical examples, which is the potential difference in ordinary apartments and where it comes from.

Causes

We all studied physics and remember that potential in itself poses absolutely no danger. You need to be wary of potential differences.

In apartments, the potential difference between pipes and household electrical appliances may arise due to the following circumstances:

  1. The wire insulation is damaged and current leaks.
  2. The grounding system has encountered stray currents.
  3. Connection diagram electrical equipment done incorrectly.
  4. Static electricity appears.
  5. Electrical appliances are faulty.

Danger

Remember from school? Any metal object conducts electricity. In our homes, similar items are everywhere. These are the central pipes heating system, cold and hot water supply; batteries and heated towel rail; ventilation box and drain; metal body of any electrical appliance.

In general house communications, metal pipes are interconnected. Let's look at a simple example. We have a bathroom with a heating radiator and a shower stall nearby. If suddenly a potential difference arises between these two elements, and a person touches both the battery and the shower stall at the same time, it will be extremely dangerous in terms of electric shock. In this case, the human body will play the role of a jumper through which electric current will flow. The path of its flow is known to us from the laws of physics - from the potential with great value to less.

Another typical example is if different potentials arise on water supply and sewerage pipes. When a current leak appears on a water pipe, there is a possibility of injury to a person while bathing in the bathtub. This will happen if a person stands in a bathtub with water, opens the drain and touches the water tap with his hand. To prevent such problems from arising, potential equalization is necessary.

The situation when there is voltage on the pipes in a residential building is shown in this video:

Kinds

In order to equalize potentials, there are two systems, we will talk about each of them in more detail.

Basic adjustment

The main one is the basic potential equalization system; in its abbreviated form it is called OSUP. In essence, this system is a circuit that combines several elements:

  • the most important is the main ground bus (GZB), it is on it that all other elements are connected;
  • all metal fittings of a multi-storey residential building;
  • lightning protection of the building;
  • heating system;
  • parts and elements of elevator facilities;
  • ventilation box;
  • metal pipes for water supply and drainage.

Each building has an input switchgear (IDU), and a main grounding bus (GZSH) is installed in it. It is connected to the ground loop using a steel strip.

There was no need to worry before, everything metal elements were united, and there were no prerequisites for different potentials. If any potential appeared on the pipe, along the way least resistance it calmly went into the ground (we remember that metal is an excellent conductor).

Now the situation has changed; many residents change metal parts during renovation work in their apartments. water pipes to polypropylene or plastic. Due to this, the common chain is broken, batteries and heated towel rails are left without protection, because the plastic does not have conductive ability and is not connected to the grounding bus. Imagine that you still have metal pipes, and the neighbor below has changed everything to plastic. When potential appears on your pipes, it has nowhere to go, the path to the ground is interrupted plastic pipes neighbor This is how a potential difference occurs.

The main system has a small problem. IN multi-storey buildings communication paths are very long, due to this the resistance of the conductive element increases. In the magnitude of the potential on the pipes of the first and last floors there will be a noticeable difference, and this already poses a danger. Therefore, an additional potential equalization system is created and installed on each apartment individually.

Additional adjustment

An additional potential equalization system (abbreviated name DSUP) is installed in bathrooms and combines the following elements:

  • metal body of a shower stall or bathtub;
  • ventilation system, when its outlet to the bathroom is made of a metal box;
  • heated towel rail;
  • sewerage;
  • metal pipes for water supply, heating and gas services.

And here you will need a potential equalization box. A separate wire (single-core, material made of copper) is connected to each of the above objects; its second end is brought out and connected to the PMC.

Performing installation

The PMC varies depending on how the building is constructed and where the box itself will be mounted:

  • into a solid wall;
  • into a hollow wall;
  • on the wall surface ( open method installations).

It is a housing made of plastic, inside of which the main element is located - the grounding bus. It is made of copper and has a cross-section of at least 10 mm 2.

Copper wires from plumbing, heating and gas systems; from electrical appliances located in the room, as well as from sockets and lighting fixtures installed in the bathroom.

Wires are connected to the listed elements using bolted connections or clamps. Sometimes special contact petals are used, in which case the metal connection between the protected element and the wire will be especially strong. For the potential equalization system to work in dangerous situations, reliable contact is needed. Therefore, the place on the pipes where the clamp will be installed must be cleaned to a metallic shine.

The internal bus is connected with a separate copper wire, called a protective PE conductor, to the input panel of the apartment, and through it it is connected directly to the main switchgear. The cross-section of the PE conductor must be at least 6 mm 2. Important condition If you decide to run this wire in the floor, it should not intersect with other cables.

Such a box is like an intermediate link between all grounded elements and the input panel. It is very convenient that from each element it is enough to extend the wiring only to the control panel, and not to the general apartment panel.

When the wiring is made with plastic pipes, wires from water taps and mixers are connected to the control panel.

Before installing the SUP, you need to find out how the grounding is done in the house. If using the TN-C system (when the protective conductor PE and the working zero N are combined into one wire), equalization cannot be performed. This will cause danger to other neighbors if they do not have such a system.

Requirements

When installing the control unit, you must adhere to some requirements and rules:

  1. Its installation in bathrooms and toilets is mandatory. Firstly, these rooms contain a lot of metal bodies and surfaces. Secondly, there is a considerable amount electrical appliances. Thirdly, these rooms always have high humidity.
  2. The box is installed in the place where the plumbing risers pass.
  3. It is necessary to connect all electrical equipment to which there is open access (this is, first of all, the housings of water heating boilers, washing machines), as well as third-party conductive elements.
  4. Access to the PMC must be free.
  5. Installation of the PMC is prohibited when the grounding is installed in the house without a grounding conductor (using the grounding method).
  6. The DSUP must not be connected via a cable.
  7. The DSUP along the entire length, starting from the control panel in the bathroom and up to the entrance panel itself, cannot be torn. It is prohibited to install any switching devices in this circuit.

Finally, I would like to say, do not confuse the concepts of equalization and equalization of different potentials. To equalize means to connect conducting elements electrically to make their potentials equal. And to level is to reduce the potential difference on the floor or surface of the earth (step voltage).

If you have little experience in electricity, then do not take on such work yourself, entrust it to professionals. Among other things, a specialist upon completion installation work I must also measure the grounding resistance and check for the presence of a circuit between the grounding elements.

According to the laws of physics Each conductor has a certain electrical potential. But in itself it is not dangerous, but the danger comes from the potential difference between various metal objects. And the higher this difference, the higher the risk of electric shock.

Potential equalization and its purpose

Potential differences can be caused by various phenomena: atmospheric overvoltages, stray currents, static electricity, etc. But cases of current leakage from electrical wiring through metal objects in the house or housings of electrical appliances are especially dangerous. For example, you are in the bathroom and, when touching a metal water pipe, you receive an electric shock because the pipe has a different potential, caused by current leakage through it due to damage to the insulation of the electrical wires in the apartment on the floors below.

So, to avoid the possibility of potential difference, all metal pipes, housings of household appliances, lamps, etc. are connected metal conductors between themselves. As a result of the electrical connection that arises between them, all metal objects have the same potential.

But that alone is not enough, you also need the energy of the electric current arising in unforeseen circumstances It is safe to take it into the ground, so all metal parts are connected by wires on the grounding bus and an additional conductor from the PE grounding bus of the electrical panel is connected to it.
If you don't do this, then, for example, in the event of an insulation breakdown and if on the body washing machine appears, then the person will receive an electric shock not in contact with other metal objects, but with any of them while standing on the ground. That is an electrical circuit will arise, passing through the human body to the ground. And if all objects are grounded through the PE bus of the electrical panel, then the current will follow the path of least resistance through the grounding conductor. And through person will pass proportional to its sufficiently large resistance - a safe value of current.

IN apartment building The basic potential equalization system must be carried out during construction. Everything in the basement and on the roof metal stairs, doors, pipes, metal structures, electrical panels, etc. .
But unfortunately, this connection may be interrupted or may not be effective according to the laws of electrical engineering, due to long distances, therefore, an additional potential equalization system is required in each apartment.

Potential equalization circuit

Due to the fact that the bathroom is a particularly dangerous type electrical safety premises due to wet conditions and the concentration of metal pipes there, it is in it or immediately next to it in the bathroom that a plastic box with a tire is placed. All conductors connected to a bolted connection or clamp to all metal parts of the bathroom are clamped under the grounding bus bolts.

Attention, each metal object is connected to a separate conductor from the box; you cannot connect several in series with one wire metal parts. In exceptional cases, only one serial connection can be made, but without breaking the conductor.

Needs to be connected together separate wires not only for the bathroom body, lamps, water pipes and heating, but also for the grounding contacts of sockets and the box metal doors in the bathroom.

Usually, a box with a grounding bus is installed either in the bathroom, but more often in the bathroom behind sewing up the pipes passing through there. Access to it, like water meters, can always be gained through the door in the lining.

By modern requirements An additional grounded strip 50 millimeters wide or a galvanized wire with a diameter of at least 6 mm is installed along the interfloor riser with pipes, to which a potential equalization box is connected with a separate copper conductor. Thanks to this, a ring is created between the electrical panel and the grounding system of the house, and this is double reliability.

How to make an additional potential equalization system

It will be easy to make a potential equalization system yourself in your private house or apartment, without turning to specialists.
Step-by-step instruction:

That's it! Once a year or several years, check the reliability and tighten all contacts.

Related materials:

In short, potential equalization is the connection of conductive elements of a building so as not to create a potential difference in the zone of simultaneous human contact with different metal structures and buildings. Let's take a closer look.

What is potential and why does it need to be leveled?

In order to deal with potential equalization system Let's briefly remember what electric potential is, and as a result, what electric current is. For example, let's take any electrical conductor. For example, an electrical wire.

In a “quiet” state, any conductor has an even distribution of electrons, both positive and negative, throughout its internal structure.

If we connect a conductor to a device that creates a deficiency of electrons at one pole and an excess of electrons at the other pole, all the electrons in our conductor will begin to move in a directed manner to equalize this deficiency and excess. That is, come back to the “calm” mode. This directed movement of electrons is an electric current, and the excess or deficiency of electrons created at the pole of a conductor is called negative and positive electric potential

The difference in electrical potential at the poles results in the generation of electric current. If the potential difference does not change and the electrons move in one direction, then the current is called constant. If the positive and negative potential often change places, then the current is called alternating. In our electrical networks potentials change at a frequency of 50 times per second. This creates an alternating electric current with a frequency of 50 Hertz in our electrical circuits.

Having remembered a little about electric current, let's return to the potential equalization system

During operating mode, electric current “runs” along an insulated conductor from one electrical potential to another, changing direction 50 times per second. All hardware, which our homes are stuffed with, and any other room, and through which no current should flow, ideally have zero electrical potential.

There are many such potential conductors in rooms and buildings. Iron fittings are built into the walls, and the water supply system must include metal water pipes. Ventilation, air conditioning, lightning protection, heating systems also include metal constructions. Yes, myself Appliances, powered by electricity, has metal structural elements. But this is ideal.

Suppose that somewhere in a neighboring apartment, as a result of an accident, a live wire touched a heating radiator. The current “spreads” throughout the heating system and changes the electrical potential on your battery.

1. You are on the floor or wearing shoes that do not conduct electricity. Nothing will happen. The current won't hit you.

2. You are on a grounded floor. Electric shock is inevitable. To protect against such damage, a device is used protective shutdown(RCD).

3. You are on a non-conductive floor and at the same time touching a live battery and a nearby pipe. The pipe and the battery are at different electrical potentials, and the current will flow safely through you. Electric shock is inevitable.

Here, to protect against the last electric shock, the potential equalization system protects.

If you connect all metal structures and products in a room that should not be energized, then in the event of an accident they will all be at the same potential. And even if all the pipes in the apartment have 220 volts, you won’t get an electric shock. True, under one condition: you must stand on an insulated surface.

For a visual example, think of birds sitting on high-voltage, uninsulated power lines.

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A prerequisite for installing a potential equalization system

Important! Before installing a potential equalization system (EPS), it is imperative to find out what system is used to ground the house. If using the TN-C system, then you cannot make a potential equalization system! This is dangerous for the lives of all your neighbors who did not make SOUP.

Potential equalization system (EPS)

The connection at the entrance to the building of the following conductive elements is called main system potential equalization. They are connected at the entrance to the building, in the input switchgear (IDU) or next to it:

  • Main protective conductor (PE or PEN conductors);
  • Main grounding conductor;
  • Steel communication pipes in the building and between buildings (cold and hot water supply, gas, heating, sewerage);
  • All metal parts building structures, centralized systems ventilation and air conditioning, as well as lightning protection

They are connected to a special main ground bus (GZSh) or clamp.

Additional potential equalization system (APE)

The additional potential equalization system combines, at the same time, accessible to the touch, open conductive parts, third-party conductive parts, as well as neutral protective conductors of all equipment, including plug sockets.

A system of additional potential equalization (APE) is being created in areas with a hazardous environment.

An additional potential equalization system (APE) is required for bathrooms. If the system does not have equipment with neutral protective conductors connected to the potential equalization system, then an additional potential equalization system must be connected to the PE terminal conductor at the input.

Important! The potential equalization system in the bathroom, as well as saunas and baths, is an additional system (DUP), which complements the main potential equalization system (SUP). Install in these premises a local potential equalization system not associated with common system Potential equalization Prohibited!

How to arrange an additional potential equalization system in the bathroom (DUP)

Short. To set up an additional potential equalization system in the bathroom, you need to install a plastic wiring harness in the distribution cabinet. junction box with terminal block. It is called a box of additional potential equalization, KDUP or KUP. The box size is standard.

From the PE bus (grounding/neutral conductor) located in the apartment panel, lay copper wire grade PV3-1x6 mm 2 to the additional potential equalization box (APE). From the bus installed in the KDUP with separate wires PV3-1x2.5 mm 2 we connect everything that needs to be combined in the additional potential equalization system. An example in the figure below. Potential equalization wires are laid in corrugation.

Regulatory documents regulating the device of SUP and DUP

Any premises, office, hospital, industrial or residential building must be designed based on the following standards, norms and rules:

  • GOST 13109-97 Electrical energy. Compatibility technical means electromagnetic Quality standards electrical energy in general purpose power supply systems;
  • GOST R. 50571.1-93 Electrical installations of buildings. Basic provisions;
  • GOST R. 50571.2-94 Electrical installations of buildings. Main characteristics;
  • Rules for the construction of electrical installations (PUE ed. 7). Clauses: 1.782; 1.7.83; 1.7.87; 1.7.88. Figure:1.7.7.

About the main and additional potential equalization systems and their functional purpose.

Residential building. Many floors and apartments. Whole kilometers of communications: wires, metal pipes, ventilation ducts, metal hoses and the like. Our apartments have various metal bathtubs, sinks, and who knows what else. In other words, the whole house is simply full of elements and structures that can conduct electric current, but are often not designed for this.

However, each conductor has electric potential. It's just a law of physics. Potential is a relative value. This means that the electric potential, for example, metal surface The refrigerator itself has no meaning at all. The only important thing is how much higher or lower it is than the potential of the water pipe passing from it (the refrigerator) in relative proximity.

If there is a difference between the potential of the refrigerator and the potential of the pipe, then this difference can be considered voltage. Someone may assume that such a voltage cannot be of a significant value: after all, both the body of the electrical appliance and the water pipe should not be “out of phase”. But there is no need to rush to conclusions. In reality, there are many reasons why even an innocuous metal ventilation duct can acquire a dangerously high relative electrical potential.

Among these reasons, for example, is not only the failure of the insulation of phase conductors of power supply system cables, but also atmospheric overvoltages, stray and circulating currents of grounding systems, and much more.

So what should we do? How can we protect ourselves from all these misfortunes and live peacefully, without fear that one day we will be electrocuted by our own bathtub?

This issue is resolved by creating potential equalization systems. The idea is quite simple. If live parts have direct electrical connection, then their potential is always the same, and tension between them will not arise under any circumstances.

Therefore, the potential equalization system includes everything that can become dangerous: namely metal pipes, metal structures of the building, lightning protection devices, ducts, trays. All this connects to main ground bus (GZSh) at the building entrance. Such a system is called main potential equalization system.

But until engineering communications reach a separate apartment located on some high floor, the distance from the main building can become impressive. The laws of electrical engineering characteristic of so-called “long lines” will come into force.

In accordance with these laws, the resistance of long-distance conductors cannot be neglected. That is, the electrical potential of the same metal pipe at the entrance to the building and on the fifteenth floor can differ, and very much. Thus, the main potential equalization system becomes less and less effective as it moves away from the main shield.

Therefore, each apartment has its own additional potential equalization system. The elements that are included in it are connected to the PE (or PEN) bus in the apartment or house panel. These are again water pipes, ventilation ducts, and besides this, bathtubs, sinks and other bulky metal objects.

Additional potential equalization system in the bathroom

Not every electrician who undertakes repairs or repairs knows about potential equalization systems and attaches due importance to them. Therefore, it is better for each homeowner to monitor the condition and quality of such a system in his apartment on his own, without relying on anyone else. After all, this is a question, first of all, of personal safety.

Alexander Molokov,