Basic potential equalization system. Protective measures in electrical installations

Electricity has long been an integral part Everyday life each of us. People are so accustomed to this good that sometimes they forget about the dangers that may arise during the operation of electrical installations ( household electrical appliances). On initial stage power supply design for any facility, Special attention paid to safety. Almost all users of electrical appliances know what a bare wire, insulation, grounding is. But the term "potential equalization" is familiar only to professional electricians. If we don't see the outward signs of a problem, a false sense of no danger arises. And this despite the fact that alternating voltage over 42 volts can be fatal to humans.

When voltage or electric current can pose a threat to health or life

The presence of voltage (or potential) in itself does not pose any problem. The danger is electricity... It occurs when there is a potential difference between the ends of the conductor.

It's important to know! The human body is a good conductor for electric current, due to the presence of fluid in the cells.

What is potential difference

Let's take an ordinary finger-type battery as an example. On its positive contact there is a potential value of approximately 1.5 volts, on the negative one - 0 volts. If you connect measuring device(multimeter) with a positive terminal (using both leads), the value will be zero. And if we measure between "plus" and "minus", we will see a voltage of 1.5 volts on the device.

Why it happens? There is a potential difference of 1.5 volts between the positive and negative contacts. Accordingly, if you connect these terminals with a conductor ( electrical circuit, metal wire, etc.) an electric current will flow between them.

How it works with electrical appliances

Let's take a household 220 volt outlet. On the phase contact there is a potential of 220 V, on the zero contact - 0 V. There is a potential difference of 220 volts between them. If you connect the contacts with a piece of wire with low resistance (conventionally 1 Ohm), then an electric current of 220 amperes will appear in the conductor (according to Ohm's law). Of course, in practice, this cannot be done, the wire will instantly melt, and the insulation will catch fire.

If a person takes two contacts, then despite the high resistance of the body, the current will be enough for a fatal outcome.

All devices that generate electricity have a zero-contact connection to ground: literally physical ground. This means that between any phase conductor and physical earth there is always a potential difference equal to the phase voltage.

The same thing happens in the premises (residential, industrial, and others). A phase can be applied to the body of the appliance. This can occur in an emergency: insulation damage, moisture ingress into the contact group, power supply failure. At the same time touching an energized enclosure and an element of the room's infrastructure that is electrically connected to physical earth (for example, a pipeline), there is a danger of electric shock.

If the appliance has a properly connected ground, the phase on the housing is connected to ground: a short circuit occurs, and circuit breaker disconnects the circuit. Electric shock does not occur.

This is an ideal situation when the norms of the Electrical Installation Rules (PUE) are fulfilled in the room.

In practice, the situation may be different

Let's say your neighbor at the entrance has connected a zero wire to the heating system (we will not consider the reasons: from simple illiteracy to the desire to rewind the electricity meter). On metal pipes ah, a dangerous potential arises: from 50 to 220 volts. Theoretically, the voltage should "go to the ground", because steel tubes laid in the ground. However, if a section of the pipeline is replaced with plastic between your apartment and the basement, the conductor opens. And your heated towel rail in the bathroom has a potential of, say: 170 volts.

You touch a metal pipe and a grounded washing machine... The same potential difference arises (with a voltage dangerous to life), only the source of the problem is not your electrical appliance, but the heated towel rail, which is energized.

As you can see from the illustration, the protective grounding does not work in this case.

Let's consider another option:

You have a power wire laid in the wall, next to which passes water pipe... On load (for example, the boiler is on or electric oven), EMF can be induced in the pipe ( electromotive force). The water will get unwanted potential, up to 50 volts. It may not be a lethal voltage, but when you touch the faucet in the kitchen, you will feel unpleasant tingling with an electric shock. Especially if there is steel reinforcement in the floor screed, which has contact with physical soil along the damp walls of the room.

In this case, the working ground also does not work.

Reasons for the appearance of an electrical potential difference

In addition to obvious conditions, such as breakdown of insulation on the case of an electrical installation, or unauthorized connection to structural elements, there are hidden factors:

• Static stress. It occurs during friction (for example, the movement of water in a plastic pipe), dry air, dustiness of premises.
• Electrochemical accumulation of potential arising from the interaction of dissimilar metals.
• Atmospheric phenomena (thunderstorm, strong wind) contribute to the accumulation of electrical potential.
• Stray and induced currents, electromagnetic radiation (microwave ovens, switching power supplies, monitors, televisions).

How to protect yourself from such situations? Electrical Installation Rules (PUE) provides for a potential equalization system.

Leveling and leveling

Let's analyze the basic concepts and terms:

• Potential equalization- leveling the difference in values electrical potentials between the metal elements of the electrical installation, in the room where the electrical installation is located, including the conductive elements of the building. In this case, a situation is considered dangerous when it becomes possible to simultaneously touch a person with conductive parts. It is achieved by non-disconnected connection of all live parts with each other using conductors.
• Potential equalization is a system for reducing the relative difference in electrical potential between grounding, touching conductive parts of electrical installations, the ground surface and all metal structures of the building. For this, the potential equalization system must have a non-disconnectable connection to a working (protective) earthing switch.

In addition, potential equalization refers to the reduction of the electrical potential difference on the ground surface (floor, floors) to prevent the effect of step voltage.

What does the term "non-disconnectable" mean? All conductive lines are permanently connected to each other (terminal blocks, screw connections, soldering, welding, etc.). Installation of disconnecting devices is not allowed: fuses, switches, circuit breakers. That is, the entire potential equalization system is a single conductive loop combined with a similar protective ground loop.

Thanks to these systems, at all points that a person can touch at the same time, an equalization of the electric potential takes place up to the same value... The situation when, while touching at one point, there will be a voltage of 220 volts, and at another 10 volts, is excluded.

Your home becomes completely safe.

Important! The system works only when all, without exception, metal objects united. If at least one element or electrical installation is excluded from the connection by conductors, consider that the entire circuit is not operational.

What is the difference between the potential equalization system and protective grounding

Earthing is a deliberate non-detachable electrical connection of parts of an electrical installation or a circuit with an earthing switch. Designed to reduce voltage (at a point where it should not be under normal operating conditions) to a safe level.

As you can see, there is no concept of potential (potential difference) in the definition. In addition, the organization of grounding is carried out only on electrical installations, or electrical circuits. Equipotential bonding applies to infrastructure elements as well as metal objects that are not electrical installations.

At the same time, protective grounding works effectively only in combination with residual current devices (safety inserts, circuit breakers). Without such devices, the organization of grounding does not reduce the safety of electrical installations, and can lead to a fire if a phase-to-ground fault occurs.

Unlike grounding, the potential equalization system is self-sufficient; additional protective devices are not required. The only condition is the presence electrical connection with physical earth.

Requirements for the organization of the potential equalization system in the PUE

There is no clear and universal definition of this system in the Electrical Installation Code. The potential equalization device is specific depending on the place of use. V different types premises when working with different kinds electrical installations and the laying of current-carrying lines, there are methods.

For example, consider the imposition of a portable protective grounding, when carrying out repair work in electrical installations with three-phase power supply:

All busbars within the same electrical installation are interconnected (potential equalization), and then connected to the earthing switch (potential equalization). When a voltage appears on any of the parts, there will be no difference in electrical potentials, the work is carried out in safe conditions.

The PUE contains a list of protective measures, where this system is mentioned as one of the points that must be applied:

• organization of protective grounding;
• automatic shutdown of voltage supply;
• equalization of potentials;
• potential equalization;
• double or reinforced insulation of conductors and the body of an electrical installation;
• organization of power supply with low voltage (for alternating current- not higher than 50 volts);
• protective separation of electrical circuits;

Creation of potential equalization systems

The design of each system is individual, and is developed in accordance with the configuration of the room. Exists general rules installation that must be performed:

Which objects are connected to the potential equalization system

• Metal enclosures of all electrical installations (if they are not properly grounded). The list also includes conductive housings of lamps (floor lamps).
• Of course, the entire protective grounding system. Actually, the potential equalization system begins from it.
• Metal parts of the building frame, reinforcement of the foundation, walls, floors.
• Self-installed metal infrastructure elements. For example, steel mesh under the floor screed or metal profile under drywall sheets.
• Metal pipes and casings of the ventilation system.
• Copper pipes of the refrigerant supply system in air conditioners (if they are long).
• Metal sheaths for armored cables.
• Screen braiding of information cables (TV, Internet).

Let us dwell on this point in more detail. The braided metal cable starts from a distribution or amplification device that is located far outside your room. At the same time, you do not have the ability to control the correct organization of power supply or grounding of these devices. A situation may arise when a phase will come to your house on the screen.

Without suspecting anything, you can simultaneously touch the live braid and a grounded metal object (for example, a heating radiator). The consequences are obvious - electric shock. When connecting the screen to the potential equalization system, external phase breakdown to the cable is not terrible.

• All metal parts of the water supply and sewerage system: pipes, mixers, stainless steel sinks, pallets and metal shower cubicles, bathtubs.
• Components of water heating systems: boilers, internal pipes.
• Heating system: pipes, radiators, heated towel rails.
• Gas supply system.
• Lightning protection grounding (if you have a private home, in apartment buildings"Option" is not available). In this case, the lightning rod is connected to the common system and its own ground electrode at the same time.
• Reinforced-plastic window frames (if the conductive elements are not covered with plastic).
• Steel doors and door frames.

On the diagram, it looks like this:

1. Potential equalization bus.
2. Lightning arrester from the power board. Connected to the phase. In a normal state, there is no contact between the phase and grounding conductors - there is a sufficient gap in the arrester. When lightning strikes power cable, an arc current to ground occurs, and a potential difference of several thousand volts will not occur.
3. Data line surge suppressor.
4. Brackets for fastening grounding conductors to metal pipes.
5. Foundation earthing switch with a bus included in common system potential equalization.

Installation of a potential equalization system for an apartment building (industrial premises)

The installation of system elements begins during the construction process. When creating the foundation, a metal bus is laid around the entire perimeter of the future structure. This is a closed conductor (steel strip or reinforcement) with welded branches for connecting to grounding conductors, and for internal routing of conductors. To ensure uniform spreading of potential into the physical earth, several groups of ground electrodes are installed along the contour of the building on equal distance... If possible, an equal distance is ensured between them.

From common bus branching is performed in each section (entrance), where the input power board is installed. A grounding shield is formed, connected to the potential equalization system.

It is located in the panel room, or in basement... Access to the flap should be limited (if it is not private house). Only representatives of the energy company, or SUE, are allowed to service.

Important! The entire contour (frame) system is connected to each other by welding. Only after checking the reliability and electrical conductivity of the connection, is the final pouring of concrete made.

Floor reinforcement is welded to the vertical elements of the system. If necessary, bus transitions are made from room to room.

After the walls were erected, outside wall a conductive bus is laid for lightning protection installed on the roof. All these conductors are included in the potential equalization system.

Bends in the form of reinforcement or steel strips into the mines, along which vertical pipelines (risers) are laid, are obligatory. After the installation of the water supply and sewerage systems, conductors are welded to the steel pipes to connect to the potential equalization system.

Important! In old houses where renovation work(without overhaul), there may be plastic inserts in the risers.

This means that the integrity of the potential equalization system is violated. It is recommended to duplicate the connection by simply connecting the grounding conductor to the ground bus. This can be done using a contact clamp.

Information for reference

To maintain aesthetics, no potential equalization bus is created in residential buildings in each apartment. Its role is played by the grounding bus located in the lead-in box. According to modern electrical safety requirements, in all access shafts with risers, a steel strip is laid (for the potential equalization system), connected to a protective ground. It kind of loops the common circuit in the second circle, duplicating the grounding.

When creating your own system in an apartment, it is allowed to use this connection point. By creating your own shield, you can connect objects that are not electrical installations to it. For example - a bath (if it is not made of acrylic or plastic).

For this, there must be a special contact on the body. If not, use standard fasteners.

Creation of a potential equalization system in a private house

The principle is the same as in multi-apartment housing, only the amount of work is significantly less. After installing ground electrodes (this is a topic for a separate article), you lay a potential equalization bus joint with grounding. Parallel wiring is made from it in accordance with the rules:

• Standard grounding points for sockets, electrical installations. Including conductive housings.
• Connection of all metal infrastructure of the building, including lightning protection on the roof.

To estimate the number of objects covered - take a look at the illustration.

Connection points are marked with circles.

When building a new home, you can optimize costs by providing several basic shields for connecting grounding and potential equalization systems. This will save the grounding conductor when wiring to different rooms.

• In the bathroom, you need to create additional system equalization of potentials, even if the house has a main one.
• When installing electrical heating elements underfloor heating systems, it is recommended to lay a steel mesh on top. Then the valve is connected to the potential equalization system, and finishing fill screeds or self-leveling mixture.
• If your water supply system is normally grounded, and small area metal-plastic pipe(such a scheme is widespread), the mixer body must be grounded with a separate conductor. This is especially true for the bathroom.
• Differential protection system (RCD) electric boiler does not conflict with potential equalization. Sharing is acceptable.

Non-residential premises

V technical rooms, workshops, in production, the potential equalization bus (as a rule, which is also a working ground) is laid open way on inner wall... Grounding conductors of electrical installations are connected to it, as well as lines connecting all conductive elements of the room. Thus, an ideal potential equalization system is formed.

In office buildings so as not to spoil interior decoration, you can hide the tire in a decorative plastic box for cable laying. Often, owners ignore grounding conductors from heating radiators. This is unacceptable - most cases of electric shock occur precisely when the equipment and radiators are touched at the same time.

Important!
Office premises are more dangerous in terms of potential differences in the most unexpected places. Uncontrolled tenant neighbors can throw up any "surprise" in the form of voltage in the water supply system, or connecting a phase wire with a braided Internet cable. Therefore, before starting work in such a building, spend some time and money checking the protective grounding and potential equalization systems. You will save both the health of employees and office equipment.

Outcome

After studying the material, you learned to distinguish between security systems when working in rooms with electrical installations. Someone's life is behind every requirement of the Electrical Installation Rules. Don't get bad experience at the cost of your mistakes. The equipotential bonding system is installed once, and gives confidence in safety forever.

Related Videos

Equalization of potentials is intelligible. Every person who studied physics at school remembers that any conductor is endowed with its own potential. The potential itself does not pose any danger, the difference in potentials that any metal product has is dangerous. The more significant the difference, the higher the likelihood of getting an electric shock. How is potential equalization carried out?

What is the point of potential equalization?

Such a phenomenon as a potential difference can be triggered big amount various factors. Some of them look like this:

- Overvoltage in the atmosphere;

- Wandering clots of energy;

- Static stress;

The most dangerous is such a potential difference, which arises as a result of voltage leaks from faulty sections of electrical wiring by means of things made of metal or electrical household equipment. As an example, consider the following situation: a person living in multi-storey building while in his bathroom, he touches a pipe made of metal and receives an electric shock. A similar situation arose due to the fact that the insulation of an electrical appliance located in another apartment is faulty. Due to faulty insulation, the potential of the metal pipe changed and a person who touched it received an electric shock.

In order to carry out the potential equalization of all electrical devices that can be dangerous, they must be combined. The easiest way to perform this manipulation is with copper wire, combining nearby devices, pipes and other objects. By creating a common circuit between pipes or between devices, a person equalizes the potential.

However, combining all potentially dangerous objects is not enough. For complete safety in the process of using electrical household appliances, it is necessary that the wiring is grounded.

Potential equalization system

The potential equalization mechanism is sufficient important system... At the same time, everyone who wishes, having the necessary information at their disposal, can assemble such a mechanism with their own hands, without involving outside assistants. The installation of such a system is carried out in 5 stages, these stages look as follows:

- Installation of a box in which the grounding bus will be placed;

- Installation from the bus and connection of an insulated copper electrical cord. The section of the cord should not be less than 4 millimeters;

- Separate cords are placed in a pre-prepared channel inside the wall, which will connect the devices to each other. This is how the potential is equalized.

Modern apartment buildings equipped with various engineering systems and numerous household appliances, the metal elements of which serve as conductors of electric current and have their own potential. During normal operation, the potential is close to zero and does not differ from the potential of the surface and other surrounding objects. In the event of an accident, for example, insulation damage or potential drift through pipes, the potential of conductive parts can rise to several hundred volts. When a person touches two objects with different potentials at the same time, there is a danger of electric shock. The cause of voltage on metal conductive parts can be not only damaged insulation, but also static electricity, as well as stray currents grounding systems. If an electric current flows through the grounding device, it also becomes energized and does not guarantee a sufficient level of safety.
Reliable protection provides a potential equalization system (PFC), organized according to the principle of electrical connection of all conductive parts of the building accessible to touch with a zero protective PE conductor. In this case, potentially hazardous metal elements will have the same potential, which reduces the likelihood of electric shock when touched at the same time.

Standardization of the equipotential bonding system

Additional potential equalization system

In areas of increased risk of electric shock to people, such as a bathroom, sauna, kitchen or shower room, an additional potential equalization system (APE) should be performed to ensure a sufficient level of electrical safety in the event of an emergency. The additional equipotential bonding system connects all simultaneously accessible to touch open and third-party conductive parts, neutral and grounding protective conductors of all equipment (depending on the type of system), including the protective conductors of the sockets. see clause 1.7.83 of the PUE. The APCS wiring diagram is shown in the figure below.

As can be seen from the diagram, all potentially hazardous conductive structures are connected to the terminal box (bus) in the equipotential bonding box, which makes it possible to organize an EAPS without extending protective conductors from each element to the switchboard of the apartment (house).
A DCSP bus is made of copper with a cross section of at least 10 mm 2, connecting six or more connectors to it.
The KUP is connected to the grounding bus of the input distribution board using a copper protective PE conductor with a cross section of 6 mm2, thus grounding all metal parts of the room. Third-party conductive elements extending outside the premises are also subject to mandatory connection to the DSPP.
In the houses of the new housing stock, the EMS conductors are laid during the construction phase, together with the installation of electrical wiring. If they are absent, for any reason, the conductors can be laid on their own by cutting narrow grooves in the floor screed. Before starting work, you must make sure that there are no other communications in the floor. Conductors are connected to grounded objects with bolted connections, clamps or welding contact lugs, which provides a strong metal bond between them.
DSPP is performed using specially provided conductors or open and third-party conductive elements are used that meet the requirements of clause 1.7.122 of the PUE for protective conductors. see clause 1.7.83 of the PUE. In the absence of mechanical stress, the required cross-section for conductors is 2.5 mm 2 or more. In case of possible mechanical stress, conductors with a cross section of 4 mm 2 or more are used. The connection of two open conductive elements is performed with a conductor with a cross-section of at least the cross-section of the smaller of the protective conductors connected to them. The cross-section of the DSPC conductors connecting the open and third-party conductive parts must be at least half the cross-section of the protective conductor connected to the open conductive part. see clause 1.7.138 of the PUE.

Equipotential bonding limitations

Installation of the EMS is performed at the stage of building construction. However, there is a limitation on its use in existing buildings. In houses with a TN-C grounding system, with a combined PEN conductor, it is strictly forbidden to perform additional equipotential bonding. Otherwise, if the neutral wire breaks, there is a danger of electric shock to the rest of the residents who have not done the DCS. As a rule, this restriction applies to multi-storey buildings of the old housing stock.
The problem is solved if it is possible to switch to the TN-C-S grounding system: why, at the GZSh in the input distribution device of the building, the PEN conductor is divided into PE and N conductors, a ground loop is made and connected to the main grounding bus copper wire... The current tendency to carry out communications (water supply and sewerage) plastic pipes, does not require their integration into a potential equalization system. Replacing metal pipes with non-conductive plastic pipes in an existing DSPC leads to a breakdown in electrical connection with the grounding bus of all other metal elements of the room (batteries, heated towel rails, etc.), making them potentially dangerous to humans if touched at the same time.

Conclusion

Modern norms and construction rules pay special attention to the correct installation of the equipotential bonding system. First of all, it is examined and checked for compliance. project documentation when putting the house into operation. Electrical safety is ensured by organizing the electrical connection of all conductive parts of the building accessible to touch with the GZSh using PE-conductors. The BPCS is supplemented with a potential equalization system in areas with increased risk of electric shock.
It is important to remember that the implementation of the DCS is possible only in houses with grounding systems with separate laying of PE and N conductors. These include modern system grounding TN-S, as well as an upgraded system to the TN-C-S circuit.
When installing the control system, it is imperative to ensure a strong metal connection between its elements, connected in a radial manner, observing the required cross-section of the protective conductors.

see also:

Continuing to analyze the questions safe operation electrical energy, we came to the conclusion that the outdated power supply system, made several decades ago according to the TN-C grounding scheme, can already create emergency situations when connecting powerful modern household appliances.

The presentation of this issue can be found in detail on the topic under consideration. To eliminate cases of possible electrical injuries, it is necessary to switch to another grounding system, made according to the TN-C-S or TT grounding scheme.

Their analysis, advantages and features are given where possible reasons malfunctions and technical methods prevention of their appearance, methods of liquidation by electrical protection in automatic mode.

However, it is worth paying attention to the fact that it will not be possible to completely solve the electrical safety of the house by switching to new standards of the grounding scheme. Applicable protective devices based on and will disconnect consumers in the event of faults in the wiring, but they will not be able to eliminate the possibility of their occurrence.

The reason lies in a large number inside the circuit of open and third-party current-carrying parts, which, in the event of emergency situations, are able to pass various currents through themselves well from extraneous voltage sources.

Vladimir Novikov's video "Electric shock in the children's pool" clearly shows the likelihood of such a case.

They need to be blocked technical means, take away to the side of the ground. This question is assigned to the potential equalization system - the generally accepted electrical abbreviation "SUP".

Purpose of the EMS

Used only in new grounding schemes (it is forbidden to change the TN-C grounding project without recalculating electrical processes), the EMS system equalizes the potentials:

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

How potential equalization differs from equalization

At first glance, two words of the same root in the Russian language are synonymous, but in electrical engineering they are given a different, albeit similar, meaning. The similar name of the two terms creates confusion even among electricians. Therefore, we focus on the issue.

Leveling system

The building scheme is built on metal connection- short-circuiting of open, touch-sensitive conductive parts of stationary electrical equipment and third-party conductive elements, together with metal building structures of buildings, when the potentials of all connected devices are short-circuited to the ground circuit of the electrical installation.

Due to the very small electrical resistance of the connecting elements, the potentials of all shorted parts take on the same value - the potential of the earth circuit.

Leveling system

Here, too, open conductive elements of electrical equipment are assembled in a single circuit and separately - building structures buildings with their own additional section, which is also grounded, but on its own circuit. Therefore, the electrical connection between them is created through a piece of ground that has a higher resistance than a metal bus. Moreover, it depends on the season.

As a result, the potential difference between these chains decreases, approaching the ground potential, but differs from it, albeit insignificantly. As a result, when potential equalization in the protected chain, overflows through the created protective connections are still possible, which will have a negative impact on the safety of the electrical installation.

The effect of the resistance of a chain on the passage of current through it is well explained by the video "Potential drop along the conductor" of the Scientific Institute MEPhI.

Types of soup

By ensuring the safety levels, the control system is subdivided into two types of equalization systems:

1. the main one - BPCS;
2. additional - DSPP.

Let's look at their differences.

Basic BPCS System

V modern conditions during the construction of a building, it is included in the project of the scheme of the house and is mounted before the occupants move in. It includes:

• main bus of the ground loop (GZSH);
• wiring of the "grid" of PE conductors in the building, connected to the GZSH;
• potential equalization conductor system.

The BPCS is entrusted with the function of ensuring the protection of the building from the penetration of electric current from the outside through any metal parts included in it. building elements: water and gas pipeline, metal fire escape, etc.

A high potential accidentally caught in them from an external source of enormous magnitude will instantly reach the building and, thanks to the design of the BPCS, will be instantly redirected to the ground contour, where its energy will be reliably extinguished without causing damage to building structures and internal equipment.

If lightning strikes the lightning protection of the building, then it is immediately directed to the ground through the lightning rod, bypassing the structure and equipment of the house along the shortest path.

The BPCS system is used by different principles in existing:

• for TN-C it is prohibited to use it. If there is a need for equipotential bonding, it is required to switch to one of the new grounding standards;



• in TN-C-S, the PEN conductor coming along the line is connected to the BPCS circuit electrical supply from transformer substation... Moreover, at the entrance to the house through the installed re-grounding, its branching is made through the main grounding bus on PE and N. All third-party current-carrying parts of the PE building are electrically connected to the GZSh by conductors;



• for the TN-S grounding circuit, the protective role of the BPCS is carried out through the GZSh connected to the elements of the building structures through PE-conductors;



• for the TT circuit, an individual grounding of the house is performed and the PE-conductors are connected to it.

Features of BPCS installation

They can be summarized in three important questions:

1. after the GZSh, it is forbidden to combine the working zero N with the PE protective conductors anywhere in the circuit;
2. the only way to connect the components of the BPCS to the GZS is the radial method, when each grounded element of the house is mounted with an individual conductor. The use of a loop in this situation is strictly prohibited;
3. it is forbidden to embed any switching devices into the BPCS circuit.

Additional DSPC system

If the BPCS is entrusted with protecting the entire building as a single structure, then the BPCS has a different task - to ensure the electrical safety of a certain room, for example, a bathroom.

The tasks of the APS appear at the most unexpected moment, when residents begin rebuilding and repairs, violating the integrity construction project... For example, replacing metal water pipes with plastic ones can break the electrical contacts already created for the BPCS. In such a situation, the DSPP reserves the protection and safety of the bathroom and kitchen, eliminating the risk of electrical injuries in them.

To create an EAPS, it will be necessary to combine all the dangerous metal constructions and open conductive parts of the electrical installation with their connection to the ground circuit.

In this situation, you cannot do a typical mistake when grounding is not done. Infiltrated on common connection the dangerous potential will remain on it. When a person touches it with any part of the body, then the discharge current will start flowing through it to the ground: electrical injury is guaranteed.

Ask questions about unclear points of the article and the design of the BPCS in the comments.

What is a potential difference, and why is it dangerous to humans? Any metal object big size(water pipe, heating radiator, bathtub, refrigerator body) is a good conductor of electric current. Even without direct contact with a voltage source, an induced electric current can occur on the surface of these objects, by analogy with step voltage.

How it works

Let's assume that all outlets and electrical appliances in your apartment are grounded. In theory, you feel safe. Your downstairs neighbor replaced sewer pipe from cast iron to plastic. There is now no reliable electrical connection between your cast-iron bathtub and physical earth. A neighbor's insulation broke through in the chandelier, and through the damp floor of your bathroom, a potential of about 100 volts appeared in the bathroom with water.

Since in sewer plastic insert, there was no ground fault and the circuit breaker did not trip. All the potential has accumulated in your bathroom. You touch the mixer while in the water. Through the steel pipes of the water supply, it has a reliable electrical connection with the ground. You get guaranteed electric shock.

Why did it happen?

Any conductor contains electrons. As long as there is no difference in potentials at the ends of the conductor, the electrons stand still, and the electric current does not flow. In the described situation, the water pipe has zero potential along its entire length. Bath with water, due to the spread of voltage from faulty wiring on the floor below, through a segment cast iron pipe, has a potential of 100 volts. These objects do not touch each other, so there is no electric current.

After touching both an energized bathtub and an actually grounded faucet, an electric current flows through your body. Man is 80% water, so he is quite a good conductor. Electrons simply rush from a point with less potential to a point with more potential. Therefore, special attention should be paid to equipotential bonding in the bathroom.

In fairness, if you just ended up with a bathtub energized (without touching anything), and also left it, there would be no electric shock. Have you ever wondered why birds sitting on a power transmission line with a voltage of over 1000 volts do not die from an electric shock? Because they have the same potential as a wire: 1000 volts. They do not touch other wires, there is no potential difference, respectively, there is no electric current through their carcasses.

One more example. Insert a piece of wire (in phase) into the disconnected outlet, and hang it loosely so that it does not touch the wall and floor. Apply voltage - nothing happens. However, there is a potential of 220 volts along the entire length of the wire. It is worth connecting the wire to any object whose potential relative to "ground" is lower, a current will flow through the connector (for example, a person).

Hence the conclusion: any objects that are not energized under normal conditions (with the exception of emergency situations) must always have equal potential. In the case of living quarters - equal to zero. For this, all metal elements of a residential building, including fittings in the walls, are connected to the ground loop even at the construction stage.

It is called: basic potential equalization system (PMO)... A main grounding bus (GZSH) is located near each building, reliably (usually by means of welding) connected to the ground electrode (loop). It is checked periodically special services(over time, it can crumble from corrosion), and is mounted at the stage of laying the foundation.

You can be sure that all metal objects in your high-rise building have electrical contact with the GZSH. Immediately after commissioning, the equipotential bonding circuit works flawlessly. This requirement of the Electrical Installation Code is always respected. Until the repairs begin in the apartments.

What is the danger

• Areas of heating and water supply systems are changed to polypropylene pipes... The physical connection with the ground electrode is lost.
  You cannot rely on water in pipes. Today it is there, and tomorrow the pipe will be dry.
• The neighbor decided to rewind the meter readings, and connected zero to his heating battery. A potential appeared throughout the system: from 220 volts near the neighbor's apartment, to zero in the area where the pipeline is connected to the main grounding bus.
• Someone has a boiler without grounding installed, and it breaks the phase into the water tank. A couple of the nearest floors, receives voltages up to 110 volts in taps with water.
• An "advanced" neighbor electrician organized the grounding of the electric stove to the riser with hot water(it really has good contact with the ground, moreover, it is structurally connected to the GZSH). And after the accident, on the second floor, a piece of steel riser was replaced with plastic. At the neighbor's "electrician", a phase was shorted to the body of the electric furnace, and the entire entrance above the 2nd floor received a potential of more than 127 volts on the riser.

You will say that this is all illegal and prohibited? Yes it is.

But this is the logic of a pedestrian who sees a car rushing towards him and continues to be at the crossing, relying on traffic rules. A pedestrian will be knocked down, the driver will be punished. Who will get better from this?

Do not rely on the fact that everyone around you adheres to the Electrical Installation Code. Therefore, we will organize additional potential equalization.

Equalization or alignment

Many people confuse two basic concepts:

1. Equipotential bonding is a leveling of the potential difference between open conductive surfaces accessible to touch by one person. Refers to piece electrical installations or conductors.
2. Potential equalization is a reduction in the potential difference by large area: soil, concrete floor. For example, in a building, these are the connections of all the reinforcement in the walls to each other, and to the GZSH.

Creation of a system of additional equipotential bonding (DUP)

General rules:

Equipotential bonding in the bathroom is carried out with all the elements located in the bathroom. Even if the incoming pipe is already connected to the ShDUP or SHUPP.

Connection with elements that do not have special contacts for connection is made using clamps, clamps.

The organization of the DUP system in a private house may not be carried out; during the construction and organization of power supply, the main potential equalization system must be installed. To ensure safety, an additional system should be installed in the bathroom.

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