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 damage electric shock.
Potential equalization and its purpose
The potential difference 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 household appliances, lamps, etc. are connected by metal conductors to each other. As a result of the electrical connection that arises between them, all metal objects have the same potential.
But that alone is not enough, it is also necessary to discharge the energy of the electric current that arises in unforeseen circumstances safely into the ground, therefore 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 an 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 premises on electrical safety due to humid conditions and concentration there metal pipes, it is in it or immediately next to it in the bathroom that it is placed plastic box with a tire. 
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:
Electricity has long been an integral part Everyday life each of us. People are so accustomed to this benefit that they sometimes forget about the dangers that may arise during the operation of electrical installations (household electrical appliances). On initial stage designing the energy supply of any facility, Special attention is given to safety. Almost all users of electrical appliances know what a bare wire, insulation, and grounding are. But the term “potential equalization” is familiar only to professional electricians. If we don't see external signs problems, a false sense of absence of danger arises. And this despite the fact that AC voltage above 42 volts can be fatal to humans.
When can voltage or electric current pose a threat to health or life?
The presence of voltage (or potential) in itself does not pose any problem. The danger is electrical current. It occurs when there is a potential difference between the ends of the conductor.
It is important to know! The human body is good guide for electric current, due to the presence of fluid in the cells.
What is potential difference
For example, let's take a regular AA battery. On its positive contact there is a potential of approximately 1.5 volts, on the negative one - 0 volts. If you connect measuring device(multimeter) with the 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 is this happening? 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.), electric current will flow between them.
How does this work using electrical appliances as an example?
Let's take a 220 volt household outlet. At the phase contact there is a potential of 220 V, at the zero contact - 0 V. Between them there is a potential difference of 220 volts. If you connect the contacts with a piece of wire with low resistance (conventionally 1 Ohm), then an electric current of 220 amperes will arise 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 grabs two contacts, then despite the high resistance of the body, the current strength will be enough to cause a fatal outcome.
All devices that produce electricity have a zero contact connection to the “ground”: literally to the physical ground. This means that between any phase wire and the physical ground there is always a potential difference equal to the phase voltage.
The same thing happens in indoor conditions (residential, industrial, etc.). A phase can be supplied to the body of the electrical appliance. This can occur in an emergency: damage to the insulation, moisture entering the contact group, or a malfunction of the power supply. If you simultaneously touch a live enclosure and an element of the premises infrastructure that has an electrical connection to physical ground (for example, a pipeline), there is a danger of electric shock.
If the electrical appliance is properly connected to grounding, the phase on the housing is connected to ground: short circuit, and the circuit breaker disconnects the circuit. No electric shock occurs.
This is an ideal situation when the premises comply with the standards of the Electrical Installation Rules (PUE).
In practice the situation may be different
Let’s say your neighbor next door connected the neutral wire to the heating system (we won’t consider the reasons: from simple illiteracy to the desire to rewind the electricity meter). A dangerous potential occurs on metal pipes: from 50 to 220 volts. Theoretically, the voltage should “go into the ground”, since the steel pipes are 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 bathroom heated towel rail has a potential of, say: 170 volts.
You are touching a metal pipe and a grounded washing machine. The same potential difference arises (with a life-threatening voltage), only the source of the problem is not your electrical appliance, but the energized heated towel rail pipe.
As can be seen from the illustration, protective grounding in in this case does not work.
Let's consider another option:
You have a power wire in the wall, next to which there is a water pipe. Under load (for example, the boiler is on or electric oven), EMF (electromotive force) can be induced in the pipe. The water will receive an unwanted potential, up to 50 volts. This may not be a fatal voltage, but when you touch the faucet in the kitchen, you will feel an unpleasant tingling sensation of electric current. Especially if the floor screed contains steel reinforcement, which along the wet walls of the room has contact with physical soil.
In this case, the working ground also does not work.
Reasons for the appearance of electrical potential differences
In addition to obvious conditions, such as breakdown of insulation on the body of an electrical installation, or unauthorized connection to structural elements, there are hidden factors:
- Static voltage. Occurs due to friction (for example, the movement of water in a plastic pipe), dry air, dusty rooms.
- Electrochemical potential accumulation that occurs during 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, TVs).
How to protect yourself from such situations? The electrical installation rules (PUE) provide for a potential equalization system.
Leveling and Leveling
Let's look at the basic concepts and terms:
- Potential equalization- leveling the difference in electrical potential values between the metal elements of an 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 for a person to simultaneously touch conductive parts. It is achieved by non-disconnecting connection of all current-carrying parts to each other using conductors.
- Potential equalization is a system for reducing the relative difference in electrical potential between grounding, accessible conductive parts of electrical installations, the surface of the earth and all metal structures of the building. To do this, the potential equalization system must have an unbreakable connection with the working (protective) grounding conductor.
In addition, potential equalization includes reducing the electrical potential difference on the ground surface (floor, ceilings) to prevent the effect of step voltage.
What does the term "unbreakable" mean? All current-carrying lines are permanently connected to each other (contact blocks, screw connections, soldering, welding, etc.). It is not allowed to install disconnecting devices: fuses, switches, circuit breakers. That is, the entire potential equalization system is a single conductive circuit combined with a similar circuit protective grounding.
Thanks to these systems, in all points that a person can simultaneously touch, the electrical potential is equalized to same value. The situation when, when touching at the same time, the voltage will be 220 volts at one point and 10 volts at another, is excluded.
Your home becomes absolutely safe.
Important! The system only works when all metal objects without exception are combined. If at least one element or electrical installation is excluded from the connection by conductors, consider that the entire circuit is inoperative.
What is the difference between a potential equalization system and a protective grounding system?
Grounding- this is an intentional non-detachable electrical connection of parts of an electrical installation or circuit with a ground electrode. Designed to reduce voltage (at a point where there should not be any normal conditions operation) to a safe level.
As you can see, the definition does not contain the concept of potential (potential difference). In addition, grounding is carried out only at electrical installations or electrical circuits. Potential equalization also applies to infrastructure elements, as well as metal objects that are not electrical installations.
At the same time, protective grounding works effectively only in conjunction with residual current devices (fuse links, automatic switches). Without such devices, 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 not required. The only condition is that there is an electrical connection to physical ground.
Requirements for organizing a potential equalization system in the PUE
There is no clear and universal definition of this system in the Electrical Installation Rules. The potential equalization device is specific depending on the location of application. IN different types premises, when working with various types electrical installations and laying current-carrying lines, there are their own methods.
For example, consider the application of portable protective grounding during repair work in electrical installations with three-phase power:
All current-carrying busbars within one electrical installation are connected to each other (potential equalization) and then connected to the ground electrode (potential equalization). If voltage appears on any of the parts, there will be no difference in electrical potential, the work is carried out in safe conditions.
The PUE has a list of protective measures, where this system is mentioned as one of the points required for use:
- organization of protective grounding;
- automatic power supply shutdown;
- equalization of potentials;
- potential equalization;
- double or reinforced insulation of conductors and electrical installation housing;
- organization of low voltage power supply (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. Exist general rules installations that need to be performed:
What objects are connected to the potential equalization system
- Metal enclosures of all electrical installations (unless they are properly grounded). The list also includes conductive housings of lamps (floor lamps).
- Of course, the entire protective grounding system. Actually, this is where the potential equalization system begins.
- Metal parts of the building frame, reinforcement of the foundation, walls, ceilings.
- Self installed metal elements infrastructure. For example, steel mesh under a floor screed or metallic profile under sheets of drywall.
- Metal pipes and casings of the ventilation system.
- Copper pipes of the refrigerant supply system in air conditioners (if they are long).
- Metal sheaths of armored cables.
- Screen braiding of information cables (television, Internet).
Let's dwell on this point in more detail. The braided cable starts from a distribution or amplification device that is located far outside your premises. However, you have no way to control the correct power supply or grounding of these devices. A situation may arise when a phase comes across the screen to your house.
You, without suspecting anything, can simultaneously touch the live braid and the 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 on the cable is not dangerous.
- All metal parts of the water supply and sewerage system: pipes, faucets, stainless steel sinks, trays and metal shower cabins, 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 general system and its own grounding conductor at the same time.
- Metal-plastic window frames (if the conductive elements are not covered with plastic).
- Steel doors and door frames.
In the diagram it looks like this:
- Potential equalization bus.
- Lightning arrester from the power panel. Connected to phase. In the normal state, there is no contact between the phase and grounding conductors - there is sufficient gap in the arrester. When struck by lightning in power cable, an arc current to ground occurs, and a potential difference of several thousand volts will not arise.
- Data line surge suppressor.
- Brackets for fastening grounding conductors to metal pipes.
- Foundation grounding switch with bus included in common system potential equalization.
Installation of a potential equalization system for an apartment building (industrial premises)
Installation of system elements begins during the construction process. When creating the foundation, a metal bus is laid along the entire perimeter of the future structure. This is a closed conductor (steel strip or reinforcement) with welded branches for connection to grounding conductors, and for internal wiring conductors. To ensure uniform spreading of potential in physical land, several groups of grounding conductors are installed along the contour of the building at an equal distance. If possible, equal distance is provided between them.
From the common bus, branches are made into each section (entrance), where the input power supply panel is installed. A grounding shield is formed, connected to a potential equalization system.
It is located in the panel room, or in basement. Access to the shield must be limited (unless it is a private house). Only representatives of the energy company, or state unitary enterprise, are allowed to perform maintenance.
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 carried out.
The ceiling reinforcement is welded to the vertical elements of the system. If necessary, bus transitions are made from room to room.
After the construction of the walls, external wall a conductive busbar is laid for lightning protection installed on the roof. All these conductors are part of the potential equalization system.
Bends in the form of reinforcement or steel strips must be made into the shafts through which vertical pipelines (risers) are laid. After installation of water supply and sewerage systems, steel pipes conductors are welded to connect to the potential equalization system.
Important! In old houses where they were held repeatedly renovation work(without major repairs), there may be plastic inserts in the risers.
This means that the integrity of the potential equalization system has been compromised. It is recommended to duplicate the connection by simply connecting the grounding conductor to the grounding bus. This can be done using a contact clamp.
Information for reference
To maintain aesthetics, in residential buildings A potential equalization bus is not created in each apartment. Its role is played by the grounding bus located in the input panel. According to modern electrical safety requirements, in all access shafts with risers, a steel strip is laid (for the potential equalization system), connected to protective grounding. It seems to loop the general circuit in a second circle, duplicating the grounding.
When creating your own system in an apartment, you can use this connection point. By creating your own panel, you can connect objects that are not electrical installations to it. For example, a bathtub (if it is not made of acrylic or plastic).
To do this, there must be a special contact on the case. If it is not there, 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 the grounding conductors (this is a topic for a separate article), you lay a potential equalization bus together with the grounding. Parallel wiring is made from it in accordance with the rules:
- Standard grounding points for sockets and electrical installations. Including conductive enclosures.
- Connection of the entire 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 house, you can optimize costs by providing several basic panels for grounding connections and a potential equalization system. This will save the grounding conductor when wiring to different rooms.
- In the bathroom it is necessary to create an additional potential equalization system, even if there is a main one in the house.
- When installing electrical heating elements"warm floor" systems, it is recommended to lay on top steel mesh. Then the reinforcement is connected to the potential equalization system, and the final screed or self-leveling mixture is poured.
- If your water supply is normally grounded and connected to the mixer small area metal-plastic pipe(this scheme is widespread), the mixer body must be grounded with a separate conductor. This is especially true for the bathroom.
- The differential protection system (RCD) of an electric boiler does not conflict with potential equalization. Sharing is acceptable.
Non-residential premises
IN technical rooms, workshops, in production, a potential equalization bus (usually representing a working grounding) is laid open method By interior wall. The grounding conductors of electrical installations, as well as lines connecting all conductive elements of the room, are connected to it. This creates an ideal potential equalization system.
IN office buildings so as not to spoil interior decoration, you can hide the tire in a decorative plastic box for cable laying. Owners often ignore grounding conductors from heating radiators. This is unacceptable - most cases of electric shock occur when equipment and radiators touch simultaneously.
Important!
Office premises are more dangerous in terms of the occurrence 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 the connection of a phase wire with the braid of an Internet cable. Therefore, before starting work in such a building, spend a little time and money checking the protective grounding and potential equalization systems. You will save both the health of your employees and your office equipment.
Bottom line
After studying the material, you have learned to distinguish between safety systems when working in rooms with electrical installations. Behind every requirement of the Electrical Installation Rules is someone’s life. Do not gain sad experience at the cost of your mistakes. The potential equalization system is installed once and provides confidence in safety forever.
Video on the topic
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 baths, car washes, and you never know 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 current-carrying parts have a direct electrical connection, then their potential is always the same, and voltage 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 for now engineering Communication will reach a separate apartment located on some high floor, the distance from the GZSh 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,
Or, in addition to electrical equipment, the building has many other engineering components that are not energized under normal conditions. These are elements such as metal pipelines hot and cold water supply, sewerage, metal ventilation ducts, metal hoses, building structures, etc. In other words, any building has many elements and structures that can conduct electric current, but are often not designed for this.
Each metal part of communications has electrical potential. Due to the laws of physics, these potentials for each metal element may differ, forming a potential difference i.e. electrical voltage.
Electrical voltage between bare metal parts creates a danger to humans. Also, the cause of voltage between non-current-carrying elements can be failure of the insulation of phase conductors of power supply system cables, atmospheric overvoltages (lightning), static electricity, stray currents, and so on.
In order for the potentials of all metal elements to be the same, a potential equalization system . If current-carrying parts have a direct electrical connection, then their potential is always the same, and voltage will not arise between them.
In accordance with current regulatory documents, each building (structure) must have a basic potential equalization system, which should be implemented by connecting to main ground bus (GZSh) electrical installations of the following conductive parts:
— protective conductors;
— grounding conductors of protective, functional and lightning protection grounding devices, if such devices are provided in the electrical installation of the building (structure);
- metal communication pipes entering the building (structure) from the outside: cold and hot water supply, sewerage, heating, gas supply (if there is an insulating insert at the entrance to the building, the connection is carried out after it from the side of the building), etc.;
- metal parts of the building (structure) frame and metal structures industrial purposes;
— metal parts of ventilation and air conditioning systems;
- basic metal parts for reinforcement building structures, such as steel reinforcement reinforced concrete, if possible;
— metal coatings(sheaths, screens, armor) telecommunication cables (in this case, the requirements of the owner of these cables or the organization servicing these cables regarding such connection should be taken into account).
Conductive parts that enter the building (structure) from the outside must be connected to the conductors of the main potential equalization system as close as possible to the point of entry of these parts into the building (structure).
An example of constructing a diagram of a potential equalization system in our projects is given in the article ““.
Sometimes, to ensure safety, in addition to the main potential equalization system, it is necessary to create .
An additional potential equalization system is performed in addition to the main potential equalization system when protective device cannot meet the automatic power-off timing requirements.
In some special electrical installations with an increased risk of electric shock, for example, located in bathrooms and shower rooms, regulations, in which these electrical installations are considered, may require implementation additional system potential equalization under any circumstances.
An additional potential equalization system can cover the entire electrical installation, part of it, or individual devices of the electrical installation.
An additional potential equalization system must combine (by connecting with protective conductors) all exposed conductive parts of stationary electrical equipment and third-party conductive parts accessible at the same time, including, if possible, main metal parts for strengthening building structures, such as steel reinforcement of reinforced concrete.
The protective conductors of all electrical equipment, including plug sockets, must also be connected to the additional potential equalization system.
To perform functions conductors of the main and additional potential equalization systems As a rule, specially laid stationary conductors should be used.
The cross-sectional sizes of the conductors of the main potential equalization system must be no less than 6 mm 2 for copper, 16 mm 2 for aluminum and 50 mm 2 for steel.
The cross-section of the conductor of the additional potential equalization system must be at least 4 mm 2 for copper (if available mechanical protection allowed 2.5 mm 2) and 16 mm 2 for aluminum.
When there is electric shock from metal pipes in the bathroom, this problem can be solved by installing special protection for metal objects, which is called a potential equalization system.
Typically, such protective systems against electric shock are planned and implemented in new buildings. But in old houses this option does not always work. Let's figure out what a potential equalization system is (its abbreviation is SUP), its types, and how you can make it yourself.
Purpose
Let's find out whether a potential equalization system is necessary in ordinary apartment. All objects made of metal conduct electricity. We know this from school physics lessons. In our apartments dangerous places are heating pipes, as well as water supply pipes, drainpipe, running water, heated towel rail in the bathroom, ventilation ducts.
All metal communications in the house are connected to each other. If a potential difference occurs between certain metal objects, for example, a bathtub and a heating radiator, a person touching these two objects at once can result in an electric shock. This happens because the body acts as a bridge between the battery and the bath, so current flows through the person's body from the object having a higher potential to the object with lowest value potential.
A similar case of danger is the appearance of a potential difference on sewer and water pipes. If a current leak occurs on water pipes, when a person washes in the bathroom, there will be a high probability of electric shock when touching the turned on faucet. Water conducts current from the water supply to the sewer, and you close this circuit with your body.
To eliminate the presence of such a danger, it is necessary to equalize the potentials using special system installed in the apartment.
Kinds
There are two types of potential equalization systems:
- Basic (OSUP).
- Additional (DSUP).
BPCS
This is the main potential equalization system, which is a circuit that combines the following elements of this system:
- Ground electrode.
- GZSh is the main grounding bus. It is located at the entrance to the building.
- Metal parts of the fittings of a residential building.
- Ventilation system duct.
- Metal water pipes (hot and cold water supply).
- Lightning protection.
IN early times by combining all these parts there was no danger of potential differences occurring. But today the situation has changed radically, as the owners of many apartments are replacing rotten metal pipes with plastic or polypropylene pipes, which do not conduct electricity. Plastic pipes break the circuit, resulting in a potential difference between different metal parts in the bathroom.
The main type of system has a significant problem, which is that over a significant length of pipes, for example, in a 12-story building, the electrical potential of the same pipe on the first and top floor will make a big difference. It leads to dangerous situation. Therefore, an auxiliary system is needed, which we will discuss below.
DSUP
This system is optional and is located in the bathroom. It includes the following elements:
- Body of a shower cabin or bathtub.
- Towel dryer.
- Pipes: gas, water supply, heating.
- Sewer system.
- Ventilation system box.
Each element of this system is connected by a separate wire to a copper core. The second end of this wire is led out into a special box (KUP).
Exist certain requirements to the creation of a DSUP according to the rules of the PUE:
- You cannot connect the components of the DSUP with a cable.
- It is prohibited to perform DSUP, provided that the apartment does not have a ground loop installed.
- The additional system should not break along its length from the PMC box to the apartment panel. Switching devices cannot be installed in the circuit.
If you do not have such a protective circuit as potential equalization, we will tell you below how you can do it yourself.
Installation of potential equalization system
Installing an auxiliary potential equalization system is not very difficult. It is called the local system. But it is better to carry out such work when carrying out repairs in an apartment, since it is necessary to run a wire to the switchboard from the control panel box under the floor, and this is associated with damage to the floor covering and related repair work.
To begin installation, prepare some materials according to the following list:
- Terminal box complete with copper busbar (SHDUP).
- Copper wires consisting of one core. The cross-sectional area of the wires should be from 2.5 to 6 mm 2, grade PV-1.
- Fastening elements: bolts, clamps, fixing tabs. They are necessary to connect the wires of the entire equalization system with pipes and metal parts.
With such a set of elements, you can begin installing the DSUP. First, a wiring diagram is drawn up to perform correct potential equalization. The diagram also shows the places where the wire passes from the PMC box to the grounding bus in the apartment panel. The figure shows one example of the project.
Next, the communications themselves are prepared for connection, that is, the contact area between the clamp and the pipe is cleaned until a metallic sheen appears. This is necessary for connection reliability. In a dangerous situation, potential equalization will work as expected.
Then connect the wires to each element of the system. If you are sure that the wire will not be damaged, then a wire cross-section of 2.5 mm 2 is sufficient. But if there are any doubts about this, then it is better to use a 4 mm 2 wire. All conductors are led into the box and carried out reliable connection with a tire.
The terminal box for the bathroom must have a degree of protection of at least IP54. a wire with a cross section of 6 mm 2 must be led from the box bus to the apartment switchboard. There is a requirement here that this wire should not intersect with other cables of different lines.
At the end of the work, the wire is connected to the grounding bus of the shield. At this point the installation can be considered complete. To reassure yourself, you can call a qualified electrician to check the operation of the system using instruments, as well as a visual inspection.
Limitations of EMS installation
It is recommended to install the SUP during the construction of the building. But there are some restrictions on its use in already built houses, in which the grounding is carried out according to the TN-C system, with a combined PEN conductor. In such houses it is prohibited to perform potential equalization. Otherwise, when the neutral wire breaks, there is a danger of electric shock for residents of other apartments that do not have an emergency control system. Most often, this restriction applies to multi-storey buildings of an old foundation.
This problem is resolved by switching to grounding according to the TN-C-S system. For this purpose in switchboard At home, on the main grounding bus, the PEN conductor is separated into PE and N wires, the grounding loop is connected and it is connected to the main grounding bus with a copper conductor.
Currently, there is a tendency to replace metal pipes with plastic ones, which do not require their connection to the control system. If you already have additional potential equalization of metal pipes, and you decide to replace the pipes with plastic ones, this will lead to a break in the electrical connection with the grounding bus of the remaining elements made of metal. This will make them dangerous to humans if several parts are touched at the same time.
New construction rules and regulations are aimed at ensuring the correct installation of potential equalization. This system is inspected and checked according to the design before delivery of the house. Electrical safety is created by making electrical connections of all metal parts accessible to human contact with the main grounding bus using PE wires.
The main system is supplemented local systems equalization in places with a high risk of electric shock. We must not forget that when installing the control system, reliable communication must be ensured between the system elements that are connected in a radial manner. In this case, the wire cross-section must be no less than the recommended value.
Potential equalization of lightning protection system
When a lightning strike occurs, a large current strength and the rate of its increase occur. Because of this, a potential difference appears greater than from current leakage in the network. Therefore, to create lightning protection it is necessary to equalize the potentials.
To prevent uncontrolled short circuits during a lightning strike, you need to directly connect electrical devices, metal elements, grounding, protective system from lightning with protection devices. The conductors of the entire system are connected to an equalizing bus, which must be accessible for testing purposes, and it is connected to the ground loop. Large buildings usually have several of these buses. Moreover, they are all connected to each other.
The lightning protection potential equalization system is carried out at the entrance to the building, and in places where safe distances cannot be maintained, for example, at ground level or in the basement.
In a concrete building, or with a metal frame or with a separate lightning protection, lightning protection equalization is performed only at ground level. In tall buildings above 30 meters, lightning protection potential equalization is done for every 20 meters.
Lightning conductive parts are located at a safe distance from the control system to avoid impulse flashovers. If such a distance cannot be ensured, then auxiliary connections are created between the lightning rod, lightning rod and control system. At the same time, they take into account the fact that auxiliary connections make it possible for high potential to enter the building.