Modern standards for the operation of electrical equipment prescribe to provide a room in which there is electricity, a potential equalization system. There should be two such systems - the main one and the additional one. The role of an addition is usually a KUP - an equipotential bonding box that prevents the risk of electric shock to a person.
Content
- Potential difference
- Additional KUP device
- Fitting the leveling box
- Lightning protection design
Potential difference
Inside buildings, there are many elements that are conductors of electricity. If these conductors are not closed, then as a result of certain reasons, a potential difference may form between them. It leads to its occurrence:
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atmospheric overvoltage; - electricity leak due to damaged insulation of power wires;
- incorrect connection of devices or their malfunction;
- the formation of a wandering current;
- manifestation of static stress.
As a result of all these situations, there is a real risk of electrical injury of varying severity (up to death). This is especially dangerous in rooms with high humidity - showers, bathrooms. To avoid such serious problems, it helps to combine the conductive elements into a common circuit by connecting them in parallel.
Main system
Steel structures of buildings (fittings, pipes, ventilation ducts, lightning protection and elevator parts) are used as the main potential equalization systems. Due to the large length of these communications, an increase in the resistance of electrical conductors occurs. That is why the potential of pipelines on the upper floors of buildings is much higher than on the first.
To create a single safe circuit, the metal structures are connected to the main grounding bus. At the same time, they adhere to certain rules:
- Do not combine the equalization system wires with the working zero.
- A separate conductor is connected to each element.
All conductors included in the main equalization system must not be interrupted. Therefore, the presence of any switching devices in it is strictly prohibited.
Recently, there has been a tendency for the widespread replacement of old pipes with new ones made of various kinds of plastic. Plastic elements have no connection with the grounding structure and do not have conductive properties; therefore, metal radiators lose protection, a potential difference arises on them. To solve this problem, the ShDUP box (buses of additional equipotential bonding) is used.
Additional KUP device
The add-on system is often used in domestic areas. It includes the following constituent elements:
- Potential equalization box. It is completed with a special terminal block intended for switching additional elements with conductive properties. The size of the PCC depends on the number of such elements. Most often, the box has standard dimensions of 100x100x50 mm.
- Electric cables. For their manufacture, copper wire with a cross section of about 2.5-6 mm is used. Aluminum conductors are not suitable for these purposes, since the thin film formed on them breaks the contacts and the use of an equalization system becomes useless.
When choosing a suitable potential equalization box, you should pay attention to how well the internal terminal block is made. It is also necessary to take into account the name of the manufacturer specializing in the production of the PMC.
Fitting the leveling box
Before installing the potential equalization box, a wiring diagram is required. It allows you to avoid gross errors during the installation process and to determine the most suitable location. The device must be located so that it is easily accessible.
Installation should be started by laying the grounding conductor from the main busbar to the equalization box. Then you need to secure the box. At the stage of building construction, it is easy to place it in a hollow or solid wall, but if the installation is carried out already in a finished room, then the KUP body will have to be mounted in an open way. After fixing the box you can proceed to connecting the following parts:
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Hot and cold water pipes. - Sewer pipe.
- Bath bodies (if it is metal, not acrylic).
- Heating radiator in the bathroom.
- Metal door box.
- Underfloor heating screen.
- Ventilation grilles.
Before joining metal parts, their surface should be thoroughly cleaned. This must be done to ensure the most reliable contact and more efficient operation of the entire system. If plastic pipes are used instead of metal pipelines in the house, then they are used to connect special dielectric inserts, evenly installed along the entire circuit of the potential equalization system.
The wires that will connect the components of the alignment system must pass along pre-planned routes. A separate cable must be routed from each conductor along a radial path to the box. The box also needs to be connected to the outlets and cables using grounding cables.
The most suitable place for the installation of the ShDUP box is the place where the risers pass, since in such case, it is in the public domain, which greatly simplifies the procedure for its technical service. An important condition for operation is the connection of open elements of electrical equipment and third-party conductive parts.
Despite the fact that the ShDUP box has an important protective function, it cannot be installed everywhere. The exceptions are houses of the old foundation, in which grounding is implemented according to the TN-C scheme, when a combined PEN conductor is used. If, in this case, a break in the neutral wire occurs, then the equalized potentials will create a danger of electrical injuries in houses where there is no KUP.
The transition to the TN-C-S grounding scheme will help to correct the situation. It is realized by splitting the PEN conductor located in the switchboard into separate PE and N cables. They are connected to the ground loop and connected using a copper conductor to the main bus responsible for grounding.
Lightning protection design
Lightning strikes provoke the fact that the current strength increases sharply and begins to grow rapidly. The potential difference arising in this case is several times greater than the difference that is formed when electricity is leaking from the network. In order to avoid negative consequences, this difference must be leveled.
This can be achieved by combining electrical devices, metal parts, grounding and protective equipment. Connect the conductors to the equalizing bus, which is connected to the grounding structure.
The lightning protection equalizing system is installed at the entrance to the premises and in places where a safe distance cannot be ensured (on the ground, on the ground floor).
In buildings with a concrete or metal frame, or in places equipped with lightning protection, alignment is carried out at ground level. In buildings of great height, the potentials are equalized every 20 meters.
When installing conductive elements, they must be located at a safe distance from the alignment system. Otherwise, there will be dangerous connections between the control unit, the lightning rod and the lightning rod.
