How to protect people living in a private home from electric shock? For this, there is a safety measure, in which the main electrical installation is connected to the ground by means of a conductor. Possessing basic skills, you can make a private home grounding yourself, saving a lot on the services of special organizations.
It is necessary to study in detail the rules for the installation of electrical installations( PUE), the safety of working with devices. The choice of equipment and tools should be approached carefully, giving preference to reliable manufacturers. Before starting work, you should examine the existing equipment and actual house wiring. The initial data are necessary for the correct calculation of the grounding device - the most important component of the entire system.
Earthing a private house with your own hands
As a result, the optimum values of the resistance value, the number of electrodes and the distance between them will be obtained. Then, marking is done on the terrain near the building to determine the best design option. Depending on the type of grounding device selected, the methods of trenching and electrode burial depend. Installation of the installation is the most important stage, depending on the literacy of its performance, it depends on whether the entire earthing system will work effectively.
The role of grounding
Ask a question. Why do we need grounding? The abundance of household appliances and other electrical appliances imposes stringent requirements on housing security. As in any building, the grounding in a private house is the establishment of the contact of the body of the electrical installation with the soil soil. It provides protection of the person from the negative influence of current, and also performs a number of other important functions:
- optimization of electrical installations;
- warning of network problems;
- preservation of working capacity of equipment in case of overvoltages;
- power reduction of high-frequency electromagnetic radiation.
Principle of grounding
When a person comes into contact with a device on the surface of which a voltage has appeared, the electric current is sent to the soil not through his body but through a conductor. It's all about the difference in resistance values: a person has 1 kΩ, and a conductor has 4 ohms. Electric current chooses the easiest and fastest way to earth, which has a high electrical capacity. As a result, the residual current device( RCD) responds to the leakage current in the circuit and turns off the problem area.
Basic concepts
A key element of the system is a grounding device, which can be factory or self-made. It consists of:
This is the earthing conductor and the ground conductor. Photo
1. Earthing switch is a metal construction in contact with the ground. It carries out the descent and dispersion of the current. Types:
- natural( parts of building elements buried in the soil);
- is an artificial( specially manufactured conductors. It is used when the resistance of natural is not the norm).
If a private house is grounded by its own hands, PUE recommends the use of natural earthing:
- steel pipeline;
- street metal structures( pillar, support);
- protective lead coating of power cable;
- metal or reinforced concrete part of the building structure, located in the ground( foundation, column).
2. An earthing conductor is an element connecting the earthing switch and the electrical installation. It represents wires of wires in isolation of yellow color, parts of external and internal contours, a tire in a switchboard.
How to calculate the resistance of the grounding device
The magnitude of the conductivity of the earth electrode directly affects the resistance of the entire system. As the size of the electrode increases, the resistance decreases, and the amount of current received increases. According to the PUE, the maximum permissible resistance values are as follows:
In order to correctly ground in a private house, preliminary calculations are necessary. Example of the formula for a single earthing switch with a circular cross-section:
The initial data is in specialized reference books. To verify the operability of the assembled equipment, a measurement is made directly on site. If the value exceeds the norm, it is required to increase the number of earthing switches or the depth of their location.
When using multiple electrodes, the calculation becomes more complicated. For each, the indicator is given by the formula indicated above, in order to obtain their total value. Further, a utilization factor is used showing the effect of the earthing switches on each other. The most effective distance between electrodes is equal to the length of their penetration multiplied by 2.
The following formula is used to calculate the number of electrodes:
Grounding rules in a private house
Before you can make a ground connection in a private house, you need to familiarize yourself with the ways of its implementation.
Nulling
A working, but not very reliable, way. Through the switchboard passes a wire - zero potential, contacting the body by means of a bolt connection. To ground a new conductor, it must be secured under this bolt or similar fixation is to be made next to it. However, in this case the wire is not protected from combustion at the inlet.
Grounding circuit
Grounding scheme in a private house. Photo
The safest way. How to implement it:
- near the house to dig a pit deep in two bayonets of a shovel. Mechanical drilling of a hole in the ground can not be made, since such a circuit will not work;
- to hammer into the bottom of the pit a metal corner( about 3 m long, 40 x 40 cm wide or 50 x 50 cm wide);
- connect to the angle of the flexible multi-conductor PV-3 wire( section from 6 mm2) and bring it to the shield.
In order for the earthing loop in the private house to have the maximum effect, its construction must have a metal bond: consist of 3-4 corners welded together by a metal strip of similar width.
In addition to direct grounding, at least one of the following conditions must be fulfilled:
- equalization of potential values;
- voltage reduction;
- installation of the device for automatic shutdown;
- using double insulated wires;
- application of isolating transformers.
To help ensure proper grounding in a private house, specially designed and regularly updated PUEs are designed. This regulation prohibits:
- to ground electrical installations to any kind of pipeline, including plastic;
- output the grounding conductor to the outside to connect to the bus on unprotected contact areas.
What will be required for the work of
? As artificial earthing, you can use steel corners, pipes, rods, galvanized electrodes. These elements can not be painted to avoid reducing their conductivity. For anticorrosive purposes, they are treated with special compounds. Other values are equally important:
- the minimum cross-section of electrodes: rectangular rolling - 48 mm2, a rod made of ferrous metal - 10 mm, galvanized - 6 mm. The thickness of the walls and shelves is 4 mm;
- the minimum cross-section of materials for metal connection: rod - 5 mm, rectangular steel - 24 mm2.The thickness of the walls and shelves is 2.5 mm.
Earthing rail. How to make grounding at the dacha
Also grounding in a private house involves the use of tires from electrical bronze. It will require a sledgehammer to penetrate the natural electrode or a jackhammer - for artificial, stepladder, arc welding for black rolled products.
When routing through the rooms you need:
- wire( minimum section for copper non-insulated - 4 mm, insulated - 1.5 mm, aluminum non-insulated - 6 mm, insulated - 2.5 mm);
- socket with earthing contact;
- bracket, plinth or box for fixation and decoration.
Stages of installing a grounding device in a private house
- Preparatory work.
- Deepening of the structure.
- metal connection. Connection to the switchboard.
Preparatory work for .The layout of the location of the earthing switches is made based on several conditions:
- the distance to the foundation is about one meter, the shape of the contour is any: a line, a triangle, a circle, etc.;
- the optimal gap between the electrodes is 1.2 m;
- minimum parameters of the trench: for natural earthers 50 cm deep, width at the depths of 1 m;for artificial - pit 0.5 x 0.5 x 0.5 m.
If metal rolling is used, then for the best immersion in the soil its end can be sharpened by applying the Bulgarian. Material that was in use must be cleaned of any coatings. When mounting the factory module on the electrode, twist the pointed head, and place the joints with a paste.
Deepening of the structure. Metal studs of their own production are driven into the ground by means of a sledgehammer. When the metal is not very hard, it is advisable to put on wooden gaskets for compaction during strokes. The upper part of each earthing switch should leave the bottom of the trench for 15 - 20 cm.
The knockout hammer with a cartridge impact power of 20 - 25 J is buried factory electrodes. At the first lowered to a depth of 1.5 m of the pin, the clutch and the next part of the earthing rod are wound. Then the work continues with a hammer and the joining of other parts until reaching the design depth.
Collection of metal .To connect all the electrodes can be using metal bands to get a ground loop in a private house - the final element of the design. Black metal is joined by a welded seam, non-oxidizable materials - bolted joints.
When the strip is ready, it continues to the side of the house and is attached to the foundation. At the end of the contour, the M8 bolt is welded to fix the conductor. In the factory installation for this purpose, a clamp is hung on the final pin, which is then protected by a waterproofing tape. The trench is buried by dense fine-grained composition or seized ground. In the factory module with one electrode, a plastic well can be provided.
Connection to the switchboard .The conductor can be brought into the house using a plastic or metal pipe-sleeve. Further, its end should be pressed with a bolted connection and connected to the grounding bus located on the housing according to the TT system( when the ground loop is not connected to the zero working conductor N).The yellow wires of the wires must also be clamped in the bus connectors. Multimeter checks the resistance of the grounding device.
Conclusion
It is very important to use high-quality materials and comply with safety regulations. The presence of minimal electrical engineering experience, good awareness of the house in which it is necessary to work and careful preparation of all stages is the key to successful grounding.
