Practically in all objects connected with electricity, it is necessary to protect people from electric shock. Everyone knows why grounding is needed, but few people know how to properly install it so that it fully performs its functions.
If all metal parts of the equipment are connected to the grounding device, then when the potential is placed on them, the electric current will go into the ground. Then, when touching the metal, a much smaller current will pass through a person, which is not dangerous for him.
How is electricity transmitted to consumers?
Electricity comes from the source through power lines, first to the substation, and then to consumers. Three phase wires are used for its transmission. The fourth conductor is earth. In a three-phase network, the substation transformer windings are connected according to the "star" scheme. The common point (neutral) with zero potential is grounded. This is necessary fornormal operation of electrical equipment. Such grounding is called working, not protective.
The apartment is usually supplied with a voltage of 220 V between the phase and neutral conductors to a common electrical panel. In a private house, the input can be 380 V - three phases and a neutral. Then the wires diverge to sockets and lighting fixtures throughout the premises. Here, too, one should not forget why grounding is needed. To protect against electric shock, one more is laid along with the phase and neutral conductors - grounding.
How to protect yourself from electric shock?
One way to prevent or greatly reduce electric shock is to install a grounding device. Why is a ground loop needed? It is necessary for household appliances with metal cases: washing machines, electric stoves, refrigerators, etc.
When building a potential on the metal cases of home equipment, the current should go into the ground. But for this, you first need to make a device in the form of a metal structure that creates electrical contact with the ground. It can be solid or consist of conductive elements immersed in the ground.
Ground socket
Why is it necessary to ground electrical appliances in the presence of metal cases or other elements? This question is clear to many. They can be accidentally energized when the insulation of the wires is destroyed or from a short circuit, which is dangerous for a person at the moment of touch.
This is alsorefers to the metal parts of lamps and chandeliers. In a residential building, a grounding conductor with a cross section of 2.5 mm or more 2 is laid from the electrical panel to each outlet. Why do you need grounding in the outlet? This is necessary to connect the earth through its contact to a household appliance. Otherwise, it would be necessary to lay a bus around the entire apartment and make connections from it to the body of each device, which is not very aesthetically pleasing.
Grounding pins are designed so that they are connected first as soon as the plug from the cord of the household appliance is inserted into the socket. If the sockets are connected by a loop, grounding is connected separately to each of them from the junction box.
Ground installation
So, why do we need grounding in an individual house? It is made in the form of a closed loop. The shape can be any, but the least materials are spent on a triangular one. Along the perimeter of an equilateral triangle, a trench is dug in the ground to a depth of 1 m, and steel pipes or corners 2.5 m long are clogged at the tops. To protect against corrosion, it is better to use materials with zinc or copper coating. Do not paint electrodes. You can only varnish the welding spots.
The electrodes should protrude 20 cm from the bottom of the trench. The circuit is scalded with a strip, and a grounding conductor made of the same material is led from it to the house. A bolt is welded to the free end, and a PE wire with a cross section of 6 mm 2 or more is inserted into the electrical panel. An ohmmeter checks the electrical resistance of the circuit. According to the requirements of the PUE for residential buildings, it should be no more than 30 ohms.
If the indicator exceeds the set limit, additional corners are clogged near the contour, and a jumper is made. In this way, the area of contact of the structure with the ground is increased. To reduce the resistance of the circuit, the wire from it is replaced with copper, which has greater conductivity. After the trench is covered with soil. Crushed stone, screenings or construction debris are not allowed to be used for this. Moisture-retaining material should be used: clay, peat, loam.
Potential equalization
Today even children know why grounding is needed. It is important to ensure that the potential difference on the surface of the earth is reduced so that the person is not affected by touch and step voltages. On the site located above the closed loop, the potential changes smoothly, and outside it, the decline occurs sharply. To prevent this from happening, horizontal steel strips connected to the electrodes are buried outside.
According to the requirements of the PUE, protective grounding is made of copper. There are special kits on sale, but they have a high cost. For grounding structures of private houses, steel parts are usually used.
Conclusion
Summarize. So, why do you need grounding in a private house? First of all, this is due to the protection of people from dangerous electric shocks. It is important to properly equip the ground loop and make the necessaryelectrical appliance connections. The he alth and safety of residents depends on how it is installed and the materials chosen.
