In almost all objects associated 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 you connect all the metal parts of the equipment to the grounding device , then when you induce potential on them, the electric current will go into the ground. Then, when touching a metal, a much smaller current will pass through a person, which does not pose a danger to him.
How is electricity transmitted to consumers?
Electricity comes from a source through power lines, first to substations, and then to consumers. Three phase wires are used to transmit it. The fourth vehicle is earth. In a three-phase network, the transformer windings of the substation are connected in a star pattern. The common point (neutral) with zero potential is grounded. This is necessary for the normal operation of electrical equipment. Such grounding is called working, and not protective.
A voltage of 220 V is usually supplied to the apartment between the phase and neutral conductors to a common electrical panel. Entrance to a private house can be at 380 V - three phases and neutral. Then the wires diverge to outlets and lighting devices throughout the premises. Here, one should not forget about why grounding is necessary. To protect against electric shock, along with phase and neutral conductors, another one is laid - grounding.
How to protect yourself from electric shock?
One of the methods that excludes electric shock or significantly reduces it is to install a grounding device. Why do you need a ground loop? It is necessary for household appliances with metal cases: washing machines, electric stoves, refrigerators, etc.
When building potential on the metal housings of home equipment, the current should go into the ground. But for this, you first need to make the device in the form of metal, creating electrical contact with the ground. It can be solid or consist of conductive elements immersed in the ground.
Grounding at the outlet
Why do you need to ground electrical appliances with metal housings or other elements? This question is clear to many. Voltage may be accidentally applied to them when the insulation of the wires is destroyed or from a short circuit, which is dangerous for a person at the moment of contact.
This also applies to the metal parts of fixtures and chandeliers. In a residential building, a grounding conductor with a cross section of 2.5 mm 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 tire throughout the apartment and make connections from it to the body of each device, which is not very aesthetically pleasing.
Grounding contacts are arranged so that they are connected first as soon as the plug from the cord of the household appliance is inserted into the outlet. If the sockets are connected by a loop, grounding is connected separately to each of them from the junction box.
Grounding installation
So, why do you need grounding in an individual house? It is made in the form of a closed loop. The form can be any, but least of all materials are spent on a triangular. 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. For protection against corrosion, it is better to use materials with zinc or copper coating. Electrodes cannot be painted. 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 of the same material is taken away from it to the house. A bolt is welded to the free end, and PE wire with a cross section of 6 mm 2 or more is inserted into the switchboard. 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 around the contour, and a jumper is made. In this way, the area of contact of the structure with the soil is increased. To reduce the resistance of the circuit, the wire from it is replaced by a copper wire with greater conductivity. After the trench is covered with soil. Crushed stone, sifting or construction debris is not allowed 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 earth's surface is reduced so that human contact and step voltage are not affected. On a site located above a closed circuit, the potential changes smoothly, and outside of it a recession 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 the grounding structures of private houses, steel parts are usually used.
Conclusion
To summarize. So, why do you need grounding in a private house? First of all, this is connected with protecting people from dangerous electric shocks. It is important to properly equip the ground loop and make the necessary connections for electrical appliances. The health and safety of residents depends on how it was installed and the materials selected.