The topic of making a grounding device for their own or not their own individual residential building worries a fairly large number of people. On the Internet and in books written by some respected authors, as a rule, the same implementation option is given grounding device in the form of a "triangle", in which the electrodes are located at a distance of 1-3 meters from each other, which is actually equivalent to 1 vertical ground electrode. In addition, it is not known for certain where this scheme originally came from and who calculated it. Yes, I myself used it in my articles - what can I say.
It's time to improve :)
Recently on one of the forums I came across standard design (hereinafter TP) series 5.407-155.94, which was approved by the Electricity Department of the Ministry of Fuel and Energy of the Russian Federation (link to it at the bottom of the article), in which you can find the necessary information on the implementation of the grounding device for an electrical installation private house.
This project is not without flaws, for example, in terms of terminology, since it was released before the appearance of the complex standards GOST R 50571, but, nevertheless, in it you can find the implementation of the grounding device we need for an individual residential at home. The sketches of the grounding circuits shown there have been developed and used since the times of the USSR, which indicates a sufficient test of time in practice and, therefore, high reliability.
Using TP by example
To begin with, let's agree that according to GOST R 50571.5.54–2013, the grounding device of the electrical installation of the building consists of the following components:
1) Ground electrode (also called ground electrode)
2) Grounding conductor
3) The main grounding bus - hereinafter GZSH
Next, we need to know the specific resistance of the type of soil in which the grounding electrodes will be located. For example, the soil type is clayey sand. The calculated resistivity of clay sand is ρ = 220 Ohm * m. Then, according to 5.407-155.94.1-57, we select a suitable sketch of the ground electrode system (in our case, this is circuit N4). I slightly modified it to comply with the GOST R 50571.5.54–2013 standard and it turned out as follows:
This grounding device, according to TP, is relevant for soil types with a calculated ρ ≤250 Ohm * m. And it consists of:
- 2 vertical grounding electrodes, 3 meters long and located at a distance of L ≥ 6 m.
- one horizontal ground electrode connected to the grounding conductor.
- GZSH installed in the building (not shown in the sketch) and connected to the grounding conductor. The GZSh itself is connected with a protective conductor to the ASU protective bus.
Some technical details:
- The grounding electrodes are deepened so that their upper part is 0.5 meters below the ground surface.
- The minimum dimensions for buried electrodes and grounding conductor can be found in the table 54.1 GOST R 50571.5.54–2013. For example, for a round vertical grounding electrode made in the form of a hot-dip galvanized steel rod, the minimum diameter is 16 mm. And for a horizontal grounding electrode and a grounding conductor made in the form of a round wire made of the same steel, the minimum diameter is 10 mm.
- Parts of the earthing switch that are in the ground, according to TP, should be interconnected by means of electric welding with a double seam. The length of the weld, in this case, is greater than or equal to 6 largest diameters with a circular cross section. That is, if we need to weld together two electrodes with a diameter of 20 and 16 mm, then the length of the welding seam should be at least 6 * 20 = 120 mm
- GZSH must have clamps for connecting protective conductors and protective conductors of equipotential bonding. These clamps must allow the connection of conductors with a cross section of ≥ 16 mm2. GZSh should have one or two clamps for connecting grounding conductors with a diameter of ≥ 10 mm.
Important! The article is for informational purposes only. To dive into more detailed technical details, I highly recommend that you study typical project 5.407-155.94and also explore electrician termswhich I have highlighted in bold in the article.
I also recommend reading my other articles:
1) Selectivity of household circuit breakers as an example in simple language
2) How to use UDT (RCD) in electrical installations of private houses and apartments?
3) How to color-code conductors 100% correctly? Putting an end to disputes