Modern apartments and houses, regardless of whether they are located in large cities or small settlements, are full of electrical appliances for various purposes. People strive to use the available benefits of civilization in full.
Almost every house today has a large set of household appliances, from large ones – boilers, washing machines, air conditioners, garden and construction manual power tools, to small ones – kitchen electrical appliances, TVs, audio-video equipment, computers, hair dryers, medical household appliances, appliances for communication and relaxation.
All of this technology either directly runs on electricity, or uses it to maintain it in working order with chargers. Electrical appliances surround us everywhere – at home, at work, in public places. We can say that electricity has permeated our entire life..
Table of contents
Meanwhile, electricity is a great danger and requires proper handling of electrical consumers. This danger consists in electric shock. Accidental or abnormal contact of voltage to the case or other parts of the devices, which are normally not energized, can be fatal. The grounding of a residential building is aimed at preventing this hazard..
The main document, which sets out the requirements for protective grounding, are PUE (Rules for the Arrangement of Electrical Installations). This document provides for two types of grounding, depending on the function performed: working and protective. Working grounding refers to a professional type of work; it is not required to perform it in a domestic environment. Therefore, in the future, the protective grounding of the house will be considered..
Things are more complicated in the old house. New household appliances won’t plug into old sockets – the plug won’t fit. And the instructions for the equipment indicate that it is strictly forbidden to use it without grounding. We have to figure out whether and in what condition there is grounding in a panel house, if it is an old building, or, even more so, grounding in a wooden house. In recent times, household appliances did not require grounding, and grounding in older homes was optional. With the advent of modern technology, this issue has to be resolved anew. This is especially true for old private houses. In the vast majority of cases, there is no grounding in a private house..
The power supply of residential buildings is carried out only through networks with a solidly grounded neutral. For such networks, GOST R 5051.2-94 regulates the use of grounding according to TN and TT schemes.
A feature of the TN system is that the grounded parts of the consumers are connected to the neutral of the power source by neutral conductors. Includes three schemes:
- TN-C. Neutral conductors – working and protective – are represented by one conductor along the entire length of the line. It is ubiquitous in old houses. Currently deprecated.
- TN-C-S. It is similar to the TN-C subsystem, but at the entrance to the house, the common conductor is split into a zero working one and separately a zero protective one. In this case, it is required to additionally re-ground the residential building. Recommended instead of TN-C.
- TN-S. Neutral conductors – working and protective – are laid separately along the entire length of the line. Provides the greatest security. Recommended in modern construction. Requires the use of a five-core cable in a three-phase network, and a three-core cable in a single-phase network.
Unlike the previous system, in the TT system, the solidly grounded neutral of the power supply is not connected by conductors to the grounded parts of the consumers. For protective earthing of consumers, a separate earthing device is required. The use of the TT system was previously prohibited. Now its use is possible, but only if an RCD is installed in the house. At least one at the entrance to the house. The most expedient and economical grounding systems for a private house according to the TN-C-S and TN-S schemes.
In order to decide how to properly ground the house, you need to find out which of the grounding systems was used in the power line connected to the house.
In old power supply systems, a three-phase system is made with a four-core cable, and a single-phase system with a two-core cable. They do not have a special conductor for protective grounding. And the zero core is grounded at the power source. That is, the TN-C house grounding scheme is used. In most cases, it was this kind of electricity supply that was made to the houses of the private sector. Therefore, grounding in a private house has to be done anew. In this case, it is required not only to make a ground loop of the house outside, which is part of the re-grounding, but also to redo the internal wiring. As a result, a private house grounding scheme of the TN-C-S type is implemented..
If the cable connected to your house has a special conductor for protective grounding, then it is possible to implement the TN-S scheme. Additional re-grounding of the house may be required only if it needs lightning protection.
To ground a private house with your own hands competently and with the expectation of a long service life, it is not at all necessary to be a professional electrician.
Let’s start considering the question of how to ground a house with a simpler case. Let’s imagine that electricity is supplied to your house according to a modern scheme – with a special conductor for protective grounding. In this case, grounding work will only be done inside the house. In the panel where the cable is inserted, there must be two buses:
- for the zero core of the cable;
- for the protective earth conductor.
The zero bus must be isolated from the shield body, and the grounding bus must be fixed directly to the body with electrical contact. Neutral and grounding conductors are connected to the corresponding bus. In this case, the connection of buses to each other is strictly prohibited. The connection to each consumer requiring grounding must be carried out with a three-core cable. The grounding conductor must be connected to the designated terminal. All sockets in the house must be grounded (euro sockets).
If the power supply is made with a cable without a grounding conductor, it is necessary to split the zero conductor in the input panel. The shield should still have a neutral and ground bus. But in this case it is necessary to connect them together. And to consumers, as in the first case, two conductors must be connected – zero and grounding from the corresponding buses. This is called splitting the zero core. In this case, the grounding bus must be connected to a re-grounding constructed directly near the house..
Re-earthing is absolutely necessary when using TN-C-S and TT earthing schemes. When using a TN-S circuit, it may be required for a lightning protection device. Re-earthing is installed directly near the earthed house. Structurally, such grounding includes a ground electrode and a grounding conductor. A metal pin, corner, pipe are used as a ground electrode. Usually, not one, but several ground electrodes are used. Most often, three ground electrodes are taken, from which a triangle-shaped contour is formed. The distance between the earthing switches should be about 2 m. The earthing switches are driven to a depth of at least 2-3 m. A shallow trench is dug between them (about 50 cm). It accommodates horizontal connectors, usually made of strip metal. All ground electrodes are interconnected in the form of a closed loop. The best way to join is by welding. From the circuit, a grounding conductor is also laid along the trench, connecting the grounding circuit with the grounding bus in the lead-in shield. It is not difficult to make such a grounding device at home. But it is better to make grounding in a private house using standard kits offered by the industry, for example, ZANDZ-6, or kits for the implementation of typical grounding schemes: “Crow’s paw”, “Combined grounding”, “House closed ground loop”.
The use of such kits guarantees correct grounding of the house and ensures the safety of people when working with electrical appliances..