Electrical equipment, light, lighting

How to make grounding in an apartment

Today it is difficult to imagine comfort without a variety of household appliances and a variety of lighting devices, but the possibility of their safe use depends on high-quality electrical wiring, as well as the presence of grounding in the apartment. The latter is especially important, since it serves as a reliable protection against electric shock, allows you to save electrical appliances from breakdowns and voltage surges. Unfortunately, on the territory of the CIS, in the houses of the old housing stock, grounding of apartments was not carried out. Only in new houses, starting in 1998, they began to install real electrical grounding.

And if in new buildings the problem with grounding is largely solved, then for houses of the old housing stock it remains relevant. Often, the owners of such apartments begin to think about grounding when they make major repairs or purchase expensive household appliances. And the first thing they encounter is the lack of the possibility of arranging high-quality grounding. There are many reasons for this, but having knowledge of what grounding is, how it is done, and what needs to be done for this, you can complete all the work without much difficulty.

Grounding systems

You can create protective grounding in an apartment in any case, it is important to know where and which wire to connect. To do this, you will have to familiarize yourself with the different types of grounding systems. This is important for a number of reasons. First, houses built at different periods of time use different types of grounding systems. And in order not to confuse anything, you need to understand them at least a little. Secondly, an error in creating grounding can lead to a failure of the entire network as a whole, or even lead to a fire. The safety of the use of electrical appliances and the life of people depend on a properly connected ground..

So, according to GOST, there are the following types of power grid grounding systems: TN-S, TN-C, TN-C-S, TT, IT. The difference between the two is the presence of a separate ground wire. The fact is that in some systems there is “phase”, “zero” and “earth”, and in some – only “phase” and “zero”. The first two letters indicate the nature of the grounding of the power supply and the exposed parts of the conductor. The second part of the marking is of more interest to us. It is from it that you can find out where there is a separate ground wire, and where it is combined with “zero”. So the letter “S” means that the system has a separate wire for “zero” and a separate one for grounding. The letter “C” indicates that “ground” and “zero” are represented by the same wire. The letter “N” marks the neutral, which is grounded in AC systems..

The grounding scheme in the apartment may contain the PE and PEN markings. In fact, this marking indicates the presence of a separate or combined ground. PEN is a combined “zero” and ground (C), and PE – separate conductors for “zero” and ground (S).

Important! The TT system provides for direct earthing of the equipment case. The IT system provides for the grounding of the equipment case through the resistance or complete insulation of current-carrying conductors. These systems are commonly used in enterprises.

Knowing the marking of grounding systems, it can be noted that the TN-C system is used in houses built before 1998. In such houses, two-wire wiring made of aluminum or copper is laid. Therefore, in high-rise buildings of that time, three phases (L) and one PEN (C) conductor are fed into the riser. Such grounding is also called grounding..

Marking on the wiring diagram

Grounding scheme in the apartment of the old housing stock:

Grounding system diagram for houses of old housing stock

TN-C 1 – power supply grounding; 2 – open conductive parts.

Modern houses are marked with TN-S or TN-C-S systems. Three phases (L), one zero working conductor (N) and one protected PE (S) conductor are connected to the riser of the house, and a three-wire wiring is laid in the premises. Connection to such a system is much easier in comparison with the TN-C system, since separate connection points are provided for each conductor, and the grounding has a separate connection with the metal housing of the shield.

Grounding scheme in an apartment of a new housing stock:

Grounding diagram for TN-S system

TN-S 1 – power supply grounding; 2 – open conductive parts.

Grounding diagram for TN-C-S system

TN-C-S 1 – power supply grounding; 2 – open conductive parts.

It should be noted that the ground loop is set up in a multi-storey building even at the stage of its construction, so it makes no sense to calculate the grounding. The creation of the outline diagram and all calculations are carried out at the design stage of the house. And if you need to make new calculations, it is better to contact specialists or use a special program.

Installation of grounding in a house with a TN-C-S system

Grounding scheme in an apartment of a new housing stock

There are several ways to determine which grounding system is in the house. The first is to contact the housing and communal services with an electrician with a question about grounding. The second is just to look into the distribution box on the floor and carefully examine the lead-in cable. The TN-C-S grounding system is characterized by the use of a five-core cable: three phases (L), zero (N), and grounding (PE). All wires are color-coded to facilitate identification. So “phase” (L) is brown or red, “zero” (N) is blue or blue, ground (PE) is a yellow wire with a green stripe or just green.

As noted earlier, it is quite simple to make grounding in new buildings with a TN – C – S system. The fact is that a three-core wiring was originally laid inside the premises, and a separate grounding cable was provided in it. But if, having purchased an apartment after the builders, the absence of divorced wiring is found, then there is also nothing to worry about, you can do everything yourself. It will not be difficult to bring all the wires to the dashboard in the apartment..

Connecting wiring and grounding to the panel inside the apartment

The wires are connected as follows. If the switchboard has not been installed in the apartment, you will have to deal with its installation and installation of the RCD inside the panel. Typically, the shield is placed next to the front door in an easily accessible place. Next to the shield, we drill a through hole and pass a cable through it to connect to the shield on the landing. We connect the wires of the incoming cable to the panel in the apartment as follows:

  • yellow-green (ground) is connected to the ground bus. The tire itself is located in the lower right corner of the guard;
  • the blue or blue wire (zero) is connected to the zero bus. It is located in the upper left corner of the dashboard;
  • the supply wire (phase) is connected to several RCDs in series.
  • now we connect the wiring from the apartment to the dashboard. We carry out the connection in the same way as described above, with the only difference that we connect a separate group of electrical appliances to a separate RCD.

Now we call the electricians to turn off the power to the riser. Once this is done, the electricians will connect to the main switchboard and turn on the electricity again. Upon completion of all work, you can test the network for grounding. Grounding check is carried out in the presence of a conventional voltmeter, other methods are unsafe. On the voltmeter, we set the maximum voltage to 250 V and apply one probe to the ground, the second to the “phase”. The arrow should deviate by 230 – 240 V, then everything is in order.

Important! It is forbidden to connect to the main panel on your own. Firstly, you cannot turn off the riser yourself, and even if you can, you do not have permission to do so. Secondly, the connection to the general power grid should be made by a person with the appropriate authority, knowledge and skills. Third, you may be fined or more severely penalized for disconnecting without permission. In addition, any mistake can lead to fire or damage to the power grid..

Installation of grounding in a house with a TN-C system

Earlier it was noted that the TN-C grounding system is typical for the houses of the old housing stock. You can check this in the same way as described above. The only difference is that by looking into the distribution board, you can see the absence of a yellow-green wire in the lead-in cable. There may be three phases and zero. Grounding in such houses, in fact, is absent, and making it for a single apartment is somewhat more difficult, but possible. To do this, you will have to carry out a major overhaul with a complete replacement of all wiring. This is important, since the old wiring is a two-wire aluminum wire, and a third wire is also needed to create a ground..

Grounding scheme in an apartment of an old housing stock

Important! When completely replacing the wiring and laying a new one, it is necessary to draw up a plan-diagram of the laid wires with all junction boxes and connection points. All work is carried out in strict compliance with safety regulations, requirements for wiring, installation of connection points and lighting devices. When choosing wires and electrical appliances, you should know the requirements that apply to them for installation in residential premises. Compliance with all the rules during installation will determine your safety when using the power supply.

After laying the new wiring, we install the distribution board and the RCDs in the same way as described above for the TN-C-S grounding system. We call the electricians and they make the connection. But the connection to the main switchboard itself will be done in a slightly different way. It’s all about the missing ground wire. And at this stage, you can go in two ways: perform grounding or full grounding.

Zeroing in the TN-C system

Zeroing in the apartment

This path is somewhat easier, but also less secure. The fact is that the GOST recommendations for TN-C systems are somewhat outdated, not to mention the partially worn out supply cable, worn out electrical equipment and the deplorable state of the shields. As noted earlier, for such systems, grounding is performed by combining the neutral conductor with the grounding conductor. Which, combined with worn out equipment, can cause a fire. But there is nothing you can do about it, according to GOST everything is as it should be.

Complete grounding in the TN-C system

The second way involves the creation of a full-fledged grounding loop. It is more complex, but also more reliable. You will have to create your own ground loop. To do this, having agreed with the electricians, you can bury the electrodes in the basement of the house and stretch a separate wire from them along the riser and from it start grounding into the apartment. Some homeowners on the lower floors dig in a ground loop directly next to the house. But it is worth noting that the creation of a full-fledged grounding in old houses is a very expensive business, requiring calculations for the ground loop itself..

Complete ground loop

Important! Some owners ground their wiring by connecting the wire to radiators or cold water pipes, as well as to gas pipes. This is an extremely flawed decision. First, such grounding reduces the reliability of the pipes. Secondly, no one will like that from touching a warm battery he will be shocked. Thirdly, the strength of the current leaving through such grounding can be large enough to leave a child who accidentally touched the pipe..

Creating grounding in an apartment is a very responsible occupation. The safety of using electrical appliances will depend on how well and reliably it is made. And compliance with the rules and requirements for the installation of wiring will allow you to forget about problems with the power grid for many years.