Does not work without grounding. How to connect an ouzo without grounding with your own hands. Connecting a four-pole ouzo to a three-phase network using a neutral

It will protect the wiring in a private house or apartment from leakage currents, but at the same time it will not protect the wires from short circuits and overloads of the electrical network. That is why this product is installed together with a circuit breaker. Next, we will look at how to correctly make a diagram for connecting a single-phase RCD to a network with and without grounding!

It is best to install the product after electric meter, but in front of the machine.

For your attention 4 typical schemes RCD connection in a single-phase network.

Connection of one common RCBO:

Multiple Device Mounting Diagram protective shutdown for each group:

Connection of several residual current devices together with an introductory RCBO:

Installation in a two-wire network (without grounding):

Please note that you need to connect the device from above, the last picture is provided only for clarity, so that you understand how the RCD is mounted in a network without a grounding conductor. Also note that each of the options has the following sequence of connecting elements: introductory machine - counter - RCD. Such a scheme protects your wiring as much as possible from all types of threats.

• If the wiring in a private house or apartment will include more than one powerful electrical appliance, then it is better to install a separate residual current device for each group of conductors. This option will allow you to control each device separately and, in turn, in case of malfunctions, turn off the electricity not in the entire electrical network, but only in a certain place.
• If the power grid is simple, without a powerful household appliances, it is better to use . This machine simultaneously protects the network not only from leakage currents, but also from short circuits along with overloads (AB functions).

The video below clearly discusses the provided installation options for the residual current circuit breaker, and also explains where each of the connection methods is rational.

Modern apartments and private houses are equipped large quantity various household appliances. In this regard, the protection of people from electric shock comes to the fore. The main priority protective measures are the installation of traditional circuit breakers - circuit breakers and residual current devices - RCDs. However, in each specific case, in the presence of one- or three-phase networks, technical questions arise, for example, RCD without grounding, does it work or not? In many old houses, there is no grounding, so the possibility of using protective devices in these conditions is of particular relevance.

Do I need grounding for RCD

Many homeowners believe that the protective device will only work correctly if there is a three-wire electrical circuit, with phase, zero and ground conductors. For the same reason, the question often arises, RCD or grounding, which is better. In order to give the correct answer, it is necessary to understand the purpose of each of them.

It is known that the main function of the RCD is to turn off the equipment when a current leakage occurs on the case. Thus, it is possible to avoid electric shock to a person. Grounding is installed for the same purpose, only it works according to a different scheme. When an electric current appears on non-current-carrying parts, a short circuit is created due to grounding. As a result, the maximum current protection of the machine is activated and the equipment is de-energized.

Therefore, both methods of protection can be used separately, and if necessary, jointly, complementing each other. Therefore, the mandatory installation of grounding when using RCDs is not required and the protective device can be used even in a two-wire single-phase network in which there is no standard grounding. This conclusion is also confirmed by the design of the device itself, where there are phase and zero terminals, and there is no separate terminal for the ground wire. Special attention should be paid to this, since grounding in without fail installed only in houses modern building.

In old houses built back in Soviet times, two-wire networks are still used, without a ground conductor. In such cases, protective devices are especially needed. The whole difference in the operation of an RCD with and without grounding is only in the response time. In the presence of grounding, operation occurs almost instantly. RCD without grounding works only at the moment of touching the body of the device, which is energized. Therefore, the degree of protection is no longer as reliable as in the first option, but nevertheless, even in this case, the RCD protects against the unpleasant consequences of electric shock.

How RCD with grounding works

The residual current device is selected in accordance with the network configuration where it is planned to be installed. You should immediately determine the presence or absence of a grounding conductor PE. In modern buildings, it is initially provided for by the project. At the facilities of the old building, the PEN scheme is still used, which provides for the combination of a protective conductor with a neutral wire.

Mounting the connection to the ground is considered more efficient, since the circuit is disconnected in this case, immediately when it appears. In the PEN scheme, as already noted, the shutdown occurs only after direct contact of a person with the equipment.

If there is still grounding in the circuit, then before installation protective device its type should be specified. For example, the TN circuit assumes that the power supply neutral is solidly grounded. Its variety is, combining in a single wire the zero working and protective conductors in the entire electrical circuit. This simple and inexpensive option has a significant drawback: in the event of a break in the PEN conductor, if the device has its own ground, there is a danger that the entire potential will transfer to its case and the voltage on it will appear the same as in the entire circuit.

Sometimes electricians use a jumper that shorts out the neutral and ground terminal in the outlet. Such a scheme is considered incorrect and dangerous due to the high probability of electric shock. When the PEN wire breaks, the RCD will not work, and a dangerous voltage will appear on the device case. Damage can only be avoided by accident: a person at the time of contact with a current-hazardous body must also touch the ground loop, for example, water pipes or heating pipes.

The TN-S circuit is considered the most reliable for connecting an RCD, where the connection of the neutral protective conductor is carried out separately. It is combined with the neutral only in the power source, which ensures maximum protection and almost completely eliminates the possibility of electric shock. Even if the neutral or ground wire breaks, all devices in the circuit will continue to work. Dangerous voltage will not appear on the housings, since the potential will transfer to another, the remaining wire. With two wires at once, all devices and the circuit itself will not pose a danger to people, since the electricity will be completely turned off.

There is another so-called intermediate scheme TN-C-S connections when the neutral and ground wires can only be combined on separate sections and acquire the properties of a PEN conductor. In this case, the installation of an RCD is mandatory, otherwise the circuit will be left without protection at all.

Will an RCD work without grounding

The operation of the protective device in a two-wire network occurs in special conditions. Therefore, many owners have a question, will the RCD work without grounding and will it provide protection against electric shock? In order to get an answer, it is necessary to trace the entire triggering mechanism. When a breakdown occurs on the equipment case, the RCD will not immediately trip, since there is no grounding and there is no way for current leakage to pass further. At the same time, a potential is formed on the body of the device that is dangerous to human health and life.

At the moment of touching the case, the leakage current path to earth will pass through human body. After a certain period of time, the current value will become equal to the threshold of the RCD, and only then will a shutdown occur with the cessation of the current supply to the faulty device. The amount of time a person is exposed to the current will depend on the pickup setting of the protective device. Despite the fairly quick shutdown, this is quite enough to cause a serious electrical injury. In the presence of grounding, the RCD would work immediately after a current leakage and would turn off the device even before a person came into contact with it.

Thus, an RCD without grounding can be connected, however, such a circuit does not guarantee 100% safety. However, two-wire networks are still used in older houses, and their conversion to more modern three-wire networks is not always possible from a technical point of view. Therefore, in many cases, RCD is the only option to protect people and household appliances. When used together with residual current devices, circuit breakers must be installed to disconnect the network in case of overloads and short circuits.

How to connect an RCD in an apartment without grounding - Scheme No. 1

The only protective device is installed at the entrance and covers all the wiring in the apartment. The power supply is supplied to the switchboard through input cable. Then it goes to a two-pole machine, and then to the RCD. After that, the machines are installed on the outgoing lines.

A significant advantage is the low cost of such a circuit due to the use of only one protective device. All devices can be compactly placed even in a small switchboard. But, a significant drawback of such a shutdown will be the operation of the RCD during current leakage, as a result of which the entire apartment will be de-energized.

Scheme No. 2

The operation of an RCD without grounding can be carried out according to one more scheme. In this case, protective devices are installed not only at the inlet, but also at each outgoing branch. The introductory RCD is mounted in the same way as in the previous version, and all the rest are installed after the machines that protect the outgoing lines. The total number of safety devices will depend on the specific configuration home network. Often, water heaters, electric stoves, dishwashers and washing machines are separately connected to the protection.

Thus, in case of current leakage on any line, the RCD installed on this line will trip. That is, in all other parts of the apartment, the voltage will not disappear, and the rest of the equipment will continue to work. The only drawback of this scheme is big sizes switchboard required for placement a large number UZO and machines. In addition, the protective devices themselves are not cheap.

Often the question arises of the need to install an introductory RCD if each line is protected. The fact is that the outgoing protective device may, for one reason or another, not work with current leakage. In this case, the introductory RCD serves as insurance and after a certain time will turn off the entire network.

RCD in TN-C system

Very often there are questions about the possibility of connecting an RCD in the system grounding TN-C and its effectiveness. Variants of this system can be three-phase with four wires or single-phase with two wires. In the first case, the wires consist of three phase and one zero, and in the second - of two phase and zero conductors.

Most experts unconditionally recommend the installation of protective devices in such systems, since they are the ones that work with current leakage that is dangerous to humans. However, there is the so-called "opposition", according to which the installation of an RCD in the TN-C system is not only ineffective, but also dangerous. This is due to the fact that the protection works only with direct contact with live parts, and not in advance, with the appearance of a leakage current. In addition, in houses with old wiring, such devices will turn off for no apparent reason.

Most electricians and apartment owners are still in favor of installing an RCD. In any case, it will not be useless and will work at the right time, saving health or even life itself. The protective device significantly increases electrical safety and makes the life of living people more peaceful.

This device has long established itself as effective remedy protection of a person from electric shock in different situations, for example, when touching the current-carrying parts of various home appliances or to electrical circuit wires with damaged insulation. The same device, whose second name is a differential switch, is an effective protection against fire, which can occur due to current leakage in various electrical household appliances.

However, many electricians argue that it is impossible to connect an RCD without ground, without a costly upgrade of the entire electrical network of a house or apartment, since standard wiring is made in a two-wire version. Let's see if this is actually the case. But first, let's talk about the RCD itself.

As mentioned above, its task is to protect people and electrical appliances in case of current leakage. In this context, leakage is a change in the route of flow electric current, that is, when the current begins to flow not through the laid wiring or past the electrical appliance connected to the network, as well as when the resistance of the conductor changes under the influence high temperature(insulation fire). It is to these situations that the residual current device reacts, completely de-energizing the electrical network in the room.

Please note that a situation where a person simply shorted the current-carrying contacts in the outlet is not a current leakage. In this case, the differential switch will perceive a person as a normal load. Therefore, the disconnection of the electrical circuit will not occur, and a person will be electrocuted!

• in the electrical circuit of the kitchen;
• in the electrical circuit of the bathroom.

After all, these premises are characterized not only high humidity, but also the highest saturation of electrical household appliances.

If you look at the residual current device itself, you will not find a third terminal on it, where you could connect the room ground wire. That is, the differential switch is designed for installation in a two-wire circuit.

Thus, we have answered the question of whether it can be installed in a circuit in the absence of grounding. This is also confirmed by practice. For example, many electricians find that an RCD connected to a 3-wire circuit has continued to operate successfully by performing a protective shutdown, even if the ground has failed!

How does an RCD work in a two-wire circuit?

In order to understand the principle of operation of this device, let's compare it with a conventional analyzer that compares the magnitude of the currents flowing through the phase and neutral wire. As soon as there are deviations in the values ​​of currents caused by the occurrence of leakage current, for example, when shorting to the body of the washing machine, the relay contacts of the differential switch open, which leads to a de-energization of the circuit.

Let's look at a typical household example, which, I hope, will convince you that it is necessary to install an RCD. Let's say that the insulation of the wiring in your washing machine is damaged. As a result of the contact of the bare current-carrying wire with the metal case of the machine, the current began to flow through it.

If a person touches such a washing machine, he will be shocked and beaten until the machine is de-energized, or the person stops touching its body (which will be very problematic). Thus, if a person remains alive as a result of the flow of an electric current through him, then serious consequences of its impact on individual internal organs and central nervous system generally.

If in the circuit of the room where it is installed washing machine, the RCD is turned on, then if the situation described above occurs, the relay will instantly trip, which will de-energize the entire circuit of the room. A person does not even have time to be frightened and feel any discomfort!

Connection options for a differential switch without earthing

The residual current device is not equipped with an automatic device that protects the circuit breaker from overloads in the electrical circuit. Therefore, in the circuit, simultaneously with the RCD, it is also necessary to connect automatic machines that trip when overloads occur. At the same time, the power of the differential switch itself should be slightly greater than the power of the machine installed with it in the same electrical circuit.

This is necessary in order to protect the RCD from burnout, since when an overload occurs in the circuit, the machine does not work instantly, but after a while. If the power of the RCD were equal to the power of the machine, then during this time the differential switch would have time to burn out from the current passing through it.

Typically, electricians use two options for installing RCDs.

A common differential switch is installed for the entire apartment. This way you can protect even table lamp standing on computer desk. However, such an RCD, designed for a current of 40-60 amperes, is very expensive. Yes, and when the protective device is triggered, you will not be able to find out what is the reason for the shutdown, and where to look for a faulty electrical appliance.

Of course, you can get to the bottom of the reason by checking each electrical appliance in the apartment in turn, but this can take a lot of time.

In addition, the operation of a protective device, for example, on a current leakage in the bathroom will lead to a de-energization of the entire electrical circuit in the apartment, and this creates a lot of unpleasant "surprises":

• turning off the computer before you managed to save the typed text that you worked on for several hours in a row;
• turning off the air conditioner, which led to its "hanging" and the like.

However, if you still decide to connect one RCD to the entire electrical network of the apartment, then you need to do this according to the diagram shown in the figure.

Several separate differential switches are installed in potentially hazardous rooms:

• in the electrical circuit of the bathroom;
• in the electrical circuit of the kitchen;
• in the electrical circuit of the basement;
• in the electrical circuit of the garage.

Despite the fact that the total cost of all devices will exceed the price of one powerful RCD, the reliability of the entire electrical network in the apartment (in the house) will significantly increase, and the search faulty device, which caused emergency turn-off electric current, will come down to examining one or two "culprits".

How to independently connect the device to a two-wire network?

It is desirable that this work be performed by a qualified electrician, but if this is not possible, then you can make the connection yourself, following the recommendations below.

1. Buying right amount UZO and machines. In this case, as already mentioned, the differential switch must have a power of 1 step more than the machine. For example, if the machine is designed for 25A, then the RCD should be rated for 40A / 30mA, where 30 mA is the leakage current at which the differential switch relay operates, since this current value is dangerous for humans.
2. If the circuit wiring in the apartment is complex, then the amount of natural leakage current can even exceed 30 mA, which will lead to constant false trips of the RCD. This can be avoided by dividing the entire load of the electrical network in the apartment into two separate RCDs, designed to operate at a leakage current of 30 mA.
3. A differential switch must be installed in the bathroom circuit, the trip threshold of which is equal to a leakage current of 10 mA. The standard RCD, which is recommended to be installed in the bathroom, is 25A / 10 mA.
4. Never install a differential switch in front of the meter, as the Energy Supervision Inspector will force you to remove it so that it is not possible to power the apartment network bypassing the meter (this is theft).
5. Paired with an RCD for sockets in the apartment, an automatic machine is installed, designed for 16 A.
6. Paired with a differential switch for lighting switches in the apartment, an automatic machine is connected, designed for 10 A.
7. In front of the meter, it is necessary to install not a single-pole machine, but a two-pole one, which will open, when overloaded in the circuit, not only the phase, but also zero. This will greatly increase the security of the system.
8. The connection of the RCD must be carried out in strict accordance with the inscriptions on its body.
9. It is necessary to place the differential switch in places inaccessible to unauthorized persons.

Connect several RCDs for each potentially dangerous room according to the diagram shown in the figure.

After all the RCDs are installed, it is necessary to make sure that the system is working, that is, to check whether there will be false positives appliances. To do this, turn on the machine installed in front of the RCD, and the differential switch itself, and then press the "Test" button on the device. If a shutdown occurs, then the RCD is working properly.

Now check the performance of the system under load. To do this, plug in one of the household electrical appliances. If the RCD did not turn off, then you did everything right!

Typical mistakes made when connecting

It often happens that you seem to have done everything right, but after a while you began to notice that the RCD starts to work even when there is no current leakage in the circuit, and the load in it does not exceed the permissible power.

Very often, this behavior of the device is due to errors made when connecting it. These errors lead to the fact that the differential switch ceases to fulfill its functional purpose - it will not turn off the current when a leakage occurs, but, on the contrary, will work with an absolutely healthy electrical circuit.

Here is the list common mistakes allowed during installation of the RCD:

• Earth connection after the differential switch to neutral, for example, the neutral conductor of the circuit is connected to an open part of the electrical installation or to the protective neutral conductor (PE). To avoid such an error, it is necessary to take only the phase and zero of one particular differential switch, which will make it possible to exclude the connections of the phase and zero that have passed through the protective device with other zeros and phases.
• Open-phase connection of the protective device, consisting in the erroneous connection of the load to the differential switch of the working neutral (N). In this case, the current flowing through the load will become a differential current for the RCD, which will cause false operation of the device.
• Twisting the ground and neutral conductors in the outlet (that is, (N) and (PE) are connected together). False alarm in this case will occur with some electrical appliance or when the load is connected to a circuit that is not included in security zone of this RCD, that is, the current will begin to flow through the jumper.
• Connection of two differential switches with twisted neutral conductors. This is the reason that differential load current will flow through both devices, which will cause the operation of one or both RCDs at the same time.
• When installing several RCDs, the neutral conductors were incorrectly connected. This will cause all differential switches to trip at the same time.
• Incorrect connection of the phase and neutral conductors when connecting several RCDs (not from one differential switch, but from different ones). For example, when the load is connected to the neutral conductor of the RCD, designed to protect a completely different circuit. In this case, false alarms can occur, both of one device and both at the same time.
• The polarity of the device connection is not observed: the phase is connected to zero, and zero is connected to the phase. In this case, the differential switch will not operate, since the currents will flow in one direction, which will make it impossible for the magnetic fluxes to compensate each other. Be sure to connect the incoming phase to the terminal marked L and the incoming zero to the terminal marked N. Also, remember that the top terminals on the device are inputs and the bottom terminals are outputs.

Thus, you were able to make sure that connecting an RCD to a two-wire circuit is not only possible, but also necessary, since this will save not only your life, but also your property from possible fire. In addition, if you are sure that you will not make mistakes when installing a differential switch in a circuit, then you can do it yourself!

In buildings of old construction, not subjected to overhaul, as a rule, the wiring is made according to a two-wire circuit. There is no ground conductor. If the wiring is not changed to three-wire, there is a safety hazard to use various appliances and devices that require AC power.

The need for installation

Grounding effectively works when a phase conductor breaks down on the housings of instruments, equipment, and on the conductive parts of structures. The presence of grounding will prevent electric shock, as it will eliminate the occurrence of a potential difference between the instrument case and the ground.

How to improve operational safety electrical network in a room without grounding, if there is no possibility to replace the wiring? There is an exit.

Often, owners or owners of premises find themselves in difficulty, wondering whether it is possible to install residual current devices or differential circuit breakers in a two-wire single-phase network when there is no grounding? It is not only possible to install, but also necessary. Moreover, even in the presence of earthing, it is recommended, and in some cases mandatory, the use of differential protective devices. Such devices are installed in a single-phase two-wire network on both conductors at once.

Electric shock protection

The operation of a differential automaton or residual current device (sometimes called differential relays) is based on determining the difference in phase and zero currents.

If there is a difference, the device cuts off the electricity supply. The difference can be fixed when a current leakage occurs. With a working electrical appliance or equipment, no leakage occurs in it, that is, the value of the current flowing through the phase conductor is equal to the value in the neutral conductor.

If insulation damage occurs phase wire, there is a potential difference between it and any grounded object. The same thing happens when there is a breakdown on the body of an electrical appliance. Grounding in this case will only help to remove this potential difference from the case, but the device itself will remain energized. If a person touches the case, the latter most likely will not feel the effect of electricity, because the resistance of the body is greater than the resistance of the grounding conductor. You can imagine what happens if the grounding is faulty or non-existent.

Differential machine, when similar situation turn off the power supply and de-energize the device. A person, even exposed to electricity, will not feel it, because the current value will not exceed 30 milliamps, and the shutdown time is 0.3 seconds. Such parameters for RCDs and difavtomatov used in residential premises are defined by the standards.

Schema selection

In a three-wire network with a ground wire, connection in separate rooms or individual consumer groups. The rest of the groups are protected by setting circuit breaker with the corresponding load rated current.

In a two-wire network, the connection diagram must provide for a protective device at the inlet to the switchboard. Only under this condition will all electrical wiring be protected.

For correct and reliable operation wiring in a two-wire network, it is advisable to install differential circuit breakers or residual current devices for each group. Each circuit must be protected by a separate device. The introductory difavtomat must have rated current parameters not less than the total, which may occur in protected circuits.

The differential current of this machine must be at least 100 milliamps so that the machine does not operate simultaneously with any of the subsequent ones. It is also necessary that the introductory difavtomat be designed for selective operation in circuits. In this case, there should be special designations in the marking on the body of the device.

Connection rules

When using several differential devices in the wiring diagram, there may be cases of incorrect operation of difavtomatov. They may either trip when a load is connected, or they may not operate even if there is a leak. If you know how to properly connect a difavtomat in a network without grounding, you can avoid many mistakes and save time debugging the circuit. Simple Rules connections are described below:

• the difavtomat power supply is connected from above to the terminals with screw terminals. The load is connected to the lower terminals. In this case, the phase or polarity must be observed;
• the difavtomat must be connected to the break of both conductors during single-phase wiring, otherwise, if any conductor bypasses the device, it will work when the load is connected;
• phase and zero in one single outlet should come from one difautomatic device, if the phase is from one difavtomat in the outlet, and zero from the other, both automata will turn off;
• an electrical appliance or a group connected to one machine must not have contact with appliances of another group. Often, in order to save space in the switchboard, all neutral conductors from loads are connected to a common bus, connecting all difautomats through the neutral wire. As a result, each difavtomat fixes the zero of the neighboring group, as a conductor with a leak, since part of the current returns through the neighboring device.

Checking the correct connection can be controlled by pressing the "TEST" button on the body of the difavtomat. When connected correctly, it should turn off. This is a necessary condition, but not sufficient. Sometimes when the "TEST" button is triggered, the machine still turns off when the load is connected. The reason may be hidden in violation of the rules described above.

If the parameters of the differential machine correspond to the wiring diagram and the connection is made correctly, then this device is the only reliable means of ensuring electrical safety in the absence of grounding.

Hello, dear readers of the site.

In it, we will consider the use of RCDs in a circuit without a protective conductor PE (without grounding), which is typical for the old two-wire wiring in Soviet-built houses.

The realities of our time are such that in new apartments and houses of modern construction, electrical wiring is used with a separate protective conductor PE:

- phase, zero and PE conductor in single-phase networks (three wires);

- three phases, zero and PE conductor in three-phase networks (five wires).

At the same time, in the houses of the old Soviet construction, electrical wiring is still used, in which the neutral and protective conductors are combined into one PEN conductor (the so-called "two-wire" ).

In single-phase networks, this is a phase and zero together with a protective conductor - PEN (two wires), in three-phase networks - these are three phases and a PEN conductor (four wires). Such a system, in which the functions of the working N and protective PE conductors are combined, is called TN-C.

Those. there is no separate ground conductor in the two-wire.

Let's take a closer look at how the RCD will work in two-wire.

In a two-wire network, in the event of insulation damage and a breakdown on the device case, the RCD will not work, since the case is not grounded and there is no path for the leakage current to pass. At the same time, a potential dangerous for human life will be located on the body of the device.

At the moment when a person touches the body of the device, a circuit is formed for the passage of current, and a leakage current will flow from the shorted device through the body of a person to the ground.

If the leakage current reaches (the value then 0.5 to 1 the value of the RCD setting for differential current), then it will disconnect the circuit of the appliance from the mains.

The time spent by a person under the influence of electric current will depend on the time of operation of the RCD. Although the RCD will disconnect such a line quickly enough, the current exposure time may be sufficient to cause serious injury.

Thus, from the moment of insulation damage electrical appliance and until the moment of disconnection, when the RCD disconnects it from the network, there will be a potential dangerous for humans on the device case.

If the body of the electrical appliance were grounded, i.e. connected to ground, then the RCD would disconnect the device from the mains immediately upon breakdown of the insulation on the case.

According to the PUE (clause 1.7.80), it is not allowed to use RCDs that respond to differential current in four-wire three-phase circuits (TN-C system). If it is necessary to use an RCD to protect individual electrical receivers powered by the TN-C system, the protective PE conductor of the electrical receiver must be connected to the PEN conductor of the circuit supplying the electrical receiver to the protective switching device.

At the same time, many experts refer to other guidance documents who recommend installing RCDs in two-wire systems.

Nonetheless, the use of RCDs in electrical installations with a TN-C earthing system, allows you to further increase the degree of electrical safety apartments, because in this case it also provides effective protection from electric shock.

In the future, all electrical wiring in old houses should be upgraded to systems with a separate PE conductor - from TN-C systems to TN-C-S systems.

If there is no grounding in your electrical panel, then you need to wait for the reconstruction of the wiring.

An energy service organization should be responsible for upgrading your home's electrical system. The separation of the PEN conductor into a zero working N and a protective PE conductor should be carried out by an energy service organization at (ASU) of your home.

Therefore, if you decide to replace the old two-wire wiring in your apartment, use a three-wire cable, as recommended by the standards, but do not connect the third conductor either in the electrical panel or in sockets(that is, you have it for the future, but you do not connect it, but isolate it on both sides and leave it like that until the reconstruction of the power supply system of your house is carried out).

In the absence of grounding in the apartment do not connect the third protective conductor to zero in the electrical panel, in the distribution network of the building (which happens quite often), under the dangerous voltage of the electrical network, through a protective conductor connected to zero, all conductive cases of electrical appliances connected to the network will be.

See the video for more details RCD connection without grounding