Ouzo is installed. What is an RCD and how does it work? Scheme with a common RCD in a single-phase network

- this is a residual current device, its purpose is to protect people from electric shock in case of breakdown of electrical equipment, or involuntary contact with metal parts of electrical equipment in case of current leakage. Also, it can protect the power grid from ignition of the wiring during a breakdown of current to the case or ground.

The RCD is a high speed circuit breaker. Its work is based on the comparison of the current strength at the input and output of the protected object. That is, the current flowing in the phase and neutral wire must have the same value for a single-phase connection.

If you have three phases, then the sum of the currents in the three phases is equal to the sum of the neutral wire currents. If the indicators have a different value, then this means that there is a leakage current in the circuit.

Current sensors used in RCDs are made on current transformers built on toroidal cores. Threshold protective elements of operation are manufactured mainly on a magnetoelectric relay with high sensitivity.

Although, recently, residual current devices made using special electronic circuits are gaining popularity. Such a circuit activates a protective spring mechanism that breaks the electrical contacts of the circuit in the event of emergency situations.

Connection methods in a private house and apartment

Having decided to put an RCD in your apartment and house, first of all, you need to choose its parameters correctly. First of all, pay attention to the current load, and for what purposes the device is selected.

If there is a need to protect only one device, for example, a washing machine or, then you can limit yourself to the rated current of the device with a small margin.

In the case of installing the device on the entire apartment or house, it is necessary to sum up the value of all loads, and select the appropriate value. The second value will be the differential current, upon reaching which, the protection will operate. After the choice has been made, one thing remains - to correctly connect the RCD.

Phase line connection:

As can be seen from the figure, the RCD is installed after the input machine and the electricity meter. After, the RCD phase wire goes to controlling different load groups. Further, after the switches, it is diluted to lighting fixtures and sockets.

Along the neutral line, the wire goes to the terminal block, after it, it is routed to consumer devices.

This circuit does not have a zero bus, which is typical for old apartments and houses. In such cases, a scheme using several RCDs to protect individual consumers may be better suited.

Connection to a single-phase network of single-pole and four-pole RCDs

In fact, the principle of connecting a single-pole RCD is shown in the diagram above. It is the most common for a single-phase circuit. Using it as an example, you can safely do the installation in your apartment or country house.

The main thing is not to confuse the places of connection of the phase and neutral wires. Usually, for the incoming phase wire, designation 1 is used on the case, for the outgoing phase wire, designation 2. The designation N is used to designate the neutral wire.

The use of a four-pole RCD in a single-phase circuit is, in most cases, unprofitable. It can be used as a temporary replacement, or when a three-phase upgrade is expected soon.

Further, by analogy with a single-pole connection. We connect the neutral wire to the terminal with the designation N. It is desirable to connect the phase to the terminal in the circuit, which includes the Test button. In most cases, it is located next to the zero circuit. It is advisable to carry out a check using the button at least once a month.

Installation location

Usually, the installation location of the RCD in the electrical panel. It contains various devices for accounting and distribution of electrical energy of voltage up to 1000 V. In the electrical panel, along with RCDs, circuit breakers, electric meter, distribution terminal blocks, and other electrical appliances.

If you have an electrical panel installed, then you will need a minimum set of electricians to install a residual current device. It will include pliers, side cutters, a set of screwdrivers, a marker.

In rare cases, a set of socket wrenches may be required and the RCD is mounted on a DIN block. If there is no space on the existing block, then you will need to install an additional one.

How to connect RCDs and machines?

Walkthrough:

1. Modern electrical appliances have a modular design. For their installation, special mounting . Their use makes the installation process much easier. Switches, residual current devices and many other equipment have a mount for installation on such a rail.
2. Next, we place all the necessary devices and parts at the attachment points in the electrical panel. After that, guided by the PUE, we connect the devices according to the diagram.
3. At the input of electricity to the shield, there must be a two-way circuit breaker. Its main task is to protect the electric meter from short circuits, overload, and make it possible to carry out work on replacing equipment.
4. The input machine also serves as a limiter for the maximum power consumption of an apartment or house. Its rating is selected according to the maximum allowed value of power consumption. Mount the input machine on the top DIN rail.
5. After input circuit breaker, connect an electric meter. To connect the meter, unscrew the sealing screw and remove the bottom cover. Below it will be a group of contacts. Usually, the connection diagram is located on the inside of the cover. If it is not there, look in the instructions for the device. Electric meter contacts have two clamping screws for each connected wire. Their task is to provide reliable contact. After connection, the meter is sealed, and there will be no access to contacts.
6. In most meters, the supply phase comes to the first contact. The outgoing phase is connected to the second. To the third incoming zero wire. To the fourth outgoing neutral wire.
7. After the counter, connect the RCD. The contacts on the device are usually labeled. The input voltage is applied to the top contacts. Accordingly, contacts are connected from the bottom of the device that will go to subsequent circuit breakers and other devices. AT this case, polarity must be observed. A phase should come to the phase contact, not zero.
8. After the installation is completed, it is necessary to check the RCD for operability. For this purpose, there is a Test button on the instrument. When pressed, the leakage current is simulated. The device should work by turning off the voltage supply.

Possible errors and their consequences

Most errors occur at the installation stage, especially if it is done by non-professionals:

1. Incorrect connection of supply contacts. Often, zero is confused with phase.
2. Supply voltage from the bottom of the device. With these errors, the device may fail.
3. Zero outputs of several devices must not be interconnected. As a result, the device will lose its sensitivity and will not be able to respond correctly when dangerous situations occur.
4. Also, it should be remembered that it is unacceptable to connect the neutral wire to ground in sockets. This will also lead to malfunctions.
5. You can not make power contacts from different sides of the device, for example, the supply phase from below, and the supply zero from above. The device will not work properly.

If you plan to install one device, then put it right after the electric meter. The problem in this case will be a complete de-energization of the apartment, in the event of a current leakage. Electricity will not work until the leak is repaired.

If you have many different electricity consumption zones, install several devices. This will help you narrow down the troubleshooting area, and provide comfort in other areas.

It should be noted that the installation of such devices in the fire and other alarm circuits is prohibited by safety rules.

When starting to assemble an electrical panel, many are faced with the problem: how much to install an RCD - one or more? Let's try to find the answer to this question.

The very first argument that you usually hear about installing several is just a money scam on the part of the contractor. A lot of RCDs, respectively, you will be charged more for work. Plus, you'll pay more for materials.

In addition, it can work and turn off electrical appliances, why install it, no one bothered with this before and did not know any problems. Everything seems to be obvious!

However, why do many still put several RCDs in their shields? Do they really not see the seemingly obvious things?

Let's dig deeper and try to figure it out.

RCD is designed to protect a person from electric shock. If the insulation, current-carrying parts are damaged, if accidentally touched, etc., the RCD will turn off the damaged area and will not allow us to be electrocuted. It turns out that RCD is still the right device!

Then how many should be installed? One, maybe more?

Yes, you can install only one RCD for the entire apartment and it will work great. Many people do just that. But a situation may arise when the electricity is turned off in the entire apartment. The reason for this is that it worked. And this can happen over and over again, although there is no obvious damage to the wiring and appliances. Probably it was impossible to warn that it would work and turn off the whole apartment, it was still necessary not to install it!

But we are not looking for simple solutions and will try to get to the bottom of this problem, and understand why the RCD works in this case?

As we know from the principle of operation of the RCD, it responds to leakage currents. In any electrical wiring, even new ones, there are background leakage currents. Their value directly depends on the length and branching of the lines, the quality of the branches made in the branch boxes and their quantity, the quality of the cable used.

Many modern electrical appliances also create impulse pickups during their operation, and if there are many such devices, then their total impulse can lead to tripping of the RCD.

To protect a person, an RCD with a sensitivity of not more than 30mA should be used. In "" I showed that RCDs start to operate at values ​​from half the value of the leakage current setting. Those. RCD with a setting of 30mA can operate at currents from 15mA.

It turns out that it is necessary to install several RCDs, at least two. This will reduce the total background current in the group and reduce the amount of possible total impulse noise from the operation of electrical appliances. If, when installing several RCDs (provided that they are correctly calculated and selected), it works, then this can happen mainly for two reasons:

1. RCD connected incorrectly;
2. An accident occurred in the group and the RCD performed its protective function.

But there is one more thing! In everyday life, devices that come into contact with water are widely used: storage heaters, washing machines, etc. To protect such devices, it is recommended to install more sensitive RCDs with a leakage current setting of 10mA. And it can technologically operate at currents from 5mA. According to the norms, such RCDs are prescribed to be installed for one device connected by a separate line.

As a result, we come to the conclusion that in a modern apartment it is necessary to install at least three RCDs: two for all electrical wiring and at least one for a device in contact with water (washing machine, boiler ...)

Only in this case we will get a safe system that will protect as much as possible from electric shock and fire.

As a bonus to such a scheme, we will be able to more easily identify the source of the malfunction, and the ability to use the working part of the system while troubleshooting is being carried out in the emergency group.

And if you use (multi-stage) differential protection, the security of the system will be even higher!

If you want to build a reliable and safe system, then you simply cannot do without the use of several RCDs!

Detailed RCD video - one or more ???

In order to protect the electrical network of a house or apartment, circuit breakers or fuses are used. These elements allow you to avoid fire during a short circuit, but are completely unable to protect against electric shock. The product for protective shutdown of electricity, the principle of which is aimed at preventing current leakage to the device case, allows you to instantly de-energize the entire home network if the phase current is outside the “permitted” section of the conductor.

The use of RCDs allows you to protect not only the home electrical network, but also powerful three-phase installations in production. Why install such electrical products and how to do it correctly will be described in detail below.

Why do you need an RCD in an apartment

In old apartment buildings, often there is no third protective conductor in the wiring, in which there should be grounding. With such a wiring diagram, powerful devices, the “mass” of which is connected to the ground terminal of the socket, are not protected, and if a phase current leaks to the case, the device can pose a serious threat to life and health. If you install an RCD in an apartment that is not equipped with a grounding conductor, then in the event of an electricity leak, the home electrical wiring will not be automatically disconnected from the mains.

As a rule, the impact of current, when a person touches the body of the device, in this case will be negligible time, so the negative manifestation of dangerous voltage is practically not observed.

If the apartment is connected to a common ground, then there will be an automatic power outage at the moment when there is a “breakdown” to the housing.

Why you need an RCD in an apartment is now clear, but why use this device for private households?

RCD in a private house

Many private developers do not understand why an RCD is needed in a house, because such an object can be easily equipped with high-quality grounding, which will ensure the “utilization” of dangerous voltage from the body of any electrical appliance. So why do you need a residual current device in a private house?

Connecting a high-quality grounding conductor allows you to protect a person from severe electrical injury when touching the case on which a leak has occurred, but in this case, the current does not turn off, and an electric arc can form between the “ground” and the phase, in the device itself, which is often the cause of the fire.

To protect the internal conductors from such an effect, it is necessary to disconnect all devices equipped with a ground wire from the outlet after use, or you need to put an RCD in the circuit of an electrical device. Next, we will talk about why to install a protective device in the bathroom.

RCD in the bathroom

The bathroom should also have an electric shock protection device installed. Even if the bathroom is located in an apartment or house that is not equipped with grounding, the device will still turn off the electricity supply at the time of a leak. So why should you install a safety device in the bathroom?

To maximize the effectiveness of this safety mechanism, choose a model with a sensitivity of 30 mA or less. If powerful devices are not connected in the bathroom, then the ideal option for a room with high humidity would be to install a protective product with a leakage current of 10 mA. Such devices will cost much more, but their use will make it possible to protect people from the effects of electricity as much as possible. Why is it easy to understand, but why install protection on lighting fixtures?

RCD for lighting

RCD for lighting must also be installed in accordance with all the rules. Why this should be done will be discussed later. Even in the case when the phase wire was put through the switch, it is necessary to install a protective product on the entire circuit of the lighting device, because an emergency power outage may be necessary during non-standard operation of the lamp.

For example, a heavy chandelier can come off and, together with the light bulbs on, fall on people. At this point, it is guaranteed that there will be a power outage if it leaks. Will protect the product from electric shock and in damp rooms with a low ceiling.

For example, in a damp basement, it is imperative to install a device that will turn off the supply of electric current to the lighting element at the moment
when a person touches the damp insulation of the conductor or lamp socket.

It is also necessary to equip all street lamps with a protective device, because the operation of such products takes place in very unfavorable heat conditions, high humidity or low temperatures in winter. Despite the increased protection of street lamps from moisture, over time, from mechanical damage, or for other reasons, the insulating layer may become significantly thinner, and the metal surface
lighting device will be under life-threatening voltage.

Why install a protective mechanism for lighting is understandable, but why an RCD for a three-phase network if its function can be replaced by powerful circuit breakers?

RCD for a three-phase network

All equipment operating from a three-phase network must also be connected to a protective power outage system. The leakage current in such networks can be too high, so these products do not protect a person from an electric shock, but they allow you to turn off electricity consumers when a phase breakdown occurs to the "ground" of the device. Thus, it is possible to completely eliminate the possibility of a dangerous electrical potential appearing on the instrument case. This wiring diagram can only be connected if there is protective earth in the wiring of a house or apartment.

Why install an RCD is described in detail above, but where is the best place to place this device?

Where to install RCD

The protective power cut off system must be installed in such a way that the power of the devices connected to the electrical network is not higher than the maximum allowable for this RCD model, for which, before carrying out installation work, you should study the instructions for the protective device.

For better and more reliable protection of home electrical wiring, you need to install one device of greater power in the shield, and equip the bathroom and other most dangerous, in the electrical sense, rooms with additional devices with less leakage current. If you need to install a protective device for a free-standing powerful electrical appliance with a metal case, then installation work can be carried out in the immediate vicinity of the protected object. In this case, the most suitable model would be a protective product that has a built-in circuit breaker. The installation of such an RCD allows not only to ensure the minimum probability of electric shock, but also to protect electrical circuit from short circuit.

Why do you need to install an RCD in an electrical circuit, and why do it in accordance with the safety regulations and the operating manual this device? Many home craftsmen do not understand why this is necessary and pay with serious consequences, because electric shock is a fairly common cause of death not only for people whose profession is connected with electricity, but also for ordinary users of home appliances.

Usually, many home craftsmen no longer care about the question: “Why do I need to install a protective device”, after they feel the effect of an electric current of 220 V. Why this should be done according to the rules, choosing a protective device for power, is also often found out through trial and error.

The purpose of the RCD and its use is to save human life, therefore, in some countries of the European Union, such protection is mandatory for installation in private households. It is desirable that this rule be introduced in our country, then the number of accidents will be significantly reduced.

Modern apartments and private houses are equipped with a large number of different 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 are sure 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. Particular attention should be paid to this, since grounding is mandatory installed only in houses of modern construction.

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 an 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 objects 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 installing the protective device, its type should be clarified. 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 go to its case and the same voltage will appear on it 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 provides 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 TN-C-S connection scheme, when the neutral and ground wires can only be combined in 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 a protective device in a two-wire network occurs under 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 housing, the current leakage path to earth will pass through the 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. Power is supplied to the switchboard through the 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 security devices will depend on the specific home network configuration. 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 the large size of the switchboard, which is necessary to accommodate a large number of RCDs and automata. 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 TN-C grounding system 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.

Hello Dear reader site site. Today we'll talk about RCD protection person from leakage currents (residual current device). RCD protection is installed in electrical networks to protect a person from leakage currents and prevent fires.

Purpose

RCD is an electrical device specially designed to cut off the power of electrical appliances at leakage currents. Leakage currents occur with minor violations of the insulation of current-carrying phase conductors. If the insulation is broken, the current begins to "leak" through the metal cases of electrical appliances or conductive structures of an apartment or house. Leakage current is also called differential current.

Since the leakage current is small in size, the circuit breakers installed in the mains do not work on it and do not turn off the power supply. Automatic circuit breakers turn off the electrical network when short circuit in the network (touching the phase and neutral wires or two phase wires) or overload. Circuit breakers do not respond to small leakage currents.

Leakage current is a dangerous malfunction of the electrical network for a person. For example, if you touch a conductor carrying a current of 0.3 milliamps, you will feel an ant bite, at a current of 15 milliamps it will be difficult to break away from the conductor, but it is still safe. This cannot be said for a current of 40 milliamps. When you “touch” such a leakage current, you are guaranteed convulsions of the body and diaphragm, which is undoubtedly very life-threatening. It is to protect a person from leakage currents that RCDs are designed. Such devices should have a cut-off current of no more than 30 mA.

To protect the premises from fire, fire, a general RCD is installed to protect a person from leakage currents, with a cut-off current of 100 mA or 300 mA.

Installation Guidelines

According to Russian standards for residential premises, an RCD with a tripping current of not more than 30 mA is installed. The response time of the RCD, that is, the time from the appearance of leakage currents to the disconnection of the electrical circuit, should be in the range of 0.1-0.3 seconds, this disconnection time is enough to protect a person from death. But do not think that with the RCD installed, you will not feel the shock at all. There will be a shock, but the device must turn off the current in time and save your life.

I note that the same standards apply in Europe. In America, according to their National Electrical Code standard, RCDs installed in residential premises must have a trip current of 5 mA

Note: The serviceability of the device must be checked before installing the RCD, after installing the RCD and every six months using the "Test" button on the case. If, when you press the "Test" button, the RCD works, that is, it turns off the network, then it is fully operational. If it doesn't work, it needs to be replaced.

Where is the installation of an RCD in the electrician of an apartment and a house

According to our regulatory documents, RCD is additional device protection. (PUE ed. 7, p. 1.7.50; p. 1.7.156).

Optional doesn't mean optional.

The installation of the RCD is carried out in all groups of the electrical circuit, in which the sockets are installed. The rated breaking current of the device must be no more than 30 milliamps. At least one General Device Protective Shutdown for the whole apartment (house) must be installed.

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If you have an electrical network where there are many power supply groups, installing an RCD for each group, along with a common RCD, will only improve the safety of the dwelling. It is allowed to install one RCD on several separate power supply groups, provided that separate circuit breakers are installed for each group.

The choice of RCD to protect a person from leakage currents

RCD has two main characteristics.

• Rated load current (in amps)
• Rated cutoff current, also known as differential current (in milliamps).

Rated load current RCD

The RCD is installed in the electrical circuit necessarily together with overcurrent protection circuit breakers, after the circuit breaker. The rated operating current of the load of the device must be selected one point higher than the rating of the circuit breaker.

For example: Introductory circuit breaker for an apartment 50 Amperes. So for the whole apartment, you need to install an RCD with a rated load current of 63 Amperes.

Rated cut-off current

for residential premises, the rated cut-off current is selected:

• To protect a person from leakage currents, an RCD with a cut-off current of 30 mA is installed;
• For wet areas (bathrooms) and children's rooms powered by a separate line, an RCD with a cut-off current of 10 mA is installed;
• To protect the house from fire, the cut-off current should be 100mA or 300mA;
• Device selection is based on SP 31-110-2003.

Rated cut-off time RCD

• The nominal cutoff time should not exceed 0.2 milliseconds for a supply voltage of 230-400 Volts.
• In apartments and houses, it is better to install an RCD of type "AC" or "A". Type "AC" respond only to sinusoidal, alternating, leakage currents. Type "A" responds to sinusoidal and pulsating leakage currents. Pulsating currents arise from the operation of tape recorders, televisions, washing machines, dimmers.

RCD installation

• The device is installed after overcurrent protection circuit breakers.
• It is recommended that the device be installed in such a way that the phase and zero working conductors are disconnected simultaneously. At the same time, it is not necessary to install an overcurrent protection circuit breaker on the neutral wire.
• The following shows the correct and incorrect connections of the device in the apartment and house.
• In the upper diagram, the device is installed immediately after the electric meter, without a circuit breaker. This is unacceptable (PUE 7.1.76).

It is forbidden install human protection against leakage currents in group circuits where there is no protection against overcurrents. From the side of the source, in front of it, you need to install an overcurrent protection circuit breaker (PUE).

Regulations

In these regulatory documents you will find information about the RCD protecting a person from leakage currents.

• PUE (Rules for the Construction of Electrical Installations) ed.7
• SP 31-110-2003, Design and installation of electrical installations
• GOST R 50571.8-94, ELECTRICAL INSTALLATIONS OF BUILDINGS, Part 4
• GOST R 50571.11-96, Electrical installations of buildings, Part 7, Requirements for special electrical installations.