It will protect electrical wiring in a private house or apartment from leakage currents, but at the same time will not protect the wires from short circuit and power grid overloads. 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 the electric meter, but before the machine.
For your attention 4 typical schemes RCD connections in single-phase network.
Connection of one common RCBO:
Installation diagram of several residual current devices for each group:
Connecting several residual current devices together with the input RCBO:
Installation in two wired network(without grounding):
Please note that the device must be connected from above; the last picture is provided for clarity only, so that you understand how an RCD is mounted in a network without a grounding conductor. Also note that each of the options has the following sequence of connecting elements: input machine - meter - RCD. This scheme maximally protects your electrical wiring from all types of threats.
- If the wiring in a private house or apartment includes 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 problems, turn off the power not in the entire electrical network, but only in a certain place.
- If the power grid is simple, without a powerful household appliances, then it is better to use . This device simultaneously protects the network not only from leakage currents, but also from short circuits along with overloads (AB functions).
The video below clearly examines the provided options for installing a residual current circuit breaker, and also explains where each connection method is rational.
There are a lot of terms, I honestly couldn’t read them all, I confess!
I'll try simple question set -
Everyone recommends calculating grounding, they write that it is better not to do it at all than to do it incorrectly, etc. And hence the question: And if the grounding is incorrect (few pins, wrong depth, wrong resistance, etc.) won’t the RCD work? Won't it protect?
I'll be honest, I did it out of the blue - i.e. without calculations, as I read here on the forum - three corners under 1800mm. drove in a triangle 1.5 x 1.5 x 1.5 m. , scalded with a steel busbar and brought it to the shield, from the busbar with copper 6 sq. I inserted earth into the shield onto the block (tire). And now I connect all the yellow-green wires to this bus.
Wiring is natural, but 3-wire. Everywhere! There are RCDs. Zero, of course, on your block. I've been using El-vom since that spring. Everything works. I used a welder to cook, plow submersible pumps, etc.
What could be the danger? Otherwise it may disconnect from the “ground”. But will the RCD work then?
I didn’t make any lightning rods - as I read again on the forum - it’s better not to look for adventures in F... True, there is no television antenna yet, but it could become a “trap” for the discharge? Are there any “fuses” for the antenna input? - It's better to take care of it in advance.Z.Y. Sorry if I wrote a lot of nonsense, but it’s generally difficult for a non-electrician to talk about professional topics with electricians
I wanted to clarify your question a little, but everything seems to be on point.
The grounding was done correctly, the yellow-green wires only go to the third ground wire in the socket? Did I understand you correctly, if so, then everything is correct.
The operation of the RCD is based on the principle of a differential transformer, and does not depend on the presence of land near the house; the RCD measures the equality of currents
on each line of wires, what flows into the RCD should flow out, any imbalance causes the RCD to trip, for example, when working in the yard with an electric mower, or a drill in the garage, if its motor breaks down, the current will flow through you to the ground, there will be a imbalance and the RCD will be 10 or 30 mA. right there
will turn off the voltage in 20 MSK.
In the event of a breakdown, a submersible pump will also cause an imbalance in the currents through the RCD and its operation; a washing machine (wet zone), in the event of a breakdown and leakage through the supply and drain water, will also cause an imbalance.
The TV antenna does not have fuses, and its area is negligible, the probability of lightning hitting it is simply incredible, thousandths of a percent, you probably have trees nearby with their spreading hair, and the electrical network has a large area and at the same time contains arresters, and the poles are re-grounded.
Instead of an antenna, it makes sense to buy a dish for 600 rubles. watch dozens of programs a year.
I think he told me everything.
Good luck
About the need to install residual current devices in places of increased risk of injury electric shock Probably heard everything. However, many electricians, among whom there are often professionals, are for some reason convinced that in a two-wire network is impossible, which leads either to an expensive modernization of the electrical network in the premises, or to the abandonment of the RCD altogether.
However, such a prejudice is incorrect in its very essence, because the RCD has only two contact connectors, and there is simply nowhere to attach the grounding wire! And the principle of operation of such devices does not require connection to grounding at all.
This is confirmed by many cases when an RCD connected to a three-wire network, in which there is grounding, works quite well and has been functioning for a long time, even despite damage to the grounding (for example, a break in the grounding wire) continues to perform its protective functions.
Note: It makes sense to install an RCD even with a conventional two-wire connection diagram, where only phase and zero are present. And, for greater clarity and better awareness need to install additional protection, let's define how the RCD works, and then imagine a typical everyday situation.
In fact, the RCD can be considered a kind of “calculator”. RCD connection diagram without grounding is very simple - a phase and neutral wire pass through the device, the load on which is carefully monitored and compared. In the event of damage to the wiring or consumer, a so-called leakage current appears in the electrical network - the same current that flows through the damaged insulation. The magnitude of this current is usually extremely small - tens and hundreds of milliamps - but is sufficient to cause serious damage to human health.
Residual current device- compares the current passing through the phase and neutral wires, and, in case of deviation of these values, opens the contacts, thereby interrupting the supply of electricity to the damaged section of the network. From theory, let's move on to a completely understandable everyday situation.
For example, you have a washing machine in your bathroom at home. Electrical wiring is two-wire phase and zero, there is no grounding. The RCD has not yet been installed either. Now imagine that the insulation in the machine was damaged and the phase wire began to touch the metal body of the machine, i.e. The metal body of the machine was energized.
Now you approach the machine and touch its body. At this moment you become a conductor and electric current will flow through you. Electrical current will flow through you until you release the metal casing. Meanwhile you shaking and pounding from the flowing current and there is no hope for protection that will disconnect the damaged area. The only hope here is own strength will (or you will lose consciousness and fall).
If it were RCD installed when touching a metal case that is energized, The RCD would instantly sense the current leak and trigger, disconnecting the damaged area.
At the first signs of current “distortion” in phase and neutral wire the automation would have worked and the machine would simply have remained de-energized. And the person would barely have time to feel a slight tickling in the body and would be more puzzled by the sonorous click of the relay from the hallway than by the unusual sensations.
Moreover, this time is so short that a person practically does not feel the electric current. There is a video on the Internet on testing an RCD, and there a person specifically grabs a bare wire that is connected to a residual current device, the person touched the wire - the RCD instantly worked (he didn’t even feel any discomfort).
Attention! The benefits of RCDs are obvious, and in a two-wire power supply system, the presence of such devices in the most dangerous areas electrical network is simply necessary.
I hope I have convinced you that An RCD must be installed , regardless of whether you have grounding in your house or not. In addition, if you have a two-wire power system, then it is even more necessary to install a residual current device. Don’t listen to advice that says it won’t work in such a network or will always work.
Before you produce connecting an RCD without grounding I would like to remind you of one important point.
Note: A feature of residual current devices is the lack of overload protection. Therefore, they must need to be combined With ordinary "automatic machines" . In this case, the connection diagram may be different.
There are, in general, two options. Can install one common RCD throughout the entire house, thereby protecting even the bedside lamps. But only devices capable of passing 40-60A through themselves are noticeably more expensive than their less powerful counterparts, and even if the relay is triggered It will be difficult to find out the reason– you will have to check every electrical appliance.
Besides power outage throughout the house immediately causes a lot of inconvenience - unsaved documents on the computer, a frozen air conditioner, a switched off water heating tank, or washing machine– the list could take a long time.
If you decide to install one RCD for the entire group of consumers, then the RCD connection diagram without grounding will look like this:
Second option – installation of a separate, less powerful RCD on each of the “dangerous” lines: bathroom, basement, garage, kitchen. In this case, the shield will require more free space, and the price of three or four devices will be even higher than one, but powerful one - however, the reliability of the entire energy system increases, and the search for the cause of the shutdown will be reduced to only inspecting one or two outlets.
Experienced electricians are advised to approach the same judiciously selection of RCD power – it should be slightly higher than the machine that will be paired with it.
The reason is simple - a circuit breaker with overload protection does not operate immediately (from several seconds to tens of minutes), and exceeding the rated current passing through the RCD can cause its breakdown.
Example: If you have two circuit breakers in your panel, one powers the entire apartment (lighting and sockets), the second powers only the boiler in the bathroom. Install your own residual current device on each line separately: separate RCD for sockets And separate RCD not water heater. Although of course it is a little expensive, but still safety comes first.
Note: It is advisable to split the network, i.e. Connect all sockets in the apartment and separate lighting to a separate machine. For lighting, you will need to pull a separate cable from the panel into the apartment.
Since in an apartment all the wiring is usually walled up in the walls, the maximum that can be done is to stretch a separate cable from the panel into the apartment to the first distribution box and connect lighting only in the hallway; in other rooms it will not be possible to connect lighting from this cable. Therefore, lighting and sockets usually remain on the same machine.
To connect a residual current device, select VD1-63 series circuit breakers with rated current 16 A and differential current 30 mA.
Attention! It is impossible to combine zeros after an RCD - this iserror when connecting RCD . In the panel, make the connection in such a way that the phase goes through the machine, and the zero is taken from the panel body. To connect an RCD disconnect the power cable from circuit breaker(phase) and from the metal part of the shield (zero).
Having installed the RCD in the panel, we proceed to the connection. We immediately connect the phase and neutral of the supply cable to the output terminals of the device (for the apartment to one RCD, for the boiler to the second).
We start the phase at the input of the residual current device from the output terminal of the circuit breaker, and at the zero input we take zero from the panel body. Thus, the neutral conductors of the wires that came out of the RCD and go into the apartment are no longer combined with other neutrals (there is no connection with the panel body).
The connection is complete. In order to check the RCD itself, how it behaves in operation, whether false alarms will occur when incorrect connection- you need to turn on the machine in front of the residual current device and, of course, the device itself, then create a load (plug any device into the outlet). If no disconnection occurs, we can assume that all connections are made correctly.
Attention! After connecting the breaker or RCD, you must check them for leaks.
How to check the RCD for tripping in that case? With the help of a button, of course. TEST. To do this, when the device is turned on, press the button, if when you press the button it will turn off immediately- means it’s working properly.
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WITH electronically controlled, for example, difavtomat IEK AD 12, IEK AD 14, if the phase or neutral conductor breaks, the power to the electronic control circuit is de-energized and the differential protection stops working. There are difrels with an electronic control circuit in which, when the power is lost, the consumer is switched off, similar to a starter. To connect the consumer after the power supply has been restored, you need to manually turn on this type of difrel. This type of difrele can be used to power electrical appliances where it is dangerous to re-energize after a power failure.
If done incorrectly it can be more dangerous than without grounding!!!
Grounding without an RCD or grounding is prohibited!!!
Attention!!!
Do not connect the ground terminals of sockets and electrical appliances protected only by automatic circuit breakers, which only protect the wiring from short circuits in the phase-neutral and phase-phase circuits, to natural, artificial, and especially homemade grounding. You expose yourself and others mortal danger. Automatic machines operate only from currents many times higher than the nominal value of the automatic machine. Natural, artificial and especially home-made grounding in the vast majority of cases has a resistance that cannot create such currents and, accordingly, produce a protective shutdown of circuit breakers within the safety-standardized 0.4 seconds.
For example, if the neutral grounding at the substation, according to the rules, is 4 Ohms, taking into account repeated groundings, and your grounding will also be 4 Ohms and a breakdown occurs in one of the electrical appliances, then a dangerous potential will appear on all grounded housings of electrical appliances connected to grounding, through protective grounding conductors 110 volts. If your grounding resistance is more than 4 Ohms, the dangerous voltage on the housings of electrical appliances will be even greater.
For example, in a widely used circuit breaker with characteristic C of 16 amperes, the current to ensure a safe protective shutdown time of 0.4 seconds must exceed the rating of the circuit breaker by 5-10 times, that is, for a reliable shutdown in 0.4 seconds, the current passing through the circuit breaker must not be less than 160 amps.
If the resistance at the substation and local grounding is 4 Ohms, then the current during a single-phase short circuit to grounding through this machine will be I=V/R, 220 volts / (4 Ohms of substation grounding + 4 Ohms of local grounding) = 27.5 amperes, this is without taking into account the resistance of the line itself. If you take them into account, the current will be even less. The C16 circuit breaker will not turn off in 0.4 seconds at a current of 27.5A; the shutdown will occur in approximately 40-180 seconds due to the thermal overload protection of the circuit breaker. All these 40-180 seconds on the conductive housings of electrical appliances and other electrically connected objects there will be, although less than 220 volts, a dangerous potential. Also, during all these 40-180 seconds, the wiring must withstand a current of 27.5A so that a fire does not occur.
It is very problematic to achieve a grounding resistance of even 4 Ohms with three pins, especially driven in in the form of a triangle.
Now let’s calculate what the total grounding resistance should be so that a short circuit current of 160 amperes flows through the C16 circuit breaker and the circuit breaker turns off in 0.4 seconds. R=V/A, 220 volts / 160 amperes = 1.375 Ohms, even professionals with experience and equipment are not always able to achieve such a total resistance at the substation and local grounding. Automatic machines C25, C32, C40, etc. will not work at all with a total grounding resistance of 8 Ohms at the substation and local.
Attention!!!
Do not connect the ground terminal of sockets, electrical appliances, metal casings of electrical appliances to pipes and third-party conductive objects of the building.
If there is a breakdown on the body of an electrical appliance connected to a pipeline or other third-party conductive object, the machines may not work for many reasons. All electrically connected conductive objects will be under network voltage, including those in neighboring apartments and houses. As a result, massive, deadly electric shock and the risk of fire are inevitable!
At any moment, a grounded, neutralized pipe may cease to be so, for example, during pipe repairs or in a place threaded connections due to corrosion. Nowadays they are increasingly used plastic pipes, therefore pipes cannot be a natural grounding, much less a protective conductor.
Some incompetent publications, including on the websites of companies licensed to electrical installation work they recommend such a deadly and criminally responsible pseudo-protection as the use of pipes as natural grounding or grounding, and the rest of the vast majority of publications are re-publications of these publications by people who have little or no understanding of electrical engineering.
With centralized heating, water and gas supply in a private house, I would recommend placing plastic couplings, which are used in metal pipes, at the entrance to the site or, as a last resort, at the entrance to the house, to protect against the grief of the grounding workers.
If the neutral is broken, if done incorrectly, it is deadly, even with an RCD!!!
Attention!!!
In houses with two-wire wiring, do not connect the ground terminal of sockets, electrical appliances with such a terminal, as well as metal housings of electrical appliances to the neutral wire of the electrical wiring, that is, do not neutralize the ground terminal of sockets and electrical appliances. Some people make such a deadly mistake by running a wire from the “ground” terminal of an outlet or electrical appliance into the panel and neutralize it there, or, even worse, connect the “ground” terminal of the outlet with a neutral wire with a jumper.
At any moment, in any place, a break in the neutral wire can occur, which is usually remembered by the combustion of almost all electrical appliances connected to the network, the phase and neutral will mistakenly change places, the wires will overlap air lines, after which a dangerous network imbalance voltage will appear on the neutralized housings of electrical devices.
The PUE describes the grounding of conductive surfaces of electrical installations, which include elevators, pumping stations, transformer substations, input panels of buildings that are serviced by qualified personnel, and not household electrical appliances with single-phase power. According to paragraph of the Russian PUE 7 1.7.132, combining the functions of the neutral protective and neutral working conductors in single-phase and direct current circuits is not allowed.
7.1.45. The selection of conductor cross-sections should be carried out in accordance with the requirements of the relevant chapters of the PUE. Single-phase two- and three-wire lines, as well as three-phase four- and five-wire lines when supplying single-phase loads, must have a cross-section of zero working (N) conductors equal to the cross-section of phase conductors. Three-phase four- and five-wire lines when supplying three-phase symmetrical loads must have a cross-section of zero working (N) conductors equal to the cross-section of phase conductors, if the phase conductors have a cross-section of up to 16 mm2 for copper and 25 mm2 for aluminum, and for large cross-sections - at least 50 % cross-section of phase conductors. The cross-section of PEN conductors must be at least the cross-section of N conductors and at least 10 mm2 for copper and 16 mm2 for aluminum, regardless of the cross-section of the phase conductors. The cross-section of PE conductors must be equal to the cross-section of phase conductors with a cross-section of the latter up to 16 mm2, 16 mm2 with a cross-section of phase conductors from 16 to 35 mm2 and 50% of the cross-section of phase conductors with larger cross-sections. The cross-section of PE conductors not included in the cable must be at least 2.5 mm2 - if available mechanical protection and 4 mm2 - in its absence.
The photographs show floor boards of residential multi-apartment buildings, with two-wire wiring of apartments, in which there is no PEN conductor responsible modern standards cross-section of conductors, and especially PE conductor. Only the time-worn PEN conductor, which in some panels has breaks prohibited, even by the old rules, on each floor, is made of aluminum wire with a cross-section of about 6 mm, which does not comply with modern cross-section standards, to which the neutrals of the meters and the shield itself are not connected with a reliable connection and, accordingly, it cannot perform protective functions. The neutrals of the apartments are connected directly to the meters. There is also no connection to the building's ground loop.
Maybe the photos will convince you not to go to zero, it’s not clear where.
To protect against electric shock in houses with two-wire wiring, especially in the presence of children, boilers, Jacuzzis, washing machines, microwave ovens, dishwashers, etc., only correct option This is the installation, first of all, of a 10 mA RCD after the introductory machine or apartment traffic jams.
Most best option This is after the machine of each group to install a 10 mA RCD, and after the introductory machine to install duplicate 30 mA RCDs.
It would not hurt, instead of a pair of existing plugs or a black single-pole circuit breaker, to install a two-pole circuit breaker with characteristic B, which would simultaneously disconnect the phase and neutral. Or make an apartment shield and separate and protect different consumers with avomatic machines with lower denominations.
Attention!!!
If three-wire wiring is already installed and connected, but grounding is missing as such or has not yet been done, then disconnect the protective conductor from all sockets, chandeliers and other electrical appliances and the protective busbar in the panel, and insulate it. In the event of a breakdown in one of the devices, all conductive housings of electrical devices will be exposed to dangerous mains voltage through the protective conductor, this is especially dangerous in the absence of an RCD. Also, when protective conductors are connected and there is no grounding, the static and capacitive currents of all connected electrical appliances are summed up through the protective conductor, as a result of which a fatal electric shock is possible even if the electrical appliances are in working order. Therefore, before disconnecting protective conductors You need to remove all plugs from the sockets and completely turn off the electricity.
The RCD primarily protects against electric shock, although the rules interpret the RCD as additional protection, the machine protects wiring from short circuits, grounding removes static, capacitive currents of electrical appliances and, not completely, reduces dangerous potential. Therefore, the cost of an RCD cannot be compared with human life. A friend of mine’s son died from electric shock in the bathroom!
For those who don’t understand anything about electrics, you need to find an adapter on sale with a built-in difavtomat, which is plugged into a socket, and the plug of the electrical appliance is plugged into it, although it contains a difavtomat for a leakage current of 30 mA and a protective current of 16A. The use of such an adapter in any case greatly improves the use of any electrical appliance.
Installing sockets, switches, and electrical appliances in the bathroom without using a 10 mA RCD is deadly!
RCD (residual current device) is connected according to different schemes. You will not make a mistake if you first understand for yourself how not to connect it.
The connection is as follows:
when the RCD is installed immediately after the meter NOT CORRECT.
A circuit breaker (AB) must always be installed in front of the device.
The only exception can be the installation of a differential circuit breaker (AD) instead of an RCD.
This connection scheme has its drawback - in the event of a current leak on one of the consumers (washing machine, electric stove, electric kettle...), the protection will work and turn off the power to the entire apartment, which is not very convenient. And there will be no opportunity to supply voltage, even for lighting, until the fault is completely eliminated. Imagine that the breakdown occurred in dark time days... Repair will be very difficult.
When I take an apartment for renovation, I suggest my customers install an RCD on each individual consumer line ( washing machine, boiler, el. stove, socket group, bathroom power supply, heated floors...). And, for example, install only automatic switches for lighting and air conditioning.
The connection diagram looks approximately like this:
This option is an order of magnitude more expensive than the usual one and the increased number of devices may not fit in the switchboard, but you have to pay for comfort and safety. And you can save space in the panel if you install a differential instead of a circuit breaker with an RCD. machine. It takes up less space, and performs the same functions as AV and RCD combined.
