Connecting an RCD (residual current device) is a generally accepted security measure for those living both in an apartment and in a private house.
RCD has saved the lives of many people, such a device is a true fuse against fires and short circuits.
But do not forget that in the absence of a responsible approach and knowledge, RCDs can do more harm than good.
It is not in vain that there are fundamental rules that exclude the possibility of error when connecting an RCD and protect a person from injury.
Therefore, you need to have a good understanding of the principle of operation of machines. When connecting immediately, a serious problem may arise.
If you have an old Soviet TN-C system in your house (and this is not uncommon even in our time), where the protective conductor is combined with a neutral one, then it will be very difficult to connect the RCD.
However, this does not mean that the device does not need to be installed. It's just that the procedure will be somewhat more complicated than usual.
It is equally important to choose the right RCD that is suitable for a particular network and will not fail.
Before we start connecting, let's figure out what is the principle of the device on the network?
The RCD cuts off electricity in the event of an emergency. An indicator of an accident is a leakage current - if its level rises in the network to a predetermined limit, then the electricity circuit opens.
Important nuances in the operation of the device
For any network, it is important to select the appropriate RCD. Experts advise to connect an RCD without grounding or with it in an apartment or in a private house nearby with an electricity meter.
That is, the closer the device to the source of electricity, the better. The RCD must be connected together with an automatic circuit breaker.
The best option: connecting the device and a pair of machines.
To connect the machine, you can use the following methods:
- Connection to the entire RCD circuit. But here you can see the cons, which later threaten to develop into serious mistakes: in the event of a breakdown, you will not be able to immediately understand in which area the short circuit occurred; if the device works, then this is fraught with turning off the electricity in the entire network in the house or apartment;
- In the second case, the machine is connected to any separate network. If the device works, then the current will turn off only in a certain section of the network in the apartment. The rest of the circuit works as before. This method can be called more expensive (connection will be half the price). However, all the pluses here on the face.
The latter option allows you to simultaneously ensure the protection of single-phase and three-phase activity of devices in the apartment. In such a network, a zero bus and an earth bus are combined.
The account must be connected between the device and the automatic switch. The principle of operation and connection of a three-phase device is not much different from a single-phase system.
The difference is only in the number of phases (the presence of a single-phase or three-phase system).
We connect the RCD correctly
The principle of operation when connected is quite simple for both single-phase and three-phase systems.
The basic rule here is to connect a fuse that will protect both the RCD and itself.
It would also be correct to install a circuit breaker that will turn off the system if the current exceeds the normal mark. The tripping current must not be greater than the operating current of the RCD.
In this way, maximum protection can be achieved.
Please note that when connecting, it is better to use a neutral wire and make sure that it is connected to the RCD.
Most often, the device itself has a special terminal with a designation; it can be located on the top or bottom of the case.
The principle of this stage of work is that in case of an error and connecting to the wrong terminal, the device may burn out.
Here you need to adhere to the polar principle: we connect the neutral wire to the "ground", and not to the wire with voltage.
RCDs are connected where most often there can be damage from electric current. Common options are the kitchen and bathroom.
Here, not only high humidity, but also the saturation of the area with electrical appliances.
Connection without grounding: is it possible?
First of all, it should be understood that the device is sold without a machine that would protect the switch from overloads.
Therefore, it is important to ensure, at the connection stage, the connection of automatic machines that operate when the network is overloaded. As mentioned above, connecting across the entire network would be a mistake.
Therefore, RCDs are installed in the electrical circuits of the bathroom, kitchen, basements and garages. At the same time, it is considered that the connection of an RCD without grounding does not affect the operation of the circuit breakers in any way.
The principle of operation here is such that the protective properties are not reduced in any way. In a modern house, we can find a system with either three-phase wiring or five-phase wiring.
However, not every apartment has such conditions - much more often wiring is used, where the neutral and protective conductors are combined into one conductor.
That is, in such a system there is no grounding element.
Therefore, if there is no machine, and you want to connect an RCD, then use a three-wire cable. However, we do not connect the third cable to either the shield or the sockets.
It is necessary to isolate it from above or below, and ideally, leave it in this form until the wiring is completely replaced with a more modern one. The third protective wire must also not be connected to zero in the shield.
The principle of operation of RCDs with different characteristics and designs differs from each other.
Before connecting from above or below, you need to understand what RCDs are, to know the main features that you will rely on when choosing.
First of all, the device is distinguished by the presence of a pole element. Understanding the choice of a pole RCD is quite simple.
If you have a voltage of 220 volts in your house, then choose a pole type design with two poles. If 380 volts, then the choice of a four-pole machine will be correct.
The advantage of a 4-pole machine is that it can be easily used even at a voltage of 220 volts, simply by using not all poles.
Another one the most important characteristic when connecting RCD - leakage current. It will also not be superfluous to pay attention to it.
So, you can find an automatic device that will protect against electric shock from above or below. There are varieties of machines that simultaneously protect against current and fire.
The most resistant to fire are separate RCDs of a fire-fighting three-phase type. The issue is usually in the price, but do not make obvious mistakes - excessive savings will not lead to good.
You can not do without assessing the power of the RCD. The device must successfully withstand the load from the consumer.
The classification of automata looks like this: low-power (the average current here does not exceed 10 A), medium-power (current up to 32 A), and also powerful (load above 40 A).
Remember that the more powerful the RCD you connect, the higher the leakage current should be.
The safety of the use of all wiring depends on the speed of the RCD. The device of the selective machine is considered the fastest - among them there are two classes S and G.
The second option is referred to as high-speed.
The technical assembly of the machine also affects the principle of operation. Devices are divided into electronic and electromechanical.
The difference between them is in the structure of the machine: for example, electromechanical ones do not need to be connected to the network. In the event that one phase or zero disappears, the work will continue.
Electronic starters do not work without constant power supply, the phase disappears - normal functioning stops.
Another indicator is associated with leakage current - its type. When connecting an RCD, the current can be direct or alternating. In a household network, the current is usually alternating.
Pay attention to the marking: AC - alternating current, A - acts on both types of current.
Device Connection Sequence
When connecting, it is important to remember that both the phase component and the zero of the circuit on which protection is placed must go through the device. RCDs are equipped with output and input contacts.
Each terminal has its own marking, so it's quite easy to figure out what goes where.
Most often, we can find input contacts at the top, and output contacts at the bottom.
That is, from above you need to connect wires that give current, and from below - cables that will go to the devices. When connecting the contacts from above, follow the pressing force.
All devices, both above and below, must fit snugly, otherwise heating cannot be avoided. Conventionally, all connection schemes are divided into two types: with one level and multilevel.
The first type is suitable for individual systems or protection of the entire wiring at once. The device of the machine provides protection only from electric current in an apartment or house.
Common example: voltage protection during operation washing machine in the bathroom.
Just do not forget that with such an RCD you still need to organize correct connection circuit breaker, which will save the circuit from a short circuit.
When you connect an RCD for all consumers, then place the device next to the meter.
With multi-layered protection, you will have to make accurate calculations for each device that operates on the network.
If an error is detected, the system will shut down. RCDs of the lower level must work in coordination with the main circuit breaker.
In other words, the connection should be carried out so that in the event of a burnout of one of the RCDs, all other machines remain operational. This rule also applies to the main machine.
If it is turned on, then the RCD both from above and from below should function without problems. It is believed that the connection of such a complex system is best left to professionals.
The price may seem high to you, but such a move will be much safer for the whole family and household appliances.
Do not forget that the most dangerous circuits are protected by separate RCDs. For sockets, the contacts should be brought to the input zero terminal in the shortest possible way.
Cascade connection of devices is also allowed if the upper RCDs are less sensitive than the terminal ones.
An important nuance: if the RCD has tripped and the electricity has turned off, you can’t just turn on the devices again. First you need to find the problem, and only then make the connection.
) is not universal remedy protection of electrical circuits. RCD is a device that supplements the main protection of an electrical circuit (protection against overcurrent short circuit and overload). The RCD cannot turn off the network when overloaded. If there is only one RCD in the circuit, then when overloaded, it will simply burn out. True, it is worth noting that instantaneous RCDs can act as additional protection against overcurrents in the event of a short circuit.
Note: This article discusses the rules for installing an RCD. The installation of automatic differential current circuit breakers (RCBOs) of the UZO-D type is not considered.
RCD installation rules - residual current device
The rules are formulated as they are significant and binding. The list is ranked from mandatory to recommended.
2. An RCD is installed in the floor or;
3. RCDs without built-in protection must be installed together with circuit breakers (). Circuit breakers will protect the RCD from burnout during overload and short circuit;
4. RCD not installed on a wiring group without a circuit breaker. The tripping current of the circuit breaker must be no more than the rated current of the RCD. For example, a 40 Amp RCD should be protected by a 36 Amp circuit breaker, in extreme cases, 40 Amperes;
5. A circuit breaker in a circuit with an RCD can be either single-pole (per phase) or two-pole (phase + zero) and it must be installed before the RCD from the power supply side;
Explanations for the diagram: RCD 3 is protected by circuit breaker 1 and is installed for three groups with circuit breakers 4, 5, 6.
6. You can install one RCD on several, provided that each of the groups is protected by a separate circuit breaker;
7. If you plan to install several RCDs, then for each RCD, at the output, you need to install your own zero bus, separate from the others;
More rules
It could be said about the prohibition of grounding of instrument cases and ground contacts of power outlets in the RCD coverage area. But I will say differently: Forget about zeroing in the apartment and house. It's dangerous, inefficient, and unnecessary. If the house has a “clean” TN-C grounding system, forget about the RCD and zeroing.
For electrical circuits in wet rooms (bathroom, etc.), the installation of an RCD with a tripping current of not more than 30mA is mandatory. It is better to install an RCD with a trip current of 10mA;
It is better to install a 30mA RCD on individual household appliances that come into contact with water ( washing machine, dishwasher);
Do not confuse the RCD terminals zero (N) and phase (L). The N terminal of a two-pole RCD is located on the right side of the device and is usually marked with the corresponding letter;
Both the top and bottom terminals of the device can be used for input. But for the order and uniformity of installation, I advise you to do a classic installation: input at the top, output at the bottom of the device;
I repeat, each RCD of the circuit must have its own zero pad. All working neutral wires of this group are connected to this block, and not to the main zero block of the network. That is, they put the RCD immediately to it with their zero block. The outgoing zero from the RCD was brought to this block and to it all the zeros of this group;
Having decided on the rating and manufacturer of the RCD, you can begin its direct connection. Devices of this class are mounted in a protective electrical panel, which must comply with the technical conditions for this electrical network, be spacious enough to accommodate circuit breakers and connecting wires.
As a rule, a metal electrical panel is installed at the input of the network. Some of its varieties are locked, have a separate sealed compartment for the electric meter. For outdoor installation, the electrical panel must have a robust anti-vandal housing and weather protection.
For connection via RCD individual groups users, it is best to install it directly on site. In this case, plastic shields are used, they are cheaper and more aesthetic. They can be both overhead and wall-mounted or drywall constructions.
From simple to complex
Presented the simplest circuit connecting the RCD makes it possible to understand the principle - the neutral wire after the protective device must be insulated as well as other conductors. It must not come into contact with either the input neutral conductor or the PE ground wire.
The principle of connecting RCDs with machines Understanding this simple rule allow you to independently assemble a shield of any configuration, no matter how complicated the circuit may seem. Another important rule is to use a circuit breaker in series with the RCD.
This circuit is great for connecting one or more parallel-connected sockets, and can be successfully used to power electrical appliances in the bathroom, kitchen, garage or basement.
Scheme with several circuit breakers
This type of connection can be used in the input shield, to protect the entire apartment with the help of one RCD. The image shows that in addition to additional circuit breakers, a new element has appeared - a zero bus insulator mounted on a din rail.
zero tavern The fact is that after each switch, a phase wire comes out, which is paired with a neutral conductor to its consumer. These neutral conductors must be electrically connected to the output terminal N of the circuit breaker. It is clear that with a large number of them, they simply physically will not fit into the clamp.
Some electricians file the current-carrying cores if the cables are single-core, or bite off a few cores in multi-core cables to squeeze the entire twist of the neutral wires into the connection socket. This is highly undesirable due to the fact that the cross section of each sawn conductor will be smaller, respectively, there will be more resistance and heating.
Many contacts at one point will also create additional heat dissipation, exacerbating the situation. The solution to this problem is to connect neutral conductors to an isolated zero bus.
These products are available with different numbers of mounting holes of different diameters. The insulators that hold the busbar can be mounted both on the DIN rail and on the shield body. The PE ground wire bar is attached directly to the housing.
The connection of all neutral wires into one bundle is also undesirable due to additional difficulties in finding a fault on the line, or when dismantling one of the cables - you will have to unscrew the clamp once again, unwind the twist, which will lead to microcracks in the conductive cores.
But simultaneous installation of two wires in one socket is allowed, as can be seen from the figure, the inputs of the circuit breakers are connected by jumpers. Professionals for these purposes use special connecting tires, called "combs".
"comb" Copying the previous diagram
To install selective multilevel protection, you need to use the previous scheme, simply copy it, and paste it to a lower level, adding or removing circuit breakers, changing the rated current and the differential tripping current of the protective device.
The input RCD in this case should be of type S - selective. In the above diagram, we have a series and parallel connection of the RCD. In this way, you can assemble an arbitrarily complex protection system.
It is also worth noting that the connection of a three-phase RCD is fundamentally no different - instead of single-phase machines, three-phase ones are used. Electric motors can be connected in three phases without a neutral wire.
Preliminary preparation
Electrical panels must be provided with fastenings for 35mm DIN rails. In some products, it is installed by the manufacturer initially. When installing the RCD directly at the place of its operation, the connection diagram must be in front of your eyes in order to avoid mistakes and confusion of wires.
Arrange the machines and connected devices in such a way as to avoid excessive interlacing of conductors. The entire system assembly should look ergonomic and aesthetically pleasing.
And the point here is not the beauty of the work done, but the fact that later, when repairing, replacing, or connecting additional elements, it will be easier to figure out all the intricacies of wires. For the same reason, you need to stock up on a multi-colored cable of the VVG type, corresponding to the section currents. It is also worth using an insulating PVC tube (cambric) for marking conductors.
To install RCDs and other machines with your own hands, you need to have the minimum required set of tools:
- screwdriver
- pliers;
- knife or strippers;
- wire cutters.
Professional electricians use special pliers (strippers) to strip the insulation. With a small volume installation work you can get by with a knife, trying to carefully remove the insulation without damaging the core. But for stripping many cables, it is better to stock up on a specialized tool - it will be faster and more reliable.
Don't make mistakes
With such an extensive system of wires, it is easy to make a mistake, especially if the entire installation is carried out in one shield. It is necessary to connect each RCD in stages, starting from the input, ending with the reduction of neutral wires to an isolated zero bus, for each RCD its own.
It is very important not to mix up the neutral wires from different devices protection. In addition, the correct installation of sockets plays a key role: if the neutral wire is confused with grounding somewhere, the device will work immediately when the load is turned on.
Polarity
Among some electricians, there is a belief that the RCD can be connected in any way, changing the neutral and phase conductors. For electronic RCDs, such neglect of the rules can be fatal - the internal power will fail.
Electromechanical devices will work, but there will be nuances during shutdowns - the phase contact opens a fraction of a second faster. Since the manufacturer indicates the marking of the conclusions, then he carried out the appropriate tests and calculations.
Some of the electricians, trying to save on wires, can connect the RCD "from the bottom up", swapping the input and output. The device will work, but the arc extinguisher may fail in this case, and under heavy load, at the time of protection operation, several thousand degrees of plasma can cause a disaster. You should not experiment with the correct connection, you must always observe the polarity.
Installation culture
It is important not to allow tension or sagging of the wires. The insulation must be removed for the entire length of the entry into the mounting socket, but no more. Do not repeatedly bend-unbend the conductors. Clamp the terminals with a suitable screwdriver, preventing it from slipping, do not overdo it with the use of force. Check the reliability of the installation of each wire, twitching it with your hand.
Hello dear readers of the site. Today, the inclusion of an RCD (residual current device) in the home electrical network has become the norm. But not everyone understands why this device is needed and how to connect RCD.
The main task of the RCD is to increase the level of protection against fires caused by leakage currents or earth faults, when the amount of current is not sufficient to trip the circuit breaker.
The second task of the RCD is to protect a person from damage. electric shock, under which it can fall when accidentally touching bare live wires, or when touching an electrical equipment case with damaged insulation.
According to their design parameters and appearance RCDs are practically no different from circuit breakers. They, like switches, are produced for operation in single-phase and three-phase circuits, and in the event of an emergency, they automatically turn off the supply voltage from the damaged section of the electrical circuit.
But if the circuit breaker is triggered by a short circuit current or an overload current that exceeds the operating current of the circuit breaker itself, then the RCD is triggered only by the leakage current, for which it is designed.
The industry produces residual current devices designed for a leakage current of 10mA, 30mA, 100mA, 300mA.
Connecting an RCD, as well as Distinguishing an RCD and a circuit breaker is very simple.
The rated operating voltage, operating current and structural scheme devices.
In this example, the circuit breaker has an operating current of 25 amps and a rated operating voltage of 400 volts. Terminals "1" and "3" are energized, and terminals "2" and "4" are de-energized.
The rated operating voltage, operating current, rated differential breaking current (leakage current), the block diagram of the device are indicated on the RCD case and a button is installed "TEST".
Unlike circuit breakers, residual current devices additionally have a special circuit that creates a leakage current. This circuit is designed to check the health of the device.
When the "TEST" button is pressed, the circuit is closed and a current leakage is artificially created. And if the device is working properly, then the actuator will work and turn off the load.
In this example, the RCD is designed for an operating voltage of 230 Volts, an operating current of 32 Amperes and a leakage current of 30 mA. The upper pair of terminals "1" and "N" is supplied with incoming voltage, and the voltage is removed from the lower pair of "2" and "N".
Zero is applied to the "N" terminal.
There is another major difference in the operation of these devices that you need to know.
If a two-wire electrical circuit is sufficient for the operation of the circuit breaker: “phase - zero”, then for correct operation RCD must have a third conductor - grounding. That is, a three-wire electrical network should be laid in the building: “phase - zero - grounding”.
Grounding acts as a protective conductor through which voltage “flows” in the event of an emergency. For example, when a phase is closed to the electrical equipment case, the phase, using the least resistance, will go along the protective conductor RE and create a leakage current. And if this current exceeds the setting, and in our case it is 30mA, then the device mechanism will work and turn off the power to this electrical equipment.
And one more important distinctive nuance in the operation of these devices.
Through the RCD, as well as through the machine, "phase" and "zero" pass. But for proper operation, the device must have its own “phase” and “zero”, relative to which it monitors leakage currents. These "phase" and "zero" are obtained from the output of the RCD.
The phase, if there are several consumers, is propagated through circuit breakers.
For zero, a separate bus (block) is used, relating only to this RCD.
And if two RCDs are used in the network, then there will be three zero tires: one common N, from which the main neutral conductor comes to the input of both devices, and two additional N1 And N2, which are formed from the outputs of these RCDs.
The figure below shows a circuit with one RCD.
Phase L and zero N go to the input of the device QF1. From the exit QF1 phase is distributed over circuit breakers SF1 , SF2 And SF3, each of which supplies a phase conductor (phase) for its consumer.
Zero N enters the RCD input, and leaves the device output as N1 and connects to the zero bus N1, from which consumers take a zero working conductor (zero). With ground bus zero protective conductor RE applied to each consumer group.
As a sample, I offer you one of the options for the scheme of how to connect the RCD of a home shield, implemented on three RCDs, as well as the approximate distribution of voltage among consumers.
Also remember: that when installing several RCDs located in series, the one closest to the power source must have an installation and response time of at least 3 times greater than that of an RCD located closer to the consumer.
Well, in conclusion, one more moment.
In a two-wire electrical network, the RCD will also be able to work, but only if you create a third conductor for it and a path for the current to pass to the grounded elements of the building.
You can find a short video about connecting an RCD in our social groups. networks.
Now I don't think you should have any questions. how to connect RCD to the home electrical network. Good luck!
RCD is a tool that protects people from electric shock. In addition, it is designed to protect an apartment or house from a fire that can occur when the electrical wiring ignites. The RCD connection diagram without grounding must be correctly drawn up, otherwise it will only bring harm.
Factors affecting the correct connection of the RCD
- Understanding how it works. This depends on the connection method for certain operating conditions.
- For a particular network, you should choose the right RCD.
- The RCD disconnects the network in an emergency when the leakage current reaches a predetermined limit value.
Connecting an RCD and an automaton: a circuit without grounding
For the home electrical network, certain protection devices and methods for connecting them are selected. The RCD connection scheme without grounding involves the installation of devices on separate lines or common to all wiring, after the main circuit breaker and meter. Preferably, when the device is located as close as possible to the source of electricity.
Usually, an RCD with a large rating (at least 100 mA) is installed at the input. It is mainly used as a fire extinguishing agent. After it, RCDs must be installed on separate lines with a cut-off current of not more than 30 mA. They provide human protection. When they are triggered, you can easily find out in which area the current leakage has occurred. The rest of the sections will work in normal mode. Despite the costly connection method, all the positive factors are evident.
For simple wiring with a small number of branches, a 30 mA RCD can be installed at the input, which performs the functions of human protection and as fire protection.
Connected mainly in places that represent the greatest danger. They are installed for the kitchen, where there are most electrical appliances, as well as for the bathroom and other rooms with high humidity.
Important! The RCD connection scheme without grounding requires the installation of a circuit breaker with each device, since the devices do not protect against short circuits and current increases above the norm. The switch is purchased separately, but you can buy a differential machine that combines the functions of both devices.
It is not allowed to connect wires to the wrong terminals of the device. If you make a mistake, it may fail.
The connection diagram of a single-phase RCD without grounding allows the installation of a three-phase device instead, but in this case only one phase is used.
How RCD works in the absence of grounding
When the insulation of the wires is damaged or the fasteners of the current-carrying contacts of the devices are loosened, current leakage occurs, leading to heating of the wiring or sparking, resulting in a fire hazard. If a person accidentally touches a bare phase wire, he can receive an electric shock, the passage of which through the body into the ground creates a danger to life.
The RCD connection diagram without grounding in an apartment or in a house provides for continuous current measurement at the inputs and outputs of protective devices. When the difference between them exceeds a predetermined limit, the electrical circuit is broken. Usually, grounding is done on the protected object. But it may not be.
In old Soviet-built houses, RCDs are used in circuits where there is no PE protective conductor (grounding). From the main three-phase house network, a phase wire and a neutral wire are connected to the apartment wiring, which is combined with a protective conductor and is designated PEN. In a three-phase apartment network, there are 3 phases and a PEN conductor.
A system with a combination of the functions of working N and protective PE conductors is called TN-C. From the city overhead line, a cable with 4 wires (3 phases and neutral) is introduced into the house. Each apartment receives single-phase power from the interfloor shield. combines the functions of a protective and working conductor.
RCD connection diagram in single-phase network without grounding, it differs in that if the phase breaks down and hits the case, the protection will not work. Due to the lack of grounding, the cutoff current will not flow, but a life-threatening potential will appear on the device.
When touching the electrically conductive parts of the housing of the electrical appliance, a current is created for the passage of current. electrical circuit into the ground through the body.
If the leakage current is below the threshold value, the device will not work, the current will be safe for life. If the limit is exceeded, the RCD will quickly disconnect the line from touching the case. If there is grounding on it, the circuit can be disconnected before a person touches the case, as soon as an insulation breakdown occurs.
Connection features in three-phase networks
In accordance with the PUE, the installation of an RCD in three-phase networks TN-C system is prohibited. If the receiver needs to be protected, the grounding PE conductor should be connected to the PEN conductor before the RCD. The TN-C system is then converted to the TN-C-S system.
In any case, the RCD must be connected to increase electrical safety, but this must be done according to the rules.
RCD selection
The differential machine is selected with a power one step higher than that of the one connected to it in one line. The latter is designed to work with an overload for several seconds or minutes. An RCD of the same power as it is not designed for such loads and may fail. Low-power devices are used at a current of not more than 10 A, and powerful ones - above 40 A.
With a voltage in the apartment of 220 V, a two-pole device is selected, if 380 V is a four-pole device.
An important characteristic of the RCD is the leakage current. It depends on its value whether to use the apparatus as a fire-fighting or for protection against electric shock.
Devices have different speeds triggering. If you need a high-speed apparatus, a selective one is selected. There are 2 classes here - S and G, where the latter has the highest speed.
The structure of the machine can be electromechanical or electronic. The first does not require additional power.
By marking, you can distinguish the type of leakage current: AC - variable, A - any.
Errors in the installation and operation of the RCD
- It is not allowed to connect the output neutral wire of the RCD to an open area of \u200b\u200bthe electrical installation or switchboard.
- The neutral and phase wires must be connected through a protective device. If the neutral bypasses the RCD, it will work, but false positives may occur.
- If you connect zero and ground to the same terminal in the outlet, the RCD will constantly trip when the load is connected.
- It is not allowed to install a jumper between the neutral wires of several groups of consumers if separate protective devices are connected to them.
- The phases are connected to the terminals marked "L" and the zero to "N".
- It is not allowed to turn on the device immediately after operation. First you need to find and fix the problem, and then connect.
RCD connection without grounding in the apartment
Insulation breakdown in the absence of grounding leads to the appearance of a potential on the instrument case that is dangerous to humans. Leakage here will occur only after touching. In this case, the entire leakage current will pass through the body until it reaches the threshold value and the protective device disconnects the circuit.
Connecting the RCD to sockets
In the presence of a TN-C system, the instrument case is sometimes connected to the neutral wire. The connection diagram of an RCD without grounding for sockets provides for connecting the neutral to the side terminal 3. Then, if the wire breaks down, the current from the device case will go through it. Connection should be made at the entrance to the apartment.
This is a violation of the rules, as the likelihood of electric shock increases. If voltage hits the neutral in the external network, it will be on the cases of electrical appliances grounded in this way. Another disadvantage of this method is the frequent operation of the circuit breaker when connecting loads.
This connection cannot be made independently. If everything is done according to the standard, it is necessary to order a draft change in accordance with the requirements of the PUE. In essence, this should be a system change to TN-C-S as follows:
- transition inside the apartment from a two-wire to a three-wire network;
- transition from an intra-house four-wire network to a five-wire network;
- separation of the PEN conductor in an electrical installation.
Features of wiring for connecting RCD
When an RCD is connected in a single-phase network without grounding, the wiring is done with a three-wire cable, but the third conductor is not connected to the zero terminals of the sockets and instrument cases until the system is upgraded to TN-C-S or TN-S. With the PE wire connected, all conductive cases of the devices will be energized if the phase falls on one of them, and there is no grounding. In addition, the capacitive and static currents of electrical appliances are summed up, creating a danger of human injury.
Having no experience in wiring and electrical equipment, the easiest way is to purchase an adapter with an RCD for 30 mA and use it when connecting to electrical outlets. This method connection significantly increases electrical safety.
For electrical appliances and other rooms with high humidity, it is necessary to install an RCD of 10 mA.
RCD connection diagram in a single-phase network without grounding in a private house
The home network may be the same as in the apartment, but here the owner has more options.
The easiest way is to install one common or several RCDs on the main lines of the home network at the entrance. For a complex network, several layers of protective devices are connected.
An introductory RCD of 300 mA protects all wiring from fire. In addition, it can operate on the total leakage current from all lines, even if they have leakage within the normal range.
Universal RCDs for operation at 30 mA are installed after the fire, and the next lines should be a bathroom and a children's room with I y \u003d 10 mA.
How to connect grounding in a private house
You can make a ground loop and convert the network to TN-C-S. It is not recommended to independently connect the re-grounding to the neutral wire. When voltage hits the neutral from the external network, this grounding may become the only one for all neighboring houses. If not properly executed, it can burn out and cause a fire. It is advisable to re-ground at the outlet from the overhead line, which minimizes the likelihood of a fire in the house.
Connecting an RCD in the country
In the country, the wiring diagram is simple, and the loads are small. Here, the RCD connection diagram in a single-phase network is suitable (photo below). RCD is selected for 30 mA (universal), with protection against fire and against electric shock.
The scheme for connecting an RCD without grounding in the country requires the installation of a main input and a pair of machines for lighting and sockets. If a boiler is used, it can be connected via a socket or a separate machine.
Conclusion
An RCD connection scheme without grounding is a common method of protection. The ground also serves as a protection and must be connected correctly. It is important to pay attention to the additional protection of the bathroom and other rooms with high humidity. RCDs are expensive, but electrical safety is more important here. IN complex schemes electrical wiring, it is advisable to install several stages of protection with selective operation of an RCD of a smaller rating.
It is important to understand that the RCD is the only type of apparatus designed to protect a person from electric current.
