Connection of a three phase flow water heater through an RCD

Is it possible to connect a water heater by 8 kW per phase in a three.Phase network?

The Stiebel Eltron DHC 8 with a capacity of 8 kW was bought. It was assumed that it was three.Phase and therefore extended to it NYM 5×4 kV.Mm.

Now it turned out that it is single.Phase (see. A photo). I want to avoid installing such a powerful device per phase.

Use three veins from NYM 5×4? But whether they will pull the current in 40a? And the maximum machine current for 4 kV.Mm., If I am not mistaken, only 32A is possible, but at least 40A is needed?

connection, phase, flow, water

Is it possible to somehow “put” a single-phase device on three phases?

Released capacities: installation. 22 kW. Permitted –14 kW. Three phases.

With such permitted power with three.Phase input, the current for each phase should not exceed 22 A. This is less than the water heater consumes. It is necessary to solve, first of all, the question of increasing the permitted power.

MWW08 wrote: It is necessary to decide, first of all, the question of increasing the permitted power

I examined this option immediately after buying an apartment. But have repelled all the desire.

You can somehow put it on three phases?

Either the replacement of the water genera, or the replacement of three.Phase entry into the apartment with a single.Phase.

No, well, you can still put a trance (3) 380/220, 10kva. But this is more and heavier than the accumulative water, and more expensive than increasing power

Kamikaze wrote: either the replacement of a three.Phase entry into an apartment with a single.Phase

Here in this topic (”) people connected single-phase hobs to two or three phases.

The question arises: these panels have such a hardware opportunity (work from both 220 and from 380V) or I quote “. It is installed by jumper and appropriate connection to the desired terminals. “? Maybe with a groove can be “jumpers”?

I have, damn it, and Num5x4 is also laid on the hob is also laid.

Upon careful consideration. Your water heater has two heating elements. If the power is equal, you can tie the water heaters for a two.Phase regime. In phase on the heater.

Kamikaze wrote: If the power is equal, you can tie the water heaters for a two.Phase regime. In phase on the heater.

Or replace the “little thing” pos.4 on a similar, but three.Pool, or refuse to switch the working zero. Is small in trouble (see.). 4x4mm2 cable is required (in fact, 2.5mm2 under AV 20A is enough). The fifth residential is advisable to duplicate (carry out separately for the second heater) working zero.

Kamikaze wrote: either replace the “little thing” pos.4 for similar, but three.Pool, or refuse

Little thing pos.4 is a temperature limiter (see. Pictures).

Tomorrow I will take a picture of this proton and post here.

connection, phase, flow, water

However, even if the heating elements of different capacities, say, 62kW, then short.Term work in two.Phase mode with introductory AB 25A is also possible, in the absence of other consumers with significant power on a more loaded phase.

Airuser wrote: you can somehow put it on three phases?

Perhaps not worth it, but two, as Kamikaze suggested in p.9, in my opinion, the best option.

Airuser wrote: you can somehow put it on three phases?

Airuser wrote: Quote: Message from Kamikaze

If the power is equal, you can tie the water heaters for a two.Phase regime. In phase on the heater. Only if the protection against overheating is two.Pole, and not that you will have to serve two phases through the starter, and assemble the control circuit and protection in the rupture of the zero wire of the starter (the reel in the switch on the phase, zero on the chain not supplied to the water heaters. Third phase, switch of water switch and a zero wire working on the zero shield bus).


To determine which RCD to install you need to familiarize yourself with the main parameters and characteristics of the equipment:

  • Two.Pole (operating voltage 220 V) or a four.Pole device (380 V), depending on the network (single.Phase or three.Phase), in which a dialog will be installed.
  • The nominal charge power. This is a current (in amperes), which can flow through the device for a long time. The standard range is: 6, 10, 16, 20, 32, 40, 50, 63a.
  • Temporary characteristic of the current (“b”, “c” or “d”), which indicates the dependence of the response time.
  • Nominal differential current. This is the current leakage to which the dialog will respond and disconnect. There is also a standard series of differential currents −10, 30, 100, 300, 500 mA.
  • Nominal disconnecting ability. This parameter represents the maximum value of a short circuit current, which the differential circuit breaker can withstand and stay in operation.
  • Temperature Range. Usually it is from −20 degrees to 45.

Principle of operation

The principle of operation of the RCD is very simple. It includes a core with two windings and is actually a small transformer. The number of turns into the winding, material and cross section of the wires are the same, t.E. The physical and electrical properties of windings are the same. In this case, the current flows through one winding in one direction, registering devices in the room, and then flows in another direction to another. Regardless of how extensive the network is, as a result of this, the wiring in the room should have the same total current at the entrance and output. This is already an axiom (Kilhofer Law).

Two magnetic fields created by each winding are compensated, so the general magnetic field strives for zero. With a leak, the total current at the entrance and exit from the room will be different, the balance of the magnetic field in the core will be disturbed, and the dominant field will appear from the incoming current. As a result, the mechanical part will work, which will turn off the power supply.

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Three.Phase and single.Phase networks.Differences and advantages.Disadvantages

In electrical equipment of residential apartment buildings, as well as in the private sector, three.Phase and single.Phase networks are used.

Initially, the electric network leaves the power plant with three phases, and most often the three.Phase power supply is connected to residential buildings. Further, it has branches into separate phases.

This method is used to create the most efficient transmission of electric current from power plant to the destination, as well as to reduce loss during transportation.

To determine the number of phases in your apartment, it is enough to open a distribution shield located on the landing, or right in the apartment, and see how many wires enters the apartment. If the network is single.Phase, then the wires will be 2. Phase and zero. The third wire is possible. Grounding.

If the electric network is three.Phase, then the wires will be 4 or 5. Three of them are phases, the fourth is zero, and the fifth is grounding. The number of phases is also determined by the number of circuit breakers.

Three.Phase networks in apartments are rarely used in cases of connecting old electric stoves with three phases, or powerful loads in the form of a circular saw or heating devices. The number of phases can also be determined by the value of the input voltage. In a 1-phase network, a voltage of 220 volts, in a 3-phase network between the phase and zol is also 220 volts, between 2 phases-380 volts.


If you do not take into account the difference among the wires of networks and the connection diagram, then you can determine some other features that have three.Phase and single.Phase networks.

  • In the case of a three-phase power network, a phase distortion is possible due to uneven separation according to the load phases. A powerful heater or stove can be connected on one phase, and on the other TV and washing machine. Then this negative effect arises, accompanied by the asymmetry of voltages and currents in phases, which entails a malfunction of household devices. To prevent such factors, it is necessary to distribute the load on the phases in advance before laying the wires of the electric network.
  • For a 3-phase network, more cables, conductors and switches are required, which means that money is not too much saved.
  • The capabilities of a single.Phase household network in power are much less than three.Phase. If it is planned to use several powerful consumers and household devices, power tools, it is preferable to bring a three.Phase power supply to the house or apartment.
  • The main advantage of a 3-phase network is a small voltage drop compared to a 1-phase network, provided that the power is the same. This can be explained by the fact that in a 3-phase network, the current in the phase conductor is three times less than in a 1-phase network, and there is no zero at all on the wire.

Advantages of a 1-phase network

The main advantage is the efficiency of its use. Three-wire cables are used in such networks compared to the fact that in 3-phase networks-five-wire. To protect equipment in 1-phase networks, you need to have single-pole protective machines, while in 3-phase networks without three-pole machine guns can not do.

In this regard, the dimensions of the protection devices will also be significantly different. Even on one electric machine, there is already saving in two modules. And in terms of dimensions, this is about 36 mm, which will significantly affect when placing machine guns in a shield on a DIN rail. And when installing a differential machine gun, the savings of the place will be more than 100 mm.

Three.Phase and single.Phase networks for a private house

Electricity consumption by the population is constantly increasing. In the middle of the last century in private houses there were relatively few household devices. Today in this regard a completely different picture.

Household consumers of energy in private houses breed not by leaps and bounds, but by the hour. Therefore, in their own private possessions, there is no longer the question of which power supply networks to connect.

Most often, in private buildings, power networks with three phases are performed, and they refuse a single.Phase network.

But is there a three.Phase network of such superiority in the installation? Many people believe that by connecting three phases, it will be possible to use a large number of devices. But it does not always work out.

The greatest acceptable power is determined in the technical conditions for connecting. Usually, this parameter is 15 kW for all private housing. In the case of a single.Phase network, this parameter is approximately the same.

Therefore, it is clear that there is no particular benefit in power.

But, it must be remembered that if three-phase and single-phase networks have equal power, then for a 3-phase network you can use a smaller cable, since the power and current are distributed through all phases, therefore, it loads less phases of phases. The nominal value of the current of the protection machine for the 3-phase network will also be lower.

The size of the distribution shield is of great importance, which for a 3-phase network will have sizes noticeably larger.

It depends on the size of the three.Phase counter, which has dimensions more than a single.Phase, and also the input machine will take more space.

Therefore, a distribution shield for a three.Phase network will consist of several tiers, which is a disadvantage of this network.

But three.Phase power has its advantages, expressed in the fact that you can connect three.Phase current receivers.

They can be electric motors, electric boilers and other powerful devices, which is the advantage of a three.Phase network.

The working voltage of the 3-phase network is 380 V, which is higher than in a single-phase type, which means that electrical safety issues will have to be paid more attention. The situation is also with fire safety.

As a result, several deficiencies in the use of a three.Phase network for a private house can be distinguished:

  • It is necessary to receive technical conditions and permission to connect a network from energy consumption.
  • The danger of current damage increases, as well as the danger of fire due to increased voltage.
  • Significant overall dimensions of the distribution of power input. For the owners of country houses, such a disadvantage does not matter much, since they have enough space.
  • It is necessary to install voltage limiters in the form of modules on an introductory shield. In a three.Phase network, this is especially relevant.

Choosing a device

Choosing an RCD for a boiler should take into account the main characteristics of the water heater and the electric network. Thus, with a properly selected RCD, the operation of the water heater will be safe and reliable. You should adhere to the following requirements for choosing a protective device:

എന്താണ്‌ MCB, ELCB, MCCB മലയാളത്തിൽ വിശദീകരണം. MCB, ELCB, MCCB MALAYALAM

  • The power of the device depends on the rated power of the electric network. Divided into single.Phase and two.Phase models.
  • The voltage of the electric network. Single.Phase RCDs are designed for a boiler working from a network with a voltage of 220 V, and three.Phase for 380 cotton network.
  • The degree of protection of the RCD. It is recommended to use protective devices with a degree of protection of 30 mA. You can also choose a 10 mA device, but in a domestic situation, such a degree of protection is not always necessary.
  • Place of use of RCDs. For a more correct choice of a suitable protective shutdown device, labeling is used both letter and digital. To use an RCD in a private house or apartment, an apparatus with a marker C16 or C25 is suitable.
  • Design features of the RCD. The water heater is considered an electrical appliance with high energy consumption and therefore it is better to choose protective devices of class A. In some cases, you can choose a class of AS, but such devices do not always qualitatively cope with high loads.

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How to connect a boiler, a boiler connection diagram through an electric outlet

Industrial models of small capacities up to 1.5 ÷ 2 kilowatts are created, as a rule, for such a connection. With this method, long.Term safe work is provided by:

  • The technical condition of the boiler, which changes with a long operation
  • The correct choice of the design of the outlet on the load power
  • Accounting for the condition of electrical circuits for which voltage from the apartment shield is supplied
  • The use of protective devices that prevent the consequences of accidental occurrence of accidents in the scheme

Features of connecting the boiler to an electric network through a socket

Power contacts of the detachable switching apparatus are calculated for a certain type of load, for example, 6, 10 or 16 amperes. Its value is indicated on the case. If the socket is lower in power, then overheating and destruction of contacts occurs. For this reason, you can not connect a boiler to a random that does not correspond to its load to the outlet.

Another requirement of the safe operation of such a scheme is the need to have an automatic circuit breaker in it, by means of which you can break the power supply chain under load. Contacts of the outlet and forks are not designed to extinguish the electric arc that occurs in this case.

The state of the electrical wiring

The wires of the household network connecting the outlet for the boiler with the apartment shield will completely perceive the load of the heater. They should not overheat. Their material and thickness should be correctly taken into account, otherwise a fire may occur.

You can not connect to the outlet with aluminum wiring, as well as copper, thinner than 2.5 mm kV. It is better to use a section of 4 or 6 square. It must be pre.Calculated by heat emission and analyzed by installation methods.

Protective devices

The boiler is created to work with the nominal characteristics of the electrical network, taking into account the occurrence of random malfunctions in it. To prevent accidents, protection against:

If the manufacturer of the equipment did not provide such protection in the internal structure, then they should be mounted in the apartment shield.

Emergency mode with exceeding the pressure inside the boiler

A prerequisite for safety is the presence of a device that prevents boiling of water and the release of dissolved gases from it, because with this process, increased pressure is created, which can break the case.

  • When sticking power contacts, when they received a command from the temperature sensor through the control unit and are not able to break the electric current through the heater
  • Malfunctions of the temperature sensor, logic unit or binding control circuits

To prevent such an accident, the second stage of protection is used to a higher temperature setting than for the working regime. Its value is selected close to the boiling point, and the shutdown is carried out by another, backup contact.

A similar rupture of the chain is called the thermal fuse. The use of a separate temperature sensor for him or the use of an autonomous mechanical structure operating according to the principles of bimetallic releases increases the overall reliability of the system.

Emergency mode with leaking currents

The metal case of the boiler may be under the potential of the phase when the isolation of the heater or connecting the wires to the housing. This situation is a direct prerequisite for a person to receive an electrical injury. Correct it can be fixed, built into the electrical circuit. Industrial samples of boilers can be produced with an mounted protective shutdown device or not have it.

For the proper operation of the RCD, it is necessary to ensure a reliable connection of the boiler case with the main ground tire through the protective river conductor.

Short circuit

Disconnect the electrical circuit from the KZ is called the circuit breaker is called.

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Rules for connecting an RCD to a single.Phase network without grounding: the best schemes of work procedure

A single.Phase electric network is familiar to each household. Regardless of whether a private house or a municipal apartment is operated, users in any case actively consume electricity.

Ormen Lange three-phase pipe flow

This type of energy, meanwhile, cannot be considered completely safe. Therefore, the urgent task is to connect an RCD to a single.Phase network without grounding. A special device that significantly increases the degree of safety when using electricity.

Generalized view of protective modules

Despite the construction of electrical wiring schemes made according to the approved rules, the risk of electric shock always remains. Therefore, it is important to take care of security in a timely manner.

The protective shutdown device. This is how the alignment of the UZO abbreviation is interpreted into the technical language.

From the point of view of the design of the structure, it does not look in the most difficult way among modern electrical equipment. Nevertheless, the defense functions are sufficiently qualitatively and reliable.

This is what the functionality of the electrical system looks like, with the help of which effective protection of users of electrical networks is carried out, as well as the protection of various household equipment

It should be noted that there are varieties of RCD, based on which a certain protective scheme is organized in each case:

Guaranteeing touch safety; proactive technical damage; counteracting fire hazard.

Each device with specific functionality differs from other designs with working parameters, in particular. With a nominal current and current of cutting off.

The appearance of the device with a small current cut. When operating household networks, such devices are used to protect people from unintentional contact with electric potential in conditions of emergency current leakage

The most sensitive device, of course, is an RCD designed to block a power source in case of an unintentional touch of people to live details of the circuits. The current cutout range for such devices is within 10-30 mA.

The best schemes for connecting an RCO

For the lines of electrical networks of household purposes, the introduction of RCD without “Earth” is characteristic. The main share of the circuit solutions of the household sector is precisely a single.Phase wiring, where in principle there are only two lines: phase and zero.

Features of circuits without grounding

The schematics of the device of an electric circuit without grounding are necessarily performed taking into account the inclusion of automatic protection by “short circuit” (short circuit) and the overload current.

This is an obvious factor, because individual devices of the RCD are not intended to protect from such phenomena. These devices save only from leakage currents.

Automatic switch. Approximately these are placed, as a rule, in the scheme for organizing protective cutting due to network overload. Constructive execution of RCD does not imply this type of cut

The range of cutting currents and technical characteristics of circuit breakers is slightly different from the working parameters of protective RCDs.

Meanwhile, there are universal cut.Off devices that combine the functions of the circuit breaker in one device and protect against unintentional touches to the current.Forced electric tires.

Each protective device constructively involves the switching of both conductors of the supply cable. Phase and zero.

At the same time, when installing the electrical wiring, the conductors should accurately connect to the working terminals. Incorrect installation threatens to damage the protection device, which will lead to the inoperability of the protective system as a whole.

Classic inclusion version

Depending on the technical load (number of household appliances) and the number of premises, a single full network or network consisting of several subnets may be operated in an apartment or house.

The simplest at first glance scheme for including the device in the user network has its own nuances. Therefore, incorrect connection threatens not just the failure of the protective devices themselves, but is fraught with a dangerous operational situation

For the first case, one RCD for organizing a protective shutdown is usually enough for the first case. Based on the parameters of the current consumed or the total power consumed, in this case, the protective apparatus is selected according to the rated current and are determined with the cutting current.

For the second option, the devices are introduced for each of the existing subnets. At the same time, as a rule, all installed RCDs are supplemented by automatic circuit breakers designed for the power consumption of a single subnet.

This is what a circuit solution looks like to introduce an RCD in a classic connection version. This simple wiring option provides protection for the apartment/home network as a whole. Complete de.Energization

The classic performance of the circuit of the inclusion of RCD “without earth” is traditionally performed as follows:

The main supply cable consisting of two cores (phase, zero) is brought to the machine. From the circuit breaker, both veins are brought to the electric meter. Further from the electric meter, two power wires are included in the introductory terminals of the RCD.

After a protective device, for an option without subnets, a duplicate circuit breaker can not be set, but in some cases, experts recommend doing this.

If the scheme with subnets is used, then after the RCD for each branch you need to put a separate machine.

The appointment of RCDs and Difavtomats

To understand why it is precisely the RCD or difavtomata must be used to protect the bathroom chains, you need to know their principle of work and tasks that they are designed to fulfill.

RCD or difavtomat, in contrast to the circuit breaker, works according to the leakage current that occurs in case of violation of the external insulation of the conductor or when the conductivity of materials occurs, which are dielectrics in their properties.

How a dielectric can conduct electricity? This happens if, for example, the surface of the material is moistened or the material of the porous structure is nourished with moisture. And these states are precisely characteristic of objects in the bathroom.

Aircraft will only work when closing between the phase and zero, that is, when, for example, water got into an electrical appliance or outlet and shortened both conductions. However, for the human body, the case when the potential difference between the phase and the “earth” arises is much more dangerous.

This can happen when the phase contact on the body of the device can happen, which may be the result of the penetration of water inside the body. Until the case is touched by a person, the voltage will not occur. Both the machine and the RCD will remain included.

But when touched, the tension will occur, and the likelihood of its appearance increases due to the fact that the floor or wall in the bathroom can also be moistened, which increases their conductivity.

In this case, the machine, unlike the RCD, will remain turned on, because the current passing through the body is unlikely to exceed the nominal, in which the machine is turned off.

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