How to connect an RCD

RCD Connection Rules Table of contents:

  • 1 Why do I need
  • 2 Connection Methods
  • 2.1 Connection of a two-pole RCD to a single-phase network
  • 2.2 Connection of a four-pole RCD to a three-phase network with using neutral
  • 2.3 Connection of a four-pole RCD to a three-phase network without use neutral
  • 3 Connection in an apartment and in a private house
  • 4 videos
  • 5 Schemes

If your apartment has a large number of household techniques, then you must install such apparatus like an RCD. Otherwise, all household appliances will be under big threat. In the article we will look at how to connect a similar device and a machine in an apartment and a private house, We will demonstrate schemes, photos and video instructions.

Why do i need

The installation of such devices is necessary for several reasons. The main Thus, it was designed for protection. From what? First, RCD protects people from electric shock, especially when There are malfunctions in the electrical installation. Secondly, the device trips and disconnects current due to accidental or erroneous contact with live parts of the electrical installation, in case when current leakage occurs. And thirdly, prevented ignition of electrical wiring in the event of a short circuit. As seen from of the above, this machine actually performs the most important function.


Today you can meet differential automata, a feature which consists in combining a circuit breaker and RCD Their advantage is that in the shield they occupy less space. In all cases, when connected, all contact connections should not be connected to it from below, but only from above. One reason is a more aesthetic look. But there is a much more significant reason. The fact is that RCDs can reduce coefficient of performance of all household items. More Moreover, during repair work, the electrician will not get confused, and he will not have to learn complex, intricate schemes. So now it’s come time to consider connection options.

Connection Methods

Four connection options are known:

  1. Connection of a bipolar to a single-phase network.
  2. Connecting a four-pole to a three-phase network using neutral.
  3. Connection of a four-pole to a three-phase network without use of neutral.
  4. Connection of a four-pole in a single-phase network.

We consider each case individually.

Connection of a two-pole RCD to a single-phase network

Bipolar RCD to a single-phase networkBipolar RCD to single phase network

Among all the listed connection methods, this is perhaps the most common pattern. When connected, no complex turns. Moreover, such a device can be connected and by yourself. To do this, on the case or in the passport it is necessary find out exactly where the neutral or zero is located on the machine, and also phase. As a rule, such signs 1,2 and N. are indicated on the machine – implies incoming phase conductor, 2 – outgoing phase conductor conductor and N denotes zero or neutral.

One of the main conditions for connecting such an RCD is that it is installed in all cases after automatic breaker! This requirement protects the meter from increasing current.

There were times when the device failed. Why? All the fact is that a current exceeding its rated current passed through it working current. To avoid this in your case, buy a device with as high rated current as possible. Moreover, with When connecting, it is important to follow the correct sequence. Otherwise in its operation may cause problems. For example, if When connecting, mix terminals zero with phase, then the device immediately will fail.

Connection of a four-pole RCD to a three-phase network with using neutral

Four-pole RCD three-phase network, neutralFour pole RCD three-phase network, neutral

This connection method is also quite common. Principle its connection is practically no different from a single-phase network. Only in this case is a four-pole RCD mounted. It has four incoming wires, which are marked on the machine as A, B, C and zero (N). Typically, the wiring diagram is indicated on the housing. automatic machine. The only difference may be that on a four-pole device, zero can be on the other side. The most important thing is to properly connect the outputs and inputs.

Such RCDs are used to protect electrical wiring from fire high leakage currents. If used to protect against damage current of a person, it is recommended to use a leak point, which equals 10 to 30 mA.

For the very protection of the device directly in front of it mounted circuit breaker.

Connecting single-phase networks is best through zero shanks, which is mounted directly in the shield on DIN rail.

Also, when connecting, it is extremely important to observe the color coding wires, as well as connecting the neutral and phase conductors.

Connecting a four-pole RCD to a three-phase network without neutral use

Connection to a three-phase network without neutralConnect to three-phase network without neutral

This scheme is used in most cases to connect three-phase electric motors. The machine will disconnect it from the network, as only a short circuit of the windings occurs. To connect a three-phase motor requires three phases of supply voltage, and namely A, B and C. A protective conductor PE, which will serve as the grounding of the chassis. As a result no it makes sense to acquire five core wire, but four will be enough veins.

Connection of a four-pole RCD in a single-phase the network

Four-pole RCD single-phase networkFour Pole RCD single phase network

This use can be safely called irrational and appropriate. However, in some cases this is the only true decision. For example, if in the future you plan to expand electrical wiring, transferring it to a three-phase network or add several single-phase networks. Moreover, such a scheme is used in temporary use of emergency replacement faulty bipolar RCD. Connection is quite simple. For of this zero and phase is connected to the corresponding terminal. Wherein connecting the phase conductor to the terminal is only if the “Test” button is currently connected. Such a terminal located next to zero.

Connection in an apartment and in a private house

For the washing machineFor washing machine

The connection diagram in the apartment is carried out only on a single-phase network. For this reason, the connection is as follows order:

  1. Introductory machine.
  2. Electric meter.
  3. RCD 30 mA.
  4. Electrical wiring in the apartment.

Connection in the apartmentConnection in the apartment

If you have power consumers in your apartment electricity, such as a washing machine or an electric furnace, then it is recommended to connect an RCD protective device additionally.

Choice of RCDRCD selection

As for connecting the machine in a private house, then The connection sequence is as follows:

  1. Introductory machine.
  2. Electric meter.
  3. Automatic from 100 to 300 mA, the choice is made depending on the amount of current consumed by all household appliances.
  4. Automatic machine for individual current consumption. Usually, 10 to 30 mA is used.

So, we have examined with you some features and differences RCD connection in certain circumstances. The most important thing, remember that if you have no idea what system, it’s better not to experiment.


A few words about typical errors when connecting an RCD:


To correctly install the RCD, we suggest that you familiarize yourself with some schemes of its connection:

Connection diagramWiring diagram

Operating principleOperating principle

Residual current deviceProtective device shutdowns

Electrical panel diagramCircuit board

RCD connection with automationRCD connection with automation

How to connect an RCD

Connection to a network 380VConnection to a network 380V

Four-pole RCD without zeroFour-pole RCD without zero

Housing group shieldHousing panel

Four-pole UZOFour-pole RCD

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