Learning to distinguish RCD from a differential automaton - 4 external signs

Very often, inexperienced electricians and home masters do not know how to determine what is in the shield - an RCD or a difavtomat. As a result, it can be mistakenly thought that the wiring is protected from overloads and current leakage, although in fact, protection from the first unsafe situation is not provided, because in the shield is a conventional residual current device. In this article, we not only consider the functional difference between these two devices, but also tell you how to distinguish RCDs from the difavtomat visually.

Feature Difference

Briefly describe how the residual current circuit breaker differs from a differential circuit breaker. Everything is quite simple:

  1. RCD only works when it is detected in the circuit leakage current.
  2. Difavtomat The functions of the residual current device + circuit breaker are included. Total differential machine is triggered not only during current leakage, but also when short circuit, and network congestion.

Combined protection

This is the main functional difference between the two devices. Discover, what is better to put an RCD or difavtomat, you can in our corresponding article. Now we will tell you how to distinguish them in appearance.

Visual difference

Now in the photo examples we will clearly show how to determine what is installed in the shield. In total, we will talk about 4 obvious signs that you need to remember.

  1. See what is written on the case. Unless of course you bought cheap Chinese products, it is unlikely that it will be written on the side wall or in the front. However, all domestic devices, and even some foreign products, have a clear designation on the case - "differential switch" (aka RCD) or "differential current circuit breaker" (aka diffavomat). This method is inconvenient in that in order to distinguish products that are installed next to each other, you will have to remove them from the DIN rail, otherwise the name will be closed.Specific name
  2. Pay attention to the name again. Yes, the marking also gives a clear idea of ​​what is installed in the shield. According to the full name of the devices written in paragraph 1, you can understand what “VD” is and what is “AVDT”. The disadvantage of this method of determination is that on foreign devices there may not be a domestic abbreviation, as, for example, on Legrand products.Designation AWDT
  3. We look at the characteristics. Both on the RCD and on the differential machine, the technical specifications are indicated in the form of numbers and letters. So, if you see a figure, and after it the letter "A", for example, 16A or 25A, this means that an RCD is installed in the shield, on which the rated current is indicated. If a letter is marked on the case, and then a number, for example, C16, then this is an AEDT. The letter "C" in this case indicates the type of time-current characteristic. Read more about technical characteristics of circuit breakers You can find out in the corresponding article. Here by this technique, you can easily distinguish devices.In the photo below, we duplicate this rule again:Difference in performance
  4. We look at the diagram. Well, the last, so to speak, control method that allows you to distinguish between RCDs and difavtomat is to look at the diagram. On the circuit of the differential automaton, the thermal and electromagnetic trip units that are not on the circuit of the differential circuit breaker will be additionally indicated. This difference is also significant in determining the device.Scheme

In addition, we recommend that you watch a video that clearly shows how to determine in appearance what is installed in the electrical panel:

Main differences

So we have provided instructions for young electricians and home craftsmen. As you can see, there is really nothing complicated, and the difference between the residual current circuit breaker and the differential circuit breaker is quite significant. We hope that now you know how to distinguish an RCD from a difavtomat visually!

It will be interesting to read:

Main differences

(13 votes)


  • Victor

    On the machine side barcode. With the help of the program on the android I found out that this is an automatic machine.

    To answer
  • MAX

    I laughed heartily at the teaching) How then explain these pictures, on which the current begins with C and is immediately written - Residual current device.

    To answer
    • Admin

      There are exceptions, therefore, a win-win option is to look at the diagram.

      To answer
    • Pavel

      and you forgive me, then I read the marking, or got stuck on the first phrases ?? ouzo-wad2

      To answer
  • Andrew

    In the UZO-VAD2 photo, that is, the residual current circuit breaker-circuit breaker is automatic differential, so the current starts from C).

    To answer
  • Dmitry

    Thank you for the article! And thanks for the comments too. Indeed, in terms of such confusion, when each manufacturer in his own way understands what an RCD is and what is an automatic machine, excuse me, Difavtomat

    To answer

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