Why does an RCD fail to work with a short circuit - is this normal?

Mary asks:
Hello, tell me, they wired themselves in a new house. Everything was done according to the rules. Everything works fine, but for some reason, in the event of a short circuit (for example, cutting wire VVG3 * 2.5, which is energized, with scissors for metal), the input circuit breaker in the input cabinet on the street turns off, rather than an RCD in the lighting panel. What could be the reason? Or maybe it should be so? Thanks in advance for your reply.
The answer to the question:
Hello! RCDs should not operate during short-circuit and overloads, since there is no thermal and electromagnetic release in it, it only works on the leakage current. At short circuit, overload and leakage current, the difavtomat responds, and a conventional machine only on short circuit and overload. When you cut the cable next time, disconnect the voltage. Be careful!
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9 comments

  • Maria

    Thank you, but you can still ask a question, I will send a photo, if you can, please see what is wrong and what can be installed for normal safety at home? For example, to install this same difavtomat in an opening cabinet? There is no room for a difavtomat in the lighting panel. And the automatic machine that is sealed, to which the input wire arrives, works on a shorty, I can not understand what kind of machine it is (is it differential)
    The opening cabinet was not made by us, the specialist did from the power grids, but judging by the grounding from the fittings, which, it seems, cannot be used for these purposes, one can only guess about the quality. Therefore, it is very important to know the opinion of specialists. Thanks in advance.

    To answer
    • Admin

      As for there is no place - you are wrong. Look on the Internet schneider electric easy 9 rcbo ez9d33616 (the last 2 digits are the current strength, 16, 25, 32 ...) - this is a difavtomat in a "single-pole" case, i.e. narrow. You do not have a single RCD here, these are only machines. In a differential machine, there are always 2 terminals at the top and bottom (for phase and zero), as in an RCD, in the machine there can be both one terminal (only for a phase) - then it is single-pole and there are more terminals (two or more poles) .

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      • Maria

        Ie it turns out they should work on short circuit and overload?

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      • Maria

        It turns out the second two-pole machine in the shield is not a difavtomat ?? and what will it work for ???

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    • Admin

      the armature can be used, depending on how deeply you hammer it and how many pins. If along the perimeter of the house and deeper - even as it can (until it decays 🙂). And so you got a shield filled with a bunch of cheap assault rifles, they say see the customer what a cool and complex shield.

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      • Maria

        No, the fact is that the pins themselves are not made of reinforcement, but the conductor from the shield that is horizontally in the ground, I read that the resistance of the reinforcement is either too high, either from the tape or from a round six, for example (Wire rod or which I do not know).
        We added the X machine ourselves.

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  • Maria

    Opening cabinet

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  • Maria

    In the lighting panel there are machines with the letter designation C16, C25 ... Is it Simple Ouzo or Difavtomat ??

    To answer
    • Admin

      answered the question about the generator. C16 and C25 are ordinary single-pole machines.

      To answer

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