Connecting a Differential to a 1-Phase 2-Wire Installation in an Apartment Block - Quick Answer

At the outset, I apologize to my colleagues that this topic returns, I know that it was rolled over on this forum a hundred times, but each time the discussion deviated from the initial question and ended with a quarrel of experts. This time I need a quick - short answer and I close the topic, so please be understanding.

It is like this:
1.) 1-phase installation in a block, meter in the apartment
2.) There are two wires to the meter
3.) There are security features on the meter
4.) Further in the apartment there is a two-wire installation.
5.) Sockets for the so-called "pass" zero, bridged with the grounding pin
6.) It is not possible to pull any additional wires in the apartment

The meter board with protections will be replaced, the electrician persuades me for a differential. It says that it is possible to connect on a two-wire installation because (quote here) "the differential will detect the current leakage from the phase conductor" and turn it off.

Please let me know if it will actually work or is the guy tricking me?

Quote:

The meter board with protections will be replaced, the electrician persuades me for a differential. It says that it is possible to connect on a two-wire installation because (quote here) "the differential will detect the current leakage from the phase conductor" and turn it off.

And what is leakage to detect for? If the leakage occurs to the PEN conductor, the differential will do nothing. However, some bright solution may elude me, because I'm not an electrician.

@down:
I'm not saying it won't work. I only point out that it will be much more unreliable.

Hello.

Get that electrician over here.
Let it enlighten us.

I installed so many differentials and I did not know that if there is no PE it will not work. This means that when I catch the phase, e.g. when mowing grass and the phase wire is damaged, I will remember because I am not connected to PE. Greetings on behalf of those who will walk with the PE attached to each other.

He explained to me that the current from the phase circuit flows, let's say, to a light bulb (this is his example) and continues to the neutral wire. And if the phase conductor has a puncture and I touch the metal holder, I will take some of the load on myself and take it with my body to the floor which has some ground potential ... then the differential will detect it and turn it off because the current coming from the differential was higher than returning zero because I collected these many mA.

I am a layman in this topic, but I must admit that this story seems suspicious to me, so I ask.

Added after 3 [minutes]:

Enpro wrote:

I installed so many differentials and I did not know that if there is no PE it will not work. This means that when I catch the phase, e.g. when mowing grass and the phase wire is damaged, I will remember because I am not connected to PE. Greetings on behalf of those who will walk with the tether attached to each other.

Dude, a friend, please, less rhetoric and more patience because the layman asks ...

The question was simple: Does the difference in such a system as described in points make sense.

Thank you in advance for your story

I will say yes, it is not entirely with the regulations and pieces and it does not meet 100% protection because there is no PE and the devices do not have full protection, but I will give you two examples, you do not have a differential and you have a pinned neutral wire in a PE socket old method for 2-wire installation, everything complies with the regulations and now you are burning the zero wire on the board and all devices are live, you touch the refrigerator which at this moment is live on the housing. Nothing will help you because the fuse will not turn off. And now you remove the reset on the housing appears If you touch it and you have a differential, if you touch it and the current will flow through you to the ground, e.g. a tile, and there is a differential, it will turn off. The choice is yours. Regards.

The differential works on the principle that what flows in one conductor must return in the other. Two wires are enough for this. It is an LN circuit. The PE conductor is needed so that whatever "escapes" from the LN has to run off somehow.
But if the current from the protected circuit flows in a different way, for example through the human body, it is all the more desirable that the differential should work.
And it will work if, for example, 30mA will "leak" from the protected circuit (i.e. as much as the RCD has a plate), but it does not matter whether through a PE wire, a damp wall to a water supply or through the body of an affected person. It is important that it works!

Thank you very much colleagues for accessible explanations ...

Maybe at the end (before closing the topic), In Castorama there is a promotion for a residual current circuit breaker with an overcurrent option. Perhaps Legrand P312. is it necessary to give a fuse for such "cus" or what is "built-in" is enough?

In my opinion, nothing will happen to anyone if you insert. You can sometimes have trouble with unnecessary operation, it may be that you will not turn on at all. But if it will be OK, then it is better protection than none.

Moderated By Łukasz-O:

Warnings are given for such advice. Since when can "zero" be disconnected with a switch? This is just no protection!

Hello.

Well, now sign up for such an installation.

Don't give such irresponsible advice. And you forgive yourself this difference.

Enpro wrote:

I will say yes, it is not entirely with the regulations and pieces and it does not meet 100% protection because there is no PE and the devices do not have full protection, but I will give you two examples, you do not have a differential and you have a pinned neutral wire in a PE socket old method for 2-wire installation, everything complies with the regulations and now you are burning the zero wire on the board and all devices are live, you touch the refrigerator which at this moment is under voltage on the housing. Nothing will help you because the fuse will not turn off. And now you remove the reset on the housing appears If you touch it and you have a differential, if you touch it and the current will flow through you to the ground, e.g. a tile, and there is a differential, it will turn off. The choice is yours. Regards.

Yes. Differential is a panacea for all evil. In my life, I would not enter an apartment with such an installation.

Also, I believe that the RCD on the TN-C is a misunderstanding.
A well-performed reset and the SWZ + conditions are met if there is a possibility of GSW / MSW.

Miniax wrote:

Also, I believe that the RCD on the TN-C is a misunderstanding.
A well-performed reset and the SWZ + conditions are met if there is a possibility of GSW / MSW.

I am a layman when it comes to electrics, so I do not know if the Ministry of the Interior is the Ministry of the Interior ?? (I guess not) so please no shortcuts ...

zbich70 wrote:

In my opinion, nothing will happen to anyone if you insert. You can sometimes have trouble with unnecessary operation, it may be that you will not turn on at all. But if it will be OK, then it is better protection than none.

["Łukasz-O"] You receive warnings for such advice. Since when can "zero" be disconnected with a switch? This is just no protection!

Thanks for the warning. Indeed, I "flew" impulsively without carefully reading the context. I'm sorry

dziabaq wrote:

I am a layman when it comes to electrics, so I do not know if the Ministry of the Interior is the Ministry of the Interior ?? (I guess not) so please no shortcuts ...

MSW - local equalizing rail
GSW - main equalizing rail

The differential should not be used just because the neutral conductor (PEN) must not (should not be broken).

Some of them are having fun, since when can RCDs be used in a two-wire system with zeroing?

Dear author of the topic, change the electrician!

Thank you very much - everything is clear.

I will give up the differential, I will only give new overcurrent protection "plugs".

greetings
Jack