TN-C to TN-S Conversion in an Old House: Grounding at Distribution Point?

Hello dear friends!

Please analyze the two drawings below.
Briefly about the topic. There is an old house and a connector on the wall. Power supply from the pole with a 4-wire cable. Power supply to the apartment on the first floor via a 4-wire cable.

A new TN-S installation and switchgear prepared for TN-S have been installed in the apartment.

I understand that the most optimistic solution is to ground the PEN distribution point, i.e. connect PE from the ground electrode to the board.

So this is the arrangement:

Rules for pasting photos are here: https://www.elektroda.pl/rtvforum/topic1491634.html
[retrofood]
What if it is not possible to conduct the EP? Will grounding the N point in the connector do the trick?

What I mean, of course, is whether the differential will work, because that`s what the problem comes down to.

I will be grateful for factual answers, because there are various versions on the forum - extremely different from each other.

Thanks for the help in advance.

EDIT: there is an error in the drawing: the N wire in the switchgear is disconnected with a 4-pole disconnector.

EDIT2: Sorry, I`m pasting the pictures correctly

layout 1:


layout 2:

The power supply to the building and the entire installation is TN-C. Only the apartment being renovated was constructed with 3- and 5-wire cables, with the planned power supply being connected to the connector with a 5-wire cable.
Unfortunately, for some reasons, the 4-wire power supply had to remain.

The question is whether the 4th wire of the power cable from the pole can be called PEN, but since it is grounded in the transformer station, it probably is.

Is it possible to ground PEN in a connector? Ew. without interfering with the connector, make grounding along the way (between the connector and the board there is a box with protection which I have not drawn).

The first thing you should do is call ZE and ask about the network layout.
If it turns out that it is TN-C, then you divide the PEN wire in the RG into PE and N by inserting this wire into the PE strip and then bridging it to the N strip. Grounding the distribution point is not required. Additionally, a 4-pole disconnector is also unnecessary - a 3-pole one will be sufficient. As for the PEN grounding in the connector, you can do it, but the connector probably does not belong to you, so you need to contact the administration in this matter.

Moreover, in the drawing, if you separate the PEN cable in front of the FR, where do the four wires come from to the FR?

PEN conductor cross-section too small.

Bronek22 wrote:

To the author of the topic.
How can you perform an installation if you don`t understand how an RCD works?
You won`t be able to check robots if you don`t know how it works.

I don`t do it, did I write about it somewhere? If I were doing this installation, I probably wouldn`t ask such a question.

Bronek22 wrote:

Does the RCD have a terminal for grounding or protective conductor?
Does the RCD manual say anything about grounding or protective conductor?
A thinking person will understand that this is irrelevant to the operation of the RCD.
Because the producer would write about it.
Bronek

Indeed, there is nothing about PE grounding. I know the principle of operation of the differential (I think so).
My only concern is the case when there is a breakdown inside the device from the N wire to the metal casing, which is made of PE. In a "correct" installation, this will be a breakdown to ground and before anyone can touch the housing, the differential switch will turn off the voltage. If PE only appears in the table (no grounding of the distribution point) and is actually a duplicate neutral wire - will the differential switch turn off? Theoretically, a differential current will flow through PE from the receiver to the board, so... it will turn off

The differential will work either way, the division point does not need to be grounded. Remember about the appropriate cross-section of the PE cable. You cannot use grounding in ZK without ZK`s consent.

I would like to thank my colleagues for their substantive tips.

Bronek22 wrote:

A thinking person will understand that this is irrelevant to the operation of the RCD.

Bronek22 wrote:

As you can see, you don`t know anything and you don`t know what a protective conductor is.
What do the letters "PE" and possibly "PEN" mean?

Buddy Bronek, you clearly have extensive knowledge on this subject, there is no doubt about it. It`s a pity that you can`t share it properly, suggesting the low level of intelligence of your interlocutors. And that`s rude

Bronek22 wrote:

It is not possible to give broad lectures on how security works on a forum. That`s what books are for. And school.
Bronek

Look at the title of the section "Electricians for beginners", bite your lip and please answer a little more broadly.

Maybe in diffrent way. The differential detects the residual current and turns it off if it exceeds (probably) 0.5 IΔn, i.e. above 15mA, a typical RCD can turn off, but at 30mA it must.
When, for example, a person touches a phase wire directly, current flows through it to the ground. This is basic knowledge that every user of this forum, thinking or not, should have.
If a breakdown occurs from the phase or N conductor to the PE conductor (or to the metal casing connected to the protective conductor), current will also flow to earth and the RCD will also trip. Of course, when PE is connected to earth.

Bronek22 wrote:

The 30mA RCD is not intended to detect leaks to the housing.

I agree that it`s not for that purpose, but it will work in the event of a puncture to the housing, right?

Are you suggesting that S-ka (i.e. overcurrent switch, to be precise) is used to detect leakages?
If I decipher SWZ correctly - Automatic Power Off is a concept that applies to automatic switches, including RCDs.
So what`s it like?

An overcurrent switch will not protect the circuit against leakages It will continue to work as if nothing had happened and will not turn off. This is why RCDs are used. ;)

Added after 2 [minutes]:

Maroo_s wrote:

I agree that it`s not for that purpose, but it will work in case of a puncture on the housing, right?

Are you suggesting that S-ka (i.e. overcurrent switch, to be precise) is used to detect leakages?
If I decipher SWZ correctly - Automatic Power Off is a concept that applies to automatic switches, including RCDs.
So what`s it like?

And, of course, there are overcurrent circuit breakers with a differential element

And I still haven`t received an answer to the question: how come 4 wires enter the FR and three come out? Additionally, what is this 4th vein, since PEN has already been isolated?

Instead of asking whether the differential switch will work, you should ask whether the circuit breaker will work and this should be the most important question - checking the IPZ.
When current flows through the housing, "es" is supposed to act and this should be checked. The differential serves as SUPPLEMENTARY protection. Moreover, it is unlikely that in ordinary home conditions, when touching a phase wire, the RCD will trip.

Miniax wrote:

And I still haven`t received an answer to the question: how come 4 wires enter the FR and three come out? Additionally, what is this 4th vein, since PEN has already been isolated?

Instead of asking whether the differential switch will work, you should ask whether the circuit breaker will work and this should be the most important question - checking the IPZ.
When current flows through the housing, "es" is supposed to act and this should be checked. The differential serves as SUPPLEMENTARY protection. Moreover, it is unlikely that in ordinary home conditions when touching a phase wire, the RCD will trip.

"Es" It will only operate when a current flows through it equal to or higher than the "switching on" current to which it has been adapted at a specific time. So I don`t agree that "es" has to work when the housing expires. The leakage can be of the order of mA. However, checking the short-circuit loop shows whether "ES" will operate in the REQUIRED time in the event of a short-circuit regards

Krawiecow wrote:

"Es" It will operate only when a current flows through it equal to or higher than the "switching on" current to which it has been adapted at a specific time. So I don`t agree that "es" has to work when the housing expires. The leakage can be of the order of mA. However, checking the short-circuit loop shows whether "ES" will operate in the REQUIRED time in the event of a short-circuit regards

See how the circuit closes when a breakdown occurs on the device housing in the first protection class in the TN-S network system. And then say "es" won`t work.

Don`t write nonsense! The point of division of the PEN cable into PE + N must MUST be grounded! This is the basis.

Kuba_jb wrote:

Don`t write nonsense! The point of division of the PEN cable into PE + N must MUST be grounded! This is the basis.

Then I`m waiting for a recipe (quote + source) that REQUIRES grounding the chapter point. I`d love to read it
Until your friend finds such a provision, he better not spread heresy further.

Miniax wrote:

Krawiecow wrote:

"Es" It will operate only when a current flows through it equal to or higher than the "switching on" current to which it has been adapted at a specific time. So I don`t agree that "es" is supposed to work when the casing expires. The leakage can be of the order of mA. However, checking the short-circuit loop shows whether "ES" will operate in the REQUIRED time in the event of a short-circuit regards

See how the circuit closes when a breakdown occurs on the device housing in the first protection class in the TN-S network system. And then say "es" won`t work.

In the case of a breakout - I agree, but not in case of a breakout after

Hello!

And now we have other gentlemen suggesting the lack of protection against electric shock without a residual current device. Highly sensitive, of course.

What danger (apart from an imaginary one) does a leakage of several milliamps between the phase and the housing of a stationary receiver made in protection class I pose to the user?

Miniax wrote:

Kuba_jb wrote:

Don`t write nonsense! The point of division of the PEN cable into PE + N must MUST be grounded! This is the basis.

Then I`m waiting for a recipe (quote + source) that REQUIRES grounding the chapter point. I`d love to read it
Until your friend finds such a provision, he better not spread heresy further.

I agree, to this day I have not come across an act requiring the use of grounding of the PE N chapter point.

Added after 17 [minutes]:

PN-IEC 60364-3
ELECTRICAL INSTALLATIONS IN BUILDINGS
Part 3: Establishing general characteristics
312.2 Types of grounding system

I suggest you read that`s all I found.

Added after 22 [minutes]:

On a certain forum, I found the answer to a question asked by a forum member, by the well-known Dr. Edward Musiał. Since the Doctor agreed to make it public on that forum, I think he won`t blame me for making it public on this forum.

"Good morning,
The more grounding of the PEN or PE cable in the TN system, the better. Of course, the more, the higher the cost, so you should not overdo it. Moreover, multiplying grounds close together has little or no effect. After dividing the PEN conductor into PE and N conductors, it is advisable to ground the PE conductor in one place or in many places, depending on the installation configuration. In which place or places, the designer should decide, taking into account local conditions. No standard that I know of (IEC, EN or national: D, F, GB, I, A, CH, etc.) requires that a particular distribution point be grounded PEN cable, because there is no substantive justification, and such a rigid requirement would sometimes lead (I gave examples) to absurd solutions. It is allowed to ground the distribution point if it does not cause any problems, but there is no requirement to do so. In many situations it makes much more sense to ground a completely different point (or points). ....."

If a TN-CS network system is used, the protective-neutral conductor PEN is separated into a protective conductor PE and a neutral conductor N should take place in the connector or main switchboard of the building, and the separation point should be earthed. This ensures that the earth potential is maintained on the PE protective conductor connected to the conductive parts of accessible electrical equipment.

If the PE wire is not grounded, it poses a risk of electric shock in the event of a receiver failure! Electrical voltage may then occur on accessible conductive parts. Therefore, the division point (or PE conductor) must be grounded.

Kuba_jb wrote:

If a TN-CS network system is used, the protective-neutral conductor PEN is separated into a protective conductor PE and a neutral conductor N should take place in the connector or main switchboard of the building, and the separation point should be earthed.

Not necessarily in the main one, although it is a recommended practice that sometimes does not work, especially during renovations and expansions of installations.

Quote:

This ensures that the earth potential is maintained on the PE protective conductor connected to the conductive parts of accessible electrical equipment.

With a functional PEN cable, the earth potential is also maintained. Remember that the PEN should have the appropriate cross-section.

Quote:

If the PE wire is not grounded, it poses a risk of electric shock in the event of a receiver failure! Electrical voltage may then occur on accessible conductive parts. Therefore, the division point (or PE conductor) must be grounded.

If it is not connected to the distribution point at all, otherwise the RCD will always work in my opinion.


Grounding the split point is good practice and improves safety, but is not required.

This is what happens when "theoreticians" interpret standards and regulations and transfer the requirements regarding professional energy to installations and individual consumers.

The author received an answer to the question regarding grounding of the distribution point, and instead of guides that interpret the standards, Col. Kuba_jb refers to the source. Here you can clearly see the point of the chapter...



In my opinion, the topic is exhausted. I`m closing before more theorists appear.