Managing Connection of YDYp 6mm2 Wire and 3x2.5mm² Cable: Fuse Adjustments & Protection

Hello everyone on the forum.

Imagine this situation:
From the switchboard on the first floor of the house is run a wire to the box in the attic. In the switchboard it is protected by a B32 fuse. It is a wire of the type YDYp, wire. I estimate the cross-section to be 6mm2. On the other hand, from the garage to the same box in the attic is led reinforced cable 3x2.5mm². I know that the fuses in the switchboard in the house should be adjusted to the weakest wire, which means replacing the fuse from B32 to B16. But I also know that it is necessary to additionally protect the connection of cables with different cross sections. How should this be done? Will putting an additional switchboard in the garage be a good solution?

On the wire, press the end and such a connection is screwed together using a terminal block (connector block) - the whole connection placed in the box.

Madżik wrote:

This is a YDYp, wire type cable.

YDYp is a wire so where does the wire come from? You replace it at home with b16 or install a switchgear not in the garage but at the end of this say 6mm2 wire that is in the attic. Alternatively, you replace this 3x2.5 with the same as the one in the attic and then switchgear in the garage.

A distribution box in the attic is not a desirable solution. If I can connect the two cables in the attic box without additional protection, then so be it. This thicker cable (6mm²) looks like this:

Seven wires in the conductor, each about 1mm in diameter. Do I need to press a tip on this? So far they have simply been screwed into the connection block.

Both cables: 6mm² and 2.5mm² are already installed and I would prefer to avoid running additional istalations. The ideal solution for me would be to install an additional switchboard in the garage in case it is to be used by someone other than the householder (I ignore the cost of electricity consumption). Can I therefore do as follows: I connect a 6mm² cable to the B16 fuse in the main switchboard (protected by an RCD), further connect it in a box with a 2.5mm² cable and further in the garage install another switchboard?

Madżik wrote:

I connect it in the box with a 2.5mm cable² and further in the garage I install another switchgear?

For the cable should be unquestionably pressed end.
When it comes to powering the switchgear from a 2.5mm cable:

Check in the table what is the permissible long-term load of your cable and such overcurrent protection should be installed to avoid tragedy.
Greetings.

Madżik wrote:

Imagine this situation:
From the switchgear on the first floor of the house there is a wire run to the attic box. In the switchboard it is protected by a B32 fuse. It is a wire of the type YDYp, wire. I estimate the cross-section to be 6mm2. On the other hand, from the garage to the same box in the attic is led reinforced cable 3x2.5mm². I know that the fuses in the switchboard in the house should be adjusted to the weakest wire, which means replacing the fuse from B32 to B16. But I also know that it is necessary to additionally protect the connection of cables with different cross sections. How should this be done? Will putting an additional switchgear in the garage be a good solution?

Information is unreliable, where is it? What is the rest of the installation? Why is this wire protected with B32?

retrofood wrote:

The information is unreliable, where is it? What does the rest of the installation look like? Why is this cable protected with B32?

Correction: the installation in the form of a 6mm² cable led to the box in the attic, protected by a B32 fuse in the main switchboard, was done in the past in case of pulling electricity further into the garage. Currently, a detached garage was installed AND a 2.5mm² reinforced cable was run from it to the attic. The two cables are not connected, this will happen after replacing the B32 fuse with B16 in the main switchboard. 

A sub-distribution board is provided in the garage. In the article
http://www.elektroinstalator.com.pl/instalacj...abezpieczen-w-instalacjach-elektrycznych.html
I found the following information about the condition of selectivity of fuses:
"to ensure selectivity in the fuse – fuse system, it should be assumed that the quotient of the rated currents of consecutive fuses of the same type (connected in series) should be at least equal to 1.6"


Thus, in the case under consideration, while in the main switchboard will be B16, in the garage will have to use a maximum of B10. This is not enough. Is there any other way to maintain selectivity? Regards.

Madżik wrote:

[
In the article
http://www.elektroinstalator.com.pl/instalacj...abezpieczen-w-instalacjach-elektrycznych.html
I found the following information about the condition of selectivity of fuses:
"to ensure selectivity in the fuse – fuse system, it should be assumed that the quotient of the rated currents of consecutive fuses of the same type (connected in series) should be at least equal to 1.6"

Therefore, in the case under consideration, while in the main switchboard will be B16, in the garage will have to use a maximum of B10. This is not enough. Is there any other way to maintain selectivity? Greetings.

But earlier they write there

In

Quote:

when protective devices are connected in series, selective operation of their is possible only if their time-current characteristics do not intersect or share common areas of operation. These characteristics are provided by manufacturers of protective devices. By comparing the characteristics of protective devices connected in series, it is possible to determine the limit of selectivity.

This is how foolish theories arise, because you hear a bell, only you do not know from which church. Fuse in electrical jargon is not the same as overcurrent protection.
If you don't know the characteristics then don't draw conclusions like a Soviet scientist studying a fly. He shook off its wing and says "fly!" The fly then rolled on the table so he caught it, snatched its other wing and says "fly!". The fly didn't move, so he noted in his conclusions: "after the second wing was torn off, the fly lost its hearing."

Thank you for your help. In the end, obtaining selectivity was abandoned. Regards.