Electrical installation - is everything okay with it?

In the cabinet there is an SLS in front of the meter. Unfortunately, it is too small in the picture to see what kind it is. Then at least 2 RCDs have to be installed, I only see one. Normally, these fuses are ONLY made for the heat pump circuit, which means that a distribution must actually take place BEFORE the fuse. So I would ask the electrical guild for an expert and have them take a look at it. The distribution box is MAXIMUM shoddy work!!

I listed to him what (at least) is not okay.

I would be cautious and not get involved in trivial details. One could initially generally reject the electrical trade as defective ("Due to the multitude of obvious defects ..."). Then someone sensible should probably assess the matter promptly.

Very clearly: It is not your task and you obviously do not have the competence (neither do I, this is not an attack or anything) to list the defects individually or even define necessary measures to remedy them. No one else here in the forum can fully do this by remote diagnosis either. Your "developer" will not take on this job either. You have to take care of it. My advice therefore: get an expert, who should inspect the electrical trade, give a judgment and give advice on how to proceed.

But from a safety perspective, I don't have to worry that all of this will "blow" eventually, right?

With your main fuses (the 3x 16A); and those being cartridge fuses, they will blow regularly.

As wrote, it is not clear how large the SLS (i.e., under the electricity meter) is rated.

But the main switches (HV) I have seen around me in recent months were mostly rated at 63A as main fuses and also as circuit breakers. Only the SLS in our area is commonly a cartridge fuse.

Thank you for the hint, that seems to be the best option to me as well. I have now made an appointment with the developer in which we will discuss the further procedure. But it was also important to me that my "impression" as a layperson was confirmed and that quite a few things seem to be amiss.

well, if the object burns down because of that...

the insurance will take a closer look

In my opinion, this can only be continued with experts (commissioned by ). Besides all the technical errors, they should urgently check whether the TAB is being complied with. TAB == Technical Connection Conditions (from the network operator), which specify the generally valid regulations.

By the way....the cabinet is small, but by far not equipped to the limit of what is allowed. There is clearly room in it to wire the thing properly. Even if no one sees it at first, it should be in there.