HINUŚ wrote: If it is TT, then every socket in the house would have to have a grounding point for the socket (receiver).
If TN-C, after unscrewing the socket from the wall, the N wire will be connected to the protective pin.
If TN-S, five wires will be connected to the counter board (3-phase installation) or otherwise, WLZ will be 5-wire (if it is a block)
The IT system is completely eliminated, because it is not used in residential buildings, but, for example, in hospitals, military units, and all places with their own emergency power supply.
TN-CS is only used in transmission networks.
there is no installation in the apartment in the TN-CS system
A little-known theory.
How to solve the problem / get information:
after
1.- telephone to ZE
2. - Walking to the trafo station and looking at the sign attached to the pole or written on the door;
3 - in-depth analysis of the existing installation. There is an RCD or not. Where N is connected to PE and why.
What will it give you that you will unscrew the socket, if the 3x2.5np cable can be pulled to the switchboard and PE and N are connected to one clamp without, for example, an RCD.
Please do not suggest that the RCD is a determinant of the type of network system. Where N and PE are joined together is also not always a determinant.