Hello! With a short circuit on a "bad" outlet, nothing happens - only sparks on the wires that I short-circuit. AB does not work, the outlet is still energized, you can do a short circuit again.
At the same time, on the other outlet in the room, everything works as expected - with a short circuit, the machine cuts everything off.
The thing is, I hardly ever use this outlet. But on New Year's, a Christmas tree with all the illumination is connected to it. And the quality of the garlands is not always good, so I decided to check just in case - if something closes, how AB will behave. And here is ...
I would like to understand in which direction to "dig": change the outlet itself? check the wiring to the outlet?
Put a small shield next to it and a 6A machine gun - enough for the tree, and you will sleep more peacefully.
What's the point in replacing the outlet? For the sake of interest, you can check - if the contacts are good, clamped and not oxidized, then everything is fine.
There are also outlet RCDs, but this is not quite what it is, it is from current leaks. And also there are surge protectors (extension cords) with overload protection - this is more likely what you need.
But really - you need to check the wiring to the outlet.
You can try to turn off the voltage, short-circuit the wires in the outlet (not just anything, but it is better to twist or well with a terminal block connect, check the resistance of the multimeter probes, the resistance of the shorted wires in the socket (so that the error later exclude).
And then: turn off all the switches, pull everything out of the sockets and measure the line resistance - it should be low, on the multimeter, the resistance of the probes is usually only 0.7-1.5 Ohm, plus your short circuit anyway.
Subtract what you measured from the above from the total resistance of the line from the shield. You recognize her resistance. Divide 220 by this number and you get a short-circuit current.
This is rough and rather arbitrary - but you will have a rough idea of the state of this line.
Thanks for the comment!
I also thought about a small shield with a separate machine gun - most likely I will do so if everything is in order with the outlet.
At the end of the topic.
The issue was resolved by replacing the outlet. He took off the old Soviet one, cut the wires of the wiring - AB worked as expected. So it was in the outlet, in the end I replaced it with a new one.
Thank you all for your participation.