I live in an apartment building built about 40-50 years ago, with aluminium wiring and Type E power plugs.
I noticed that the grounding pin on one of the sockets is somewhat warm to the touch, I would say about 35°C. I have experienced that on some high-powered appliances such as electric kettles, one of the plug pins gets hot during operation, but this plug has nothing inserted into it, yet is still warm.
Does this mean that the wiring in the building is done incorrectly, or is this a fairly normal condition?
Note: Since this is aluminium wiring in a somewhat old building, I suspect that a contact got loose and needs tightening and the reason why an unoccupied plug would get warm is that all the outlets are wired in series.