Misuse of the electrical power network?

I recently recognized that something must be very wrong with my cable installation of electrical-power.

In Europe the default max. AC voltage should not be above 230V as far as I know.

I just tried to quantify the voltage in my bed-room power plug and was shocked that even though my Multi-Meter should handle AD volatages up to 750V the actual seems to be way higher (not always but at least sometimes I guess).

I feel it is indeed time to cut off completely from this ill power grid as soon as possible.

As long as I have no access to ready-to-use or easy to Do-It-Yourself free energy sources I propose the following temporal work around:

Buying a cheap gasoline electrical generator - but adapting it to work with natural gas instead which does not produce much problematic emissions...

Does anyone know more about (electrical) power grids and their dirty little secrets?