Your lamp room is starting to look like Photons lab!

That looks a pretty awesome setup to me!

Yes, I was looking at that and thinking Photon too...

Why you have 250V in the mains?

There is only so much resolution in the taps of the distribution transformer

I had just the same a while back here in Israel : Compressor at a factory not starting because line voltage is about 213V (measured at the service drop disconnect). (Some asinine computerized "smart" thing yet it can't even throw out a meaningful error). Called IEC. They checked that all other customers powered from the same transformer would be ok with a higher tap, and changed the tap. Now its good 230..240, but in off-peak times (when this factory and others around are closed) the line voltage is somewhere in the 250V ballpark. A bit high but i can't think of anything that would be actually damaged. (Nobody uses incandescent lamps there, any heaters etc are on a thermostat anyway so it would only change their cycling times)

It doesn't help that I live very close to the local substation.(I can see it if I look out my window down the street). The transformer has to kick out enough juice so that the people right at the end of the run get the minimum voltage. My UPS is always complaining!