I've got a Vibiemme DoubleDomo that's developed an incredibly weird symptom in the last week or so: it's been tripping the surge protector it's on when the steam boiler is heating up. I've got the machine on a timer so that the brew boiler and brewpath can get good and hot before I need them, and that causes no issues, but when I turn the steam side of things on, it trips the surge protector right around the time the steam pressure valve tries to seat.

Opened the machine up last night, and didn't see anything immediately amiss; no evidence of water going places it shouldn't, etc. Tried it several times on a different outlet, with and without the surge protector and timer in the circuit, and couldn't replicate the issue. Back on it's usual outlet, it had the same issue this morning. Only difference between the two is that the kitchen outlet, where it's usually powered, is GFCI at the breaker box (courtesy of a recent kitchen renovation) and the other one isn't.

Any notions as to what's happening? Unlike the last couple times this machine has had issues, it doesn't seem to be melting its brainbox, which is good. Dying thermostat? Dying pressurestat? Surge protector going bad? Timer going bad? Angry espresso machine gremlins?

I would eliminate the surge protector temporally and see if the gfci tripps.

This is one of the surge protectors (vs gfci or circuit breaker) that detects too high/low voltage and turns off for awhile? Could be that it's a little too sensitive for your wiring and the amps you are drawing.