I live in Spain in a similar area. I still remember the first laptop i bought here, died after 10 min. From that moment on, all my computers and stuff is connected through UPS. I have a couple of them, most are 1500W. And if not through UPS, then through surge protector.

The CNC has connected the PC and the machine to the UPS. Only the VFD goes through spike protection only. But i have a wire from the VFD to the BOB /the reset button line/ that tells the BOB if the VFD is online, when not, it resets and all stops.

The VFD i have /Mitsubishi/ is actually protected against spikes and quite some voltage drops or rises, according to the manual.

Its useful cause not only the spikes. Sometimes they decide to repair the electricity of a neighbor or on the street while the machine is running.

Its possible also to connect instead to the reset line, for example to play like "pause" button on whatever input, so you can later resume, but the lag till mach3 stops the machine is so big, that i would NOT do that.