It turns out that dragging a USB cable across the top of the UPS for the PC (about to be) running the Sherline mill was enough to flip its flush-mounted hairtrigger power switch. Although I can’t recess the switch, adding a mollyguard should help:

The power switches on the new outlet strips also seem unduly sensitive and a preemptive strike seemed in order:

Two layers of 3 mm acrylic just barely clear the switch, but should prevent casual trips. AFAICT, the little hexagonal shape fills the hole for an indicator LED this strip doesn’t have.
Yellow acrylic is deliberately more conspicuous than the bike control mollyguard.
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