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10 months ago“Evolution” is not random and never was. It was only hypothesized that mutations were random. What we know now about how some genes activate due to environment/etc, the conclusion that evolution isn’t that random should be as obvious as 2+2…
DISCLAIMER: Not an electrician or other sparky, I just like to have fun with electronics.
“Ground” is only 0v by convention. What it literally is, is, “What ever general voltage potential everything around the circuit has that the circuit could short to.” Most circuits aren’t going to short over air, and any separate circuit can drift in its relative voltage levels to other circuits, so it’s a problem that is dealt with via extra circuitry like a physical ground connection 99.9% of the time.
The entire point of grounding is to both make sure the circuit doesn’t float off to some crazy voltage level that could end up literally sparking to other things, and also to provide an alternate path for electricity if something is wrong with the circuit (like an electrician just introduced their hand to the circuit). To provide that alternate path, ground MUST be at a lower potential than the power source (by convention, since we could have made +v = 0 and shift the whole values appropriately). Relativity is the name of the game.
The aluminum machinery could simply be an older design where both sides of the AC get used as-is, or grounded straight to chassis, or any other number of poor practices which would then require an operator to have their own ground connection to not get the everloving shit shocked out of them for simply touching the controls.
If a metal chassis or metal controls are any part of the circuit, you will have to do something to factor in people touching stuff. Ungrounded or un-looped (not completing the circuit across themselves but simply touching a live circuit) people can still be shocked even on DC circuits because an ungrounded person still acts like a capacitor. A grounded person is simply a resistor instead, but that can easily be the difference between life and death.