I suppose you could take the two-phase 120VAC from a dual kitchen outlet, that is actually 240VAC center-tapped, and make a grounded full-wave rectified 170VDC with a couple of rectifiers and a 200V filter cap. It would be "safe".
With a full-wave bridge rectifier you could make plus and minus 170VDC.
The zero volts connection would be grounded through the neutral wire if the outlets are wired correctly. :lol:
I should try connecting two-phase 120VAC (actually 240VAC) to the florescent lights I have that don't start. Their filaments glow, but I must flick the switch many times or touch the tubes with static electricity to make them start with only 120VAC. I don't want to replace them again, they look like new without being black at the ends.
Naw, they would blow-up!
These old florescent lights are inefficient and are being phased-out:
1) Their filaments glow and waste power for the entire duration the light is on. The filaments are needed only to start the tube, when warm they aren't needed. If they worked, I would add a 555 timer and relay to disconnect the filament current after a minute.
2) Florescent tubes are replaced when a filament has burned-out. More waste and expense. They would last "forever" if the filaments weren't powered all the time.