2 ms·

Why woud AC be safer than DC? AC has a higher peak to peak voltage (factor sqrt(2)), so if it's breakdown voltage related DC would be safer. but in cases dielec

Why woud AC be safer than DC? AC has a higher peak to peak voltage (factor sqrt(2)), so if it's breakdown voltage related DC would be safer. but in cases dielectric breakdown happens for both AC and DC, I can imagine AC being safer since it regularly crosses zero current, potentially allowing the breakdown plasma to extinguish... the 12V DC vs 120V AC is an apples oranges comparison, with 12V AC and 120V DC it's the other way around. both would be false comparisons. why would voltage safety tests be unethical? why would one actually test flesh, instead of the theoretical safety models? The reason we have AC everywhere is simple, historically it was easier to step up and down with transformers (which don't work with DC), but nowadays DC-DC converters are a solved problem.

cr0sh 7y ago
> Why woud AC be safer than DC? I don't know if it's only anecdotal or if there is some actual study to verify it, but the typical reasoning on why AC is "safer" than DC is that AC has a "zero-crossing" point, whereas DC (obviously) does not. Why is this considered "safer" (again, possibly anecdotal)? Because if you accidentally contact DC at a high enough voltage to shock you, your muscles contract - and stay contracted. AC, on the other hand - at least at the relatively low frequencies typically used (50/60 Hz) - crosses a "zero point" where the voltage is "zero" - and lets your muscles relax - briefly - long enough to be able to move away from the current (or in worst case - ungrip your hands). Again, I don't know if any study has been done on this potential "mythological" reasoning (I would be surprised if there hasn't) - but that's usually the reasoning given.
kragen 7y ago
> why would voltage safety tests be unethical? why would one actually test flesh, instead of the theoretical safety models? Well, Edison did it that way because it made for better PR for people to watch criminals or elephants being killed by deadly ac, than to have them read papers on theoretical safety models.

cr0sh 7y ago

> Why woud AC be safer than DC? I don't know if it's only anecdotal or if there is some actual study to verify it, but the typical reasoning on why AC is "safer" than DC is that AC has a "zero-crossing" point, whereas DC (obviously) does not. Why is this considered "safer" (again, possibly anecdotal)? Because if you accidentally contact DC at a high enough voltage to shock you, your muscles contract - and stay contracted. AC, on the other hand - at least at the relatively low frequencies typically used (50/60 Hz) - crosses a "zero point" where the voltage is "zero" - and lets your muscles relax - briefly - long enough to be able to move away from the current (or in worst case - ungrip your hands). Again, I don't know if any study has been done on this potential "mythological" reasoning (I would be surprised if there hasn't) - but that's usually the reasoning given.

kragen 7y ago

> why would voltage safety tests be unethical? why would one actually test flesh, instead of the theoretical safety models? Well, Edison did it that way because it made for better PR for people to watch criminals or elephants being killed by deadly ac, than to have them read papers on theoretical safety models.