Humans have no better ability to tolerate an AC shock than a DC - a 20ms cycle is just not long enough. AC voltages are higher at the same average current for a given power, and so have greater capacity for overwhelming their insulation. Also AC creates oscillating magnetic fields and forces that can gradually fatigue insulation (an issue for Motors in particular). But AC is nice because it allows for the use of cheap isolating transformers that 'float' the circuit with respect to everything else - so if you touch some single spot in the circuit it instantly adapts to your voltage you are not subject to any shock (except for any parasitic capacitance that might exist in the circuit).
However you can have the same isolating benefit if you use a floating DC supply (like a battery or rectified output from an isolating transformer) - and this is what you might want to do for an off-grid house with a big stack of batteries - if only we didn't have so much equipment already designed for AC. On 1 December 2011 16:51, Terry Blanton <[email protected]> wrote: > On Thu, Dec 1, 2011 at 11:05 AM, Man on Bridges <[email protected]> > wrote: > > Hi, > > > > I've always learned as well, that DC is more dangerous than AC. > > At least with AC here in the states, you have 120 opportunities per > second (100 in Europe) to let go as the voltage and current makes a > zero transition. :-) > > T > >
