It's not the amps that kill you, it's the milliamps.

And volts drive milliamps--Ohm's Law. 12 VAC doesn't typically drive enough current to kill someone. Although it can, under the right (wrong) conditions. 120 VAC often can drive enough current to kill. 480 VAC is a lot more likely to kill than 120.

I use the term "VAC" above because frequency is related to lethality. DC is much safer than AC. It turns out that Mr. Westinghouse's choice of 60 Hz puts our AC power system pretty close to the peak of the lethality curve.

The VA rating of a transformer is pretty much irrelevant here--I don't know what the power is that's needed to kill, but it's much less than the VA rating of most transformers.


You're barking up the wrong tree trying to understand transformers though Ohm's Law--they don't work that way. Resistance is just a parasitic that's incidental to the operation of the transformer; if you could make the resistance zero, the transformer would work better. Transformers work by magnetic reactance and by magnetic coupling.


Seriously, if you really want to understand this stuff, I'd suggest a couple semesters of Differential Equations, a semester each of Complex Variables and Linear Algebra, and then take a few courses in Circuit Analysis and Engineering Electromagnetics. That's what the rest of us have to do to really understand what's going on. When you can understand it as a system of interacting, time-varying tensor fields in a complex Hilbert space, a transformer is no longer such a "mind-boggling, mysterious beast."

[This message has been edited by SolarPowered (edited 12-23-2005).]