Can 12V AC burn me???

[changes]

silly question...
but i've never dealt with ac

[Paul Perry (Frostwave)]

Well, you can stick the wires on your skin & not get a burn (not that it is good practice to ever put ANY wire on you!!).
But, as anyone who has played around with car batteries or nicads can tell you, if you short stuff out, even if there is not much volts, you can get enough current to melt wires, and if that wire is on your skin, then you have an instant tattoo.
people have set their pants on fire by stuff shorting out nicads, for example.

[lightningfingers]

I think DC is more dangerous than AC....

[Rich G.]

The short of it, no-- 12 Vac is not lethal.

[edit:  I guess I'll make the necessary statements about using some common sense... I mean, as long as you're not building circuits while sitting in a bathtub full of water or testing circuits with your tounge.  If you are doing this then 12 Vac is the least of your worries.  If your building circuits on a bench and the circuit is supplied by 12 Vac from a wall wart then you'll be fine.]

The long of it... see http://www.stanselectric.com/shock.html

Other notes of interest is the current path.  If you see test engineers with one hand in their pocket, it's not because they are lazy... just the opposite-- they're doing the right thing.  By keeping one hand in the pocket it prevents a current path from cutting thru both arms and across the chest which is the most lethal.

[Rich G.]

I think DC is more dangerous than AC....

Other way around.

[zachary vex]

silly question...
but i've never dealt with ac

burn, possibly.  shock, no.  look at the mA or Amp rating on your 12VAC transformer.  if it's 1000 mA (1 Amp) then a dead short will cause the output winding to dissipate 12V X 1 Amp (roughly, this is a very crude approximation) which is 12 watts.  a night light is around 5 to 10 watts.  it'll get hot eventually, so don't keep it in your lap.

a 12 volt car battery, on the other hand, can deliver 500 Amps pretty easily.  that's a real mindblowing experience if you've ever seen one shorted.  usually you see welding sparks and dripping metal.  that'll burn ya for sure.

[lightningfingers]

other way round

Really? :shock:  I coulda swore the DC hurt more...I still have the scars on my arm...

[thomas2]

yes.. keep one hand in pocket! that's the only thing i remember from school. and if i didn't.. i wouldn't be here telling you about it. last time i had a electric shock was last week.. my hand touched a broken power cable that was connected to mains.. the current only went trough my fingers and it didn't even hurt that bad. just remember.. one hand! :!:

[Rich G.]

other way round

Really? :shock:  I coulda swore the DC hurt more...I still have the scars on my arm...

Both AC and DC are harmful, it just depends upon the magnitude of current passing through the body.

There's a nice table HERE which quantifies AC vs. DC thresholds.

The thing with AC is that it can cause a heart to go into fibrillation by causing the heart to contract/relax at 60 Hz.  Oddly enough, 60 Hz is about the right frequency to cause this.  To get out of this condition a defibrillator is used.  The defib momentarily puts DC current thru the heart causing it to contract and stay there until the current is interrupted.

[niftydog]

you should be thinking about it from the perspective that ALL VOLTAGES ARE DANGEROUS. Then, you won't make the mistake of thinking "it's only 12V" and getting yourself nominated for a Darwin award!  :shock:

AC is particularly dangerous, not just because of the reasons others have mentioned; but because it's usually sourced directly from the mains power. There's potential for a wiring error or a short in a transformer that transfers the full mains voltage to the terminals label "12VAC".

It's worth being cautious about it, because after all there should be no reason to come in contact with any potential source!

[Paul Perry (Frostwave)]

That's a good link, Rich G.
Maybe it should be in the FAQ?

[Jered]

Well they use AC for "the chair". Ever hear those stories about Edison going county to county frying stray animals with Westinghouses'  lethal AC. trying to convince local officials to power their cities with Edisons' homeowner friendly DC. Can you imagine that, there would be massive transformers littering every city. The waste dissposal problems would be mind boggling by now.  Instead we've got nukes, which believe it or not is far superior in every aspect, in the proper hands.
 Jered