[ethereal]

It is perhaps worth noting that 12/24V DC is just as deadly as 120/240V AC. There's naught deadly in voltage, it's the wattage that electrocutes you. A static shock is 6kV, as I recall, but the amperage is low enough that it doesn't hurt at all.

I'm a little sketchy on the details (been a while since I studied this sort of thing) but I can personally attest to losing muscle control in my right arm on a 6V circuit using only a standard (1Ah?) alarm battery.

[jacquesm]

> It is perhaps worth noting that 12/24V DC is just as deadly as 120/240V AC.

No it definitely isn't.

> There's naught deadly in voltage, it's the wattage that electrocutes you.

In fact, if you want to be precise, it is the current (Amps) that kills you. The reason why 24V isn't nearly as deadly is because at the resistance your skin normally has the current will be low enough that it does not get dangerous.

Up to 48V is considered a 'safe' voltage, but you can definitely feel it and DC is far more dangerous than AC (because with DC your muscles contract and stay contracted so it can be very difficult to disengage from the source).

If you lost muscle control over 6V then likely there were some other circumstances in play, for instance you could have been poking around in a spot where your skin had been breached or you may have had sweat or some other salty solution on your skin.

Real danger starts around 80V for DC and 150V for AC. Yes, you can get electrocuted at lower voltages but you'd have to really work at it.

Most high voltage circuits that you are likely to come in contact with have an internal resistance that is high enough that they can not source a high enough current to do damage, that's why you perceive high voltages as safe. But if a high voltage circuit is beefy enough that it can supply a couple of hundred milli-Amperes you're as good as dead because at that voltage your skin is no longer a strong enough barrier.

[kragen]

I recall an apocryphal story of a guy who got killed by a 12V car battery. It was a hot day, and he was trying to pick it up, but it was heavy, so he was using a couple of pairs of Vise-Grips. On the terminals.

[K2h]

In my experience the overlooked risk is burns. People think low voltage dc is safe(er) (no electrocution) because of high skin resistance, and are amazed when there are a shower of sparks from a car battery (when something goes wrong like a tool falling across the terminals). In high school I did welding with capacitors that looked like pyrotechnics using a butter knife fom the cafeteria.

On a side note, I think I read women have lower skin resistance than men on average.. Something we were going to do a little design of expirment for in highschool but never got around to completing it because shocking people and playing with electricity was more fun.

Ohh.. According to this men have lower resistance. http://van.physics.illinois.edu/qa/listing.php?id=6793

[mikeash]

Short the terminals of a 9V battery with your finger. Now unscrew an outlet cover and short the terminals within with your finger. Notice the difference. (Note: don't actually do the second one.)

People love love love to repeat this tired "it's not the volts that kills, it's the amps" line, while completely ignoring the fact that low voltage makes it really, really, really hard to obtain the necessary amps to be dangerous.

[njs12345]

I agree entirely. Nonetheless, here's an interesting story about someone being killed by 9 volts: http://www.darwinawards.com/darwin/darwin1999-50.html

[mikeash]

It's interesting both because 9V killed the guy and because he had to try pretty hard (stabbing his thumbs) to achieve it. So, while dangerous, not nearly as dangerous as e.g. 110VAC.