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When I was 18 I lived in a new apartment in Florida. One evening I was cooking dinner in the 240VAC electric oven. I had my hand on the oven door and reached over to open the 'fridge. At that moment I learned the hard way that the oven had been wired backwards and had a "hot chassis". 240 volts began flowing from the oven, through my arms, across my chest, and into the properly grounded refrigerator.

It was one of those "stop time" experiences. I remember the pulses of current as distinct events, with thoughts between the pulses: <WHAM!> "What the hell was that?!?" <WHAM!> "Man, that hurts!" <WHAM!> "What's that sound?" <WHAM!> "Oh, I'm screaming!"

The next thing I knew, I was on the other side of the narrow kitchen with the oven door in my hand. I had been thrown across the room by the violent convulsions of my muscles, and had ripped off the oven door. I'm pretty sure that's what saved my life.

From the reading I've done recently, AC current through the heart often puts the heart into fibrillation. 240 volts through the chest between solid bare metal electrodes seems like a hell of a stress to put on one's heart.

I'm not sure how much electrical engineers learn about the effects of electricity on the human body, but this seemed like as good a place as any to ask this.

Duncan C
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    So, your question is "how large a percentage of people would have died in this situation"? – Marcus Müller Mar 03 '19 at 18:31
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    Sure, to make it a quantifiable question. – Duncan C Mar 03 '19 at 18:33
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    I doubt very much that there have been controlled experiments, particularly using your refrigerator and your oven, that would allow anyone to give you a solid quantifiable answer to your question. Just don't try it again. – Elliot Alderson Mar 03 '19 at 18:59
  • There are current thresholds for these events. The heart is shielded by electrolyte around it . A 25kV Ignition sparkplug can throw one pretty far too. – Tony Stewart EE75 Mar 03 '19 at 19:10
  • Sure, although an ignition spark coil is high voltage and very low current. More like a static shock. The 240V to an oven is a good bit more "stiff". – Duncan C Mar 03 '19 at 19:26
  • I don't remember if my hands were wet or not. That would reduce the resistance quite a bit, and thus the amount of current that passed through me. I wonder how much resistance I'd present in a firm hand-to-hand grip on a couple of door-handle sized conductors? If I knew that it would be a simple matter to figure out the amount of current that passed through me. (And I dare say my grip quickly escalated from "firm" to "viselike" when the convulsions started.) – Duncan C Mar 03 '19 at 19:30
  • @ElliotAlderson it's not an experience I'm eager to repeat. And it wasn't exactly my choice when it happened. One doesn't expect a hot chassis in a modern electric oven. (Electrical codes and earth grounding of chassis are a good thing.) – Duncan C Mar 03 '19 at 19:33
  • Accidentally touched 240V AC twice. Luckily, both times the convulsion made my hand snap away from the conductor. Both times it was as painful as if someone had stomped on my arm and hand. Aside from that, I had a small burn on the finger only. I guess those people who have serious burns and heart problems after an electric shock have just touched the conductor longer than I did. – Janka Mar 03 '19 at 19:44
  • I don't remember a burn, probably because the current passed through my entire body. It wasn't just a short transit through my skin. I suspect I got a couple of seconds of current. It seemed like an eternity while I was "lit up", but as mentioned my time sense was extremely distorted. I do remember my throat being sore from the scream, and thrashing around for a bit before I was thrown free. – Duncan C Mar 03 '19 at 19:56
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    In the US, 240VAC is usally _split phase_; two hot wires that are 180° out of phase, but each only 120VAC to ground. If you touch both phases, you'll experience 240VAC, if you touch one phase and ground, you'll experience 120VAC. So you were likely shocked by 120VAC. Still very dangerous, but I suspect it does affect mortality. – marcelm Mar 03 '19 at 19:58
  • I did not realize one could rip off the oven door like that. You should hit the gym and unlock your full potential so you can do that at will. – DKNguyen Mar 03 '19 at 20:01
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    @Toor Most oven doors are made to be removed, you just have to lift them in a certain way. – Elliot Alderson Mar 03 '19 at 20:06
  • I wondered about that. I'm aware that there is "single phase 240" and "dual phase 240" (or split phase, as you called it.) I don't know which this was. It sure seemed a hellova lot more potent than the 120 I've been bitten by in the past. That might just be because it was through my chest, and because I latched on and got a lengthy jolt. – Duncan C Mar 03 '19 at 20:11
  • Keep in mind that most of Europe uses 220V (or 240V) as mains voltage, and people get zapped all the time. I tinkered a bit and probably got whacked multiple times before going to college (where I got zapped some more). While it's impressive and hurts like all come out, it very rarely results in serious injury and death. That's not an excuse to not apply proper precautions, but you weren't particularly lucky either. – Hilmar Mar 03 '19 at 23:27
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    An extended jolt through the chest, where you hands clamp involuntarily onto the electrodes, is an extreme case. That's why I wonder how close I came to death. – Duncan C Mar 04 '19 at 00:02

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Very lucky. I was taught that 100 to 200 ma across the chest is the “death zone”. It will cause fibrillation which does not go away by itself. Below about 100 ma you get a good scare. Above 200 ma the heart clamps shut but restarts when the current goes away (probably).
For typical skin resistance, 240 VAC is probably near worst-case. That’s why the Europeans are so obsessively careful with their household electricity.

Robert Endl
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