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happyjack27 · Post by **happyjack27** » Sat Dec 03, 2011 2:43 pm

ladajo wrote:The drama comes when you have a phase ground, and somebody touches the hull and something on a different phase at the same time.

"Induced Pain" is the technical term I think.

dark nerd humor.

D Tibbets · Post by **D Tibbets** » Sat Dec 03, 2011 9:59 pm

bennmann wrote:
ladajo wrote:The drama comes when you have a phase ground, and somebody touches the hull and something on a different phase at the same time.

"Induced Pain" is the technical term I think.
This kills the seaman.

Not necessarily. Apparently the current is enough to cause pain, but not (very often) death or serous injury. Increased voltage increases the chances of insulation breakdown and/ or arcing, but it is the current that kills. A/C current, especially at ~ 60 Htz has a fair chance of causing ventricular fibrillation and death, even at modest currents of ~ 50 mA. Direct current is much less likely to cause fibrillation, so most of the danger comes from being cooked, or muscle spasm with subsequent falls.

Dan Tibbets

ladajo · Post by **ladajo** » Sun Dec 04, 2011 3:54 am

Having taken 450VAC hits, I can tell you that the key part is the path it travels. If you are lucky, like I was, and it stays away from your core, you get off "relatively" easy, compared to heart cook. One hit I took, I could not move nor feel my arm after the initial pain blast for about 30 minutes. Not fun that. The guy with me said, "Did you just get shocked?" after watching my arm involuntarily flop through the air. As I pried the fuse pullers from my non-functioning fingers, while thinking of the potential dreaded trip to Tripler for 24 hours observation my answer was, "no, not at all" . Tripler was famous for admissions, and subsequent corrective actions for unrelated, nor real issues in those days. Going to Tripler was B, A, D.

Sometimes I wonder how I lived through that part of my life.

Giorgio · Post by **Giorgio** » Sun Dec 04, 2011 8:25 am

ladajo wrote:Having taken 450VAC hits, I can tell you that the key part is the path it travels.

That's an experience I am happy NOT to have made.

Teemu · Post by **Teemu** » Sun Dec 04, 2011 12:32 pm

Gentlemen, it's a nuclear device.

That's main reason for any secrecy. The military and intelligence establishment are not stupid, they realize that economic instability is bad for national security, also they have expressed concern over climate change. Any armament race advantage achieved by of keeping this secret for any longer than it is necessary to make it sure it can't be easily used as a weapon of mass destruction is lost multiple times in the economy and climate change factor when it comes to overall national security.

One other reason to keep quiet could be that other fusion research on the university level has also taken funding hits, cutting potential break-through energy research is one of things on which "there will be no energy silver bullet, bring out the solar and wind power now" people and people who are interest in cutting spending overall can agree upon. Military is more independent but better not to keep too much noise so that no one on the civilian government side gets any stupid ideas like "hey, lets get some savings by stopping that stupid useless fusion research", before you have really good results.

Skipjack · Post by **Skipjack** » Sun Dec 04, 2011 1:29 pm

IMHO, a bad economy is the biggest threat to national security.

ladajo · Post by **ladajo** » Sun Dec 04, 2011 2:15 pm

One other reason to keep quiet could be that other fusion research on the university level has also taken funding hits, cutting potential break-through energy research is one of things on which "there will be no energy silver bullet, bring out the solar and wind power now" people and people who are interest in cutting spending overall can agree upon. Military is more independent but better not to keep too much noise so that no one on the civilian government side gets any stupid ideas like "hey, lets get some savings by stopping that stupid useless fusion research", before you have really good results.

This, IMO is the primary reason they are low key.

The project is not classified, but it is considered to be funding sensitive.

ladajo · Post by **ladajo** » Sun Dec 04, 2011 2:18 pm

Giorgio wrote:
ladajo wrote:Having taken 450VAC hits, I can tell you that the key part is the path it travels.
That's an experience I am happy NOT to have made.

Ahh, to be young again...fearless, carefree, and sometimes completely stupid.

I am with you Giorgio, it is not something I wish to experience again. Pain is the best teacher. That is why we feel it. Mother Nature's, "Hello genius! What exactly are you thinking right now? Whatever it is, it is a bad idea!"

Giorgio · Post by **Giorgio** » Sun Dec 04, 2011 6:33 pm

ladajo wrote:Pain is the best teacher. That is why we feel it. Mother Nature's, "Hello genius! What exactly are you thinking right now? Whatever it is, it is a bad idea!"

So true!

rjaypeters · Post by **rjaypeters** » Mon Dec 05, 2011 12:47 am

"Pain was a valuable teacher; the universe whispered to you in pleasure, talked to you in reason, but with pain, it shouted."

- S. M. Stirling
"Drakon"

A coincidental part of that book to this thread was the antagonist sneering at "steam" technology for getting power out of fusion reactor and intending to use direct conversion instead.

MSimon · Post by **MSimon** » Mon Dec 05, 2011 12:53 am

Giorgio wrote:
ladajo wrote:Having taken 450VAC hits, I can tell you that the key part is the path it travels.
That's an experience I am happy NOT to have made.

In my youth I did speaker installations for Juke Boxes. I was working on a building under construction and backed into (sweaty) a bunch of wires while climbing down the ladder I was working on. The electricians had left the wires live after going home for the day. The hit was on my right arm about 8 inches (20 cm) apart. I was badly shook and it was "only" 120 VAC.

I packed up as best I could and went home with the job unfinished.

An experience I'm glad not to have repeated in the roughly 50 years since.

Of course the electricians apologized the next day. Some comfort.

Edit: The wires left two nice "u" shaped scars on my arm (the wires were pretwisted for the forthcoming switch installation) that are no longer visible. But you could see them clearly for 20 or 30 years after.

CaptainBeowulf · Post by **CaptainBeowulf** » Mon Dec 05, 2011 8:47 am

I hope I don't ever have the sort of encounters with electricity you guys have.

Worst shock I ever got was an electrical line going into a fridge. Was trying to be careful, but not enough so - with something simple you tend to let your mind wander and get sloppy. Somehow my thumb contacted with one of the prongs plugging the thing back in. Didn't seem to really hurt, more just a very strange sensation of electricity going through my arm and then down through me to the floor. My arm seemed to freeze in place though - had to twist my body to pull my hand off the plug. No visible damage and the tingling went away after a few minutes.

ladajo · Post by **ladajo** » Mon Dec 05, 2011 2:53 pm

You are a lucky man.

For the record, it only takes 100mA to kill. That will be enough current that it can disrupt you heart and be fatal. 30mA can be generated down to as low as 30 Volts depending on your skin. The average person risks death from any shock above 30V. If the shock path goes across your core, you have the highest risk of death. An example of bad would be right arm to left leg. Ironically, sweaty surface skin can help in some cases as it gives a surface conduction path across the surface of the skin. Or, if your hand is sweaty and you are kneeling in a puddle, or wet ground, that can be really bad.
All in all, I do not know anyone that has worked as a tech that has never been shocked. My inclination upon meeting that claim would be to call them a liar.

KitemanSA · Post by **KitemanSA** » Mon Dec 05, 2011 3:12 pm

Maybe they have been shocked so often that their memory of it is erased by each new instance?

Tom Ligon · Post by **Tom Ligon** » Mon Dec 05, 2011 4:34 pm

The most damaging shock I ever experienced actually was no more painful than common 120V mistakes, and the current was limited to one hand. I got it from a stack of series-connected 9V batteries, my recollection being that we were targeting 900 V. It happened at a lab I once worked for that used high voltage but was under extreme budgetary constraints at the time. You can guess where.

The shock left one index finger quite numb, and with a small smoking hole in the fingertip where I made contact. Curious, to hold up your finger and actually see a whisp of smoke coming from it! I recall it took forever to heal, too.