Having just finished my NFPA 70E training last week, I would like to pass along some thoughts about free electrons:
I`ve been working with and around electricity for some 25 years now and like many of you, have taken a somewhat laxadasical view of our friend Mr. electron. I suppose many of you, like myself, have found yourselves at one time or another to be an unwitting conductor in a circuit that we may have been working on. We babble some obsenity and jump back, maybe shaking the offending appendage as though we didn`t have it coming, then we return to the task at hand (hopefully now, with the power off). It doesn`t scare us like it first did. After many years, we grow to trust it. Like myself and others, we accept getting nailed from time to time as ‘part of the job’ and move on, not really considering the implications of our sometimes cavalier actions. While fully aware of the dangers of working with electricity, we grow complacient in our knowledge, sometimes forgetting to take stock of the tragic outcome that can befall even the most careful amongst us. The confluence of seeminly meaningless events can quickly converge to wreak destruction and can end our very lives, literally, in the blink of an eye.
Included in the afformentioned training was a video. This video was unlike any of the 256 training videos I have ever been required to view previously. This video was made up of home footage from many different venues of every-day life. The vidiographer and the subject alike were unknowing participants in the taping of the final moments of the subject’s life. Mundane tasks of debris removal or car washing or even practical jokes were swiftly transformed into what I like to call…”a bad day”, the results of which will visit horror upon the most careful and imformed veteran sparky amongst us. I was stunned at how casually and quickly these people were electrocuted. It was surreal, almost like a poorly executed skit. Having been shocked many times over the years, sometimes with more than the mundane 115 volts, I wondered, ‘ How was I so lucky?’ Why were these people killed and I was spared? No one knows. No one can possibly know.
I have no profound words of wisdom to pass along. Just the realization of how dangerous current flow through the human body can be. I`ve been re-introduced to an old foe that we all have welcomed into our lives, our homes. I hope to awaken some of you who may have stored the knowledge of these dangers in the dark recesses of your concious mind, as I have.
Do not become part of the circuit! If in doubt, take some time to think it through. Double check with your meter. Lock it out. Do whatever it takes to make the job safe.
Someone is expecting you home for dinner tonight. Those plans could change at the speed of light. Don`t let that happen.
Be safe.
Replies
True words of wisdom. Everytime I wire something I think of dead charred bodies. It sounds morbid but it keeps me from getting complacent. Especily when I'm working in a grid ceiling or something particularly dangerous.
Who Dares Wins.
Not to mention the scent of charred flesh and hair. Once you smell that, you never forget it.My preciousssss, I wantsss my precioussss NOW.
Speaking of charred flesh, here is a download on the subject.
Check it out.
Cork
Actaully, the video illustrates exactly what I`m trying to convey. There was no shaking, yelling, drama. Think of a static spark you would get crossing the carpet and touching something metal. These people made light contact and immediately dropped and were dead. I distinctly remember once thinking, 'hmm, I can actually feel the pulsing of the 60 cycles', I was connected that long. That`s why it was so incredible to see these people dead after just a quick touch. I guess a good low resistance path to ground is the difference. Although, once I was nailed standing in an inch of water. That really hurt. Physical pain, that is. Why am I still breathing? Luck of the draw...
In the wire nut thread I told of my refresher course.
Before the big downsizing at the company I work for, I got a visual refresher everyday. I worked with men that had arms and feet blown off. Others carried burn scars from thier tragic encounters.
The video they use for "wire walker" training is also pretty graphic.
Dave
After four years of carpentry trade school I joined the US Marines ( figure that out) anyway, one weekend on liberty in Hawaii a few of my buddies and I got a room at a fancy Wakiki Hotel for a night. Next morning there was still beer left (how that could be I don't know) so we finish off the few that was left sitting around the pool. Feeling brave (actually stupid) I say to the guys "Hey! I could jump off the balcony and into the pool" We were all wet from jumping in and out of the pool and my two buddies help me up the wall so I can reach up to the balcony. We created a puddle of water where we were standing. As I am half way up, but still in contact with my buddies, (foot on his back, that other holding my leg to steady me) I see a metal condiut running across the wall. I think "Hey, now all I have to do is reach that and grab hold and pull myself up." I do just that and after I put my weight on it, the metal conduit breaks free from the wall and bends down. At that very moment I feel a very strong electric current pass through my arm and my hand is literally frozen to the condiut. I knew at that time what was happening and I knew I had to break the bond but I could'nt. My hand was frozen and all my brain power telling my hand to let go failed. finally, after maybe 5-8 seconds, my two buddies fell away and my weight broke the bond of my hand to the conduit. I dropped to the ground very nervous and doing a check on myself, you know when you get hurt and start doing a system check on your body. Well, I figured I was ok, and said to my buddies, "#$& !! I was being electrocuted!!!" Their reply was "No #$# we were too!!!!!!"
Afterwards we laughed our a$$s off, but looking back I realize we were sooooooooo darn lucky.
"One measurement is worth a thousand expert opinions"
Reminds me of a great story from college days... the afternoon starts out with my fraternity brother telling me how much more skilled landscapers are than electricians, it ends up being a nice debate. The timing of this debate couldn't have been better. About an hour later, the guy comes over saying "yeah, the breaker just flipped for the laundry room. Where's the breaker box at for it?" With a smile I say, "the electrical closet is called that for a reason."
A few minutes later, he returns saying "You'd better take a look at 'that', I just got the s**t shocked out of me". Good level of detail for problem root-cause analysis.
So now I'm curious. I go down, carefully inspect the breaker box and so forth... nothing out of the ordinary. With extreme caution, flip the breaker back on... everything's fine. Upon further questioning I'm told "ya know those two metal bars inside the box, well I touched those." See, the breaker box didn't have its cover on at the time (due to a band that had direct fed their lighting in a semi-scary manner), and what George had lit himself up with were the bus bars that feed the breakers.
I explained to him how lucky he was to be alive, and then questioned him whether landscapers are still that much more skilled than electricians...
I worked for 25 years operating nucke power generating stations and have had to take out of service electrical sytems ranging anywhere from 12vdc to 22,500v distribution systems. I had two 4,160-480v transformers blow up as I ran by after a steam rupture in the turbine room. (My wife sealed the very spotted shirt I was wearing that day in plastic, as the rupture accured about 25 feet above my head.)
I've learned you do not mess around with the stuff that turns on the lights. Every time I work on a circuit, I try to kill the power. It doesn't always happen, as everyone knows, but electricity scares me more than any power tool. The stuff can kill in an instant.
As an aside, whenever any work must be done an an electrical component at a nuke plant, the system or component must be tagged out of service. It's a pain, sometimes, to get testing done on components that had work done, but in the years that I worked generating power, I only witnessed 2 fireballs from electrical panels that were caused by human error, and those were due to stupidity. (Who reaches in to clean a live panel with a copper ferrule paint brush? At least one overly complacent electrician that I knew, that's who.)
Be careful out there.
Apparently 120 VAC kills more people than any other voltage does. Why? More amateurs exposed to it- and more complacency amongst people who use it routinely.
A friend of mine builds high-voltage power supplies. He taught me one very important rule when working with circuits which might be live: keep one hand in your pocket. Very important reason- a short circuit from your working hand through the bottoms of your boots is one thing- a short from one set of fingers to the other, travelling through your chest, right through your heart, is quite another. It's the latter you avoid by working with one hand in your pocket.
Complacency kills. Lockout/tagout and testing prior to carrying out work are essential. But if you can keep the other hand in your pocket too, so much the better.
hand in the pocket..got it. But with all the loose change and the 'brass boys' isn't that worse?..don't want to make no prairie oysters..
Re: hand in pocket.
I was taught the same thing. However, part of this training showed that the resistance path from hand to feet is less than through hand to hand. And they both conceivably involve the heart lung area. It makes sense from a logical standpoint. Current follows the path of least resistance and your torso and legs are larger and your feet have greater surface area and because of your weight, more pressure (requirements for a good connection? pressure and area).
Touching things with your fingers presents a relatively small surface and your arms are smaller than your legs. I`ve also heard that exposing the back of the hand to operate switches and hold test probes diminishes the possibility of a hand locking onto a conductor. Sounds awkward but keep it in mind next time you`re in a panel.
You're forgetting that if you touch a conductor with each of your hands, the only insulation between your conductive bloodstream and the current is a thin layer of skin. In the finger through to the floor current path, there's generally a good pair of non-conductive boot soles between you and ground- unless perhaps you're leaning against the panel...
Actually, I`m not forgetting anything. I have given it substantial thought and heard most of the arguments for the ideas put forth. I believe my knowledge of electron theory is about as sound as anyones at this point in my career.I don`t necessarily disagree with you. No one can know exactly which path would cause the most damage on any given day or circumstance, the point could be argued, ad nauseum. I took the instructors to task on this and several other points as well. Just passing along what the "experts" are saying. Hope it helps.
my grandfather used to wire stuff like hydro dams and was absolutely fearless around household circuits, automotive electrical systems, etc. it used to drive my brother and i crazy when we would try to work with him on something. "just reach on in there- it ain't gonna hurt ya none!" "but gramps, i'm gettin shocked!" "aw bullsh!t- getta outa the way i ain't got all g**dam day" he'd poke a screwdriver in something as a "voltage tester" to find a hot lead and just let the sparks fly. scared the sh!t outa me. if he was taking us fishing he'd make sure to soak his lawn real good the day before and we'd go out at night with what was basically a cattle prod and a flashlight, jab it in the ground (the zapper, not the flashlight) and the nightcrawlers would practically swarm to the surface. if we tried to grab one too close to the probe we'd get zapped- then we'd get chewed out for whining about it. it was probably child abuse but we loved the cantankerous old ba$tard just the same. what memories.
m
ps- he passed away of cancer and old age at 81. go figure- maybe he had very low resistance or high impedance or something.
Had an old uncle when I was a kid, same type, though with jeeps and tools. 30 inch radial saw took his arm just below the elbow at the saw mill when he was in his 20's, used a metal pincher prosthetic; we would run when he came at us, the metal clicking as it opened and snapped shut.
They just don't make 'em like that any more. Modern civilization has turned the American male into button pushing shuffleboard whimps. Or it could just be me.
I never met a tool I didn't like!
No, I don`t think it`s you. I think most of America is fat, dumb, and happy. As a race, I think we`re all doomed. It`s just a matter of time and ammunition...(sigh)
Fat, dumb an happy...you are so right. I am usually the only guy on a site that walk through walls..that is go between studs with a fully loaded tool belt on..far from dumb, and qualify for the happy part..I hope my daughters inherited the good genes.
Any of you guys ever taken a second or two from one of those new 26-volt Tasers the cops are carrying these days? It's all the pain (and temporary paralysis) of a 120-vac fry without the pesky side effects, like cardiac arrest. God they hurt. And that's less than half an amp.
Since I can't imagine anyone wanting to use a taser on oneself.
what were you doing that the cops decided to zap you?
just curious
Adam
Along the same line. A number of years ago friends had one of those electronic fences installed for their dog. Their three kids decided to test it out by putting the collar on and running thru the fence ( of course, the parents weren't home ). All three said it hurt a lot. I think I would have just volunteered my little brother as the test subject and saved myself some pain.
Oh yeah, and I would also like to know where you acquired expert knowledge about police tasers.
Edited 1/24/2004 2:26:44 PM ET by Shep
That sounds like my cousins talking the city boys into peeing on the electric fence. To funny!
On a more seriouse note.
Tomorrow we have to replace a small DC drive motor for charging an Automatic Transfer Switch. Pretty simple job, except we will be working 3" from a 3000 amp bus.
BTW you can't do this work with one hand in your pocket. I wear low voltage gloves with leather protectors over them, Nomex flash jacket, safety glasses and a face shield attached to my hard hat. We will drape insulating rubber protective blankets over as much of the gear as we can, just incase someone drops a scewdriver or something into the gear. Two men will be making the repair. Knowone else is allowed within 6' of the work area, unless they are also wearing the proper PPE. 3K amps at 480v can reach out and find a ground if you screw up.
Make my a$$ tight just thinkin about it!
Dave
Good luck tomorrow. I hope all goes well with no "excitement" to break up the day.
If we get the Ice storm again..you may be REAL busy tomorrow...good luck over there..KU Rules..oh, wait that's UK ..sorry.
UK rules?
Man we get no respect!
UofL knocks off two number one ranked teams and we still get no respect.
Of course it is not yet March either.
Dave
But we had the world record attendance...neener, neener, neener..got ICE?..
Re: "3K amps at 480v " ; "Make my a$$ tight just thinkin about it!"
Pretty good pucker factor on those jobs.
Of course the ladies admire a tight butt. Electricians: We get the women AND make the big money. Or so I have ben told. Still waiting on mine.
count me as curious too 'bout how you know about tasar pains.
But just to step in on your behalf, when we were issued the older 50,000V stun guns, we had to take a charge on ourselves as introductory training. I think part ofd the reasoniong was to know what we were dealing with in case it got turned around on us. By being familiar with it, the pyschological shock is taken away..
Excellence is its own reward!
When we were issued our.........
Man, I am glad they don't do that with our PPE.
Let's see........ you put this here flash jacket on........ we're gonna send this gazillion volt fire ball fly'n at ya..........this will give you more confeedance in how it gonna work <g>
SPHERE, they canceled the repair. This ice storm has got thier shorts all in a knot.
We only have one feed into the corporate data center right now. Afraid if we loose that feed while we are working on the gear, we will only have the backup generator, and UPS to operate on. All of the dispatching for us and KU goes through this building. A big part of the state would be SOL if we drop this puppy durring a storm.
Means I can relax my pucker factor untill next Sunday.
Dave
we got some serious ice here..3/4 inch on my truck.Go Stab yourself Ya Putz! Ya think I Parked here?
Heh. Yeah, usually you have to earn the right to take a ride on a cop's Taser the hard way, by sticking up a gas station or something. But in my case, I'm the cops reporter for a small newspaper, and I was doing a story on the new 26-volt Tasers the local sheriff's office had just started using.
It's just like you said, part of the training our local cops get to be certified to pack one of these rascals is getting zapped with one for two seconds -- well, all except for one crazy deputy, who volunteered to get shot with one. (That's five seconds and a pair of quarter-inch-deep fishhooks in your back, by the way.)
Anyway, I was invited to join the (two-second) fun and, being ignorant and stupid, I accepted. I got to see video footage of me and two deputies in a row all crashing to the floormat on our faces. Those things hurt!
--Finnster
The stun doesn't really hurt, in the way I think of pain. It causes you to loses motor control of the muscles in the area. Feels more like a big time hit to the funny bone.
Take it in the groin and you will not only fall down, you will probably have a wet spot on your pants too. Makes a tough guy look pretty silly..
Excellence is its own reward!
I dunno -- I've developed a pretty solid ability to recognize pain over the years, and I will say this much: Tasers hurt like hell. At least, the new 26-volt jobs do. Unless you have the pain threshold of The Incredible Hulk, I bet you're thinking of different Tasers. I asked the deputy who took teh full five-second ride how much I'd have to pay him to do it again. He said for a hundred grand, he'd think about it.
Cheers!
--Finnster
No, you've been talking Tasers while I was refering to stun guns. I know the tasers are definitely the more potent of the two.
Like comparing a .45 to a .32
I'd rather be hit dead center with a .32 than tickled with a .45 anyday.
Excellence is its own reward!
What a fitting thread for me .
This week while trimming out a new house we had to mortise in switches in every closet door. This is not difficult to do or dangerous in any way right.
The first door I mortised the plate in then cut the hole for the splice box. Since the electrician was not on site yet I decided to put the wire in and mount the box so I could finish setting my door. All went well, UNTILL.
After finishing the casing inside the closet i grabbed up left over shims and air guns. With my arms full I stand up and spin to leave the closet. The wire sticking from the box cought me. The Ground hit my glasses and the hot hit my eyelid. This friggin hurts dont try it at home. I have a bruised eye and it is very tender but no sight damage thank god.
When sparky arrived I proceded in chewing him a new arse. He said he was sorry that the wire was hot but he did what my boss told him to do. It turns out the bass instructed him to fire up the house so we could have lights and some outlets. I blame this one on me in the end though. I know better than not to check a wire before I mess with it.
BE CAREFUL OUT THERE that is what I am trying to say. Many of us work alone on a day to day basis with noone around to get us to a hospital. This is starting to worry me more each day now.
An inch to short. That's the story of my life !
bstcrpntr --- I hope to grow into this name.
Now, that`s what I call a low resistance path to ground. Not a lot of "meat" involved there. Also sounds like you have metal framed glasses. Another no-no mentioned in the training, and you found out why. Glad to hear you`re ok. It`s amazing how many instances are coming out on this thread. Just goes to show I`m not the only lucky one out there. And if any of you are still wearing metal jewelry and such, you may want to re-think that too. I was cured when I read of the 'de-gloving injury' to a ring finger in FHB several issues ago. Hooked on a nail and just stripped the meat right off the bone. Yikes! Still makes me all hinky inside to think about it.
Yeah buddy! that story gets me too. Big time ouch.
bstcrpntr-It coulda been a whole lot worse... you could've had to change yer tag to bst1Idcrpntr.
MikeWe do Fast, Cheap, and Reliable work.
Just pick any two.
This is a really great thread, IMO. Somehow drives home the reality behind the rules.
In case you missed it the first time around, although this didn't involve injury or anything like 3K amps, it somehow fits here:
http://forums.taunton.com/tp-breaktime/messages?msg=38032.1
"I`ve also heard that exposing the back of the hand to operate switches and hold test probes diminishes the possibility of a hand locking onto a conductor. Sounds awkward but keep it in mind next time you`re in a panel."
That's true -- rescue specialists are taught to search with the backs of their hands (especially in the dark, and it's almost always dark), likewise one would crawl through wreckage with the palms facing inward, all for the same reason.
In this way, inadvertent contact with AC is more likely to jerk the forearm away rather than close the fingers around the conductor.
I've seen four accidental electrocutions, all of them severe.
Good thread -- we can all use the reminder.
DRC
"I've seen four accidental electrocutions, all of them severe. "
Most electrocutions are serious...
You have to die to be electrocuted.
Jon Blakemore
OK, I stand corrected.
I've seen one electrocution (power company guy who apparently did everything right, just did it on the wrong day), and three guys get the crap knocked out of them -- two guys got 4,400 volts run through them, one of whom looked pretty dead but he made it, and one guy get 440 in one hand and out the other, with the effects previously described. Somehow he lived, too.
Good thread -- we can all use the reminder.
DRC
I was working on a school reno a few years ago and was in working while the electrician was working. you mention people becoming careless when it comes to safety, people not wearing safety glasses must be at the top of the list.
The electrician that was working that day was by far the most careful tradesman I've ever seen. he had on safety glasses and did everything with extreme caution, but it didn't slow him down at all, he just made it part of his routine. when I asked him about some of his precautions he explained to me that one amp can kill someone. I had no idea, but I remember that moment as being a serious wake-up call for me.
I once got zapped while trying to change a simple light fixture. I thought the breaker was off but it wasn't.
the zap wasn't really what I was worried about at the time. It so happened that I was too lazy to go get a ladder and instead opted to stand on a railing. well, when I got the zap I lost my balance and almost wound up at the bottom of a large flight of stairs.
Custom Cabinetry and Furniture
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We were taught that .002 Amp could interrupt the electrical signal to the heart. This training showed that .016 is the threshold for atrial fibrillation(read; heart "quivering" and not moving any blood). Big difference but, both are very small amounts of current flow in the practical world of electricity. Once fibrillation starts, apparently the only way to restore normal heart rhythm is with a defibrillator. CPR only serves a temporary rudimentary function here and if the heart is not restored to normal sinous relatively quickly, the victim will not survive.
Maybe some here with more medical experience could expound on the subject.
And as you mentioned, secondary injuries can also be deadly. Common sense pays big dividends here as well. I vote for the ladder next time. I`m paid by the hour, how `bout you? And I`m not paid nearly as much when I`m laid up. My family is much happier when I can bring home the bacon every week.
My wife worked in the Electro-physiology lab at the hospital, where they routinely administered just enough juice to set the heart into some kind of tachycardia, and to get them out of it they had to fire up the old defibrillator and shock the heart back into rhythm. She's now in the cardiac cath lab which is more invasive, but the body count is much lower : )
I never met a tool I didn't like!
And as you mentioned, secondary injuries can also be deadly...
I knew a guy years back who got tagged by a 440 ckt. The muscle contraction yanked his arm back and shattered his elbow on a post.
Hurts just thinkin 'bout it.
MikeOne by one, the penguins steal my sanity.