Thread: For the scientifically minded...

Originally Posted by tonycraigo

Actually, you got that backwards my friend.

Higher voltages and you run the risk of having your motor functions altered. If you can't let go, that's a bad thing. Very bad.

My first electric lab class was in the mechanical room of the school. The first lesson our teacher gave us was to walk around with one hand in your pocket and if ever you had to touch something, to do it with the BACK of your fingers. The muscles that close your hand are much stronger than those that will open it. So if you touch high voltage, when your hand closes all by itself from the shock, you'll let go instead of holding on forever.

Originally Posted by Glenn24

My first electric lab class was in the mechanical room of the school. The first lesson our teacher gave us was to walk around with one hand in your pocket and if ever you had to touch something, to do it with the BACK of your fingers. The muscles that close your hand are much stronger than those that will open it. So if you touch high voltage, when your hand closes all by itself from the shock, you'll let go instead of holding on forever.

I recall my first lab was highlighted by subjecting an electrolitic capacitor rated at 450V to 1200V... I seem to remember I got marks for the ability to raise our resident voltage by 900 volts to get the desired explosion... my instructor and my Dad were impressed, but they never let on... much...

By that time I was already building antennas and amplifiers that have probably already sent signals out of our solar system... if we're ever attacked... it's my fault.

Originally Posted by Glenn24

My first electric lab class was in the mechanical room of the school. The first lesson our teacher gave us was to walk around with one hand in your pocket and if ever you had to touch something, to do it with the BACK of your fingers. The muscles that close your hand are much stronger than those that will open it. So if you touch high voltage, when your hand closes all by itself from the shock, you'll let go instead of holding on forever.

Hmm, that's a good trick. Nobody's taught me that one, in 4 years of apprenticeship. Maybe they didn't like me.

In these parts we don't have overhead wires nearby it's all underground and there is a step down transformer in the backyard. One for every 3 or 4 houses I think. So he was taking the wire that goes from the transformer directly and attached it to the electric meter. He definitely had the bare wires in his hand It was actually a very thick cable not stranded wires. I don't know if the gloves had rubber on the inside but on the outside they were plain leather.I also know he didn't touch anything on the transformer so it was live. My electrician was standing by when he did this and I asked him about the gloves and he just said electricity won't go through the gloves as long as they are 100% intact. 99.9% intact will kill you.

They had to be "hot gloves". It is actually 2 pairs of gloves, rubber inside gloves with a specific voltage rating for the amount you are working on, and leather outers to protect the ruber gloves from damage.

Class 2 Gloves
Code:E2 - * - * - *

• 17,000vac max use voltage
• Tested at 20,000vac
• 14", 16" or 18" lengths
• Available in B(black), YB(yellow inside, black out) or RB(red inside,black out)
• Standard straight cuff
• Sizes 8-12 including half sizes
• Type I natural rubber
• Extremely flexible
• Meets or exceeds ASTM D120 and IEC 903 standards
• Specify glove length, color and size
  
  • EXAMPLE: E2-14-B-11 is Class 2, 14" length, black and size 11
  
  Class 2 gloves are also available with Contour cuffs, Bell cuffs or Flare cuffs

Originally Posted by thebigspendur

I was just wondering about this as I got a minor electric shock this morning while working on some wiring.

We all know electricity is defined as a flow of electrons. But what does that really mean and what would it take to completely reverse or stop that flow. Also, how would either AC or DC differ in those respects. C'mon I know we have some Physicists here.

To stop the flow try pulling the plug, yanking the fuse, or turning off the breaker. To reverse the flow, get yourself a bigger generator than the one which provided the shocking experience and splice together the wires of the offendee and offender. You may have a bit of a shaazaam epiphany, but someone will have learned a lesson from the experience once the smoke clears.

Roughkype, another thing they probably didn't tell you is that the damage from shocks to your nervous system in general and your heart in particular is cumulative, that is it builds up over time without ever completely healing and gets a little worse with each successive shock. It's one of the reasons I'm moving from my trade into IT, since I've had a couple of ripper shocks. Some were clearly my fault, some less so, but I could have prevented all of them if I'd been pedantic about isolation instead of allowing myself to be intimidated into do "what was best for the production line". Sometimes the line just has to stop and the production foreman just has to suck it up or whatever needs to be done, doesn't get done.

Originally Posted by MickRussell

Roughkype, another thing they probably didn't tell you is that the damage from shocks to your nervous system in general and your heart in particular is cumulative, that is it builds up over time without ever completely healing and gets a little worse with each successive shock. It's one of the reasons I'm moving from my trade into IT, since I've had a couple of ripper shocks. Some were clearly my fault, some less so, but I could have prevented all of them if I'd been pedantic about isolation instead of allowing myself to be intimidated into do "what was best for the production line". Sometimes the line just has to stop and the production foreman just has to suck it up or whatever needs to be done, doesn't get done.

Thanks, Mick. In one way, I'm lucky I'm making this change later in life. Previously I was white-collar, so though I wasn't building construction-worker strength, I wasn't suffering the wear and tear either.

I'm training through the IBEW, and the only guys I've seen work hot did it to be macho. Lockout/tagout has been the very strong norm everywhere I've worked so far.

What I've seen blown off a lot, though, is meggering before powering up new installations. In that case I just go stand very very far away.

--Tim

Oh yeah, never never NEVER power up a new installation without doing those final checks. Sure they might take another hour on a large domestic or even a day or two on a large industrial where you have to do final checks on earth bonds and substations and all with some little pencil neck manager squealing that they want the job finished and written off, but if there's a problem it can turn a brand new home or million dollar machine into a pile of ashes. If THAT happens it's gonna be all YOUR fault no matter what the management did, or at least that's what your typical dodge-all-responsibility management type will try to lay on you and it's damn hard to fight.
I like to declare my work site a "hazardous area" which then requires ALL personnel to be properly inducted by the designated officer (ie ME) before they can come on site. It means I have to at least tape off the work area but it also means I have every legal right to throw anyone not properly inducted, including the property owner and any stuffed suits, out of the area on the spot "for their own safety".