Post by thread:[OT] The Importance of Following Safety Rules!

part 1 1489 bytes content-type:text/plain; (decoded 7bit) I received this from a company that sells safety posters and related materials: A real-life example of the consequences of ignoring safety procedures. Two workers at a Delaware refinery died recently when they tried to retrieve a roll of duct tape from what was a permit-required confined space (an oversized pipe being purged with nitrogen). When hooking the roll with a wire failed, one worker either entered the pipe willingly or accidentally fell into the pipe while reaching for the roll. He was overcome immediately by the lack of oxygen. The second worker then lowered a ladder into the five-foot-deep space, presumably to rescue his coworker. Unfortunately, he too was overcome by the lack of oxygen. The refinery's safety policy required the workers to get a specially trained and equipped crew to enter the space, but that would have meant significant delays; the job was supposed to be completed by the end of their shift. Besides it was just a roll of duct tape. It only takes one wrong decision. It wasn't just a roll of duct tape. It was a confined space entry. Help your workers shift their thinking with reminders to follow procedure. Here are some useful and effective reminders you can use to make sure everyone goes home at the end of their shifts -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.17.19/663 - Release Date: 2/1/2007 2:28 PM part 2 35 bytes content-type:text/plain; charset="us-ascii" (decoded 7bit)

On Fri, Feb 02, 2007 at 08:02:43AM -0700, Mike Reid wrote: > I received this from a company that sells safety posters and related > materials: > > > A real-life example of the consequences of ignoring safety > procedures. > > Two workers at a Delaware refinery died recently when they tried to > retrieve a roll of duct tape from what was a permit-required confined > space (an oversized pipe being purged with nitrogen). When hooking > the roll with a wire failed, one worker either entered the pipe > willingly or accidentally fell into the pipe while reaching for the > roll. He was overcome immediately by the lack of oxygen. > > The second worker then lowered a ladder into the five-foot-deep > space, presumably to rescue his coworker. Unfortunately, he too was > overcome by the lack of oxygen. More then that too is that you can't tell when you are about to fall unconcious due to lack of oxygen, you only feel that need to breath when your body has too much CO2 in it. So if you are in an atmosphere deficient in oxygen, but without an excess of CO2 in it, you have *no* warning. Another fun safety story I witnessed a few days ago... In my mechanics class the TA was showing off some pnumatics, including solonoid actuated pnumatic valves. The valves were operated by 120V, when I found that his plan was to touch bare wires together to turn them on and off, I told him he was a bloody idiot and stood at the other end of the room. He said "no, it's fine, I'll hold the *neutral* in my hand, (and I mean literally holding the bare conductor, terrible idea as it is) the hot will be safely connected to the other side of the coil." Before I could explain why he still was a bloody idiot his hand brushed the bare conductor on the coil, which was connected to 120V on the other side, and made him jump quite a bit... He was probably lucky that the same hand was *holding* the neutral, because the current must have shunted from the back of his hand to his fingers, but well away from his heart. A little knowledge goes a long way... a long way up that is... -- http://www.petertodd.ca

-----Original Message----- From: spam_OUTpiclist-bouncesTakeThisOuTmit.edu [.....piclist-bouncesKILLspam@spam@mit.edu] On Behalf Of Peter Todd Sent: Friday, February 02, 2007 12:01 PM To: Microcontroller discussion list - Public. Subject: Re: [OT] The Importance of Following Safety Rules! {Quote hidden}>Another fun safety story I witnessed a few days ago... In my mechanics >class the TA was showing off some pnumatics, including solonoid actuated >pnumatic valves. The valves were operated by 120V, when I found that his >plan was to touch bare wires together to turn them on and off, I told >him he was a bloody idiot and stood at the other end of the room. He >said "no, it's fine, I'll hold the *neutral* in my hand, (and I mean >literally holding the bare conductor, terrible idea as it is) the hot >will be safely connected to the other side of the coil." Before I could >explain why he still was a bloody idiot his hand brushed the bare >conductor on the coil, which was connected to 120V on the other side, >and made him jump quite a bit... >He was probably lucky that the same hand was *holding* the neutral, >because the current must have shunted from the back of his hand to his >fingers, but well away from his heart. >A little knowledge goes a long way... a long way up that is... In ASA (Army Security Agency) radio school at Ft. Devens I witnessed this. The multistriped sergeant lectured us on the evils of the R-390A hot chassis. "You must always ground the chassis of this radio as there Are dangerous currents which can kill you..." He then demonstrated how to ground the chassis. The radio is already plugged (With a 2 wire plug!) into the mains. He grabbed a big alligator clip which had a healthy braid to ground With one hand. YOU GUESSES IT! (I did too!) And with the other hand he grabbed the radio intending to attach the "gator" clip to the rails. The open (Covers removed) 80 pound tube (valve) radio was waiting... His involuntary contractions sent the radio bounding off the bench, Shedding tube glass fragments and other bits and pieces. Once he recovered his breathing, he told us that was just a demonstration of what can happen! Yea! I have been paralyzed by AC in Viet Nam in a kludged up shower. (Hey at least there WAS a shower! But no hot water.) Where an idiot wired up a light bulb to the post power grid Depending on the water pipes for the safety ground. Only the pipes didn't go to ground, they went to the tank overhead. My wet body made the connection. There was NOTHING I could do to Make my arm let go of the water valve we used to turn on/off the shower. Fortunately, I could still scream for help. When they shut off the light switch, I dropped like a rag doll! I re-wired the shower the next day. Tom * | __O Thomas C. Sefranek WA1RHPKILLspamARRL.NET |_-\<,_ Amateur Radio Operator: WA1RHP (*)/ (*) Bicycle mobile on 145.41MHz PL74.4 ARRL Instructor, Technical Specialist, VE Contact. hamradio.cmcorp.com/inventory/Inventory.html http://www.harvardrepeater.org

{Quote hidden}> > I received this from a company that sells safety posters and related > > materials: > > > > > > A real-life example of the consequences of ignoring safety > > procedures. > > > > Two workers at a Delaware refinery died recently when they tried to > > retrieve a roll of duct tape from what was a permit-required confined > > space (an oversized pipe being purged with nitrogen). When hooking > > the roll with a wire failed, one worker either entered the pipe > > willingly or accidentally fell into the pipe while reaching for the > > roll. He was overcome immediately by the lack of oxygen. > > > > The second worker then lowered a ladder into the five-foot-deep > > space, presumably to rescue his coworker. Unfortunately, he too was > > overcome by the lack of oxygen. > > More then that too is that you can't tell when you are about to fall > unconcious due to lack of oxygen, you only feel that need to breath when > your body has too much CO2 in it. So if you are in an atmosphere > deficient in oxygen, but without an excess of CO2 in it, you have *no* > warning. > It was exactly what happened here in Sweden a couple of months ago. A man dropped a broom into a cargo hull of a boat and was just going to climb down and get it. The cargo was tree products where the cellulose had consumed all oxygen in the closed area. The man died and six more was injured trying to rescue him. /Ruben ============================== Ruben Jönsson AB Liros Electronic Box 9124, 200 39 Malmö, Sweden TEL INT +46 40142078 FAX INT +46 40947388 .....rubenKILLspam.....pp.sbbs.se ==============================

> Another fun safety story I witnessed a few days ago... In my mechanics > class the TA was showing off some pnumatics, including solonoid actuated > pnumatic valves. The valves were operated by 120V, when I found that his > plan was to touch bare wires together to turn them on and off, I told > him he was a bloody idiot and stood at the other end of the room. He > said "no, it's fine, I'll hold the *neutral* in my hand, (and I mean > literally holding the bare conductor, terrible idea as it is) the hot > will be safely connected to the other side of the coil." Before I could > explain why he still was a bloody idiot his hand brushed the bare > conductor on the coil, which was connected to 120V on the other side, > and made him jump quite a bit... How many people here can honestly say they've never had a shock off the mains or off some other experiment they have been doing (the shock that made me jump the most was actually a situation pretty similar to this except instead of mains it was the output of a homemade inverter cuircuit built by a friend (i won't mention his name but he is also on this list). IIRC it measured about 700V open cuircuit but didn't have much current drive.

peter green wrote: > How many people here can honestly say they've never had a shock off the > mains or off some other experiment they have been doing (the shock that > made me jump the most was actually a situation pretty similar to this > except instead of mains it was the output of a homemade inverter cuircuit > built by a friend (i won't mention his name but he is also on this list). > IIRC it measured about 700V open cuircuit but didn't have much current > drive. *raises hand* Umn.. I'm the builder of said device. It was a 230V-to-4.5V transformer run in reverse from 9V DC, followed by a two-stage Cockroft-Walton voltage multiplier. It pulled 500V open-circuit, then after a bit of tweaking we got it up to 700 and started pulling small arcs with it. Then IIRC Peter picked up one of the output wires to do something, and brushed his hand against the other output. This was in the school dorm - a member of staff heard the scream and we got a formal warning from Health and Safety to "never do that again or we'll confiscate all your electrical equipment". Ah, good times... Actually, I think I may still have that inverter.. if not, I can probably build another one from what I remember about the circuit... -- Phil. | (\_/) This is Bunny. Copy and paste Bunny EraseMEpiclistspam_OUTTakeThisOuTphilpem.me.uk | (='.'=) into your signature to help him gain http://www.philpem.me.uk/ | (")_(") world domination.

> *raises hand* > Umn.. I'm the builder of said device. It was a 230V-to-4.5V > transformer run in > reverse from 9V DC, followed by a two-stage Cockroft-Walton voltage > multiplier. It pulled 500V open-circuit, then after a bit of > tweaking we got > it up to 700 and started pulling small arcs with it. Then IIRC > Peter picked up > one of the output wires to do something, and brushed his hand against the > other output. hmm my memory of the details is a little different to yours iirc it was a 240V to 3V transformer and we had somewhat more than 4.5V on the input (we were using a wall wart set to 12V to power the driver cuircuit iirc), we got the 700V and I got the shock before we put the rectifier/multiplier on the output. i distinctly remember getting a multimeter on the 1000V DC range to read as off scale!

On Sat, 2007-02-03 at 18:42 +0000, peter green wrote: > How many people here can honestly say they've never had a shock off the mains or off some other experiment they have been doing (the shock that made me jump the most was actually a situation pretty similar to this except instead of mains it was the output of a homemade inverter cuircuit built by a friend (i won't mention his name but he is also on this list). IIRC it measured about 700V open cuircuit but didn't have much current drive. Hehe, sadly not me. Can specifically remember two instances with the mains, one was while pulling out a plug my finger came in contact with one of the pins while it was still in contact with the hot. The other case was when I was very young, decided for some reason to pull apart two extension cords slightly and put a thin piece of chain across the contacts. Parents weren't too happy, mostly since I could have killed myself, but also because of the hole in the carpet. Otherwise, been shocked a few times by camera flash units I took apart. Friend of mine in high school loved sticking paper clips in the outlet for some reason... TTYL

On Sun, 4 Feb 2007 12:26:48 -0500, "John Ferrell" wrote: >I had a similar experience in about 1949...I was 9 years old. >Dad gave me a car batterry (6 volts) and an old car radio to amuse me. >After all, it was only 6 volts.... > >The vibrator power supply that left the scars on hand measured 325 VDC a few >years later when I had learned enough to measure voltage! > >The scars are pretty well faded now but the memory has not! > As a 9 or 10-year-old, my brush with disaster came in the form of an old 5-tube AM radio. Unsatisfied with its clunky looking bakelite case, I decided to put it into a nice sheet metal case with brass knobs. It looked terrific and worked very well. I learned there was a reason for that bakelite case (and the term 'hot chassis') when my mother unplugged the radio to do some vacuuming and plugged the radio back in with the plug reversed. (Polarized plugs? Unheard of at the time.) The next time I tried to turn the radio on, I got knocked on my butt as soon as I touched the brass knob. Wow! What a surprise. I figured out what had happened when I traced out the circuit and found that one side of the power cord was connected directly to the chassis. Regards, Bob

>And with the other hand he grabbed the radio intending to attach >the "gator" clip to the rails. The open (Covers removed) 80 pound >tube (valve) radio was waiting... His involuntary contractions >sent the radio bounding off the bench, Shedding tube glass >fragments and other bits and pieces. > >Once he recovered his breathing, he told us that was just a >demonstration of what can happen! > >Yea! I had occasion to be servicing a microfiche duplicator, on a late night callout. This thing had a xenon tube as the light source to expose the duplicate film. The tube was fed with a DC voltage at a little under the flash-over voltage, and an AC voltage was super-imposed on top of this to turn the lamp on when required. I had occasion to change the lamp in this machine, so very carefully turned off the power switch on the machine, all the motors, blowers and things that glowed turned off nicely. I proceeded to remove covers and got access to the connections on the ends of the lamp. Taking due care I used a suitable grounding lead from each end of the lamp in turn to chassis, and with no arcs and sparks ensuing, felt safe to remove the lamp connections. Somewhere in the process of doing this I managed to get one hand on one end of lamp, and other hand on other end, and was bounded on backside in ungentlemanly manner. It was probably just as well that one had to kneel down and contort a bit to get at this thing, so any involuntary motion disconnected one from offending motion source. Some later investigation showed that the DC power supply for the lamp was not controlled by the power switch, and was isolated from the chassis, so my precautious checks had achieved nothing. I know, I should have turned the power off at the wall ......... >I have been paralyzed by AC in Viet Nam in a kludged up shower. >(Hey at least there WAS a shower! But no hot water.) >Where an idiot wired up a light bulb to the post power grid ... >I re-wired the shower the next day. A church colleague went to a school in India where his sister was working as the school nurse. The school had a scheme where people could come and visit for six months or so, and they would board you, and you did some improvement work for them. He being an electrician, agreed to go there and rewire the school, which required some maintenance in this department. His tales of the wiring were that it was a wonder anything worked at all. If you started at the fuse board, the number of colour changes in the insulation on the run of a single wire would almost run through the whole gamut of available colours for mains wiring. It seemed that this bit wasn't long enough, so another bit got added, it didn't matter that it was a different colour or thickness, but that didn't quite reach either, so another bit from the leftovers was used ... until the wire reached the desired destination. There was no guarantee that the colour at the destination was the same as the other end either. By the time he had finished, their biggest problem was the city supply wasn't adequate and kept dropping out periodically, despite having a transformer just down the road.

> How many people here can honestly say they've never had >a shock off the mains My father used to tell a story against himself. A jeweller friend wanted to run a longish power cord to a lathe he had. Not sure if it was a new installation, or just moving his workplace around, but he was dead scared of electricity, and so asked Dad to deal with the power cord. Dad agreed, and so the reel of wire was obtained, and the easiest way to sort it out was put the plug on it, plug it in, run it around the wall to the lathe, and cut to length. Resulting bang only increased jeweller friends fear of 'lecky stuff, and took a bite out of the cutters. No damage to anything else.