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avoiding electrocution with a stick welder advice needed

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  • #31
    Highpower, I've installed and changed out thousands of energized meters with just bare hands as long as they weren't over 240 V phase to phase. Anything over that the meter was always changed out cold. The main danger is if the insulated standoffs that the cables terminate on have broken for whatever reason and you get a phase to ground short from it hitting the metal box when you try to remove the meter which generates an arc flash, the severity of which varies greatly depending on several factors. Once it goes phase to ground it can easily also go phase to phase, lots of ionized air to act as a high resistance conductor. I've seen a house meter blown off the meter box and land half way across the yard when the service wires were pulled down by dirt settling and the conductor insulation was cut through by grounded brackets inside the meter box, no one around. Scared the bejeesus out of the house owners. It made quite a bang which, considering the meter box was attached to the side of the house, apparently sounded and felt like a bomb to the occupants. Fortunately, I never had a flash changing meters, even though I found several with broken standoffs. I'm not sure if that was more of a "Better to be lucky than good" type of thing or if I actually had developed a 6th sense that "something" was hinky with the meter box. Either way, I never had an arc flash when changing meters. Switching on energized 14,000V lines, yes, had them there. Flashovers when breaking parallel, eh? Some so minor you barely knew it, except a fuse would blow, other quite violent, one instance was so violent it literally blew the insulated stick I was using to pull the elbow off the bushing right out of my hands and blacken the front of the padmount transformer from burning up the insulated elbow and bushing. That one sounded like a shotgun going off right besides my ear. My hearing didn't come back until a few minutes had passed and I had ringing in my ears the rest of the day.
    Arc flash can be serious. Just as an example, the energy released from shorting out the 208/120 V secondary bushings on a 500 Kva transformer is so large that you need to be more than 20 feet away from the arc in order to not be harmed.
    Location: Saskatoon, Saskatchewan, Canada

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    • #32
      Changing the meter is one thing.

      Changing the meter box is another.

      One involves basically un-plugging the meter, with most residential boxes, the other involves disconnecting and re-connecting the live wires.

      As for arc flash, the typical stick welder at perhaps 125A and arc voltage of 30V represents a bit under 4kW. It gets fairly hot close by, and obviously has a literally blinding arc. if you let the arc get longer/higher voltage, maybe a bit more power

      500kVA represents over 100 times more power, and that is not an overly large transformer in the overall scheme of things.
      2730

      Keep eye on ball.
      Hashim Khan

      Everything not impossible is compulsory

      Comment


      • #33
        JT: If they have a rating, it was never passed along to the technicians. And the only thing issued to us was the gloves. No goggles of any sort. However safety glasses were the norm in the shop.

        The folks at the regional training center showed us an every day pocket knife with about a 2.5" blade, that had made contact between the main terminals on a hybrid battery pack. A sizable chunk of the blade was missing naturally, but what they pointed out was that 3/4 of the blade was now plated from the copper that had vaporized in the arc coming off of the battery terminals. They said the HAZ in the vehicle was about a foot in diameter. I guess they were trying to say that even if you don't touch any live connections, simply being near them when an arc occurred could ruin your day without the gloves.

        Arcane: I don't doubt that you have performed lots of those operations without incident, along with many other electricians. I was just relaying what I saw being done here. BTW, he had one heck of a time getting the old meter to come loose. I sure it was probably corroded in there pretty good. My house was built in the early 40's. I was waiting for him to break out a crow-bar!

        While I'm not afraid of electricity, I do have a healthy respect for it.

        http://www.youtube.com/watch?v=6GiIV...eature=related
        Last edited by Highpower; 03-09-2011, 08:48 AM.

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        • #34
          Originally posted by Highpower
          The folks at the regional training center showed us an every day pocket knife with about a 2.5" blade, that had made contact between the main terminals on a hybrid battery pack. A sizable chunk of the blade was missing naturally, but what they pointed out was that 3/4 of the blade was now plated from the copper that had vaporized in the arc coming off of the battery terminals. They said the HAZ in the vehicle was about a foot in diameter. I guess they were trying to say that even if you don't touch any live connections, simply being near them when an arc occurred could ruin your day without the gloves.
          If the HAZ was that large, it is almost surely in "arc-flash" territory, most likely (depending on what they call "affected"). You really ought to have UV-blocking safety glasses for that, as well as possibly protection from possible spray of blasted-out metal droplets....

          I am going by your description here..... some hybrids don't really store that much total energy compared to a "Volt" or "Leaf" with very significant range on battery. Typically it is the total discharged energy potential that defines the arc hazard.

          The blade was a best-case, since it is so thin, and will burn-back quickly... a thicker conductor might allow more "action".

          it can ruin your day, AND have you seeing a big spot for quite a while.

          Batteries are a "stored energy" hazard, capable of dumping energy in a hurry. Figure the amount of gasoline to power the vehicle for the distance the battery will, and see if you'd like to cosy-up to that fire.......
          2730

          Keep eye on ball.
          Hashim Khan

          Everything not impossible is compulsory

          Comment


          • #35
            Originally posted by J Tiers
            as well as possibly protection from possible spray of blasted-out metal droplets....
            Yes, I think that was their point about always wearing the gloves when working on the hybrid side of things. Early on, they (Toyota) had a problem with the contacts in the main relays arcing and welding themselves together. That didn't become a real problem until the vehicle required servicing something on the high voltage side. With the relays stuck closed, guess where the arc occurred when the tech threw the battery "disconnect" switch!

            A misnomer really as that switch simply divides the cell packs into two 150v batteries to make it safer than handing the full 300 volts. (283v actually.)

            I believe Honda's run a 138v system IIRC.

            I guess both manufacturers don't expect you to do any arc welding intentionally so if you want goggles you're on your own.

            BTW - speaking of welding....
            What do you think of the Forrest Park experience so far? Happy with the program?

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            • #36
              Keep in mind that the Op was talking about welding in the shop.

              Pipeline welders probably face the most hazardous conditions. They have to weld under a hanging canvas cover in the rain while lying on the ground on a duck board if they are lucky. The welding inspector typically only calls the job if water trickles into the weld.

              I like the idea of a remote switch though - any suggestions as to what this would involve - could it be a big copper contact switch in the cable before the electrode holder? (that way the machine and it's cooling fan would keep running).
              "Patriotism is the last refuge of a scoundrel"

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              • #37
                Just thought I'd update, I've welded and I'm still alive. Thanks for the reassurances I received, I felt a lot better after reading all the replies than trusting my memory of what someone told me or someone on youtube. The clamps work and now I can use my screwless vise
                and yes I remembered to take a pic



                Thanks, Jim Doherty

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                • #38
                  Originally posted by J Tiers
                  Changing the meter is one thing.

                  Changing the meter box is another.

                  One involves basically un-plugging the meter, with most residential boxes, the other involves disconnecting and re-connecting the live wires.

                  As for arc flash, the typical stick welder at perhaps 125A and arc voltage of 30V represents a bit under 4kW. It gets fairly hot close by, and obviously has a literally blinding arc. if you let the arc get longer/higher voltage, maybe a bit more power

                  500kVA represents over 100 times more power, and that is not an overly large transformer in the overall scheme of things.
                  I've changed out meter boxes hot, just taped the exposed conductors up extremely well. I've also spliced conductors that have been severely damaged/burned off in a meter box while they were energized when it was doable. Sometimes it can't be safely done hot and you have to isolate the service, but sometimes isolating the service is next to impossible for various reasons.
                  Location: Saskatoon, Saskatchewan, Canada

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                  • #39
                    JIm, I'm glad you overcame your fear of doing the welding job. It's not a problem in a dry shop but it still pays to be careful when welding.
                    It's only ink and paper

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                    • #40
                      Originally posted by Highpower

                      BTW - speaking of welding....
                      What do you think of the Forrest Park experience so far? Happy with the program?
                      It's OK.

                      The instructor is good, but not quite fussy enough IMO*, but you will be welding for 2 hours a night 2 days a week, getting teh experience.

                      My biggest problem is not enough time to eat supper before the class, so by 8PM I'm hungry as heck and not as steady as I would be at other times..... At work I sometimes (if tech isn't available) end up doing repair or modification on surface mount electronics, like replacing 44pin processor chips with 0.8mm pitch leads, so I am not naturally shaky.... but at class time I get that way. I have, for instance, "stuck" the rod 4 times in a row...... that becomes irritating, which does not help a bit.

                      We have had probably 10 hours of stick welding so far.... we are on vertical now, and will progress to overhead next, then MIG and TIG. No torch welding planned, just torch and plasma cutting.

                      When you go to register, if you do, go early, and be prepared to prove you can read decently..... I believe you can take a test, or show a transcript. They seem to have a bug on about that. I am an EE, degree from WU, but they gave me a big hassle until I got a transcript from WU..... (see below)

                      * It's a "community college", I guess he might be worn down a bit by the community college student crowd.
                      2730

                      Keep eye on ball.
                      Hashim Khan

                      Everything not impossible is compulsory

                      Comment


                      • #41
                        Originally posted by J Tiers
                        When you go to register, if you do, go early, and be prepared to prove you can read decently..... I believe you can take a test, or show a transcript. They seem to have a bug on about that. I am an EE, degree from WU, but they gave me a big hassle until I got a transcript from WU..... (see below)
                        Yes, I remember reading the experience you had from your first attempt at registering. (A sad state of affairs.) Fortunately I still have my transcript from my time at Meramec. If that's not good enough for them - oh well.

                        Jim Doherty: What was it exactly that you had to weld to get your clamps/vice working?

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                        • #42
                          Originally posted by Jim Doherty
                          I'd like to make some clamps for my screwless vise and I need to use the stick welder I got about 10yrs ago and only used once. Never had any instruction except the 5 min the farmer I bought it from took to tell me about welding.

                          The time I used it the pieces were laying on top of each other so I didn't have to touch anything and I kept as far away as possible from everything. It worked and the pieces held but I was so uncomfortable using the welder I just found some other way since.

                          I need to weld 2 pieces of cold rolled steel 1/4" x 1 1/2" into a 90 degree angle. I plan to make them long and cut to size.
                          and don't have any kind of jig to hold the pieces together. I'd prefer not to have to hold anything with my hand even though I have seen welders do that on youtube.

                          Could I push one piece against the other with a brick and tack it? Then would it hold enough to let me finish? Any suggestions on where to place the ground clamp?

                          The welder is a Craftsman dual range 230 amp welder
                          The rods that came with the welder are 6011, 6013, 7018 and 8018
                          I have read 6011 is an easy rod to use would one of the other be better?

                          Sorry for all the newb welding questions but I'd rather look dumb here than make a shocking discovery that could be my last.

                          Thanks, Jim Doherty

                          LOL!!!! You sound exactly like me when I started welding. I've been zapped by car batteries before, and I assumed if any bare pieces of metal touched me when welding I'd certainly get enough juice flowing through me to, well, to weld! Trust me, you would have to do something really crazy to shock yourself welding. I've welded in the rain, standing in water, sitting on the metal I'm welding, just about anything, and the only time I ever got shocked was when I was holding the electrode in a tight spot and my hand brushed against the grounding clamp. And I'm still here to talk about it. You can just hold the metal in place with a bare hand if you want, although using a glove is a good idea because the metal can get hot. You can also use two hands to weld if your part is clamped together. I'll hold the electrode clamp with one hand, and the electrode near the tip with the other to have better control.

                          Electricity will ALWAYS follow the path of least resistance. Even somewhat rusty metal has an extremely low resistance (a few 10s of Ohms at most). Your body generally has close to 1,000,000 Ohms of resistance across your skin. Even wet skin is still fairly resistive. Weld away and don't worry so much about getting zapped. You're more likely to trip over something while wearing your welding helmet.

                          andy b.
                          The danger is not that computers will come to think like men - but that men will come to think like computers. - some guy on another forum not dedicated to machining

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                          • #43
                            Originally posted by andy_b
                            Electricity will ALWAYS follow the path of least resistance. Even somewhat rusty metal has an extremely low resistance (a few 10s of Ohms at most). Your body generally has close to 1,000,000 Ohms of resistance across your skin. Even wet skin is still fairly resistive. Weld away and don't worry so much about getting zapped. You're more likely to trip over something while wearing your welding helmet.

                            andy b.
                            Just to get the record straight here, you can prove a low resistance of yourself...... not REALLY low, but.....

                            Just lick fingers on each hand, grab ohmmeter probes. You will likely see easily as low as 10,000 ohms, maybe less, depending.
                            2730

                            Keep eye on ball.
                            Hashim Khan

                            Everything not impossible is compulsory

                            Comment


                            • #44
                              Originally posted by andy_b
                              Electricity will ALWAYS follow the path of least resistance.
                              No, it follows ALL paths of resistance. The current that flows in each path depends on the resistance of each path.
                              Location: Saskatoon, Saskatchewan, Canada

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                              • #45
                                Jim Doherty: What was it exactly that you had to weld to get your clamps/vice working?[/QUOTE]

                                I had 1/4 x 1 1/2 cold rolled steel and needed to weld a short leg to make a 90 degree angle. Now the flat of the clamp is raised enough to fit the slots in the vise. They work great my vise won't move.

                                Thanks, Jim Doherty

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