Source of arc flash video/info?

[paulengr 44]

Saw this one show up on Youtube: http://www.youtube.com/watch?v=WF364FPWSyY Any information about it at all? I've seen the one from Wisconsin in lots of places but it's not as clear what was happening.

[andybr 5]

I have just had my 3 yearly HV Switching refresher and this was used in an exercise. We were told that the guy was racking in a breaker which was already closed. There seem to be some other suggestions on the Youtube page however. Andybr

[paulengr 44]

There is a cam mechanism on most circuit breakers attached to it so that you have to defeat the mechanical protection to achieve this. So I really doubted that claim. I saw all the YouTube and elsewhere comments suggesting that the breaker was in Colombia and got wet before being installed. I just want more to go on before I do a refresher and bring my guys into it (since we're about to go hot on a brand new 10 MW substation in 2 weeks).

[JeffKiper 9]

I just did a class on a some small pad mounted X-form. From what I remember about this an autoracking motor failed to rack and these guys went to inspect it once they arrived and opened the cabinet the arm was in a bind and it finaly switched bucking legs.

[TimWilborne 108]

That Youtube video has been removed, but here is another copy of it. I was talking about this video with a customer yesterday and I found this statement about the video, do you think it could be true?

[JeffKiper 9]

TW I will ask the Arc Flash instructor Thursday. He played this video for us last week. Side note Why do those traning clips have to be so graphic? I had 2 guys get up and leave the class because of the pictures. I have not spoken to the instructor yet about it. I plan to inform him that we are paying him for ARC FLASH training not a slide show of pictures. I understand that he is trying to teach us the dangers. I feel he could do it with out all the graphic pics.

[TimWilborne 108]

I think the videos and pictures are definitely sobering but necessary. I think the main purpose of them is that shock hazards are all that has ever been preached. Many people still don't see arc flashes as a hazard. It wasn't until I saw the intensity, both in sound and in heat, that I began to understand the dangers. The picture that still sticks in my mind is the guy who probably thought that he was taking the proper safety precautions by putting on his high voltage gloves and was exposed to an arc flash. The rubber gloves melted to his skin

[paulengr 44]

That doesn't jive with NFPA 70E. Leather gloves are recommended up to hazard class 2. Rubber gloves with leather protectors are recommended up to hazard class 4. They did the testing and NFPA claims that this stuff does just as good as so-called "arc flash gloves". In addition if you didn't do this, then how would you simultaneously meet both the arc flash and shock hazard protection at the same time?

[TimWilborne 108]

Maybe I've missed something in your response Paul but that was the point of the pictures...to show people who thought they were electrically safe by being protected from shock hazards

[paulengr 44]

My point was that the response suggested that rubber gloves melted to the electrician. I'm not sure how this is supposed to happen with lineman's gloves. Are you suggesting that the "rubber" gloves in this case were PVC (melting temperature = 140 F), instead of rubber gloves (as in natural gum rubber)?

[TimWilborne 108]

I'm not suggesting anything about the actual blast or the type of gloves he was wearing. I was suggesting reasons to JAK that they might show such graphic pictures in arc flash classes. As for the gloves, it beats me. It was a gory picture of raw flesh and rubber. The glove did melt to his skin. I do remember they had to do skin graphs to 100% of his hand. Also, the melting point of natural gum rubber is 350F. I would say it is highly probable that they could melt during an arc flash/blast if you had no additional protection..

[paulengr 44]

Simply not true that it's a problem. I'll bet it was PVC but... http://www.arcwear.com/arcwear.com/article...h%20NFPA70E.htm There have also been several tests run on rubber gloves such as this one: http://www.segurancaetrabalho.com.br/downl...gloves-nfpa.pdf Summary: class 2 rubber gloves + leather protectors give you about 80 cal/cm^2 protection The overall conclusion is that up to class 2, outright leather gloves are fine (as stated in NFPA 70E). For class 3 and class 4, rubber insulating gloves + leather protectors are plenty of protection. Above class 4 (40 cal/cm^2), it really doesn't matter anyways because the arc blast is a bigger problem than the arc flash and so far in spite of the labelling from some manufacturers, there really isn't an effective protection.

[TimWilborne 108]

Ok I give up, what do you want me to do, say I imagined the pictures? Fine, I imagined the pictures. Rubber gloves alone will protect you just as well as the rubber leather combos required by NFPA 70E Your links and your post keep insinuating that there were leather protectors. Either I'm still missing something or you are. There was no leather. The point of the photo was to show that even through you were electrically protected against shock to 15kv you were not protected against an arc flash Like I said, I was not there so I have no way of knowing the guy's name, age, marital status, employer, bank account numbers, hobbies, pets, or anything else. I was only suggesting to JAK are reason that they show such graphic pictures and telling the one that stuck in my head. Let me restate that "The picture that still sticks in my mind is the guy who probably thought that he was taking the proper safety precautions by putting on his high voltage gloves and was exposed to an arc flash. The gloves of some unknown material melted to his skin" So any thoughts on this?

[Ken Moore 23]

Now, now, play nice everyone.

[paulengr 44]

I'm not trying to beat you up. I'm not questioning what you saw because I can think of lots of ways for that exact thing to happen. The whole goal behind NFPA 70E in terms of arc flash is to make things safe enough that in the worst case scenario, you'd get a 1st degree burn. What you describe sounds a heck of a lot worse than that. One of those urban legends is that that rubber gloves will melt and cause you serious harm in an arc flash. This has been used as an excuse for not wearing rubber gloves and leather protectors when they are required for shock hazard reasons, or other reasons to simply muddle up the safety rules with incorrect information. The whole idea behind NFPA 70E is a set of work rules to prevent harm from coming to electrical workers if things are done properly. How could it happen? Well, let's see here. Rubber-only is probably not good. The reference I pointed to clearly attests to that at least in some instances. Certainly going over 40 cal/cm^2 is also a good way to get hurt since the NFPA 70E rules basically provide no recommendations for any greater arc flash than that. Silicone or some sorts of aramide fabrics may be able to replace rubber gloves (but nobody seems to be selling them), but I think we can all agree that in general, most plastics would result in a sticky burning mess similar to what you described. Until the 2004 NFPA 70E edition came out, arc flash rated gloves were required and you could actually buy them (since there were no rules suggesting any non-rated gloves would be sufficient). From 2000 to 2004, several studies were done testing gloves and looking at the tests on these "safer" gloves. Obviously there were lots of questions about how to properly mix gloves for both arc flash and shock protection, and testing the validity of the manufacturers claims. The surprising result was that up to arc flash class 2, leather gloves alone were sufficient. Up to arc flash class 4, natural rubber gloves plus leather protectors (aka lineman's gloves) were sufficient. Sufficient means that you will suffer no more than a 1st degree burn. So when the 2004 NFPA 70E rules came out, rubber gloves+leather protectors, and just plain leather gloves were added to the rules. The 2009 version has very little in terms of language changes in these areas. Since that time, some manufacturers have still been trying to promote their "safer" rubber gloves, or "arc flash gloves" by continuing to promote the myth that "standard" rubber gloves are going to melt so bad that they will stick to your skin and cause 2nd or 3rd degree burns. They don't come right out and say it because the evidence contradicts them but they still keep promoting the myth. So then I get an electrician coming to me with an ad from one of these companies or fed up with the comfort/sweating/lack of tactile feel of lineman's gloves and trying to use the glove melting legend to try to get out of wearing proper PPE. So I have to deal with it and spend a lot of time researching what's true and what's concocted by these sorts of companies.

[JeffKiper 9]

Kind of OT. I did a panel changeout on a house and suited up. Cat 2 top to bottom less ear plugs. I had to pull the meter out of the base so I did it by the book. I am forcing myself to do it all the time not just at work with a panel about 50v. I don't see why those electrons don't go boom at a house and only at a factory. It must be so because we only have to protect ourselfs at work right? Several years ago we had a bus tap blow the door open on a Line to Line fault across a breaker. We found where this tap had been changed a year earlier because of a bad connection. The off shift guy said yea I changed it because the taps where arcing. Nobody had any idea that he had changed it. I adopted a new idea and highly recommend everyone else look at doing something cose to it. "At the end of the day I am going home. Maybe with a sunburn and dirty underpants, but still going home." I force all the guys on my job to do the same.

[paulengr 44]

I carry 2 sets of gloves. Set #1 is TIG gloves with extended cuffs. They are very thin and allow full tactile feel. They meet arc flash class 2 requirements. Perfect for anything 480V or below as long as it's not a distribution panel and such. No shock protection here. If my fingers go into the panel, these gloves come off, unless I've previously tested it as dead. Set #2 is class 3 rubber gloves with leather protectors. These are good for up to 30 kV (incoming power is 26 kV). I could differentiate for the medium voltage bus (2.4 kV) but it really makes little difference in terms of the gloves. These things are very thick, elbow length. They are hot, sweaty, and totally destroy any sort of tactile feeling. Every 6 months they go back to the testing lab to verify that they are still in working condition. Every time I take them out, they get a thorough inspection to look for failures. When I put them on my goal is to get whatever I need them for done as efficiently as possible and get them off again. Usually that means powering something up or down and then verifying that it did so correctly. Once in a while I need them for something else such as reaching down inside a panel to stick a meter probe some place difficult to reach. I don't like wearing either one because they slow me down and make it more difficult to get my job done. That being said, among the general population, there's an OSHA statistic that you get roughly 300 band aid cases for every fatality. With electrical workers, that number drops to 10:1 depending on who's reporting you look at. What it's telling you is that outside of bumps, scrapes, cuts with knives or components, and the usual litany of slips, trips, and falls, the general population gets their hands smashed, cut open or knocked flat by equipment, that sort of thing. They might get some broken bones but they walk away. Electrical workers do NOT walk away. Tangling with electricity will kill you dead. Wear the gloves. Wear the PPE. I'd rather go home sweaty and smelly than black and crispy.

[JeffKiper 9]

Paul I was under the impression that class 2 called for rubber gloves as well. We have category 2, 4 & danger. 2= 8 cal shirt and pants (our uniforms satisfy this) hood, ear plugs, rubber and leathers. 4= 40 cal. Suit from HE double hockey sticks, head liner, ear plugs, rubber and leathers. Danger= you can’t get in it hot. NO EXCEPTIONS. We classify everything as voltage testing. Maybe that is over rated but I will go home at the end of the job. Edited 26 Jan 2009 by JAK

[paulengr 44]

It's not overrated, it's underrated...need some additional PPE to meet the requirements. As to classifying everything as "voltage testing"...section 130.1 is attempting to get you to think about the tasks and to not work on it live (and add the extra safety hazard) unless there's no good alternative to do it. The standard procedure laid out is to fill out an energized electrical work permit for every job that requires working on it live. The exception is that if you are doing troubleshooting, testing, or voltage measuring (three instances where you almost always need it live or it might be live), and you are a qualified electrical worker (trained in NFPA 70E procedures), then you don't need a permit. In my shop, I made the two classes 1 and 4 (and obviously "no go"). As far as permits go, I require them for all class 2 or higher jobs, all medium or high voltage work, and all live work outside of "troubleshooting, voltage measuring, and testing". I added the extra conditions because I want job planning to take place as the risk increases (where you are cracking out the hoods, suits, etc.). The permit is a variation on a "hot work" permit for cutting and welding. It doesn't stop a job from happening. All it does is give a check list of things to consider when planning out the job before starting.

[TimWilborne 108]

Maybe the rubber, if it were rubber, and the skin got gooey enough to bond if it couldn't actually achieve 350F

[JeffKiper 9]

Paul I my terminology was off “by the books” Leather boots and glasses are part of the every day uniform. Easy to overlook when you get use to them. The “hood” as I called it is a hard hat face shield combo. Your glasses have to remain on under the face shield unless we are in a full respirator required area. (That is another post that will be coming soon) “Balaclava “ is the word I was looking for instead of head liner. 130.7©(10) calls for “Hearing protection (ear canal inserts) from Category 0 and up right? Why does the 70E have a call out for “Arc-rated jacket, parka, or rainwear (AN)”? Sorry but if I am working in a hot panel where I need raingear I might rethink my day.