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 Post subject: Arc Rated Gloves Dexterity?
PostPosted: Wed Feb 22, 2012 7:15 am 
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Joined: Tue Feb 21, 2012 11:45 am
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Hello all, i just joined up as i have been tasked with bringing up our stations safety standards and doing a little research into 70E it appears that we should be wearing arc rated gloves instead of class II's when racking some of our breakers, just wondering if anyone has any experience using these and how is the dexterity of the 65 cal arc rated gloves. thanks.


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PostPosted: Wed Feb 22, 2012 6:20 pm 
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First, at 65 cal/cm^2, the arc blast alone is likely to kill you. The reason that the charts, tables, etc., stop at 40 cal/cm^2 is that you are unlikely to survive regardless of the PPE. So to begin with if that's accurate part of the procedure is probably to do something else. There is a note in 70E that mentions this.

Second, just putting on PPE is incorrect at least as far as OSHA is concerned. You must first look at applying engineering approaches, administrative approaches, and so forth to reduce or eliminate the risk. Only after you've exhausted everything else do you get out the PPE as a last resort. For electrical tasks on energized equipment though unless you can do the task remotely or drastically reduce the potential for shock or arc flash hazards, often the only viable approach is to use PPE.

Arc rated gloves were popular up until around 2004-2008 because up until that point no one had actually tested leather gloves and/or voltage rated (rubber) gloves with leather protectors to verify what level of incident energy that they would work against. Then the test work came out and the determination was that simple heavy all leather work gloves work fine up to 8 cal/cm^2, and rubber gloves with leather protectors work well in excess of 40 cal/cm^2.

At this point the only reason to buy and/or use arc rated gloves is if there is no shock hazard present and there is some other reason to do so such as not having to send them out every 6 months for cleaning and testing.

So in a round about way, the answer is that first, the gloves don't really matter. If the incident energy is 65 cal/cm^2, the activity is just plain dangerous. You stand 0.0% chance of surviving a 65 cal/cm^2 arc blast. Second, I don't remember the exact number but rubber gloves and leather protectors are effective at a level higher than 40 cal/cm^2 even if it's class 0 gloves. So there is no reason to use arc resistant gloves unless there is another reason for doing so. Most of the time with both arc flash and shock hazards, those are the only choice.

There are practical applications by the way for the 65, 80, and 100 cal suits. Those are intended for use in places like working around some arc welding and foundry processes where the thermal energy really is that high but it is controlled. There is no arc flash, only massive amounts of thermal energy. Usually you will also be wearing a liquid or air powered cooling vest underneath the gear as well so that you don't end up passing out from heat stroke. I have been there. The best thing to do is to automate those tasks and take the people out of harm's way.


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PostPosted: Wed Feb 22, 2012 6:37 pm 
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well here is the thing, working in a nuclear power plant we have some unit sub stations that after and engineering evaluation some of the secondary unit substation breakers (480 volt) have an Incident energy rating of 40+ cal/cm^2. I understand the fact that we can wear leather gloves especially for work at 0-2 cat levels.

the question came up that using a class 2 glove when racking a 13.8 or 4160 breaker what is the arc rating of the glove. well come to find out per 70E insulating gloves such as class 2 are not required and you should be wearing arc rated gloves. the reason the choice of 65 came up was basically that they are the same as the suits we wear for some of the high IE rating jobs.

We have tried to use an Eaton racking device while our electrical shop has had no trouble using such a tool the eliminates all danger to employees by moving them away from the blast zone however the operators have broken 3 breakers and we currently have one breaker that we have stuck in a cubicle because we can not de-energize the unit sub right now for maintenance.

so in the meantime before we can either train people even more then we already have or install some more control in the software with in the eaton we have been racking by hand.

what is your solution if you are manually racking a Unit sub breaker with an IE rating of 44?

Or in otherwords say we have a breaker that is a hazard cat 4 and you are racking it per 70E you must have arc rated gloves on because insulating rubber gloves are not requred?


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PostPosted: Thu Feb 23, 2012 7:04 am 
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I would still wear the rubber gloves with leather protectors. Another thing to consider, the calculated Ei is based on a certian working distance (Should be on the label), often the arc rated gloves will be much closer to the potential arc source than was assumed so your Ei will be much higher. Not a problem for racking but for other tasks like checking voltages that needs to be considered.

You also may want to look into a different remote racking device if you are having so many issues.


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PostPosted: Mon Feb 27, 2012 5:51 pm 
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To answer your basic question you have limited dexterity. It is good enough for racking the breaker in or out as well as grabbing hold of the breaker and pulling it out of the cubical. I use a pair of 100 cal gloves with a 55 cal suit. Most of our breakers are rated below 40 with the exception of a few that are about 44 or 46, I don't recall right at this moment. Most of those are at 440. If you are going in to take voltage reading or the like then I would use leathers over rubber as I believe Zog stated. Every situation is different as you know and requires a bit of thought process before diving into the job. I also remember reading some where that the leather and rubbers were tested and passed with much better results then expected. Not knowing myself but if your working in a Nuke don't they have a procedure for everything to reduce risk and down time?


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PostPosted: Mon Feb 27, 2012 7:42 pm 
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We have a number of feeder breakers in double ended subs, both 480 V and 2300 V, that are in the 50-70 cal/cm^2 range. However, we handle this at very reasonable conditions. We go to the upstream breaker, and either turn on or set the instantaneous trip setting on the upstream breaker down to less than the arcing current. For instance in one case I looked at today, the incident energy decreases from 70 cal/cm^2 down to 3.9 cal/cm^2. While the equipment is in this condition coordination is shot but in this situation, the concern is safety. We flat out don't mess with anything above 40 cal/cm^2. It's not a fancy solution but it costs nothing but some administrative work to implement.

We've also tried some of the various remote operators on breakers as well. Had some problems with some of them being flimsy. The best kinds have overtorque protection. The biggest problem is getting them to mount solidly so that they actually work.


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