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 Post subject: Not using faceshield for operating breakers?
PostPosted: Tue May 03, 2011 10:46 am 
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Hi,
I've been thinking lately about PPE when operating switchgear at CAT 1 and CAT 2 locations. It appears proper switching procedures suggest the oeprator turn his head away from the possible explosion and stand to the side of the bucket. My concern is the face shield can act as a scoop to direct the blast behind him into his face. I am considering exempting face shield use only when operating breakers and using proper switching procedures for CAT 1 and CAT 2.

Thoughts? Anyone else share this concern?

Casey


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PostPosted: Tue May 03, 2011 11:11 am 
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I believe that CAT 2 required a baclava covering under the face shield. The other questions you have to ask is, is it better to have the arc flash hit you directly in the face or what happens to get around the edges of the face shield? With CAT 1 you only require safety glasses which are normal PPE in an industrial setting, and CAT 2 requires a face shield.


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PostPosted: Tue May 03, 2011 11:27 am 
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Clarification

Perhaps it wasn't clear in my original post, but an operator would have the back of his head toward the arc, saving his face from a burn if using proper switching procedures. A faceshield could direct the hot gasses to his face in this situation, so it seems safer not to wear a faceshield in this circumstance.


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PostPosted: Tue May 03, 2011 12:23 pm 
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The old school turn your head approach is no longer valid wearing a facesheild. But by exempting the faceshield and turning head allows back of head to be exposed to the arc. I don't think that would be wise to implement.


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PostPosted: Tue May 03, 2011 4:46 pm 
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I concur with Zog's response. Old school is to stand to side, turn head. But this was the only PPE available then. New school, I think would be to let the PPE do it's job. It seems to me that it was designed for a arc flash incident occuring with the individual face on, like you would be operating a volt meter or changing a fuse. By turning to the side you are operating outside what the PPE was designed for.

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PostPosted: Tue May 03, 2011 4:48 pm 
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C. Harman wrote:
PPE when operating switchgear at CAT 1 and CAT 2 locations.


Hi Casey, have you used NFPA 70E-2009 Table 130.7(C)(9) to determine the Hazard/Risk Category? Most CB, fused switch or starter operations are considered very low risk and therefore HRC0. If this is the case then your Operator wouldn't even require an arc rated arc flash faceshield. I recommend you double check your hazard analysis before making any PPE decisions.

FYI, there are different face shield products on the market.... some of which allow for more space between the worker's ear and the shield that could scoop the incident energy as per your comment. Others are designed to conform to the worker's hard cap and use side shield extenders that allow less space for concern. HRC2 as per the proposed NFPA 70E-2012 edition will require balaclava's so I would get your Operators used to wearing them.


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PostPosted: Tue May 03, 2011 4:55 pm 
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wbd wrote:
I concur with Zog's response. Old school is to stand to side, turn head. But this was the only PPE available then. New school, I think would be to let the PPE do it's job. It seems to me that it was designed for a arc flash incident occuring with the individual face on, like you would be operating a volt meter or changing a fuse. By turning to the side you are operating outside what the PPE was designed for.


This scares me..... PPE is a last line of defense. Remember that an arc rating is the 50% probability point at which the material (face shield or fabric) would allow sufficient heat to cause the onset of a second degree skin burn injury. Furthermore, the HRC tables are concensus based and dependent upon the "likelihood" of an accident occuring. Incident energy calculations are a best guess.... please don't "let the PPE do it's job"!!


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PostPosted: Tue May 03, 2011 5:08 pm 
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Jim Pollard wrote:
This scares me..... PPE is a last line of defense. Remember that an arc rating is the 50% probability point at which the material (face shield or fabric) would allow sufficient heat to cause the onset of a second degree skin burn injury. Furthermore, the HRC tables are concensus based and dependent upon the "likelihood" of an accident occuring. Incident energy calculations are a best guess.... please don't "let the PPE do it's job"!!


I understand that PPE is the last line of defense but shouldn't PPE be worn and used as it is designed? Otherwise, one would risk an increase in injury that would not be expected. For example, with your head turned, blast material and heat coming in thru the side opening on the face shield to be now between your face and the shield, instead of being deflected away as designed.

I would disagree that IE calculations are a "best guess". I would suggest that the tables are more of a "best guess" of the risk of an accident occurring. The calculations are at least based on some testing and out there for review. The tables are based on the "likelihood" of an accident occurring. What factors were applied and the weighting of the factors to determine this likelihood? For instance, what is the weighting factor for training, for maintenance, for equipment being used that is not overdutied, etc? Show me the documentation of the decision making process for coming up with the values in the tables.

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PostPosted: Tue May 03, 2011 6:32 pm 
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Jim Pollard wrote:
This scares me..... PPE is a last line of defense. Remember that an arc rating is the 50% probability point at which the material (face shield or fabric) would allow sufficient heat to cause the onset of a second degree skin burn injury. Furthermore, the HRC tables are concensus based and dependent upon the "likelihood" of an accident occuring. Incident energy calculations are a best guess.... please don't "let the PPE do it's job"!!


So not wearing a shield and just turning your head around is safer? I don't understand your arguement.


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PostPosted: Tue May 03, 2011 9:11 pm 
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Additional Clarification

We are in the process of performing arc flash studies. Where labeled, the operator must suit up to the PPE required on the label. As yet we haven't considered the task in the PPE requirements. (until now)

One consideration that I have is that I value the condition of my face much more than the back of my head (as most people I assume do). Seems by wearing a faceshield and looking at the bucket while switching still puts your face in a more dangerous place.

Good comments, keep them coming.


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PostPosted: Wed May 04, 2011 5:13 am 
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This is a good argument.

I would restrict this question to high IE devices like switchgear. I was taught (old school) to have my back face the gear, head turned away, but to also use my left arm (which is my weak hand). The theory being that should a blast occur there is more than just heat, there is also shrap metal. Better to injure your weak hand than your strong hand.

In industry, risk is usually administered in these degrees:
1) Eliminate risk
2) Engineering controls
3) Work practices
4) PPE

The PPE is rated to work for its IE 50% of the time. Thats not a great statistic.

You would want the balaclava for sure, and goggles also if you are facing away.. The face shield could increase the danger if you are facing away.

The best choice may be to donn the HRC 4 hood, even if you are in HRC 2 lower.


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PostPosted: Wed May 04, 2011 5:32 am 
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haze10 wrote:
I would restrict this question to high IE devices like switchgear. I was taught (old school) to have my back face the gear, head turned away, but to also use my left arm (which is my weak hand). The theory being that should a blast occur there is more than just heat, there is also shrap metal. Better to injure your weak hand than your strong hand.


I think the "left hand rule" has more to do with the location of disconnect handles. These are normally on the right side, so using your left hand puts your body away from the disconnect door. This is only true, however, if you are facing the wall to the right side of the disconnect. If you had your back to the disconnect and used your left hand, you would have your left arm in front of the disconnect door - not the best place even if it isn't your favorite arm. :eek:


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PostPosted: Wed May 04, 2011 2:47 pm 
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These days we do it all remotely, most of my techs PPE is still in the plastic, all racking and switching is done wireless outside the AFB.
http://www.cbsarcsafe.com/remote-switch-operators.htm


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PostPosted: Thu May 05, 2011 11:06 am 
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Zog wrote:
So not wearing a shield and just turning your head around is safer? I don't understand your arguement.


I'm not suggesting workers not use a shield, nor am I commenting on safe work procedures. My arguement was do not invest so much faith in your PPE system. Not all PPE was created equally and the hazard analysis methods available via NFPA or CSA are not an exact science. PPE should remain the worker's last line of defense. The other elements of your Electrical Safety Program, (1) qualification of workers and training, (2) use of procedures, (3) establishing work practices and (4) engineering controls can dramatically reduce the probability and/or severity of an arc flash incident.


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PostPosted: Tue May 17, 2011 8:58 pm 
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jghrist wrote:
I think the "left hand rule" has more to do with the location of disconnect handles. These are normally on the right side, so using your left hand puts your body away from the disconnect door.


+1, although I've never heard of it referred to as a rule, merely body positioning to wishfully attempt to minimize bodily harm.

We actually had a worker injured, due to an Arc Blast which wrapped around an Arc Flash Shield. I've never worn an Arc Flash Shield without an FR Balaclava since than.


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