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PostPosted: Mon May 24, 2010 2:11 pm 
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stevenal wrote:
In my opinion no interaction occurred until the breaker was operated, and that interaction stopped when the operation completed successfully. If you are collecting opinions, perhaps you want to set up a poll.


I thought about that but it would do me no good anyways. I am more interested in the reasoning behind the answers than the # of yes and no's.


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PostPosted: Mon May 24, 2010 10:08 pm 
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Opening a door is an interaction

I hate to gown up for everything but the alternative may be worse. Walking by, peeking through the screen, reading meters, touching touchscreens to get data. That is not likely to cause an arc flash as no movement of anything takes place. Opening a door seems harmless enough but it is interaction. You do not know what opening that door may cause. Loose hardware, dust, etc could be lurking. I have been in as many cabinets as anyone with my cotton long sleeve shirt and a pair of safety glasses. Not any more. I draw the line at opening a door.


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PostPosted: Tue May 25, 2010 5:30 am 
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Data Center Electrician wrote:
I hate to gown up for everything but the alternative may be worse. Walking by, peeking through the screen, reading meters, touching touchscreens to get data. That is not likely to cause an arc flash as no movement of anything takes place. Opening a door seems harmless enough but it is interaction. You do not know what opening that door may cause. Loose hardware, dust, etc could be lurking. I have been in as many cabinets as anyone with my cotton long sleeve shirt and a pair of safety glasses. Not any more. I draw the line at opening a door.


Again, in this senario there are no exposed live parts when you open the door.


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PostPosted: Tue May 25, 2010 7:55 am 
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If opening a door to expose a dead front is an interaction, then opening the door to the room that leads to the equipment is also an interaction since it also exposes dead fronts.


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PostPosted: Tue May 25, 2010 11:46 am 
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stevenal wrote:
If opening a door to expose a dead front is an interaction, then opening the door to the room that leads to the equipment is also an interaction since it also exposes dead fronts.


Might spook a rat to run into the gear :)

The line will need to be drawn somewhere at some point what is an acceptable "risk"

Haze, where are you? I know you have some pretty strong views on this.


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PostPosted: Wed May 26, 2010 12:35 am 
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The DL breaker is an exception to the majority of breakers i see located behind a door. The open frame breakers may not have exposed live parts but they are behind arc shields and there are live parts. We are not worried about shock we are trying to avoid an arc blast. Opening a door creates a change in the gear and a movement that can in result cause other things to move. A door that was taken care of and opened smoothly on a DL breaker like this would most likely pose no threat. However, I have seen people smack a door to get it to pop open because it is sticky, this may pose a problem. My facility is spotless and i could eat off of the switchgear. My concern is that we develop acceptable habits. If it is acceptable to open a DL breaker door then will it be acceptable to open the door to a Siemens RL breaker? It will be hard to define this door or that door becuse of the differences in what is behind the door. Some of this is going to have to be based on knowlege and experience.


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PostPosted: Wed May 26, 2010 5:31 am 
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Data Center Electrician wrote:
The DL breaker is an exception to the majority of breakers i see located behind a door. The open frame breakers may not have exposed live parts but they are behind arc shields and there are live parts. We are not worried about shock we are trying to avoid an arc blast. Opening a door creates a change in the gear and a movement that can in result cause other things to move. A door that was taken care of and opened smoothly on a DL breaker like this would most likely pose no threat. However, I have seen people smack a door to get it to pop open because it is sticky, this may pose a problem. My facility is spotless and i could eat off of the switchgear. My concern is that we develop acceptable habits. If it is acceptable to open a DL breaker door then will it be acceptable to open the door to a Siemens RL breaker? It will be hard to define this door or that door becuse of the differences in what is behind the door. Some of this is going to have to be based on knowlege and experience.


I assume you mean DS, never heard of a DL. I understand what you are saying and views like that are the reason I started this thread. However, the risk factor here is very low.

I had a friend burned in an arc flash last year just walking past an MCC when a starter picked up and failed causeing an arc flash that blew the door open, he was just walking by on his way back from lunch. So because that happened do we need to wear PPE to just walk past a MCC sitting on a production floor? How would that effect production at all large industrial facalities in the US? There has to be some level of acceptable risk.

Now the challange to the 70E commitee is to figure out how to assess that risk and write the standards in a usable way and still be enforceable. You can't put "knowledge and experience" in a standard because the people that think they have the most usually have the least.


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PostPosted: Sun Apr 10, 2011 3:37 pm 
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I am a big fan of the term acceptable risk.
I work in a large paper mill where risk assessments are commanly performed on converting machinery to identify and remediate hazards.
The thought of using a risk assessment approach to this arc flash issue I believe is something that each facility will have to assess on their own. In our mills we have a documented risk assessment for various tasks that allow a dress down from the label PPE. For this dress-down to occur the task worker must fill out a jha that helps him understand the hazard and the risk assessment that he is taking advantage of.


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