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 Post subject: Circuit Breaker operation-Dangerous
PostPosted: Wed Jan 06, 2010 10:56 am 
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A Arc Flash study recently completed identified many areas/equipment to be in the Dangerous Category.I know much discussion has taken place on the issue of normal operation i.e. circuit breaker operation doors open/closed.
The way I view it is that triping, closing breakers on switchgear with this rating -Dangerous -cannot take place while standing directly in front of the equipment regardless of the PPE worn.
Can anyone relate their current practices in dealing with this,is it my obligation to inform the owner that maintenance performed prior to the study can no longer be performed?
Many job plans were previously performed on this equipment with no PPE worn,doors closed of course.
I feel I have a good understanding of NFPA 70 E until it falls within this category.


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PostPosted: Wed Jan 06, 2010 12:24 pm 
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Brodie wrote:
A Arc Flash study recently completed identified many areas/equipment to be in the Dangerous Category.


Ok, first off, (here I go... :rolleyes: ) there is no such thing as a "Dangerous Category." NFPA 70E 2009 only says, in a Fine Print Note to 130.7(A), that above 40 cal/cm^2 additional precautions should be taken.
That being said, at 143 cal/cm, there is NO WAY that I would want anyone around that piece of equipment.

Brodie wrote:
Can anyone relate their current practices in dealing with this,is it my obligation to inform the owner that maintenance performed prior to the study can no longer be performed?
...
I feel I have a good understanding of NFPA 70 E until it falls within this category.


If this is for a client, and you are contracted with them to provide the study, I think the best thing to do is to inform them that they should stop all work on this equipment while energized, and provide them with full details of what is possible if they continue. This Recommendation, should be as strongly worded as possible. Ultimately, however, the decision to continue or not falls on them, and the results will be their responsibility. I would also inform them of, and recommend, mitigation strategies.


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PostPosted: Wed Jan 06, 2010 7:12 pm 
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Brodie wrote:
A Arc Flash study recently completed identified many areas/equipment to be in the Dangerous Category.I know much discussion has taken place on the issue of normal operation i.e. circuit breaker operation doors open/closed.
The way I view it is that triping, closing breakers on switchgear with this rating -Dangerous -cannot take place while standing directly in front of the equipment regardless of the PPE worn.
Can anyone relate their current practices in dealing with this,is it my obligation to inform the owner that maintenance performed prior to the study can no longer be performed?
Many job plans were previously performed on this equipment with no PPE worn,doors closed of course.
I feel I have a good understanding of NFPA 70 E until it falls within this category.


Mitigation may be easily achieved, that is always a good solution, unless you are only concerned about opertion of the equipment and don't need to do energized work.

My company provides wireless remote switching and racking solutions for this exact application. What type of breakers do you have?


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PostPosted: Sun Jan 10, 2010 11:16 am 
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All Circuit Breakers are Siemens.My main concern is "normal operation" circuit breaker opening and closing,however diagnostic work,is also a concern,how can this type of work be performed under this category?


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PostPosted: Mon Jan 11, 2010 10:10 am 
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Brodie wrote:
All Circuit Breakers are Siemens.My main concern is "normal operation" circuit breaker opening and closing,however diagnostic work,is also a concern,how can this type of work be performed under this category?


Siemens what?


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PostPosted: Tue Jan 12, 2010 2:16 pm 
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I have s similar situation with 5 pieces of gear at my plant - the secondary side of a transformer is tagged "Extreme Danger" from the EasyPower software. We always de-energize the gear before doing any work on it including opening, closing, etc. We have to go upstream of the primary switch on the transformer to the main breaker which completely shuts down our machinery, but it's the right thing to do.

TxEngr


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PostPosted: Tue Jan 12, 2010 4:19 pm 
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TxEngr wrote:
I have s similar situation with 5 pieces of gear at my plant - the secondary side of a transformer is tagged "Extreme Danger" from the EasyPower software. We always de-energize the gear before doing any work on it including opening, closing, etc. We have to go upstream of the primary switch on the transformer to the main breaker which completely shuts down our machinery, but it's the right thing to do.

TxEngr


Switching wirelessly is safer than doing it that way.


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PostPosted: Tue Jan 12, 2010 7:20 pm 
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Zog,

When did "switching wireless" become safer then opening an upstream breaker in another location? Am I missing something?


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PostPosted: Wed Jan 13, 2010 6:54 am 
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dpmac wrote:
Zog,

When did "switching wireless" become safer then opening an upstream breaker in another location? Am I missing something?


Because you still have an arc flash hazard operating you 15kV switch and need PPE inside the Arc Flash Boundary.

Or..you can stand 200ft away and operate the LV breaker (Or MV switch if you prefer) without PPE and outside the AFB.


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PostPosted: Wed Jan 13, 2010 8:48 am 
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The upstream breaker is remotely opened (and closed) from the Powerhouse Control Room in our case as are most of our 15KV breakers. Additionally, that breaker lineup is rated HC4 (really HC3 but we use the 2 level PPE) so even if we had to open it, we could readily suit up and perform the operation much more safely than dealing with the >40cal rating of the LV stuff.


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PostPosted: Wed Jan 13, 2010 9:16 am 
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TxEngr wrote:
The upstream breaker is remotely opened (and closed) from the Powerhouse Control Room in our case as are most of our 15KV breakers. Additionally, that breaker lineup is rated HC4 (really HC3 but we use the 2 level PPE) so even if we had to open it, we could readily suit up and perform the operation much more safely than dealing with the >40cal rating of the LV stuff.


Oh, if you remotly open the upstream breaker you are good :cool:

You never mentioned you had the ability to do that.


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PostPosted: Thu Jan 14, 2010 9:10 am 
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what if that we got category #3 on a small lighting panel. Do we have to wear PPE in order to just trun a breaker on and off? There is no live parts exposed and the panel cover should be able to withstand some energey if there is flash. To wear heavy PPE to operate such panel is really overkilling from my point of view.


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PostPosted: Thu Jan 14, 2010 10:16 am 
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Noah wrote:
what if that we got category #3 on a small lighting panel.


Don't see that happening, first thing would be to look at how the analysis was performed, but I will play along.

Noah wrote:
Do we have to wear PPE in order to just trun a breaker on and off? There is no live parts exposed and the panel cover should be able to withstand some energey if there is flash.


It might, but there is no way to calclate how much energy it would contain. Still interacting with equipment and therefore you need the PPE rated for the Ei that was calculated.

Noah wrote:
To wear heavy PPE to operate such panel is really overkilling from my point of view.


Not if that is the hazard level. The heat from the arc flash dosen't care what kind of panel it is comming from, it melts your skin all the same.


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PostPosted: Tue Apr 20, 2010 7:59 am 
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Remote actuator

I have submitted and received feedback to proceed with the purchase of a remote actuator to safely deal with interacting with this equipment.

The decision to purchase met with a lot of resistance from engineers/management who were either unaware of the potential hazards or were unwilling to modify their thinking.

One suggestion was to build a 1/2 inch steel shield on wheels,can you imagine! I appreciate the results of our Arc Flash analysis and the NFPA 70 E requirements that obligate owners to mitigate through engineering means.

For those of you who have not viewed here is an awesome video- http://www.liveleak.com/view?i=28f_1253869409


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PostPosted: Tue Apr 20, 2010 11:44 am 
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That is a really well done video. Does anyone have any clue as to the incident itself? I am wondering about type of gear, voltage, incident energy. The message really seems to hit home if it's equipment people work on themselves.


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PostPosted: Wed Apr 21, 2010 9:01 am 
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Quote:
Or..you can stand 200ft away and operate the LV breaker (Or MV switch if you prefer) without PPE and outside the AFB.

And then to test for voltage from 200ft away to establish an electrically safe work condition, you would do what?


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PostPosted: Fri Apr 23, 2010 4:24 am 
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Location: washington
Donnies Accident

MIEngineer-The incident occured on a 6000 Amp 480 Volt Switch-The victim returned to work over a year later ,but not as an electrician...
He cannot use his hands very well ,he does estimating..


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