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If you find overdutied equipment during an arc flash study, for labeling you would:
Label the overdutied equipment and ignore the inadequacy
Label the overdutied equipment and list the inadequacy in the report
Do not label the equipment - list the inadequacy in the report
Stop the study until the inadequacy is addressed
Something else - please comment.
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 Post subject: Overdutied Equipment
PostPosted: Sun Jun 05, 2011 4:36 pm 
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Joined: Mon Sep 17, 2007 5:00 pm
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Location: Scottsdale, Arizona
This week’s question has been frequently discussed within the IEEE committee. I thought it would be interesting to see how others handle the situation.

During the course of performing an arc flash study, what if you discover equipment that has an inadequate interrupting or withstand rating. As far as arc flash warning labels and the arc flash study are concerned, you:

  • Label the equipment and do nothing about the inadequacy (not in scope)
  • Label the equipment AND list the inadequacy in the report
  • Do not label the equipment AND list the inadequacy in the report
  • Stop the study until the inadequacy is addressed
  • Something else

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PostPosted: Mon Jun 06, 2011 8:14 am 

Joined: Sat Mar 19, 2011 6:13 pm
Posts: 14
I will include something in the executive summary, in bold letters, similar to this:

It should be noted that the following equipment and/or protective devices are rated below the available fault current at their location. A fault event affecting any of these could cause catastrophic damage to the equipment and risk the safety of personnel nearby. In addition, it could result in a lengthy power outage that could affect the facility's operation.

When doing a study, I consider myself as a messenger only. It is up to the facility management to decide how they act on the recommendations.


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PostPosted: Fri Jun 24, 2011 7:16 am 

Joined: Tue Feb 16, 2010 7:59 am
Posts: 21
Location: Minneapolis, MN
Forgive me for answering a question with another question but, having been to a number of facilities where no attention was paid to interrupting capacities, I feel this question begs another question. Consider the following scenarios.

Panel P-1 has bolted fault of 45 kA and has CB’s rated at 25 kAIC. One of these circuit breakers feed Panel P-2 where:

1) Bolted fault and arcing fault at P-2 are < 25kA.
2) Bolted fault at P-2 >25kA and arcing fault < 25kA.
3) Bolted fault and arcing fault at P-2 >25kA.

Some will label scenario 1 and list it as a deficiency in the report but scenarios 2 & 3 are a lot more dangerous. My answer is “it depends”.

Bob Ragsdale, P.E.


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PostPosted: Fri Jun 24, 2011 1:14 pm 

Joined: Sun Oct 05, 2008 5:00 pm
Posts: 17
BCR_1962 wrote:
Forgive me for answering a question with another question but, having been to a number of facilities where no attention was paid to interrupting capacities, I feel this question begs another question. Consider the following scenarios.

Panel P-1 has bolted fault of 45 kA and has CB’s rated at 25 kAIC. One of these circuit breakers feed Panel P-2 where:

1) Bolted fault and arcing fault at P-2 are < 25kA.
2) Bolted fault at P-2 >25kA and arcing fault < 25kA.
3) Bolted fault and arcing fault at P-2 >25kA.

Some will label scenario 1 and list it as a deficiency in the report but scenarios 2 & 3 are a lot more dangerous. My answer is “it depends”.

Bob Ragsdale, P.E.


We've wrestled with this one too. I have heard of some that just stop at the first inadequate panel and won't label anything past it. Others only leave the label off the equipment that is inadequate and continue to label beyond. Not sure what the answer is but you are correct, it would be great to hear other opinions. The original poll question was great. Let's carry it further.

Thanks!


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PostPosted: Wed Aug 31, 2011 4:19 pm 

Joined: Wed Aug 31, 2011 3:33 pm
Posts: 14
Location: Denver, CO
Supplemental label?

It is being discussed to supply an additional label to warn of the overdutied equipment. I know NEC 110.16 only requires arc-flash label, but NEC is usually minimal requirement.


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