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 Post subject: Overdutied Device Interrupting Ratings
PostPosted: Thu Jul 15, 2010 7:49 am 

Joined: Mon Mar 16, 2009 10:43 am
Posts: 2
NFPA 70E says that "design" and "condition of maintenance" should be taken into account for arc flash hazard analysis.

For equipment with over-dutied interrupting ratings what is the proper approach for an arc flash hazard analysis? As in what was the intention of NFPA in incorporating design, or lack thereof, into the analysis?


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PostPosted: Thu Jul 15, 2010 10:58 am 
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Joined: Mon Jun 02, 2008 11:58 am
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Location: Charlotte, NC
jkopinski wrote:
NFPA 70E says that "design" and "condition of maintenance" should be taken into account for arc flash hazard analysis.

For equipment with over-dutied interrupting ratings what is the proper approach for an arc flash hazard analysis? As in what was the intention of NFPA in incorporating design, or lack thereof, into the analysis?


I suume you mean your available fault current is > the AIC rating of your breaker? If so I would not assume that breaker is an OCPD at all.

The 70E is not a design or instalation standard, that is what the NFPA 70 is for (NEC).

Good question, interested to see what others do in this case.


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PostPosted: Thu Jul 15, 2010 1:37 pm 
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Joined: Sun Dec 23, 2007 1:44 pm
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Location: Charlotte, NC
If you cannot find an acceptable method to lower the available fault duty, then I would replace the equipment while there is still something to replace.


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PostPosted: Thu Jul 15, 2010 2:22 pm 
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Joined: Mon Mar 29, 2010 11:52 am
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Location: Yankton SD/ Lead SD
Zog wrote:
I suume you mean your available fault current is > the AIC rating of your breaker? If so I would not assume that breaker is an OCPD at all.

The 70E is not a design or instalation standard, that is what the NFPA 70 is for (NEC).

Good question, interested to see what others do in this case.


NFPA 70 should not be considered a "design standard". I would classify it more as a "minimum requirememnts installation guide".


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