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 Post subject: OSHA Interpretation Letter - Switching a Small CB Could be an Arc Flash Hazard
PostPosted: Mon Jul 20, 2009 6:44 am 
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Location: Scottsdale, Arizona
This letter has been out for a while but I thought it would be interesting to post here in light of all of the discussion about whether there is an arc flash hazard for operating small devices even with covers on.

I think this is the letter that really stirred things up.

[url="http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=25973"]OSHA Interpretation Letter[/url]

Specifically Question (2) about whether switching a device in a dead front enclosure is a shock hazard and an arc flash hazard.

They state it is not a shock hazard but it could be an arc flash hazard :eek: Even for devices below 240 volts!

The Arc Flash Protection Boundary equation is a bit out of date since this is prior to the 2009 Edition of NFPA 70E which lowered the boundary condition to 100 kA-cycles from 300 kA-cycles and also moved this equation to the annex.

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PostPosted: Tue Jul 21, 2009 4:03 am 
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Joined: Sat May 17, 2008 5:00 pm
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They can't be serious! Sounds like it was written by lawyers that are clueless about the real world. What's next, PPE for flipping a light switch?


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PostPosted: Tue Jul 21, 2009 8:27 am 
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OSHA is interpreting NFPA. Shall we go to NFPA to interpret OSHA? Perhaps it would be more appropriate for each to interpret their own documents.


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