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 Post subject: Another thread about PPE for enclosed operations.
PostPosted: Fri Jul 27, 2012 8:31 am 
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I don't like to bring up topics that have been covered in detail in the past, I am just looking for some opinions about a question I have not seen brought up.

There has been a lot of discussion about what type of PPE should be worn for doing a general LO/TO and switching breaker with the enclosure shut. Should you use Class 3 if that is what the HRC calls for? My question is, in the NFPA 70E table 130.7(C)(9) they call for differant PPE for differant types of operations, (i.e. first table calls for "0" for switch operation with covers on and "1" when working on energized conductors) why wouldn't this mind set be used after using the Arc Flash Study for requiring PPE?

I am very new to the NFPA 70E requirements, actually waiting for my handbook to arrive, and looking for some opinions.


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PostPosted: Mon Jul 30, 2012 3:55 pm 
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Shane-
You have to read the FPN-when using the generic task tables.Once your Arc Flash Study is performed the tables are no longer applicable.
Pay particular attention to the size of feeder transformers,when using the tables.


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PostPosted: Tue Jul 31, 2012 8:15 am 
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Shane Rasset wrote:
I am very new to the NFPA 70E requirements, actually waiting for my handbook to arrive, and looking for some opinions.


Remember, NFPA 70E is a "What needs to be done" not a "How to do it" standard. It is purposely written with a lot of grey areas.

It is up to your company to address these grey areas in your Electrical Safe Work Practices program. For example: if your study calculation results in an incident energy of 9cal/cm┬▓, there is nothing in NFPA70E that would prevent you from using the PPE described in Hazard/Risk Category 2 of Table 130.7(C)(16) if it has an arc rating of 11cal/cm┬▓.


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PostPosted: Tue Jul 31, 2012 8:19 am 
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Small addon to that: for an Ei over 12 cal/cm^2, a hood is mandated by 70E rather than a face shield.


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PostPosted: Tue Jul 31, 2012 8:29 am 
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Location: Camp hill Pa
Actually, hardly any of us are new to ARC Flash, I am sure you seen it many times. Our problem is we did not respect it.

We should always wear cotton, other non-flammable clothing when working. I would recommend always wearing type 0 or 1 clothing and carrying higher grades.

The first time I saw the results of an Arc-flash serious accident, was when my boss at a Bethlehem mine took me on a tour and showed me a 4160 volt 1000 ampere no load break disconnect. It was accidentally opened under load. (The Crusher foreman said the plant was shut down but actually every thing was energized with no rock being sent though the plant.) The switch blew all its insides out the front in a heap of melted metal. The electrician operating it was fortunately standing to the side of the switch and was unhurt. The boss said "Do you see why you never stand in front of anything, stand to the right, and face away, and use your left hand?" "Yes SIR!" Hardly anyone is taught this rule although, i saw it demonstrated in a training film.


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PostPosted: Tue Jul 31, 2012 11:14 am 
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The boss said "Do you see why you never stand in front of anything, stand to the right, and face away, and use your left hand?" "Yes SIR!" Hardly anyone is taught this rule although, i saw it demonstrated in a training film.[/quote]

We were testing an SOP after a SBGen intertie a few years ago. this was before we started our AF Studies. the operator was geared up though in a blue coat (don't remember the AFValue), gloves, and a hardhat with a face shield. he made sure though to turn his head and expose the unprotected back of his head to a potential blast. i pointed this out, and they've since gone throught some more training on posture when operating the gear. we've also started our Studies and upgaded our equipment. hopefully we never need it.


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PostPosted: Sat Aug 18, 2012 6:33 am 
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Brodie wrote:
Shane-
You have to read the FPN-when using the generic task tables.Once your Arc Flash Study is performed the tables are no longer applicable.
Pay particular attention to the size of feeder transformers,when using the tables.


So, the arc flash study requires that you determine the hazard and the risk associated with the hazard. Can you find me anyone doing the risk portion of the study? I can get lots of monkeys that have bought a copy of software to do the hazard evaluation but not the risk part.

Also, tables no longer needed? What if the current and/or voltage is outside the range where the calculation methods are invalid? Read the notes at the beginning of Annex D. Then what? Seems like the only alternative is to use a table, whether the ones in 70E or the ones in NESC (referenced by Annex D).


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