Arc FlaSH Labeling

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I read about this a while ago and havent revisited the subject in a little while but if I remember correctly some people are advocates of using one PPE class above recommended because the PPE pretty much only means the operator will not suffer fatal injuries in the event of an arcing fault, but some pretty harsh damage can happen to the hands, arms and chest.
 
skeshesh said:
I read about this a while ago and havent revisited the subject in a little while but if I remember correctly some people are advocates of using one PPE class above recommended because the PPE pretty much only means the operator will not suffer fatal injuries in the event of an arcing fault, but some pretty harsh damage can happen to the hands, arms and chest.
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The PPE selected has to have an ATPV rating that is greater than the calulated EI. The ATPV is based on not allowing >1.2 cal/cm2 to pass through which is the 2nd degree burn threshhold. So with the right PPE selected burn injuries will be limited to a 1st degree burn.

The pressure from the arc is a different story, PPE gives limited protection from that part but there are not any usuable calculations (yet) to determine the pressures.
 
zog said:
Arc flash PPE is required when you are interacting with the equipment, operating a breaker for example, even with the covers on.
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Are you including Hazard Risk Category 0 PPE in the arc flash PPE you are referring to?

As far as I can tell reading my 2004 (I know, time to upgrade! :roll:) 70E, safety glasses and non-melting long sleeves and pants are sufficient to operate an enclosed (or sometimes exposed) breaker. NFPA 70E T130.7(C)(9)(a).
 
The PPE selected has to have an ATPV rating that is greater than the calulated EI. The ATPV is based on not allowing >1.2 cal/cm2 to pass through which is the 2nd degree burn threshhold. So with the right PPE selected burn injuries will be limited to a 1st degree burn.

The pressure from the arc is a different story, PPE gives limited protection from that part but there are not any usuable calculations (yet) to determine the pressures.
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Good info. Again, going on memory so correct me if I'm worng but I think that the PPE rating at the 2nd degree threshold also takes into account clearance between person and equip, i.e. 3ft or so assumed since the person is supposed to stand away from the equip and extand the arms. If the PPE protection tolerance is calculated as such only the body will be protected against the said level of incident energy so that the hands and arms could still experience further burns.

I just scanned through what little stuff I have at the office on the subject. I guess 70E has not conducted any testing and provides tables indicating the proper PPE based on conservative criteria, which I believe is based on IEEE 1584. IEEE 1584 is based on actual test data and is a more percise calculation method for design as apposed to 70E which is a safety document.
 
above 50 volts needs a label...

above 50 volts needs a label...

I don't have the book here in front of me, so I am going by memory (could be a problem!!). Panels above 50 volts need to be marked. So your 208 panel will need the label.

Under 2009 70E you can provide the incident energy or the PPE level required on the label. If you don't have the ability or resources to do a calculation, you can always use the simplified approach and the tables to determine what PPE would be required. Make sure you read all of the notes though, because you might be able to reduce the PPE level required...

Also, there is a section that allows you to classify a hazard level of 0 for less than 300 Volts fed from a transformer of a certain KVA (I can't pull the number from my memory right now)

IMO you should make an effort to get a copy of 70E and read up on it. I encourage everyone to do so. If you like to read online, you can get to it through the NFPA website electronically and it's free now...
 
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