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 Post subject: Working within Arc Flash Boundary
PostPosted: Mon Nov 11, 2019 8:53 am 

Joined: Tue Dec 02, 2014 7:46 am
Posts: 14
As mentioned in the 70E that "When an employee is working within arc flash boundary, he or she shall wear protective clothing and other PPE in accordance with 130.5. All parts of the body inside arc flash boundary shall be protected".

I.E. at our main switchboard is higher than 40 cal. Arc Flash Warning (Danger) label is prohibiting energized work. Arc Flash Boundary is extending beyond the space available in front of the switchboard.

In this situation what should be guideline for the performing thermography of exposed energized circuit parts. Person doing thermography will be within arc flash boundary and how to meet warning on arc flash label about 'No Energized Work'. Please let me know your thoughts and recommendations . Thank you.


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 Post subject: Re: Working within Arc Flash Boundary
PostPosted: Tue Nov 12, 2019 8:09 am 
Arc Level

Joined: Mon Jan 18, 2010 11:35 am
Posts: 546
Location: Wisconsin
The qualified individual needs to be wearing appropriate PPE for the distance they are standing from the arc flash. You determine the AF boundary distance based on your desired PPE rating. The AF boundary shown on most labels is the distance required for effectively no PPE.

Rerun your study using different distances or different PPE ratings.

But, how will you remove covers to exposure the surfaces for the 'camera'? This is why many people have added special viewing windows to the equipment.


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 Post subject: Re: Working within Arc Flash Boundary
PostPosted: Mon Nov 18, 2019 7:58 am 
Sparks Level

Joined: Tue Jan 19, 2010 2:35 pm
Posts: 154
Good question. So there's not enough space in front of the gear for the person to stand and be outside the arc flash boundary? If you cannot shut off the gear (and that's normally the case) then I'd say those in the room when electrical doors open should be in the proper PPE.


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 Post subject: Re: Working within Arc Flash Boundary
PostPosted: Tue Nov 19, 2019 6:15 am 

Joined: Mon Feb 23, 2015 10:19 am
Posts: 8
Its a risk assessment.
Can opening a hinge panel door be considered working on?
There is a definition in the 70E for 'working on or near' which is basically coming in contact with energized parts (with a tool). Voltmeter checks are an exception to the energized work definition.

In my opinion simply opening the door (hinged), if in good working condition, no signs of impending danger, etc. does not constitute working on. Therefore a risk assessment approach could be used to enter the arc flash boundary for the task of thermography.

Bubba


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 Post subject: Re: Working within Arc Flash Boundary
PostPosted: Mon Nov 25, 2019 9:12 am 
Sparks Level
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Joined: Tue Oct 26, 2010 5:00 pm
Posts: 198
Location: Maple Valley, WA.
See Table 130.5(C) Estimate of the Likelihood of Occurrence of an Arc Flash Incident for ac and dc Systems. This table lists a activity of Performing infrared thermography and other non-contact inspections outside the restricted approach boundary. This activity does not include opening of doors or covers. The table states Likelihood of Occurrence* = NO.

In short, removing the covers is a high risk task but scanning the equipment is not a high risk task. However, I would highly recommend that the person performing the Infrared Survey be wearing Arc Rated PPE shirt and pants.

_________________
Robert Fuhr, P.E.; P.Eng.
PowerStudies


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 Post subject: Re: Working within Arc Flash Boundary
PostPosted: Mon Nov 25, 2019 10:08 am 
Sparks Level

Joined: Sat Apr 04, 2009 9:50 pm
Posts: 117
Location: San Antonio, TX
I recommend that you reconsider the DANGEROUS labels. There is appropriate PPE for AFIEs larger than 40 cal/cm2. The NFPA 70E 2018 allows working on equipment with AFIE of more than 40 cal/cm2 if you have the appropriate rated PPE (when the exceptions for working energized are met).

The new NFPA 70E 2018 deleted all references and informational notes for AFIEs larger than 40 cal/cm2.

If the AFIE at your service equipment is 70 cal/cm2 at the working distance (i.e. 18 inches), you can work on this equipment if you have PPE with an arc rating of 70 or more.

Also, it would be a good idea, as was pointed out in this thread, that you calculate the AFIE at the distance that the infrared service might take place (i.e., 20 inches) and get a lower AFIE value that would reduce the arc rating necessary for the technician performing the IR service.


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