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 Post subject: IEEE and ARC Flash Assesment
PostPosted: Sat Jul 27, 2019 12:55 pm 

Joined: Tue Dec 02, 2014 7:46 am
Posts: 14
I do not see 70E-2018 requires arc flash assessment shall employ IEEE for arc flash assessment There may be something in Annexes but Annexes are not mandatory. I am using EasyPower software , it calculates on IEEE-2018. But I guess using IEEE is not mandatory. I thank in advance to people who can express some ideas.


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 Post subject: Re: IEEE and ARC Flash Assesment
PostPosted: Sun Jul 28, 2019 10:56 am 
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Joined: Mon Sep 17, 2007 5:00 pm
Posts: 1492
Location: Scottsdale, Arizona
Standards don't generally require the use of other specific standards but usually reference those standards. An example is NEC 110.9 requires equipment that interrupts fault current to have an adequate interrupting rating but stops short of stating how this is achieved. Most recognize a short circuit study is performed.

Similarly, NFPA 70E 130.5(G) has requirements for performing an incident energy analysis (unless tables are used) and does not state how this must be done. An informational note referencing Annex D is provided that contains various calculation methods. However at the moment, the 2018 Edition of IEEE 1584 is not referenced in the 2018 Edition of NFPA 70E since IEEE 1584 was published after 70E was published.

I submitted public input for the 2021 Edition of NFPA 70E to remove the 2002 IEEE 1584 reference and equations in Annex D and add a reference to the new 2018 edition. Additional language was submitted by another person for the 70E Second Revision and this was all discussed at the NFPA 70E second revision meeting 2 weeks ago. We will see how this all works out during the balloting. - Good question!


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 Post subject: Re: IEEE and ARC Flash Assesment
PostPosted: Mon Jul 29, 2019 6:31 am 

Joined: Mon Dec 07, 2015 9:45 am
Posts: 33
Location: Massachusetts
I think you are over-simplifying the requirements of 70E.
130.5(F) Arc Flash PPE. One of the following methods shall be
used for the selection of arc flash PPE:
(1) The incident energy analysis method in accordance with 130.5(G)
(2) The arc flash PPE category method in accordance with 130.7(C)(15)

Under 130.5 (G),
Informational Note: For information on estimating the incident
energy, see Informative Annex D. For information on selection
of arc-rated clothing and other PPE, see Informative Annex H.

Annex D.1 Introduction. Informative Annex D summarizes calculation
methods available for calculating arc flash boundary and
incident energy. It is important to investigate the limitations of
any methods to be used. The limitations of methods summarized
in Informative Annex D are described in Table D.1.

Under Annex D, several methods are recognized as acceptable, Ralph Lee Calculation Method, Doughty Neal Paper, IEEE 1584 Calculation Method, as well as a method for DC calculations. There are additional methods available, especially for voltages above 15kV that are not directly referenced, which are generally accepted in the engineering community for incident energy calculations for voltage levels outside what the directly referenced methods are capable of handling. If you are the engineer performing the study and decide to use a method that is not generally recognized as an acceptable method for determining the PPE to be worn, and an incident occurs in which that level of PPE was found to be insufficient, you may be called on to defend your use of a non-recognized method for PPE selection.

Annex D does state that the "latest" edition of IEEE-1584 should be referenced.

130.7(C)(15) identifies the use of Table 130.7(C)(15)(a) to determine the level of PPE to be worn, this is the Arc-Flash PPE Category method, which is distinctly different than the method used by 130.5 (G) to determine the PPE required. This is an acceptable method and does not require the use of software or engineering supervision.


All this said, what is your purpose in asking the question? Do you have a reason to not want to use IEEE 1584? Are you trying to avoid using the "latest" edition of 1584? Do you have equipment that falls outside the equipment ranges 1584 (either method) is intended to be used for?


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 Post subject: Re: IEEE and ARC Flash Assesment
PostPosted: Mon Aug 05, 2019 9:26 am 
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Joined: Tue Oct 26, 2010 5:00 pm
Posts: 187
Location: Maple Valley, WA.
I agree with SteveA above. I see no reason why you would not want to use IEEE-1584 method/equations unless you have equipment greater than 15 kV which would fall outside of the range of the Standard. See section 4.2 Range of model for more information.

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


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