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 Post subject: 70E Annex D Update?
PostPosted: Sun Feb 03, 2019 11:13 am 
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Now that IEEE 1584-2018 has been published is Annex D of NFPA 70E going to get updated as well? Granted there have been times where Annex D and IEEE 1584 were not exactly in lock step with each other (need I mentioned NFPA 70E-2004?) but they have been very close if not identical over the last several years, and paying less than $100 vs. paying several hundred is quite a significant difference. But in the past a few pages could also be dedicated to each analysis method. This time I'm not sure IEEE 1584-2018 can be condensed down to a page or two.

If not, does Annex D become simply a list of references to other standards eschewing detailed calculations? If Annex D continues to be a summary and swallows IEEE 1584-2018 doesn't this cut into the high price tag for IEEE 1584-2018? At what point does it cross the fair use line, especially given that a lot of the ancillary information contained in IEEE 1584-2002 was eliminated or relegated to annexes in this edition?


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 Post subject: Re: 70E Annex D Update?
PostPosted: Mon Feb 04, 2019 6:59 am 
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The 2018 Edition of IEEE 1584 will likely NOT be included in Annex D of NFPA 70E for some of the reasons you cited. The vast number of significantly more complex equations, multiple calculations with iteration requirements, many tables of "k" values that need properly selected, determination of the electrode configuration VCB, VCCB, HCB, VOA and HOA, enclosure size corrections, etc. etc. have made a condensed version almost impossible.

Will the existing 2002 edition remain in NFPA 70E? - Doubtful - I submitted the public input for deletion to avoid syncing issues with the 2018 edition that could lead to quite a bit of confusion.


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 Post subject: Re: 70E Annex D Update?
PostPosted: Mon Feb 04, 2019 10:03 am 

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Jim, your response points out a hole in my understanding of AF. What ties IEEE 1584 calcs to 70E currently?


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 Post subject: Re: 70E Annex D Update?
PostPosted: Mon Feb 04, 2019 1:00 pm 
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RobertDrew wrote:
Jim, your response points out a hole in my understanding of AF. What ties IEEE 1584 calcs to 70E currently?


Great question. Although there is no direct mandate to use IEEE 1584 as part of NFPA 70E requirements (NFPA 70E PPE Category Tables are another option), it is the main standard used globally to calculate the incident energy/working distance and arc flash boundary.

NFPA 70E 130.5 Defines when and how to perform an arc flash risk assessment. This may include an incident energy analysis and arc flash boundary (PPE Category Tables are the other option)

130.5(D) Incident Energy Analysis and 130.5(G) Arc Flash Boundary both reference Annex D. The 2002 edition of IEEE 1584 has been in Annex D since the 2004 Edition of NFPA 70E.

The results of the arc flash calculations may also be listed on an energized electrical work permit (NFPA 70E 130.2(B)(2)) as well as equipment (arc flash) labels (NFPA 70E 130.5(H)).

IEEE 1584 is referenced in Table 130.5(C) Estimate of the Likelihood of Occurrence of an Arc Flash Incident for ac and dc Systems Informational Note No. 6.

So, IEEE 1584 and NFPA 70E are somewhat intertwined when it comes to electrical safety.


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 Post subject: Re: 70E Annex D Update?
PostPosted: Thu Feb 14, 2019 1:04 pm 
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Jim just read your public input so i see how you voted! I'm kind of torn on it. I'd argue that given the dearth of references to IEEE 1584-2002 as summarized in NFPA 70E in a large number of research papers it is clear that even though in this context 70E is a secondary reference, it is also vastly more accessible to a much wider audience. So I have strong feelings about leaving it in NFPA 70E but I also realize the practical issue with doing this even without getting into the old NFPA/IEEE turf battles.

I'd also disagree that 70E and 1584 go hand-in-hand. OSHA 1910.269 definitely gives broad endorsement and stops just short of outright mandating ArcPro with their "too hot/too cold/just right" argument supporting ArcPro over Duke Heat Flux and Lee. NESC is quite the opposite extreme even going so far as to use ArcPro in tables of calculated values for incident energy purposes but never mentions the software by name or gives references to it. 70E in contrast talks about using the tables within the standard OR an engineered approach and gives references to several engineerred approaches in Annex D but never recommends one over the other or gives any sort of guidance when to use one versus another. By this logic it almost makes sense to just use Lee since it's the simplest if we went by 70E in isolation for determining the method to use.

Also at one time 70E had some kind of "lower cutoff" or generic arc flash boundary value including effectively adopting the IEEE 1584 "<125 kVA transformer" rule but this was later removed and the justification was that essentially the clause is specific to one method. Similarly references to the tables in NESC were deleted. This is the only case I can think of where any particular method is denegrated but the argument is that 70E does not cover power distribution and the tables are already in the NESC standard.

Taken together NFPA 70E takes an approach of being helpful in providing guidance but not to the point of prejudicing the reader, unlike OSHA 1910.269 or NESC.


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