It is currently Wed Dec 07, 2022 4:25 am

Have you seen reports/labels with an incident energy greater than 200 cal/cm2?
 Yes No
You may select 1 option

View results
Author Message

 Post subject: Incident Energy Greater than 200 cal/cm2Posted: Sun Nov 07, 2021 6:01 pm
 Plasma Level

Joined: Mon Sep 17, 2007 5:00 pm
Posts: 1683
Location: Scottsdale, Arizona
Extremely large incident energy values are almost always due to a long arc duration/protective device clearing time. The 2 second cut off can help reduce the values but it can still be well above 100 cal/cm2. Now and then I still run into a label that is very extreme. This weekâs question is simple:

Have you seen reports/labels with an incident energy greater than 200 cal/cm2?
Yes
No

Top

 Post subject: Re: Incident Energy Greater than 200 cal/cm2Posted: Mon Nov 08, 2021 9:46 am
 Sparks Level

Joined: Tue Oct 26, 2010 5:00 pm
Posts: 201
Location: Maple Valley, WA.
Sometimes this is a result of a location that does not meet the IEEE 1584 parameters. For example, if the voltage is above 15 kV, the enclosure is too large or small then this does not meet the IEEE 1584 parameters. At these locations, many of the software programs will revert to using the Lee Equations. The Lee Equations typically will produce extremely conservative high energy and arc flash boundary values.

Above 15 kV, different methods should be used to estimate the arc flash energy and boundaries.

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

Top

 Post subject: Re: Incident Energy Greater than 200 cal/cm2Posted: Mon Nov 08, 2021 3:55 pm

Joined: Fri Sep 24, 2021 7:17 am
Posts: 28
I sure did. I have a picture of label that is showing 104311.9 cal/cm^2, analysis date 12/2017.......40kA of available fault current, 480VAC system....arc flash boundary was listed at 3366'-8"

Clearly they weren't modeling correctly. I wonder if they ever thought about the degree of precision. I'm guessing they never looked at it. The printed the label and slapped it on.

Top

 Post subject: Re: Incident Energy Greater than 200 cal/cm2Posted: Tue Nov 09, 2021 12:09 pm

Joined: Mon Mar 09, 2020 9:27 am
Posts: 30
I see them semi regularly at the line side of the main breaker, directly off the utility transformer. I believe its because the utility fuse is not modeled.

Top

 Display posts from previous: All posts1 day7 days2 weeks1 month3 months6 months1 year Sort by AuthorPost timeSubject AscendingDescending
 Page 1 of 1 [ 4 posts ]

 All times are UTC - 7 hours

 You can post new topics in this forumYou can reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum

 Jump to:  Select a forum ------------------ Forum Library / Articles The Lounge    Question of the Week - What Do You Think?    Arcflashforum.com Feedback and Announcements    Off Topic Discussions    News in Electrical Safety Arc Flash and Electrical Safety    General Discussion    Electrical Safety Practices    Equipment to Reduce Arc Flash Dangers    Personal Protective Equipment (PPE) Arc Flash Studies    General Discussion    Arc Flash Labels    Software for Arc Flash Studies    System Modeling and Calculations    NEW! Electrode Configuration Library â 2018 IEEE 1584 Codes and Standards    CSA Z462 Workplace Electrical Safety    EAWR Electricity at Work Regulations, HSE - Europe    OSHA CFR Title 29    IEEE 1584 - Arc-Flash Hazard Calculations    NFPA 70 - National Electrical Code - NEC (R)    NESC - ANSI C2 - National Electrical Safety Code    NFPA 70E - Electrical Safety in the Workplace    2015 NFPA 70E Share It Here    Arc Flash Photos    Your Stories    What's Wrong Here? by Joe Tedesco
© 2022 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883