It is currently Wed May 27, 2020 9:39 pm



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: Table method for 208Y/120V panelboards
PostPosted: Sun Oct 20, 2019 12:13 pm 

Joined: Sun Oct 20, 2019 12:04 pm
Posts: 2
Is it reasonable to use the Calculated Incident Energy method for all 480Y/277V equipment in a facility but to revert to the table method for 208Y/120V panelboards being fed by 112kVA transformers or smaller. i.e. the first category in the Table applicable to 240V or less, 25kAIC or less with clearing time of 2 cycles

I mean, is it not true that all 400A and less, 10kAIC breakers (which is all you need down stream of this range of dry types) trip in 1.5 cycles AND that the available down stream of a standard 112kVA or smaller will always be less than 10kAIC.

The table gives you a PPE of 1 for this set of circumstances. Is it not always a safe bet that such a panel, were you to calculated the incident energy would never result in a requirement for PPE higher than level 1?


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Table method for 208Y/120V panelboards
PostPosted: Mon Oct 21, 2019 5:37 am 
Plasma Level
User avatar

Joined: Wed May 07, 2008 5:00 pm
Posts: 819
Location: Rutland, VT
It appears that you are referring to what was commonly referred to as the 112.5kVA and less exemption in IEEE 1584-2002. This exemption is no longer valid as it was superseded in IEEE 1584-2018. IEEE 1584-2018 states that arcs are less sustainable for 2000A or less and 240V and less. So you need to calculate the fault current to determine the likelyhood of an arc so you might as well determine the incident energy at that point.

_________________
Barry Donovan, P.E.
www.workplacesafetysolutions.com


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Table method for 208Y/120V panelboards
PostPosted: Mon Oct 21, 2019 6:03 am 
Sparks Level

Joined: Tue Jul 01, 2014 8:40 am
Posts: 89
Hello, if you are already conducting the incident energy analysis for the 480 Volt system, my advice would be to carry on down your 208 systems. The IEEE 1584 standard has been revised to the 2018 edition and the less than 240 Volt and 125 KVA no longer applies. I hope that this is of some help


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: Table method for 208Y/120V panelboards
PostPosted: Mon Oct 28, 2019 7:56 am 
Sparks Level
User avatar

Joined: Tue Oct 26, 2010 5:00 pm
Posts: 186
Location: Maple Valley, WA.
Some of the software programs, such as SKM PowerTools for Windows, has an option to use the "IEEE 1584-2018 arcs are less sustainable for 2000A or less and 240V and less." exception. Using this exception will reduce some of the data collection time and effort for these lower energy locations.

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


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 4 posts ] 

All times are UTC - 7 hours


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

Jump to:  
cron
© 2019 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883