Author |
Message |
Paul Sedro
|
Post subject: 4 Foot Flash Protection Boundary?? Posted: Wed Jul 04, 2007 8:02 am |
|
Joined: Wed Jul 04, 2007 7:58 am Posts: 3
|
We are in the middle of conducting our first arc flash study. We are getting many calculated flash boundaries of less than the 4 foot distance that NFPA 70E has. Do any of you use the smaller calculated boundaries or do you use the 4 foot distance as the minimum??
b.t.w. Nice Forum!
|
|
Top |
|
 |
JoeB
|
Post subject: Posted: Wed Jul 04, 2007 3:27 pm |
|
Joined: Tue Jul 03, 2007 5:00 pm Posts: 45 Location: Michigan
|
4 Foot Boundary
We started out using the calculated numbers, but then decided it would be more consistant to adopt a standard "minimum" distance of 4 feet. We have a few distances greater than 4 feet but 4 is our minimum.
|
|
Top |
|
 |
Paul Sedro
|
Post subject: Posted: Wed Jul 04, 2007 3:33 pm |
|
Joined: Wed Jul 04, 2007 7:58 am Posts: 3
|
4 Foot Boundary
Joe B - what do you post on the labels? 4 ft?
|
|
Top |
|
 |
JoeB
|
Post subject: Posted: Wed Jul 04, 2007 4:44 pm |
|
Joined: Tue Jul 03, 2007 5:00 pm Posts: 45 Location: Michigan
|
4 Foot Boundary
We use the labels generated by the program so the distance will vary. We use 4 ft. as part of our electrical safety standard.
|
|
Top |
|
 |
kencybart
|
Post subject: Posted: Tue Nov 20, 2007 10:50 am |
|
Joined: Tue Nov 20, 2007 10:41 am Posts: 4
|
Default Arc-Flash Boundary
The default arc-flash boundary for systems 600V and less is 4 feet. However, it depends on the available fault current and clearing time of the overcurrent protective device. According to NFPA 70E, the combination cannot exceed 300,000 Amp-cycles. What this means - is that if the available fault current is 50,000 amps, then the clearing time cannot exceed 6 cycles (100 milliseconds).
Ken Cybart
Littelfuse, Inc.
|
|
Top |
|
 |
|
Page 1 of 1
|
[ 5 posts ] |
|
|
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
|
|