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| 4 Foot Flash Protection Boundary?? https://brainfiller.com/arcflashforum/viewtopic.php?f=4&t=4 |
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| Author: | Paul Sedro [ Wed Jul 04, 2007 8:02 am ] |
| Post subject: | 4 Foot Flash Protection Boundary?? |
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! |
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| Author: | JoeB [ Wed Jul 04, 2007 3:27 pm ] |
| Post subject: | |
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. |
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| Author: | Paul Sedro [ Wed Jul 04, 2007 3:33 pm ] |
| Post subject: | |
4 Foot Boundary Joe B - what do you post on the labels? 4 ft? |
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| Author: | JoeB [ Wed Jul 04, 2007 4:44 pm ] |
| Post subject: | |
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. |
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| Author: | kencybart [ Tue Nov 20, 2007 10:50 am ] |
| Post subject: | |
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. |
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