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| Label for 208V Panels https://brainfiller.com/arcflashforum/viewtopic.php?f=24&t=740 |
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| Author: | PAult [ Thu Oct 29, 2009 9:02 am ] | ||
| Post subject: | Label for 208V Panels | ||
Attached is a label that I am considering putting on all our 208V lighting panels that are fed from a transformer that is less than 125KVA. Since an AF study was not done what should I use for the IE level. Also provide any other comments or problems. Thanks!!
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| Author: | THE CABLE GUY [ Thu Oct 29, 2009 10:13 am ] |
| Post subject: | |
Good simple format. Published IE would be acceptable to me. I use a detailed format and is just a personal choice. I include: Required PPE to be used, Data, Equipment ID, Fed From, IE data info (e.g. IEEE-1584-SKM-Company name doing the study.) Since you will need to review in 5 years I use the date. At this point not sure if this is in regarding to labeling or not, but just in case I have the date on the lable for my info. |
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| Author: | Zog [ Thu Oct 29, 2009 10:24 am ] |
| Post subject: | |
PAult wrote: Attached is a label that I am considering putting on all our 208V lighting panels that are fed from a transformer that is less than 125KVA. Since an
AF study was not done what should I use for the IE level. Also provide any other comments or problems. Thanks!! Since you did not do a study you can't put any Ei on the label but rather the PPE HRC from the task tables. The HRC needs to cover all tasks and doing voltage testing (Among other tasks) require HRC 1. So your label should say HRC 1 unless you do a study to prove the Ei is less. |
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| Author: | PAult [ Thu Oct 29, 2009 11:52 am ] |
| Post subject: | |
Zog wrote: Since you did not do a study you can't put any Ei on the label but rather the PPE HRC from the task tables. The HRC needs to cover all tasks and doing voltage testing (Among other tasks) require HRC 1. So your label should say HRC 1 unless you do a study to prove the Ei is less.
If all our 208V panels are fed from a 75KVA 5.3% imp transformer and the feeder breaker is the same for all of them can I just use a generic worse case label for all of these panels with a 2 second clearing time? SKM reports Cat 3 12.6 Cal/cm2 with option (Report Calculated Values From Equations) Cat 0 1.2 Cal/Cm2 with option (Report as Category 0 if Fed by XFMR < 125 kVA) Sounds like I can use the Cat 0 1.2 Cal/Cm2. I guess this might be considered a "study" 
Thanks |
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| Author: | THE CABLE GUY [ Thu Oct 29, 2009 1:45 pm ] |
| Post subject: | |
I am assuming single phase 208 is that correct? So you do have the upstream results short ciricuit results but the calculations are not valid for a IE calculation at single phase 208v. Zog, I believe this is what PAult is referring to if my assumptions are correct. |
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| Author: | PAult [ Thu Oct 29, 2009 3:13 pm ] |
| Post subject: | |
THE CABLE GUY wrote: I am assuming single phase 208 is that correct?
So you do have the upstream results short ciricuit results but the calculations are not valid for a IE calculation at single phase 208v. Zog, I believe this is what PAult is referring to if my assumptions are correct. No, these are all 480/208V 3-Phase transformers. I was tring to make a generic lablel for all of these since they were all basically the same. Using SKM and having the options set to "Cat 0 if less <= 125KVA" I can find no way to get the IE greater than 1.2 Cal/Cm2 with a clearing time of 2-seconds. Is it safe to say that all 75KVA 480/208V 3-phase 5.3% xfmrs will be CAT 0 with a EI of 1.2 or less? Or am I missing something? It appears the SKM ignores the actual data when the <=125KVA option is selected and uses Cat 0 & 1.2 Cal/cm2 on the secondary of all xfmrs <=125KVA. Is it safe to label these panels with this option selected? This is all on the secondary on the transformer. Thanks |
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| Author: | THE CABLE GUY [ Fri Oct 30, 2009 12:54 pm ] |
| Post subject: | |
Size does matter. What is the upstream or primary protection? I understand you and what the NFPA 70E exception says don't get me wrong. I expect it to change in a few years. But for now your almost on your own with it comes to the study data at the lower voltages. Three phase will still calculate for me and I use this data as a starting point. But the upstream protective device will give some clue as to the actual IE potential. I go another step and look at the real hazard on top of the studys value. Such as I my push the HRC up. Examples are, if the area has a lot of exposed conductors, dark, damp, small work area, and other conditions based on where the task is being conducted. Say you have a 100A FRS vs a 100A LPS fuse upstream the secondary IE values does change. If you have RK1 type fusing upstream you should be at HRC 0 but if different or the SCA is different then what I used you could be as high as a HRC2* according to my model in Easypower. I have no working knowledge of SKM. Hope this helps are I may have confused the matter more. |
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