1. Create Your User Profile and Status Updates

    Arc Flash Forum members are invited to create a user profile. Let others know who you are, what you do and even add a picture or avatar of yourself. What are you up to? Let people in the arc flash and electrical safety community know with "status updates"!
  2. Welcome to the All New Arc Flash Forum

    Arc Flash Forum is a community where we help each other learn about arc flash and electrical safety. There is still much to be learned about arc flash, standards, PPE, studies and more and We need your HELP!

    If you have good information about Arc Flash - Post It! If you have a question about Arc Flash - Post It! If you can provide answers to Arc Flash questions - Post it!

    Sign up as a today member! Feel free to link to this site www.arcflashforum.com. Tell your friends. We want to help everyone be safe in the workplace!
  3. Bigger and Better!

    As you have no doubt noticed, the forum has been through quite an upgraded and looks and feels very nice! There are loads of new features and ways in which this site can now be even more useful to the community in learning about Arc Flash and Electrical Safety.

    Create your detailed user profile
    Add a profile photo of yourself
    Like the forum on Facebook
    "Like" users' posts
    Publish your articles in the library
    ...and much, much more!

    Learn More About the New Features Here

Label for 208V Panels

Discussion in 'Arc Flash Labels' started by PAult, Oct 29, 2009.

  1. PAult Member

    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!!

    Attached Files:

  2. THE CABLE GUY Well-Known Member

    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.
  3. Zog Well-Known Member

    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.
  4. PAult Member

    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
  5. THE CABLE GUY Well-Known Member

    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.
  6. PAult Member

    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
  7. THE CABLE GUY Well-Known Member

    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.

Share This Page