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 Post subject: 70E-2004 Cal/cm Question
PostPosted: Fri Sep 05, 2008 7:55 am 
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I've recently started using Etap 6.0 for arc flash calulations. I've noticed it calculated a Cat 0 for 1.96 cal/cm. IEEE 1584-2002 lists 1.2 to 4 cal/cm as cat 1. I contacted Etap and was told 70E-2004, table 130.7(c)(11) states anything below 2 cal/cm is classified as cat 0. I have the 70E-2004 book and can't find anything in table 130.7(c)(11) that states that. Am I missing something? :confused:


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PostPosted: Fri Sep 05, 2008 1:13 pm 
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This is listed as an exception at the bottom of page 28 (70E-28). I believe this will not be shown in the 2009 but you may want to double check that.


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PostPosted: Fri Sep 05, 2008 9:17 pm 
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It is not uncommon for sites to have a minimum PPE of Level 1. If that is the case, then I would recommend overriding whatever the actual cal calc comes out to be, and just putting in 4.0 and Level 1. When we discuss this, the consensus is that having the proper level of PPE protection required is more important, and less confusing, than having the actual IE level cited and trying to enforce policy contrary to the label.


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PostPosted: Sat Sep 06, 2008 6:00 am 
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Homerjs78 wrote:
This is listed as an exception at the bottom of page 28 (70E-28). I believe this will not be shown in the 2009 but you may want to double check that.

I believe the 2 calorie exception assumed non melting fabric offered some protection of the skin (unless it ignites :eek: ) The 1.2 calorie second degree burn threshold is at the skin surface. This did add a bit of confusion i.e. do you wear FR clothing above incident energy levels of 1.2 or 2.0? The confusion is going away in 2009. This 2.0 calorie exception has been deleted.

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PostPosted: Sat Sep 06, 2008 6:36 pm 
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NFPA must think before they act.

This is another example of the NFPA not thinking before they act. I am not referring to the fact that they are dropping the 2.0 rating, or that they originally had a 2.0 - I am referring to the damage and cost decisions like this made in the field.

I have been through 3 sites already that were using some of the well known computer programs for arc fault analysis. Software was great, it even printed a nice field label. But guess what, it followed NFPA and any IE less than 2.0 got a PPE Level of 0. Now that Level 0 is going away, we get to spend millions in reprogramming the software as well as all those factories that rushed to comply - get to do it all again. Yeh, there policy could be Level 1 min but if the Label says Level 0 and there is an accident guess where the fault lies - it won't be with the NFPA that we can be sure.

These are critical decisions, as was the condition values to use the 4 foot arc flash boundary rule, ie 3000 amp cycles. Now we can change those labels also. THE NFPA should NOT issue technical condition statements that have to be later changed, especially without statistical accident proof that its required. This shoud NOT be so haphazardly administered.

I was fortunate that in my Arc Flash studies I have always convinced management to elect a min of 4.0 cals and Level 1. My calculator has a min cal that can be input to print the label, so they read 4.0 cal and Level 1, even if the actual calc was 1.0 cals and Level 0. the guideline is about protecting the worker with the 'minimum PPE' not about having labels that match the equations.


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PostPosted: Mon Sep 08, 2008 10:27 am 
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I pressed Etap for an answer on the 2 cal/cm or less = cat 0. After several emails that was defered to a half dozen of their PE's, I finally got Etap to say they use 130.7(C)(14)(b) as the basis for their 2 cal/cm = cat 0. Reading the section it refers to flammability based on ASTM F 1959 standard. It reads "2 cal/cm or less is acceptable for either cat 0 or cat 1 if the non-flammable material meets ASTM F 1959". Ok... So, depending on the readers preference, 2 cal/cm or less can be determined as HRC 1 or 0. Talk about confusion :eek: I agree with Haze.... a worker could care less if it's 1.9 cal/cm or 3.9 cal/cm or FPB of 35" or 48", the important thing is it cat 1 PPE. Too often managment gets hung up on nit picking numbers. I make labels that simply say, as example: Arc Flash Category 1, Cal/cm: 1.2 to 4, FPB: 48", and list PPE. As long as my arc flash FPB calculations don't go over 48", if so I make individule labels for that equipment.


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PostPosted: Mon Sep 08, 2008 10:28 am 
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I pressed Etap for an answer on the 2 cal/cm or less = cat 0. After several emails that was defered to a half dozen of their PE's, I finally got Etap to say they use 130.7(C)(14)(b) as the basis for their 2 cal/cm = cat 0. Reading the section it refers to flammability based on ASTM F 1959 standard. It reads "2 cal/cm or less is acceptable for either cat 0 or cat 1 if the non-flammable material meets ASTM F 1959". Ok... So, depending on the readers preference, 2 cal/cm or less can be determined as HRC 1 or 0. Talk about confusion :eek: I agree with Haze.... a electrical worker could care less if it's 1.9 cal/cm or 3.9 cal/cm or FPB of 35" or 48", the important thing is it cat 1 PPE. Too often managment gets hung up on nit picking numbers.


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