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Do you list both the calculated incident energy AND the category?
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PostPosted: Sun Nov 01, 2009 7:41 am 
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HELP!

130.3(C) Equipment Labeling Equipment shall be field marked with a label containing the available incident energy or required level of PPE.

Can anyone clarify why the "or" was added to this article? I understand the "OR" means you can only have incident energy OR level of PPE a.ka. hazard risk category on the label? I am at a loss as to why this was added.

I believe it is pretty obvious to most people that you can not mix Table 130.7(C)(9) and calculations. That issue seems to have been addressed a few times in this forum. However I can not figure out why if HRC 2 is good for 8 cal/cm^2 as in Table 130.7(C)(11) you can not then say if I need 8 cal/cm^2 I can not call it HRC 2.

I have heard from a few people about the "OR" and they all say the same thing,

1) NFPA 70E says one OR the other, or else they say,
2) You can not mix tables and calculations

No one can really explain WHY.

It almost reminds me of "Just Because I said so!" Most everyone I know still lists both because it is easier for people to use and no one seems to have a good explaination of "OR".

NO ONE seems to have been able to provide me a technically sound reason and can not seem to explain why you can not call 8 cal^cm2 category 2 which now makes me worry that someone made a mistake by adding "OR".

Does ANYONE have an explaination of why it is Incident Energy OR HRC other than "it is in 70E" or "you can't mix tables and calculations" because neither one of those explanations is truly a technical reason.

For now we will continue to list both - the software posts both - I guess they know it makes more sense also.


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PostPosted: Fri Feb 12, 2010 3:46 pm 
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Update on incident energy AND categories

Here is an update on the debate about listing both incident energy and PPE categories on labels. You CAN NOT mix calculations with HRC / Hazard Risk Categories of Table 130.7(C)(9) - that part is well known and I believe most everyone is in agreement. However there is still a contention (and language in 70E to support it) that you can not take calculations and lump them into any form of a category - period! (even if you do not call it HRC). As an example, you can not list 7.3 calories / cm^2 and category 2 PPE on the same label.

I have yet to hear of a logical reason from anyone on why this is. All I hear is "can't mix tables and calculations" or "NFPA 70E does not allow it" or assorted double talk. It seems someone over reached "not mixing" Table 130.7(C)(9) with calculations to inlcude all three tables (C)(9), (C)(10) and (C)(11).

I have talked with many people that were involved with the original (C)(11) table and they agree it was not the original intent to lump all three in the "don't mix rule" when they were introduced.

I also went back to the ROC for the 2009 edition - the only discussion seemed to focus on not wanting to place a burden on anyone for requiring additional information on the label. No mention of either/or.

I spoke with the past Chairman of NFPA 70E and he said that it was not originally intended to make Table 130.7(C)(11) an either / or with incident energy calculations. He believed it was acceptable to correlate incident energy with categories. However when talking with NFPA people they said he is no longer associated with NFPA 70E and to discount his view on it since it is no longer "offical".

I spoke with one of the people that actually developed Table 130.7(C)(11), he also concurred making it an either/or for this table does not make sense. The response? The originator of the table works for a PPE company. Gee, who would know this issue better!

I submitted a proposal for the next edition of NFPA 70E to allow once again, correlating incident energy to PPE categories (not HRCs / Hazard Risk Categories). As support, I referenced IEEE 1584.

IEEE 1584 used this exact method of correlating incident energy to categories / levels in the development of Cf the "calculation factor". Article 9.11.3 in IEEE 1584 discusses how PPE was lumped into levels (i.e. categories) of 4, 8, 25, 40 and 100 calories per square centimeter and the equations were checked to see if they produce the same level of PPE. For voltages < 1 kV a calculation factor of 1.5 was developed to achieve the desired PPE level (category). Except for the 100 cal number, these are the same levels that NFPA 70E now says you can't use to correlate incident energy.

Their response... There was a motion made at the IEEE 1584 meeting last week from an NFPA 70E person to purge the IEEE 1584 standard of this language. It was resoundly shot down but there was mention that it will be brought up later.

When the facts don't support the desired conclusion, change the facts!

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PostPosted: Fri Feb 12, 2010 6:27 pm 
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Or when the people coming up with the conclusions don't address the facts, then just maybe the whole body is in need of a major overhaul......like so many of all of the political groups these days.


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PostPosted: Fri Feb 12, 2010 6:38 pm 
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I find posting both IE and PPE have merit. Most large companies are using the analysis method so they have an IE value. But they equip their personnel via a PPE group strategy, typically 1,2,4 or 1,4 or 2,4 PPE Level. There is also less confusion in just seeing one of four numbers, than an infinite array.

If it becomes prohibitive, then I would just 'round up' to the next IE value of PPE. 2.3cals/cm2 become 4.0, and 7.6 cals/cmw becomes 8.0 cal/cm2. There is not harm in the label indicating a higher than calculated value. Although you want to keep the actual values on record somewhere to evaluate future changes to the system.


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PostPosted: Fri Feb 12, 2010 7:24 pm 
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No problem with that....if I calc a 6 I tell them to do the 8 thing...seems pretty simple....As I said before, this whole process seems to have been removed from the reality and seems to be more of a power struggle than fact! We gotta have some relief.

You have got to have a brain disorder to have a problem with posting the IE as well as the minimum PPE....or with just posting minimum PPE after you have done the calcs.


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PostPosted: Sat Feb 13, 2010 9:06 am 
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I was thinking more about this last night. Too bad I did not think of it earlier because it is an easy fix. I already submitted a proposal to change 130.3(C) Equipment Labeling but I realized there is a better way to handle it.

Since I believe the problem is that Table 130.7(C)(11) states "Hazard/Risk Category" instead of just "Category". The concept is still the same thing used in the development of IEEE 1584 as I mentioned in my last post.

Here is what I think would be a good solution except the deadline has past for new 70E submittals.


130.3(C) Equipment Labeling. Equipment shall be field marked with a label containing the available incident energy or Hazard / Risk cateory of PPE.


That makes more sense. Again I believe everyone agrees you can not mix HRC and incident energy and this would just state you can only list either the HRC OR incident energy on the label. That should have been the intent all along.

I believe this type of language would NOT prohibit listing user generated PPE categores as long as it is not called "HRC". Perhaps I can bring this up when it is the comment period for the 70E revision cycle.

What does everyone think?

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PostPosted: Sat Feb 13, 2010 10:35 am 
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Sounds like common sense to me...it is insane that they did not figure this out yet. Yes I think most will agree that you can't mix the calcs and tables, but this has nothing to do with that concept. IMO those that argue differently are only supporting the fact that they should not have been a part of the process to begin with.


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PostPosted: Mon Feb 22, 2010 9:28 pm 
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NFPA 70E label requirements and arc flash studies

Some folks are equating HRC with the level of PPE required on the label. The level of PPE as intended in NFPA 70E refers to the calorie rating of the PPE, not the HRC. See the Handbook. There is a lot of confusion about how the HRC relates to the Arc Flash Hazard Analysis. If the label says the incident energy is 10 calories/ cm2 and also says it is a HRC 3 there is a dilemma. If there is an incident and the employee is properly dressed in 12 calorie clothing the protection would be adequate as far as calories are concerned, and 25 calorie clothing would not be required. The HRC ratings provide some good information about the type of PPE such as face shields, hoods, etc. beyond the calorie rating. HRC tables are task related and different tasks require different PPE even though the incident energy may be the same. Also, the tables only apply for the bolted fault current and clearing time.


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PostPosted: Tue Feb 23, 2010 9:33 am 
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Why would you say the employee needs to be properly dressed in 12 cal clothing when the calcs indicated 10 cal? 10 cal or greater should be adequate.....so either 10 cal or HRC3, or anything in between is sufficient.


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PostPosted: Tue Feb 23, 2010 7:24 pm 
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But isn't this just a carryover from the old edition. The label is saying 10 cals, and PPE 3, because the older clothing methods would have jumped from 8 to 25 cals. Maybe the label should say 10cal 'OR' PPE3.

I understand the problem, but not sure if I would agree that the liability is that high. You would verify that 10cal was calculated, labelled, and the employee was wearing 10 cal. So all is fine. But 'OR' would be the correct designation.


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PostPosted: Sat Feb 27, 2010 5:04 pm 
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The NFPA tables lists all of that nice ancillary PPE, other than FR clothing, like earplugs and hard hat.

What ancillary equipment is required to protect a worker against 8.1cal/cm²? Is it okay to have a 9cal/cm² faceshield and then tell the workers to make sure they always are facing towards the arc, rather than having them use a balaclava?

I find it much easier to enforce a requirement of "use PPE per nationally recognized table XYZ" instead of having to create, and defend, my own detailed list.


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PostPosted: Fri Apr 16, 2010 9:08 am 
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incident energy vs. HRC for PPE selection

Hi everyone,

First off, thanks for the great comments and discussions in this thread. This seems to be a question that some clients of mine have been asking recently as well.

I am having a difficult time with understanding what PPE should be worn for a given calculated IE. For argument sake, lets say I have a 600V class MCC with IE = 0.7 cal/cm^2 at 18" working distance. Well, from table 130.7(C)(9) we see that there are many tasks that can be performed at the 600V MCC (IR scan, switch operation with covers on or covers off etc.). How does my calculated value of 0.7 cal/cm^2 fit into a task matrix? working on energized conductors is an HRC 2* task by the Table, but if the calculated IE correseponds to HRC 0 how should this HRC 2* task be treated under the IE calculated?

Let's say I have an MCC with calculated IE of 30 cal/cm^2 at 18" working distance. Now, the "corresponding" HRC would be HRC 4, so should all jobs in Table 130.7(C)(9) for the 600V MCC then be considered HRC 4?

I am under the assumption that Table 130.7(C)(9) (or CSA Z462-08 Table 4) should be used as a minimum requirement regardless of IE calculated; if IE is greater than the HRC value listed in the Table, then the corresponding higher rated PPE should be worn in place of the table's values.

This is a question that has been popping up more and more frequently over the past few months. Honestly, if it is required that the PPE be worn as set out in Table 130.7(C)(9), regardless of calculated IE, then what is the point of the analysis? Anyone have any comments on this?


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PostPosted: Fri Apr 16, 2010 9:32 am 
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We use both. A good share of the equipment calculates under 1.2 but we've decided to make the min. PPE level level 1 to help simplify. Those that work on the equipment are all furnished level one to be worn at all times. The cal/ is more for refrence.


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PostPosted: Fri Apr 16, 2010 9:49 am 
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tricard wrote:
I am under the assumption that Table 130.7(C)(9) (or CSA Z462-08 Table 4) should be used as a minimum requirement regardless of IE calculated; if IE is greater than the HRC value listed in the Table, then the corresponding higher rated PPE should be worn in place of the table's values.


Once you have calculated the incident energy, you should tear Table 130.7(C)(9) out of your copy of 70E. :eek:

The table is based entirely on assumptions, your calulations are based on facts and engineering judgment.


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PostPosted: Fri Apr 16, 2010 10:33 am 
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JBD wrote:
Once you have calculated the incident energy, you should tear Table 130.7(C)(9) out of your copy of 70E. :eek:

The table is based entirely on assumptions, your calulations are based on facts and engineering judgment.


Alright, so let's do an example (once again assuming IE of 0.7cal/cm2 for a given MCC): Task from Table 130.7(C)(9):
"Insertion or removal of individual starter buckets from MCC"
HRC: 4
Rubber Gloves: N
Insulated Hand Tools: N

so, since I calculated IE of 0.7cal/cm can a qualified person insert and remove a bucket from this MCC wearing PPE rated 0.7cal/cm (e.g. cotton clothing)?

I agree with you that the calculated values are based on facts and judgment; my judgment is telling me that they should at the very least wear 8 cal/cm shirt and pant/coveralls and probably a face shield as well. I think many consulting companies performing the arc flash analyses are not involved in implementing safety standards for the site that is being analyzed (and nor do I think they necessarily should) but this seems to be where a large communication disconnect exists...


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PostPosted: Fri Apr 16, 2010 11:40 am 
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If you are following the calculated method, then your only obligation is to meet the level 0.7cal. Obviously, with a IE this low, the risk is low, which is why you can work in Cat 0. Under the calculated method, all tasks are treated the same.


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PostPosted: Sat Apr 17, 2010 7:59 am 
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tricard wrote:
.. my judgment is telling me that they should at the very least wear 8 cal/cm shirt and pant/coveralls and probably a face shield as well.


There is nothing wrong with requiring more PPE than the minimum based on the calculated energy. My company uses a 2-level program, standard issued PPE is HRC 2 and HRC4.

My point is that you do not need to, and should not, use the 'task tables' to make your decision.


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PostPosted: Fri Apr 23, 2010 3:25 pm 
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haze10 wrote:
If you are following the calculated method, then your only obligation is to meet the level 0.7cal. Obviously, with a IE this low, the risk is low, which is why you can work in Cat 0. Under the calculated method, all tasks are treated the same.


you mean the hazard is low, correct?


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PostPosted: Fri Apr 30, 2010 11:13 am 
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In short, my response to the poll is "YES", I print both the IE and a HRC that exactly correlates with those in the NFPA table.

This issue came to my attention a year or so ago when the point that you mention was brought up during a NFPA 70E course presented by the NFPA. I explained my situation - basically that there are thousands and thousands of labels with the "incorrect" combination of IE and HRC on the equipment in my plants. When I asked how HE would handle the situation, the instructor said he wouldn't bother to change labels. My response has been to change our documentation. Our organization has four hazard category levels that describe the hazard class. Those levels "just happen" to exactly correlate with the NFPA tables.

This really seems like a non-issue with respect to both safety and liability and I don't understand why the IEEE and NFPA even take a position on it.


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PostPosted: Mon May 10, 2010 1:25 pm 
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An update, A few different people (myself included) submitted proposals the correct this. No "offical" final word yet, it will be quite some time but the rumor from a few of my sources as well as a summary from NFPA is this might finally get straightened out.

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