Important Survey - Correlating Incident Energy to HRC

You can't be serious? It is hard enough for people to figure this out. Taking away the ability to narrow it down to 1 of 4 categories could cause more confusion than we already have. I hope the committee people can see what this would do.

It is hard enough to train people what the levels mean so our labeling standard has only the incident energy level, working distance, analysis date and equipment ID. The reasoning behind only having incident energy level is so a worker can look at the tag on their clothes and make sure the rating higher than the hazard. A CSA sanctioned Arc Flash instructor advised that the clothing always be 1.2 cal higher than the incident energy level to guarantee a safety margin.
CSA Z462-08 also has an "OR" standard for labeling.

I have to answer "yes" for the purpose of the survey, but would like to note that I am against this. It will be coming up for discussion at my site soon! (As you know, Jim, my supervisor is on the 70E committee, whereas I am a 1584 follower. This should be a fun discussion.)

I do the calculations, and would like to get away from all of the NFPA tables. We do recommend that people wear clothing that is greater than the calculated energy level as posted. Past this point, I have no use for the tables. We also list the required PPE to be worn, including hood, faceshield, etc. necessary to protect up to the calculated energy level.

As for the "debate" I don't see anything that would restrict using both. I just don't like the NFPA tables and Hazard/Risk Categories. After the calculation is performed there is no need for them. You protect up to the calculated energy level.

I guess if we can no longer use Table 11 for PPE catagores based on incident energy, we will just have to make up our own system otherwise this will be very complicated and we want to keep it simple for our crews.

It is nice to have them use Category 2 which we all know is for 8 cal/cm2 instead of spelling out the exact numbers which vary all over the place.

In lieu of Table 11, perhaps we can categorize our calculated values another way. Maybe we can set up our own system to help simplify the PPE selection process for our people.

Category A = 0-1.2 cal/cm2
category B = 1.2-4 cal/cm2
Category C = 4-8 cal/cm2
Category D = 8-25 cal/cm2
Category E = 25-40 cal/cm2

This is just one idea we have to help cut down on potentially hazardous mistakes when all we have are numbers floating around.

.... or maybe another idea is instead of using A, B, C, D, E for our categories, we could use another designation such as 0, 1, 2, 3 and 4!

Actually, TVA has done just that. They set up different categories (I, II, III, etc). These categories were set up to correspond to incident energy levels that matched readily available PPE ATPV ratings at the time (~2002). This makes it easier to select PPE to match the category.

So in the end what is the difference between:

Category A, B, C etc.
HRC 1, 2, 3, etc.
Category I, II, II etc.

In the end, call it what you want, a Duck is still a Duck.

Many people still need to categorize the levels of PPE and the levels in NFPA 70E Table 11 are those that most people seem to use.

Saying you can not use Table 11 "backwards" just causes people to use a different designation for the same thing like the examples here in this post of A, B, C and I, II, III.

I guess this might prove that who ever decided you can not use Table 11 backwards needs to think this through a little better.

Annex B of CSA Z462-08, at figure B.1, shows both.

15.3" AFB
1.1 cal/cm^2 at 18"
#0 at 18"

That figure is about changing settings on a CB to lower the IE by having the arc current in the INST region of the CB.

Better yet: Annex Q of CSA Z462-08 has sample arc flash and shock warning labels. Figure Q.2 and Q.3 both list both IE (with the working distance used to calculate it) and the HRC.

So my take is at least in Canada, we can do it

Jim,
I hope you can help get this resolved since I know we, and obviously most other people do mix calculations and categories. I know you can not mix the task tables and calculations but that does not seem to be what this is about.

It seems like the "new?" interpretation is going to cause a lot of confusion and trouble to a situation that is already confusing enough. Good Luck!

I can see a point in separating the calculated IE and the HRC, based on the standard (CSA-Z462 numbering as that's what I'm more used to, but I can dig in NFPA 70E if deemed necessary):

Clause 4.3.3.3.3 says to use 4.3.7.3.9 to 4.3.7.3.11 if PPE selection is based on HRC rather than IE.
Then, Table 4 is referenced in 4.3.7.3.9 for HRC determination based on the tasks of table 4 (and associated footnotes). Table 5 is then referenced in 4.3.7.3.10 to determine the proper PPE required by the HRC, and Table 6 is referenced in 4.3.7.3.11 for the characteristics of PPE for each HRC.
Table 4 is referenced elsewhere in the standard, but for its other columns: are insulating rubber gloves required, and are insulated and insulating hand tools required.

So, based on that, I can see a point about not using both Table 6 and calculated IE (because of the choice of 4.3.3.3.2 rather than 4.3.3.3.3), because the HRC are not supposed to exist outside 4.3.3.3.3.

But, PPE manufacturers (and resellers) often advertise their gear using both HRC and ATPV (or EBT). So it's kinda normal to label things using both, as the worker can then easily compare what he wears (or should get at his locker) with what's required for his task.

321Liftoff

Hope this and many other issues get resolved, regarding the NFPA 70E '09 criterion and their interpretations. If you want to make a difference, consider the following:

You can view the 2009 and 2004 editions as well as the timeline for approval of the 2011 document at: http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=70E

The NFPA 70E 2011 open proposal period ends Jan 5, 2010.

NOTE: For those interested, I sent T2G the .pdf form for Change Proposal - submits.

The important thing is to keep the program simple. I know that’s hard for engineers. (I am the one always going overboard) The more “or, if's and buts’” gets confusing to people trying to make sense out of what to do.

I see no reason to be able to tell the worker what the cal's of heat and proper minimal PPE is on the label. Your not limiting the workers ability to wear CAT 4 if they wish.

The label is a guide for those who need help understanding the danger. The energized work permit should be the guide for all to follow. The label is not giving permission for the person to work hot. This understanding should be part of a groups training.

Sorry to ramble. Good Luck Mr. Brainfiller we are all looking for some simple understanding of a complex issue of what to do.

yes but moving to no

Our next round of labels will just have the incident energy of the equipment. We will have a stand alone document that will then releate you from the energy rating to the actual PPE needed. That way if somebody decides to change what PPE is needed for 12 cal, we don't change all of the labels just our cross referance chart. Does this sound resonable?

And you just had to confuse me further didn't you Jim! I can't even spell Fugeeta! What's up with that?

Thanks
________
Laguna Heights Condo

Seems like the CSA Z462 committee is gearing up to officially separate them.

With 70E and Z462 currently technically harmonized, I don't know how this will develop in the future. I sure hope they stay close to each other, as this will be easier for everybody in Canada.

According to Mr. Becker from another question it appears to say; "you cannot put HRC values on the detailed label" after the arc flash analysis.
Glade to see not only the US has confusion.