The 2015 Edition of NFPA 70E Article 130.5(D)(3) permits listing the minimum arc rating of the clothing on the arc flash label as one of the acceptable methods for indicating the required arc flash protection. However with just an arc rating listed and no associated working distance, how would the worker know how close they could get to the equipment/source of a prospective arc flash?

As an example, Clothing and PPE with an arc rating of 8 cal/cm2 might be acceptable at 18 inches (just an example of distance) but it may not be suitable at 12 inches. This week's question:

When only listing the arc rating on the label, should a working distance also be provided?
Yes
No
Not Sure

This really doesn't make any sense at all UNLESS it is not one of the standard working distances.

For example open air cutout switches are typically mounted at least 12+ feet off the ground as are most other pole-mounted gear and it is generally only accessible via a hot stick. So the working distance should rightly be calculated at "hot stick" distance for open air equipment rather than the table standard of 18".

There is also the discrepancy that OSHA chose to use 15" as the standard for 1910.269 vs. the IEEE standard of 18" for most equipment when it comes to open air situations.

If we go down this road too far it quickly becomes obvious that working distance in all likelihood is not only task based but also much more equipment-specific. For instance the "working distance" for say a size 5 MCC bucket is very different from a size 1, and the working distance may be different if it is mounted at "face height" compared to being mounted at the bottom.

But either way, this quickly turns into a matter of slicing and dicing so finely that we then revert back to looking at the conditions that the table was originally based on and once again, we approach the fundamental problem of how to translate the standard test data into actual equipment models.

Good point! Incident energy needs an associated distance so it stands to reason if someone specifies an arc rating, the distance where it applies is also important. If its the normal 18, 24 or 36 inch working distance, that needs to be clear. If it something else, although that would muddy things up, it needs to be known as well. Otherwise I could see having just an arc rating listed leading to an interpretation by some that it applies no matter how close they are.

2015 code only says you cannot have incident energy and ppe level on the same label. Boundaries should still need to be on label for unqualified workers and working distances for qualified. My question, what do you put on the old "0" categories?

I agree with Paul. The question was "should" the distance be included. I think it "could" be added as a convenience.

We originally thought that "minimum arc rating" was a good idea, but because of the above-noted confusion we have reverted to using the incident energy/working distance combo in order to avoid the issue. Personally, I think you would need to have the working distance with the minimum ppe rating to make any sense to the worker.

To gastoor: you misunderstand. It is categories that cannot be used with incident energy. A "site-specific level of PPE" is one of the specifically allowed label items [130.6(D)(3)(c)]. As to the former category 0, I presume thate you are speaking of situations where the incident energy is <1.2cal/cm2. That situation is addressed in Annex H - Table H.3(a). Frankly, I do not see a problem identifying a Level 0 as part of a "site-specific level" system.

Getting off topic but I think the whole "PPE level" thing is pretty clear:

If you are using the tables, use the PPE level.

If you are using incident energy calculations, use the cal/cm^2. And while you are at it, round it off! Each of the alternatives is bad all the way around:

1. If the site PPE ever changes, all the labels have to change.
2. If you use the defaults for the table-based system (1.2, 4, 8, 25, 40), you can't really achieve full value out of tested layering combinations nor using the full rating of the PPE when it can be used such as being forced to wear a 40 ATPV multilayer flash suit for a 9 cal/cm^2 situation when virtually any good quality shirt and pants such as those made with Indura Ultrasoft would be sufficient (with appropriately rated face/head protection).

I agree with PaulEngr. The category is tied to the tables where the distance is predefined and the calculated method provides IE levels at a distance that must be identified. The customer may define that distance in their safety manual or other company documents if it is a standard distance. And as always, ensure all personnel are properly trained.