There have been several good discussions about category 0 (as we know it) being deleted from the 2015 edition of NFPA 70E.

In the past, if the incident energy (Ei) was less than 1.2 cal/cm^2 it was often referred to as Category, Level or HRC "0".

This week's question is going right to the point regarding "0" on arc flash labels.

How do/will you label equipment with Ei < 1.2 cal/cm^2?

We will still use "0"
We will list the Ei
We will list a minimum arc rating such as 4 or 8
Something else (ideas welcome!)

I've started listing the calculated incident energy values, and leaving it up to the trained, qualified worker to know what the number means.

You have a choice of using either IE analysis or PPE categories for each piece of equipment, but not both. If you use the IE analysis method, then arc-rated clothing and other PPE shall be used based on the IE. If you use the PPE categories method, then Tables 130.7(C)(15) and 130.7(C)(16) must be used and they have no Cat 0.

Our daily wear is PPE 2 for those working on and around energized equipment.
Much that is done while energized has to be done with power on because it is troubleshooting and testing.

For everyone else, there is no standard requiring wear only natural, non-melting clothing.
Those people do not cross into the Limited Approach Boundary on a daily basis.

There is traffic around the manufacturing area.
We already require safety footwear and safety glasses while in the manufacturing area.
I think it would be prudent for standard company dress code to require only natural, non-melting clothing
for anyone entering the manufacturing area.

One is risking getting 2nd degree burn or worse with only a fraction of 1.2 cal/cm2 when the energy is delivered to bare skin in less than one (1) second. It all boils down to how fast the energy was delivered. For example, no more than 0.3 cal/cm^2 is required to cause 2nd degree burn when the energy is delivered within 0.01 sec time interval. On the other hand, the 1.2 cal/cm2 is completely safe when delivered within one (1) minute time interval (equal in fact in terms of intensity and dose to the amount of incident energy delivered by exposure to sunshine within the same time period). Check please this forum thread at http://arcflashforum.brainfiller.com/viewtopic.php?f=34&t=2221 for more information.

Therefore, no label replacement would be needed if arc duration associated with the existing Category 0 IE < 1.2 cal/cm^2 label was one (1) second or more.

However, if arc duration associated with the existing Category 0 IE < 1.2 cal/cm^2 label was less than one (1) second, one might consider replacing the Category 0 IE < 1.2 cal/cm^2 with Category 1 label. Alternatively, one might want recalculating arc flash boundary as a function of threshold incident energy for a 2nd degree burn on bare skin (please note the threshold IE is variable value, not a constant) and generating new arc flash label with Category 0 or 1 depend on whether arc flash boundary is less than working distance or not.

You may do calculations manually or, to alleviate the pain, you may consider Arc Flash Analytic version 5.0 software program to do the work for you - by now the only software program taking into account the variable nature of threshold incident energy in arc flash analysis and labeling.

We generate the arc flash labels based on "Incident Energy Analysis Method." Therefore, Incident Energy(Ei), Arc Flash Protection Boundary, Working Distance, and NFPA 70E 2015 Annex H.3(b) Protective clothing and PPE are some crucial information we mention for incident energy < or = 1.2cal/cm^2.

Includingthe face shield and balaclava? That's why I got away from making 8 cal/cm^2 a standard after the 2009 edition made that change.

We still use 0. Our written electrical program is based on the 2012 NFPA70E Standard.

Actually the repair area uses a face shield only.
The Grid Tie area requires a balaclava as well.

It has to do with the amount of penetration into the Arc Flash Boundary
and the Incident Energy is higher around the Battery Strings