Q: Why does the selection of FR/AR clothing by PPE Category (or HRC) not work with the incident energy (IE) analysis?
A: In 2018, the PPE Categories are still for use with the Task Tables 130.7(C)(15)(a) and 130.7(C)(15)(b).
Using the Task Tables to pick PPE systems will overdress the worker for the energy. That is because the Task Tables must meet the worst-case energy in that equipment category within the fault current and clearing time parameters defined.
Using the Task Tables
The PPE look up table for the Task Tables, Table 130.7(C)(15)(c), when used with the incident energy analysis, would put people in more PPE than the standard requires. Many make this mistake because IEEE 1584-2002 used the PPE Categories (HRC, Hazard/Risk Categories at the time) to pick PPE. So did most of the software companies making labels until about 2015.
For example, if you have an 8.1 cal/cm² incident energy from your arc flash study, the categories would put you in an Category 3. Category 3 has a minimum of 25 cal/cm². PPE Category 2 has a minimum of 8.0 cal/cm², so Category 2 would not guarantee adequate protection.
Using the Arc Flash Study
When you do an Incident Energy Analysis or an Arc Flash Study, the PPE Level Table 130.5(G) “Selection of Arc-Rated Clothing and Other PPE When the Incident Energy Analysis Method Is Used,” gives you guidance.
This table was new in NFPA 70E-2018 (but the same as H.3 in the non-mandatory annex for years). It would guide you to choose a face shield, balaclava, clothing and gloves meeting the minimum 8.1 cal/cm² and on other PPE for that level of arc flash hazard.
You may use the PPE categories as long as you understand the issues. But you will typically be overdressing your workers. So there is nothing wrong with using an HRC3 or ARC3 or CAT3 Arc-Rated suit for an 8.1 cal/cm² exposure, but it isn’t mandatory.
When the Use of Categories Is Prohibited
The prohibition from using the categories was introduced when the PPE Categories (HRC’s at the time) would LOWER the PPE for some tasks.
For instance, at one point, voltage testing in a MCC with potentially 40 cal/cm² exposure would have only required HRC2 or 8.0 cal/cm² protection. But racking in a starter bucket in that same cabinet required a 40 cal/cm² flash suit or HRC4. This was removed in 2015, but in 2012, the committee did not feel that PPE should be lowered if the incident energy was known to be a certain level . This use of the “risk” component multiplier concept was against OSHA’s perspective on risk assessment.
This is how the prohibition entered the standard. But now, in the current versions of the Task Tables, there is nothing to make the use of the PPE categories unsafe.
However, you should choose what makes sense for your workplace. The PPE Levels for arc flash protection now required in Table 130.5(G) are the best ways to categorize your PPE. Using the categories would not cause an unsafe condition from an arc flash perspective.
But if your calculations show 8.1 cal/cm², why would you want to use an old HRC3 25 cal/cm² suit?
Have a question about electrical safety and standards?
Hugh, I am following up on an email conversation you had with Scott Barrus in March. In reading your blog, I understand what you are implying but your highlighted sentence about using PPE categories appears to be directly in conflict with the last sentence in 130.5(F).
The site we are working with wants to keep using the existing PPE descriptions, which are based on a pre 2015 version of 70E (original study was on based on the 2009 edition), but update everything else to the 2018 edition. I don’t have a problem with a site specific PPE standard as long as it meets the present standard. We can do this using the old PPE descriptions with minor modifications (adding a balaclava to the 4-8 cal/cm2 level). If we stay away from using “Categories” by calling them “Levels” or “Type” I think we can avoid a conflict with the standard. Do you agree?
Thank you
Many companies use the Level idea but use the specific PPE in the “categories”. This is really OK but some purists on the committee fight about it. The real goal of separating the idea of PPE “Levels” and PPE “Categories” is so that they are not REQUIRED to be used as prescribed.
Example: If you calculate 8.1 cal, you do not have to use Category 3 PPE as the pre-2009 standards implied. This was a misinterpretation that was even perpetuated in IEEE 1584.
Expample 2: If you have an AFB of 10 inches on a disconnect and require 4 cal in the calc, you do not have to use an AR shirt to operate from the side. If engineering judgment used in your risk assessment agrees, you can use an AR glove and an AR sleeve to cover the potential area.
Example 3: If IE calculations at a site indicate that 80% of the jobs can be done in 8 cal system and adding a coverall and hood can take that system up to a 20 cal system to cover all the other exposures, a company can call their 8 cal system Level 1 and the 20 cal system Level 2 or they can call them Level 8 and Level 20 for that matter. Just make it easy and protect your workers.
This is what the use of levels is supposed to allow.
Hope this helps,
Hugh Hoagland
questions@e-hazard.com
I’m unclear as to whether or not the 2018 Arc-Flash PPE Categoriy Tables can be used when I don’t know the specific fault clearing times and available fault currents. Any information you can provide to help me to understand exactly what I must know about “fault current/clearing time” will be greatly appreciated.
The fault current must be under the limit for that type of equipment and the clearing time must be as quick as in the limit in the table. That being said, most warehouses and smaller facilities with newer electrical systems can use tables but no larger facilities can use them because the transformers will be too large and allow higher fault current than allowed in the tables. Light manufacturing with one utility feed and a transformer no larger than 1500 kVA will often meet the limits. If the utility transformer is larger than that, it is unlikely the main will meet the limit but the rest of the plant may. It does take engineering to use the tables. We always recommend using the tables when you have no other option (say a contractor, but some quality contractors have help tables with more information than in the standard tables to assess more realistically).
According to your statement above, NFPA is worried overdressing for the workers when PPE cat. table is used along with incident energy analysis method. You said that as long as I understand this behind story I can use PPE cat. table for incident energy analysis method.
However, NFPA 70E-2018 does not allow this one with using “shall not” as below.
NFPA 70E-2018, sect. 103.5.(F) says that “The results of an incident energy analysis to specify an arc flash PPE category in Table 130.7(C)(15)(c) shall not be permitted.”
My case where I work for nuclear power plant has lots of equipment to be calculated for arc energy. Preparing individual arc energy based PPE is not practical. I would like to use PPE cat. table for the selection of PPE as a result of incident energy analysis because this is simple and convenient.
I would like to hear your opinion.
Sorry for the misunderstanding. You can use the CAT levels as PPE Levels. You cannot use the CAT Tables for choosing PPE. You can use the Table of CAT clothing. If your system has everything under 4 cal/cm2 you can state that your PPE LEVEL is 4 cal min.
And you can have PPE Level 2 and 3 and 4 which MATCH the CAT levels but you cannot use the CAT tables unless you meet the criteria.