by , on February 14, 2018
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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 since the Task Tables must meet the worst case energy in that equipment category within the fault current and clearing time parameters defined.

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 as 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, which is minimum 25 cal/cm² because a PPE Category 2 has a minimum of 8.0 cal/cm² so it wouldn’t guarantee adequate protection.

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 is NEW in NFPA 70E-2018 (but the same as H.3 in the non-mandatory annex for years), and would guide you to choose a face shield, balaclava, clothing and gloves meeting the minimum 8.1 cal/cm² and guides 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.

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 HRC 2 or 8.0 cal/cm² protection while 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 IE 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, but 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 HRC 3 25 cal/cm² suit?

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Hugh Hoagland
About author:
Hugh Hoagland is the foremost tester of clothing and PPE exposed to electrical arcs and is an arc flash expert. Read more about Hugh.

2 Comments on "Why Can’t I Use PPE Categories with an Arc Flash Study?"

Chris Inshaw - 18 May 2018 Reply

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

    Hugh Hoagland
    Hugh Hoagland - 25 June 2018 Reply

    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

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