by , on July 8, 2015
red background with burning question

 Q: In New Zealand, we have a lot of importers bringing in [Personal Protective Equipment] garments in from Pakistan or China, etc., and they are muddying the waters with different cal ratings on different garments, and then the end users get confused as to what they should wear in a level 2 environment.

There has been a drive to wear lighter garments to avoid heat stress. I know from your last visit in Auckland , we spoke about wearing the lightest / lowest ATPV and layer up for the environment; e.g., wear a light level 1 shirt in the office or the yard and put an overall on for a level 2 environment when necessary – work to reduce the heat stress.

The problem we are coming across is that whilst these importers can’t get information correct in labels (e.g., “Arch rating”!), they are putting 10.4 cals, or 12 or 16 cals on the front of overalls for a level 2 environment. This is confusing to the end user.

Am I correct in thinking that in the U.S. the ratings were changing to Arc1 / Arc 2 / Arc3 / Arc 4 , and were being put on the front of the work wear? I am sure I read something on your blog or in NFPA 70E 2015 about that. What is the general feeling ??? I feel that similar options help people who speak any language other than English understand their PPE – I liken it to the fire exit signs that only used to say FIRE EXIT – not have a picture of a running man – yet everyone understands the running man.

If users are in a 12 or 16 cal environment, should they be wearing Level 3 (25 cals) as a minimum? Why wear 16 cals unless the environment is above level 2 (8 cals)?

I was worried when we first looked at this in 2007 – say with the wool coat that was achieving a higher rating but only designed for a level 2 – that these importers would use this to confuse end users.

I would love your feedback on the scenario. Also, as we have always worked to use the same [labeling] as the U.S., what is the general movement there on labeling garments?

A: The HRC/ARC levels have been very confusing from the start.  This is one of the things we try to clarify in training.

If you have calculations, you follow those, and levels have nothing to do with it. Follow NFPA 70E H.3 for guidance, but the HRC/ARC levels are not in the equation.

If you use the tables, you use levels.  Software caused the mixing following IEEE 1584-02 which confused the issue. The 2012 and 2015 NFPA 70E makes it clear that you don’t need 25 cal/cm² (HRC/ARC 3) for 8.1 cal/cm² exposures, though IEEE 1584-02 implied that.

Sweat decreases your protection in a garment by about 50%, so overprotecting typically under-protects in reality.

That is my primary lesson in this.  Match to the hazard and no more, if possible and practicable.  Most lives are saved by the clothing not igniting or melting; better quality of life comes from less percentage body burn and less severe burns.  Match but don’t overkill the protection. More weight or even more single layer arc rating may not actually mean more protection if it causes sweating in the garment.

For additional information, read this article on ATPV vs EBT.

Another article, Addressing Comfort and Contamination in Arc-Rated Clothing”, is available.

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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.

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