by , on April 8, 2018
red background with burning question

Question: Can we expect some arc blast-rated PPE to arrive in the near future?

Answer: Neither e-Hazard nor ArcWear know of anyone developing PPE for arc blast.

To look at Arc Blast and how it could relate to PPE, ArcWear and e-Hazard researched another paper this year measuring the force (N) on an impact plate from a door ejected by an arc blast.  This is not yet published but will be presented at the 2019 IEEE Electrical Safety Workshop.

From what we have seen in our last two papers, there will be few if any concussive injuries since the blast pressure is a function of containment AND current.  A DOOR ejected CAN be like a linebacker hitting you, and we’d predict possible contusions, but the pressure when the door is open is VERY low – up to 18kA.  Small rooms could have issues as well, and equipment doors or parts blown off could deliver substantial blows.  In accidents, we have seen workers knocked down and a few knocked out, but these are VERY rare.

When doors are open, arc blast is dispersed and would rarely contribute to injury.  Of course the work that has been done to date shows noise damage to ears is possible. Equipment doors hurting workers could occur (and have, in fact, already occurred).  PPE probably isn’t a solution for equipment with high blast pressures.  Arc Resistant designs would be the best solution.

The newest version of NFPA 70E removed the 40 cal/cm2 cutoff for “arc blast” reasons.  Arc Blast isn’t a function of incident energy; it is a function of current and containment.

Maybe we will have a hazard assessment model some day, but we don’t for now.  Open doors relieve the pressure but increase your IE.  Working de-energized or wearing the proper PPE when that isn’t possible is your best option.  BUT remember to “dress to test”.

Here is a link to my first paper on the subject.

Our next paper will be at the IEEE ESW 2019.

We do talk about this issue in our Low Voltage NFPA 70E Classes.


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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