by , on July 24, 2014

Q. According to NFPA 70E Table 130.7(C)(16), an HRC 0 requires a long sleeve shirt. It is my understanding this has to be worn inside of the arc flash boundary (AFB). For a 480v machine panel disconnect, Table 130.7(C)(15)(a) lists the potential boundary at 30”. We have arc flash analysis done on our equipment, and some of the calculated boundaries are only a couple inches or less. Would a long sleeve shirt still be required for throwing the disconnects on those lower risk machines?

Tim O.


 

A. This is a great question. The idea would be that you wear AF PPE inside the boundary but outside the boundary, nothing is required. There is still language about natural fibers under AF gear but the requirements are gone in the new 2015 version of the standard IF you are outside the AFB. You must do your due diligence of an adequate risk assessment but outside the AFB, there are no PPE requirements. By calculating, you know these are not the “horrible” disconnects (we have calculated disconnects at over 40 cal/cm². Do be sure all maintenance has been done on upstream protective devices and on the disconnect itself or the risk is more than the calculated energy.

So if the AFB is 2 inches, a leather glove or an arc rated glove with an Arc Rating of greater than the calculated hazard at the location of the hand inches (likely less than 1 cal/cm²) would be all the PPE required.

If the AFB is 1 foot and the equipment can be operated from the side the AF PPE could be something as simple as a Arc Rated sleeve and glove for the hand in the AFB.  These types of solutions can really make AR PPE reasonable and less costly for operators.  For electricians, the use of AR PPE daily wear is still the most effective and least costly solution to compliance but unique solutions exist IF you have done arc flash engineering studies and have a properly written electrical safety program, a knowledgeable arc flash risk assessment, an effective arc flash training program and a robust electrical safety work practice audit.

e-Hazard still supports using ARC 4 cal/cm² minimum PPE for all 480V equipment operation other than operation of contactors.

Hugh Hoagland

 


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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