Level of Protection from Arc Flash
Q: We supposedly had an incident energy analysis done. However, the majority of our labels indicate hazard level 0 at 18-inch arc flash boundary.
After reading your newsletter question, can you even use the term hazard level on the label?
Can the level of protection only be defined by the terms PPE category or ARC category and not by hazard level?
The 2015 70E does not have a PPE Category of 0.
A: 2012 70E® has a Hazard/Risk Category HRC 0.
There is no PPE for HRC 0 in the new NFPA 70E. This category has been eliminated in favor of a risk assessment which will require calculations to comply with unless all the criteria have been met.
Earlier editions of 70E® stated that PPE for HRC 0 is non-melting, natural fiber clothing. However, non-melting, natural fiber clothing is not PPE; it is clothing in the new standard. Therefore, we are using labels that state that if the PPE Level is below 1.2 cal/cm², the recommended clothing is non-melting, natural fiber clothing.
We base this recommendation on 70E®, Table H.3(b), which states non-melting, natural fiber clothing is used for incident energies equal to and less than 1.2 cal/cm2. Table H.3(b) is part of Annex H which is an informative annex and not part of the standard.
The references in the 2015 70E® that state electrical workers need to wear non-melting, natural fiber clothing are in the context of what clothing to wear under arc-rated PPE. Since there is no PPE Category 0, there is no reference to non-melting, natural fiber clothing as PPE, except as noted above.
When calculations are done, there is a real need for a risk assessment to determine what PPE is worn, IF ANY. The standard’s Annex F with the calculations is really a starting place rather than a prescription.
We recommend to use some PPE operation of all 3-Phase equipment unless it is arc-resistant and properly maintained. The best practice is to wear AR garments in 3-Phase equipment to prevent all clothing ignition.
Contactors and some other operations which are unlikely to cause a clothing ignition can be designated in training but this requires a proper risk assessment of the equipment and good procedural training.
IEEE 1584 will likely catch up in the next cycle. Most of the new versions of the software have eliminated putting Categories or HRC’s on labels. This should reduce confusion in the field.
Typically, labels will be reviewed every 5 years (according to the standard). This would be a good time to change this time frame, but the older labels will not result in inadequate PPE unless the engineering study assumptions have changed.
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