Arc Flash Method

[timm33333]

The NFPA-70E-2015 has two arc flash methods: either the PPE method (130.7(C)(15)(A)(b), or the incident energy method (130.7(C)(16). In the past arc flash analysis was done by calculating the incident energy. How is the 2015 version of NFPA-70E different than the earlier versions of NFPA-70E? Thanks

 

[dpc]

In the past arc flash analysis was done by calculating the incident energy

Not really accurate. Earlier version of NFPA 70E had a "table" method. But in the 2015 version the "Categories Method" is completely updated and re-written. I'd suggest simply reading the 2015 version and comparing it to the 2012 version if you want to understand the changes.

 

[wbd]

There have always been two methods to determine the PPE to wear for a task. One method is the table method but that has short comings in that you need to know that you are withing the specified parameters at that piece of equipment, fault current and clearing time.
The other method is doing an actual study to determine the incident energy at the specific piece of equipment.

What changed from the previous edition of NFPA 70E is that there is no HRC anymore. They separated out Hazard and Risk. The other item is that if an actual study was done to determine the incident energy levels, the PPE category listed in NFPA 70E cannot be used. For PPE when a study was performed, one is directed to Annex H.