NFPA 70E Standard defines two methods for the selection of arc flash PPE, including: The incident energy analysis method and The arc flash PPE category method.
But NOT both on the same piece of equipment. the result of an incident energy analysis method to specify an arc flash PPE category method shall not be permitted.
♦ Arc flash PPE Category method
Arc flash PPE category shall be determined base on the estimated maximum available fault current, maximum fault clearing time and minimum working distance according to Table 130.7(C)(15)(a) and Table 130.7(C)(15)(b). PPE shall be selected based on category according to Table Table 130.7(C)(15)(c) of NFPA 70E Standard.
| CATEGORY | ARC-RATED CLOTHING |
| 1 | Arc-rated clothing, minimum arc rating of 4 cal/cm2 |
| 2 | Arc-rated clothing, minimum arc rating of 8 cal/cm2 |
| 3 | Arc-rated clothing selected so that the system arc rating meets the required minimum arc rating of 25 cal/cm2 |
| 4 | Arc-rated clothing selected so that the system arc rating meets the required minimum arc rating of 40 cal/cm2 |
♦ Incident energy analysis method
The incident energy shall be performed based on working distance of the employee, fault clearing time of overcurrent protective devices and equipment constructions. PPE shall be selected based on estimated incident energy level according to Table 130.5(G) of NFPA 70E Standard.
| LEVEL | ARC-RATED CLOTHING |
| 1 | Incident energy exposures equal to 1.2 cal/cm2 up to and including 12 cal/cm2 |
| 2 | Incident energy exposures greater than 12 cal/cm2 |
*Arc-rated clothing with an arc rating equal to or greater than the estimated incident energy.