CSLB C-10 Electrical ContractorSafety and TestingHard
During an arc flash risk assessment, an electrical contractor determines that the incident energy at a specific piece of equipment is 9 cal/cm². According to NFPA 70E, what is the minimum Arc Flash PPE Category (Hazard/Risk Category) required for work on this equipment, assuming the hazard cannot be eliminated?
- ACategory 1
- BCategory 3
- CCategory 2
- DCategory 4
Show answer & explanationAnswer & explanation
Correct answer: B. Category 3
NFPA 70E Table 130.7(C)(15)(b) or similar tables (depending on edition) specifies PPE categories based on incident energy. An incident energy of 9 cal/cm² falls into Arc Flash PPE Category 3, which requires a minimum of 25 cal/cm² arc-rated clothing.
Why the other options are wrong
- A. Category 1 is for 1.2 to <4 cal/cm².
- C. Category 2 is for 4 to <8 cal/cm².
- D. Category 4 is for 25 to <40 cal/cm².
Arc Flash PPE Categories
A classification system by NFPA 70E that specifies the minimum arc rating of PPE required based on calculated incident energy levels.
- Higher category = higher arc rating
- Determined by incident energy calculations
- Ensures worker protection from arc flash
Memory trick: PPE Categories: 1.2, 4, 8, 25!