An toànCâu 428 / 521
An arc-flash study shows an available incident energy of 8 cal/cm² at the working distance. The arc-rated clothing and PPE must have an arc rating of:
a.Less than the incident energy so it breathes better
b.Exactly 1.2 cal/cm²
c.At least equal to or greater than the available incident energy (8 cal/cm² or more)
d.Any untreated cotton clothing is acceptable
Giải thích
Arc-rated PPE must have an arc rating equal to or greater than the available incident energy—here at least 8 cal/cm². Choosing PPE below the incident energy, or ordinary cotton (which can ignite), would not protect the worker. The 1.2 cal/cm² figure is the arc flash boundary threshold, not a PPE rating for this task.
Trích dẫn luật: NFPA 70ELuyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- The arc flash boundary is best defined as the distance at which:
- In NFPA 70E, the 'limited approach boundary' is best described as:
- Crossing the restricted approach boundary toward an exposed energized part requires:
- Rubber insulating gloves used for energized work on a 480V system must be:
- Under Cal/OSHA and NFPA 70E, the primary/preferred way to protect workers from electrical hazards is to:
- An energized electrical work permit is generally required when:
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