Which statement describes the strength ratio for rope per NFPA?

Which statement describes the strength ratio for rope per NFPA?

• A. 10:1
• B. 15:1
• C. 20:1
• D. 8:1

Answer: (B)

The key idea here is the safety factor NFPA requires between a rope’s minimum breaking strength and the load you put on it. For life-safety rope, NFPA 1983 specifies a 15:1 safety factor. That means the working load you apply should be no more than one fifteenth of the rope’s minimum breaking strength. In other words, Working Load Limit = Minimum Breaking Strength divided by 15. This margin accounts for dynamic loading, knots, wear, contamination, and aging. So the correct statement is 15:1. The other ratios don’t meet NFPA’s requirement for life-safety rope.

The key idea here is the safety factor NFPA requires between a rope’s minimum breaking strength and the load you put on it. For life-safety rope, NFPA 1983 specifies a 15:1 safety factor. That means the working load you apply should be no more than one fifteenth of the rope’s minimum breaking strength. In other words, Working Load Limit = Minimum Breaking Strength divided by 15. This margin accounts for dynamic loading, knots, wear, contamination, and aging.

So the correct statement is 15:1. The other ratios don’t meet NFPA’s requirement for life-safety rope.