The strength of a rope is rated by its working load limit and tensile strength (also called breaking strength). The tensile strength is determined in a lab and measures the amount of tension a new rope can take before breaking. The working load limit is a guideline for practical use of the rope. The working load limit tells you the maximum amount of weight the rope should support at any time.
Although the working load limit is only 15 to 25 percent of its tensile strength, always determine the strength you need by working load limit and not tensile strength. Never exceed a rope’s or cord’s working load limit.
Keep these factors in mind when determining the working load limit you need.
Safety Tip: Always consult the manufacturer’s instructions for handling heavy loads. Do not attempt to use ropes in situations in which a life will depend on them without proper training.