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Understanding Break Loads and Safe Working Loads

The break loads shown are indicative only and not test certified. Break loads will also lower as a result of knotting and splicing.

A rope’s break load is calculated as an average result achieved under laboratory conditions on new rope, pulling at a slow and steady speed, in a straight line. These lab conditions however, rarely apply to real-world scenarios during which a variety of factors may cause the rope to break under much reduced loads. As a result, a rope’s safe working load is always much lower than its minimum break load.

Safe working loads differ from rope to rope and take into account all the factors that may affect the rope’s behaviour, as well as the degree of risk to life and property involved. It is not possible for us to recommend blanket safe working loads for ropes stocked, instead the following should be understood as a guide only:

In applications with minimal risk to life, or minimal risk of serious damage in the event of rope failure, the safe working load may be calculated at 1/5 of the minimum break load.
For life critical applications, or those with risk of serious damage in the event of rope failure, the safe working load should be calculated at 1/12 – 1/15 of the given breaking load.

Other factors to consider when determining a safe working load include; impact of dynamic loading, reduction in strength due to knotting, size and length.
Safe working loads should always be determined by an engineer or qualified professional.