For live or running ropes used in boom erection, the design factor must not be less than:

The appropriate design factor for live or running ropes used in boom erection is established to ensure a high level of safety and reliability during operations. A design factor of 3.0 means that the strength of the rope must be at least three times greater than the maximum load it will be subjected to during use.

This level of safety margin is vital because it accounts for various conditions that can affect the integrity of the rope, including wear, dynamic forces, and environmental factors. By using a design factor of 3.0, operators and riggers can better protect against failures that could lead to accidents or operational inefficiencies. It underscores the importance of conservative engineering practices in scenarios where the loads on equipment can be variable and unpredictable.

While the other values may also appear as options, they do not meet the established safety standards set forth in industry guidelines, where a design factor of 3.0 is deemed necessary to promote a safe working environment.