The concept of "100% tie-off" refers to ensuring that workers are continuously protected from falls by being securely attached to an anchorage point at all times when working at heights. This is a critical safety measure in fall protection systems to prevent falls and ensure worker safety.

Key considerations for implementing 100% tie-off include:

1. Anchorage Points: Proper planning for suitable anchorage points is essential. These should be identified and incorporated during the construction phase if possible, to ensure they are available for use during maintenance or other activities [1].

2. Free Fall Distance: The free fall distance should be minimized and must not exceed 6 feet (1.8 meters). The tie-off point should be at or above the connection point of the fall arrest equipment to the harness to prevent additional free fall distance [2].

3. Strength of the System: The strength of the personal fall arrest system is dependent on its attachment to a robust anchoring system. Any component that reduces the system's strength should be replaced with a stronger one that maintains the appropriate maximum arrest force characteristics [1].

4. Avoiding Knots and Sharp Edges: Tying off using knots or around sharp edges can significantly reduce the strength of the lifeline or lanyard. Alternatives such as using a snap-hook/dee-ring connection or protecting the line from edges should be considered [1].

5. Horizontal Lifelines: When using horizontal lifelines, the angle of sag should be considered as it can amplify the impact force. The design and installation of such systems should be done by qualified persons, and the strength should be increased for each additional employee tied off [1].

6. Training and Inspection: Employees must be trained in proper tie-off techniques, and the fall protection systems should be inspected regularly to ensure all components are in good condition and functioning correctly [3].

By adhering to these guidelines, employers can ensure that their fall protection systems provide continuous protection, thereby maintaining 100% tie-off and enhancing workplace safety.