How do I calculate fall clearance?

Determining fall clearance is perhaps the most important aspect of fall protection. If not properly calculated, the wrong equipment could be selected for a particular job and, in the event of a fall, the result could be devastating. 

Fall clearance is the minimum distance needed for equipment to arrest (or stop) a fall and keep a worker from striking the ground or the next lowest surface. It is not a simple distance calculation. There are many factors to consider, such as: 

  • Length of Anchorage Connecter (LA) 
  • Length of Connecting Device (LC)
  • Maximum Arrest Distance of Connecting Device (MAD) 
  • Height of Worker (HW) 
  • Safety Factor (SF) i.e., Harness Stretch, typically 2 ft. 
  • Relation of Anchor Point to Dorsal D-Ring 

If the distance between the anchor point and nearest obstruction is less than the determined fall clearance, the fall arrest system will not protect a worker from hitting a lower surface. 

Another consideration are situations known as swing falls. A swing fall occurs when an anchorage point is not directly above a worker. The nature of these falls means that adjusted calculations must be made. 

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