Will I Hit That? Clearance Calculations

Determining how far your fall arrest system will allow you to fall is a critical task for anyone using fall protection equipment.  Mistakes are often made when determining clearance requirements and it usually comes down to using the wrong “starting point” for the estimate. Once you understand the basic principles of estimating clearance requirements you can apply it to any fall arrest system.  Here are a few things to note and how to do it!

  • These methods are conservative estimates (the term “estimating clearance” is preferred rather than “calculating clearance”). If calculations are to be accurate within inches, more in depth calculations are required to determine specific energy absorber deployment distances.
  • Estimate clearances in three steps:
    1. Determine the starting point (anchor or platform height);
    2. Determine how far the equipment will let you travel from the starting point;
    3. Subtract the two to determine how close to the ground you are.
One of the greatest misconceptions is that all 6’ energy absorbing lanyards need 18’ of clearance.  This isn’t wrong, but needs to be clarified that this measurement is from the anchor.

Knowing how the equipment performs is necessary to estimate clearances because the free fall (C) and energy absorber deployment(D) changes with self-retracting devices, lifelines, and different types of lanyards.  Once you understand the different methods (shown in the poster), you can apply the same principles to whichever equipment is being used and have an idea whether the system will prevent you from contacting a lower level or obstruction.

Interested in hanging this poster in your facility?
Gravitec Systems Competent and Qualified Person courses focus on how to estimate and calculate clearance requirements for all different types of fall arrest systems.  Students learn how to predict known hazards in relation to clearance and how to correct them.

Call us at 800.755.8455 or email us at [email protected] to book the right fall protection course for you!

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