Fall Protection: Selecting Connecting Devices
Toolbox talks often make reference to the ABC’s of fall protection–Anchorage, Body Harness, and Connecting Device. In this post, our focus is the letter C.
The connecting devices are the literal lifeline between the two other points of the fall arrest system.
All connection devices work best when the anchorage point is directly overhead. There are different types of connecting devices, such as:
* Shock Absorbing Lanyard *Non-shock Absorbing Lanyard * Self-Retracting Lifelines (SRLs)
Most commonly, workers need a shock absorbing lanyard. This is normally a 6-foot line that secures the worker’s full body harness to the anchorage. These lines are flexible and absorb shock by providing deceleration distance in case of a fall. They can reduce fall arresting forces by up to 80 percent when used properly. Non-shock absorbing lanyards can be retrofit with shock absorber packs that provide shock absorbing capability.
Self-retracting lifelines allow greater mobility for the worker and activate after just two feet of a fall (shock absorbing lanyards activate after a six-foot fall arrest). Self-retracting lifelines can limit the risk of the worker hitting the ground with only two feet before activation. SRLs further categorized as shown below.
All lanyards and SRLs should be hooked up properly each time they are in use and checked regularly for wear and tear on the outside webbing.
Lanyard Length and Total Fall Clearance Distance
Selection of lanyards must consider the total fall clearance distance of a potential fall. The total fall clearance distance is the vertical distance from the anchor to the nearest lower obstruction that a falling worker would impact, such as a structural member or the ground. Five basic factors make up this distance: 1) lanyard length, 2) deceleration distance of the energy absorber in a shock-absorbing lanyard or a shockpack lanyard, 3) estimated materials stretch, 4) estimated D-ring movement, and 5) height of the suspended worker.
The illustration below shows how these factors affect total fall clearance distance for a 6-foot worker using a 6-foot lanyard anchored overhead. Safely arresting the fall of a 6-foot worker using a 6-foot lanyard requires approximately 17.5 feet of clearance from the anchorage point to the nearest lower obstruction. Were as the SRL (Class A) requires approximately 4-feet of clearance below one’s feet when properly anchored overhead.
In cases where vertical lifelines or horizontal lifelines are used, calculations of total fall clearance distances must also include the slip of the rope grab plus lifeline stretch (vertical lifeline) or the displacement plus stretch of the lifeline (horizontal lifeline). For anchorage below standing D-ring level, careful calculation and a larger shock-pack are required to control arresting force. The required total fall clearance distance may be shortened in any setup by using a shorter lanyard (3, 4 and 5-foot lengths) or by using a self-retracting lifeline (SRL).
Please remember that just because a connecting device might be adequate for the task, doesn’t make it the best choice. Make sure you weigh your options and always have a competent person review your selections.