Why is it important to know the stopping length of a fall arrest lanyard?
A fall arrest lanyard features a shock absorber which helps slows down the fall of a person. This additional length is in addition to the initial length of the lanyard. So hypnotically, a person could still receive major injury even though the fall arrest lanyard has deployed its shock absorber pack.
The overall combined length of the deployed lanyard and the height of the individual could be longer than the height of the fall. If so, injuring to the person will happen.
Fall Clearance
A 2.0m shock-absorbing lanyard allows for up to 2.0m of free-fall distance before activating, and another 1.75m of deceleration distance before arresting a fall. In addition you will have the height of the individual on top of the lanyard lengths.
So a simple calculation needs to be undertaken to understand the fall clearance:
Lanyard length – 2.0m
Shock absorber length – 1.75m
User length –2.0m
Over length of fall – 5.75m
If you have 5.75m of fall clearance or less, you're going to hit the ground.
It is advised to add an extra 1.0m to the overall deployed length to adjust for harness stretch and ‘D’ ring slip.
Anchor point will affect the fall clearance
Another element for safety of lanyards, is the position of the anchor point. The anchorage point should be at a height that minimizes the risk of contact with the ground or a lower level.
Why it is important to anchor as high overhead as possible?
If there is not enough room below to accommodate a potential fall clearance, use other equipment such as a restraint lanyard.
Restraint Lanyard
A restraint lanyard is to restraint the worker from approaching the fall edge and not to decelerate the fall. A restraint lanyard length should be specified to stop the person from gaining access to the edge of the floor or roof. This short length is to ‘restraint’ or prevent the fall, not assist in slowing of the fall.
