I had an interesting inquiry from an overseas customer about the fall distance when using a self retracting lifeline. This was an instance where the technical nature of the question caused me to check with the manufacturer…just to be sure.
What is a total estimated fall distance of Self-retracting lifeline, and detail of it (Free fall distance/length of SRL/etc..)? What if my working platform is 6 feet (1.8 M) above ground. So my self-retracting lifeline is hanging above ground about 13 feet (3.8-4.2 M), not 18 feet (5.6 M). Am I going to hit the ground? Does the self-retracting lifeline have shock absorber? If not, how is it going to decelerate the falling? I think it just might immediately stop like a safety-belt in the car.
Thank you for the inquiry. I checked with the engineers at DBI/SALA to get a response on your question. Here is what they say…
The recommended clearance below a person connected to a SRL is 6 ft. (1.8m). So someone standing on a platform 1.8 m high, attached to an SRL overhead, who falls off, will stop well within 6 ft. ( 1.8m) or less. The 6 ft. distance is worst case with the person weighing 310 lbs. and also includes a small safety factor when calculating the distance. The free fall distance will be less than 2 ft. The deceleration distance included with the free fall distance will be 3.5 ft. (1.1m).
Self retracting lifelines have built in energy absorption. Some models have a disc brake system and others have a external shock that extends to absorb energy. The brake is activated by inertia. The brake activates so you can move around easily, but if you fall, the brake activates and stops your fall.
Hopefully this answers your question. With the platform being so low, it was good to see this for myself as well.
Falls from a height of ‘only’ 6 feet can be quite dangerous. A Self Retracting Lifeline is the best means I know to protect you in the event of a fall. Of course, better not to fall in the first place. Guard rails or some other engineered solution that keeps you from going over the edge is preferable. But the workplace is not always that easy.
And, please plan for what you are going to do after the fall occurs. The SRL keeps you from hitting the ground, but now you are just hanging there. Better to plan in leisure than react in panic.