Personal Fall-Arrest Systems (PFAS)
Lifelines
A lifeline is a cable or rope that connects to a body harness, lanyard, or deceleration device, and at least one anchorage. There are two types of lifelines. (Vertical and Horizontal)
Vertical lifeline: A vertical lifeline is attached to an overhead anchorage and must be connected directly to a worker's full-body harness, lanyard, retractable device, or rope grab; it must have a minimum breaking strength of 5,000 pounds.
Vertical Lifeline System
When a worker needs to move horizontally, however; a vertical lifeline can be hazardous due to the potential for a swing fall - the pendulum motion that results when the worker swings back under the anchor point. A swing fall increases a worker's risk of striking an object or a lower level during the pendulum motion.
Horizontal lifeline: Unlike a vertical lifeline, the horizontal lifeline stretches between two anchorages.
Horizontal Lifeline System
An advantage of the horizontal lifeline is that when you connect a lanyard or rope grab to the horizontal lifeline, you can move about more freely, thus reducing the risk of a swing fall. However, horizontal lifelines are subject to much greater loads than vertical lifelines.
To reduce loads on a horizontal lifeline, increase the sag angle or connect to the lifeline with a shock-absorbing lanyard.
Example: When the sag angle is 15 degrees, the force on the lifeline and anchorages subjected to a load is about 2:1. However, if you decrease the sag angle to 5 degrees, the force increases to about 6:1.
If they're not installed correctly, horizontal lifelines can fail at the anchorage points. For this reason, horizontal lifelines must be designed, installed, and used under the supervision of a qualified person.
Knowledge Check Choose the best answer for the question.
5-9. What advantage does a horizontal lifeline have over a vertical lifeline?
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