Fall Arrester (Rope Grab) Hazard Alert No. 1

Summary

Fall arresters which are not panic-grab proof, may not arrest the fall of their user if, at the onset of the fall, the user holds onto the device in a manner which prevents the lever of the fall arrester from locking on the rope. This risk of non-arrest can be minimized by limiting the link between the fall arrester and the back D-ring on the user’s harness to approx. 2 ft [0.6 m].

The Hazard

What is it? In Fall Arrest Systems (FASs) with fall arresters (aka rope grabs) and vertical lifelines, the fall of their user is stopped due to friction between the lever of the fall arrester and the lifeline. This friction, which during no-accident conditions is very small to allow relatively smooth movement of the device along the line, has to be greatly increased during the fall arrest action. This increase happens due to the combination of the fall arrester’s main spring and the user’s weight acting on the main lever of the device. However, at the onset of a fall, the Fall Arrest System (FAS) user may instinctively grab the device in a panic. If he/she continues to hold, and the device is not of the panic-grab proof type - the main lever may be prevented from coming in contact with the rope. This will lead to non-arrest with all its consequences to the user.

Why does it exist? This hazard exists primarily because of the design deficiency in the fall arrester. Most of these devices are of a very simple design which makes them easy to use and affordable. Most of the national standards for fall arresters recognize the requirement for the panic-grab proof feature but lack an appropriate test procedure. The exception is the Canadian CSA Z259.2.1-1998 (R2004) Standard [1].

Where can you experience it? This hazard exists in all Fall Arrest Systems (FASs) with fall arresters and vertical lifelines in which the fall arrester is not panic-grab proof, and it is also connected to the user’s harness with a linkage which is longer than approximately 2 ft [0.6 m].

Who is affected by it and when? Users working off swing stages and suspended scaffolds are particularly at risk because their lifelines run on the outside of the suspended scaffold while the requirement for their mobility along the scaffold usually calls for linkages to be 5 or 6 feet [1.5 - 1.8 m] long. Such long lanyards allow the fall arresters to be in front of the users, thus within their reach. In case of a fall, the Fall Arrest System (FAS) user may instinctively grab the fall arrester in a panic situation and hold onto it, preventing the device from its normal locking action. Shortening the lanyard would remove the fall arrester from the location convenient for a panic grab.

How to Eliminate It Or Minimize Its Consequences?

1. Use only panic-grab proof fall arresters, in compliance with CSA Z259.2.1-1998 (R2004)
2. Provide proper fall protection training to all users of Fall Arrest Systems (FASs).
3. Follow User’s Instructions supplied by the equipment manufacturers.

Additional Information and Comments

There are documented cases of fatalities because of the panic-grab reflex of the users of the non-panic-grab proof fall arresters. Most of the rope grabs in use today have this deficiency. The relatively simple cure of the problem by using a short, permanent linkage should be undertaken only by the manufacturer of the fall arrester or his authorized agent. For those who require longer linkages, the panic-grab proof fall arresters or the use of self-retracting devices are two alternative solutions.

References

1. CSA Standard Z259.2.1-1998 (R2004).
2. ANSI Standard Z359.1-1992(R1999).
3. “Do We Need a New Generation of Rope Grabs (Fall Arresters)” Sulowski, A.C., IFPS’2000, International Fall Protection Symposium, Orlando, FL, October 18-19, 2000.
4. “Fall Arrest Systems - Practical Essentials”, Sulowski, A.C., CSA International, Toronto, ON, 2000.
5. “Introduction to Fall Protection”, Second Edition, Ellis, J.N., ASSE, Des Plaines, IL, 1993.
6. ANSI Z359.1-1992 (R1999) American National Standard safety requirements for personal fall arrest systems, subsystems and components. American National Standards Institute Inc., New York, NY, and American Society of Safety Engineers, Des Plaines, IL.
7. “Fundamentals of Fall Protection”, Sulowski A.C., et al, International Society for Fall Protection, Toronto, ON, 1991.