When The OSHA Required 5,000 Pounds Isn’t Enough…

Almost every rule or law has a scenario or situation where there is an exception. And because of all the potential variables that occur in a workplace, it’s important to understand and anticipate when there may be an exception to a fall protection law or requirement. Because of how wire rope systems are designed, there are a few different ways that they can potentially respond in a fall arrest situation. The design of wire rope systems, commonly referred to as, “Flexible Horizontal Lifelines,” is critical. Depending on how the systems are configured, peak anchorage forces can dramatically exceed 5,000 pounds. 

OSHA 1910.66 App C (section I-number 10) states: 

“(10) Anchorages to which personal fall arrest equipment is attached shall be capable of supporting at least 5,000 pounds (22.2 kN) per employee attached, or shall be designed, installed, and used as part of a complete personal fall arrest system which maintains a safety factor of at least two, under the supervision of a qualified person.”

And then, OSHA 1910.66 App C (Section III-letter h, number 6) states:

“Horizontal lifelines may, depending on their geometry and angle of sag, be subjected to greater loads than the impact load imposed by an attached component. When the angle of horizontal lifeline sag is less than 30 degrees, the impact force imparted to the lifeline by an attached lanyard is greatly amplified. For example, with a sag angle of 15 degrees, the force amplification is about 2:1 and at 5 degrees sag, it is about 6:1. Depending on the angle of sag, and the line’s elasticity, the strength of the horizontal lifeline and the anchorages to which it is attached should be increased a number of times over that of the lanyard. Extreme care should be taken in considering a horizontal lifeline for multiple tie-offs. The reason for this is that in multiple tie-offs to a horizontal lifeline, if one employee falls, the movement of the falling employee and the horizontal lifeline during arrest of the fall may cause other employees to also fall. Horizontal lifeline and anchorage strength should be increased for each additional employee to be tied-off. For these and other reasons, the design of systems using horizontal lifelines must only be done by qualified persons. Testing of installed lifelines and anchors prior to use is recommended.”

It should be noted that sections II and III of this portion of OSHA law are noted as “Non-Mandatory” standards. But, just because they are non-mandatory, it does not mean that these portions of the written law should be ignored. Often times, these sections will denote some of the exceptions to the regular standards that could be very hazardous for workers if they are not followed. 

Generally speaking, OSHA requires that a single anchorage point can support 5,000 pounds. But, if a worker falls on a flexible overhead lifeline fall protection system, the fall forces will be dramatically amplified by the flexible lifeline. Since the fall forces are increased, the anchorage points for a flexible lifeline may need to support more than 5,000 pounds.  Because wire rope systems can generate significantly high pull forces, consult with the manufacturer for anchor loading. Depending on what the flexible horizontal lifeline manufacture requires, you may need to find a way to provide reinforcement for the structure that is supplying the anchorage point.

One of the main reasons that people purchase a wire rope fall protection system is because it is an inexpensive fall protection solution. However, if you decide to use an overhead flexible lifeline fall protection system, you must carefully analyze the spans and loadings in order to identify the largest potential fall forces. Once you have an idea of what sort of force could be applied to the anchorage points, you will have a better idea of how the anchorage points can be reinforced to maximize their successful support of the fall protection system and the worker during fall arrest. 

Until the next time, stay safe up there!

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