Ask Rigid Lifelines: C-Clamps as an Anchorage in Fall Protection
QUESTION: Can we use a C-clamp as an anchorage on a fall protection travel restraint system?
ANSWER: The answer to this question is a resounding NO. C-clamps should never be used for fall protection. In fact, they're actually referred to as the "widow maker" in the field. Here’s why:
C-clamps are designed to hold two things together with no outside forces applied to the assembly. Misapplying a C-clamp as an anchorage point is doomed to fail. That’s because, in the event of a fall, forces are applied to the C-clamp assembly that it was never designed to withstand.
Furthermore, C-clamps are intended to apply an axial force along the clamps’ screw. The moment you apply a lateral force to the C-clamp, it will fail because it is not designed to hold that type of load. It’s important to keep in mind that you must always use a professionally-made anchorage and install it per the manufacturer’s requirements.
Sadly, this is an innocent mistake that many people make, and workers pay for it with their lives. This novice application may sound good until you experience a fall event and the C-clamp fails catastrophically.
So What Type of Anchorage Point is Acceptable?
Selecting an appropriate anchor point for your system is an essential part of protecting yourself and your workers from fall hazards. But how do you know what qualifies as a suitable anchorage point?
The Occupational Safety and Health Administration (OSHA) defines the parameters for a safe anchorage point in Section 1910.66 (Appendix C) as follows:
“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.”
“The anchorage should be rigid, and should not have a deflection greater than .04 inches (1 mm) when a force of 2,250 pounds (10 kN) is applied.”
This regulation literally tells us that—for non-engineered systems— the rigid anchorage must be able to withstand 5000 pounds. Often times, a non-engineer will survey a location and simply estimate that a particular anchorage can bear a 5,000-pound load.
The statement which mentions “the design of a system to a safety factor of at least two, under the supervision of a qualified person” is only important to the Qualified Person who engineers complete fall protection systems. As long as the individual designing a system is a “Qualified Person” as defined by OSHA and ANSI Z359, they can engineer a “complete personal fall arrest system” to a safety factor of two. A safety factor of two simply means that if—for example—the system needs to withstand a load of 2,000 pounds, the anchorage point must be capable of supporting twice that much (4,000 pounds). Again, the engineer must be in conformance with the “Qualified Person” requirement as defined by OSHA. This means the fall protection system will be safe but not overdesigned.
NOTE: For safety related questions such as this one, please consult a qualified engineer with any questions or concerns.
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