Ask Rigid Lifelines: What’s my structure’s anchorage requirement?
November 9, 2015
Question:
Does my structure holding your track need to meet the 5,000-pound anchorage requirement?
Answer:
To begin, OSHA defines “anchorage” as “a secure point of attachment for lifelines, lanyards or deceleration devices, and which is independent of the means of supporting or suspending the employee.” OSHA’s 5,000-pond anchorage requirement has three sections, OSHA 1926.502(d)(15), (d)(15)(i), and (d)(15)(ii):
- OSHA 1926.502(d)(15): “Anchorages used for attachment of personal fall arrest equipment shall be independent of any anchorage being used to support or suspend platforms and capable of supporting at least 5,000 pounds (22.2 kN) per employee attached, or shall be designed, installed, and used as follows:
- OSHA 1926.502(d)(15)(i): as part of a complete personal fall arrest system which maintains a safety factor of at least two; and
- OSHA 1926.502(d)(15)(ii): under the supervision of a qualified person.”
The safety factor of at least two mentioned in OSHA 1926.502(d)(15)(i) is the key to this question. OSHA’s 5,000-pound rule and the safety factor of two come from the force load generated at the maximum allowable free-fall height of six feet. With a 220-pound worker, a free-fall from six feet generates 2,500 pounds of force. The 5,000-pound requirement comes from a safety factor of two based on the 2,500 pounds of force. Even though a six-foot free-fall generates 2,500 pounds of force, the worker is only allowed to experience up to 1,800 pounds of force per OSHA. The force exerted on the worker can be reduced by decreasing the free-fall distance or by using a shock-absorbing lanyard (SAL). The best way to decrease the free-fall distance is to use a self-retracting lanyard (SRL). However, ANSI standards limit the maximum allowable force exerted on a worker to 900 pounds. Using the safety factor of two, the anchorage must be able to withstand 1800 pounds of force. 1800 pounds is considerably less than the 5,000 pounds. But when can you use the safety factor of two instead of the 5,000-pound anchorage requirement?
There is an easy way to determine if it is safe to use the safety factor of two: if you’re tying off to an engineered fall protection system that meets ANSI standards, then it is safe to use the 1800-pound safety factor of two. If your tying-off to a point that hasn’t been tested or designed for fall arrest, such as a beam, then that point must be able to withstand 5,000 pounds of force. In fact, ANSI Z359.2 uses the terms “non-certified anchorages” and “certified anchorages” in their standard. As always, if in doubt, seek an expert out.
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