Why did OSHA Decide on 5,000 lbs of Anchorage Strength? Is it Strong Enough?

In my last blog, I explained the requirements from OSHA for anchorage strength and who determines the strength of the anchorage. But where did the actual number of “5,000” lbs OSHA anchorage strength come from? And why is it 5,000 lbs and not 3,000 lbs, or 10,000 lbs? My research has led to many different explanations, from the theory that 5,000 lbs was the ultimate strength of the old Hemp rope originally used in fall protection, to the theory that European medical testing showed that 2,700 lbs was the limit of harness force before injury took place (OSHA approximately doubled it), to the theory that 5,000 lbs was the onset of death when dogs were used as test subjects in “live” drops tests. (Gruesome! Thank goodness that testing protocol never made it into ANSI standards.)

Unfortunately, there exists no clear explanation as to the origin of the 5,000 lb value. I can tell you this however... As I sit on many different standards committees that write specifications (not only for fall protection but also other products), sometimes the values are determined simply by consensus among the members. And considering 5,000 is a nice “round” number, my guess is it was exactly this consensus process that generated the number “5,000”. Unfortunately, much time has passed since this value was originally defined by OSHA back in 1968-1970. We know much more, now and are much better informed about fall protection these days. Usage (and unfortunately mis-usage) is much higher today. As a result, this OSHA requirement of 5,000 lbs of anchorage strength can in some cases actually be too small…..

Let’s look at where 5,000 lbs of anchorage strength may not be strong enough.

Is 5,000 lbs per employee OK for a single point attachment? Yes, absolutely. As long as a Competent Person (as defined by OSHA) can determine the attachment point can withstand 5,000 lbs without failure in EVERY direction that the forces will be applied, it will be OK for use per OSHA. This type of anchorage is called a “Non-Certified Anchorage” because a Qualified Person did not certify it.
What about hanging a light weight rigid track for fall protection? Generally this will not be a problem, but call the manufacturer to be sure. They, like me, will be more than happy to supply you with hanger loads and clarifications on how to determine anchorage strength. (See my first blog for the explanation as to where 5,000 lbs of anchorage strength may NOT be required.)
What about stringing a horizontal wire rope between two anchorage points? This is where things can become VERY very dangerous on many different levels. But for the sake of brevity, let’s just talk about anchorage strength (the dangers of wire rope fall distances and other hazards will be covered in a different blog update). Most people do not realize that there exists absolutely NO federal regulation for equipment design standards of horizontal wire rope systems in OSHA 1910 and 1926. There is only a requirement that a Qualified Person design the system, and also brief reference to generic horizontal lifelines buried in OSHA 1915. Does this mean that you can do as you please? No, because of two reasons:
- First, OSHA does have commentary on wire rope systems. This can be found in OSHA 1910.66 App C Section IIII (Non-mandatory). Here OSHA correctly defines the anchorage forces on a wire rope system can be up to 6 times the applied force. So if you are using a 900 lb Maximum Arresting Force lanyard, the anchorage forces can be six times this 900 lbs which equals 5,400 lbs!!!!! That is well over the 5,000 lb minimum requirement. So be very careful with wire rope systems. (When in doubt call the wire rope manufacturer.)
- This brings us to our second reason. As a member of the Z359 ANSI standards committee, I know that there will soon be a new ANSI standard coming out for flexible horizontal wire rope systems in (probably) November of 2010. It will be called Z359.17. This standard will then become the de facto “law” that OSHA can cite under their General Duty Clause (more about the dreaded “General Duty Clause” in a later blog). This new ANSI standard will require that all installations of wire rope be engineered to a very specific set of equipment standards by a Qualified Person.

The bottom line is anchorage will most likely be safe if a Competent Person determines the anchorage is good for 5,000 lbs of strength on most single point attachment. Wire rope systems should NEVER be attached to Non-Certified Anchorages, and light weight rigid track systems have benefits that may allow users go below the 5,000 lb requirement when the manufacturer’s directions are followed. (Again, the manufacturer’s, like us, will be more than happy to supply you with hanger loads and clarifications on how to determine anchorage strength.)

So good luck everyone. Choose your fall protection carefully.

Stay tuned for more fall protection insight and news every month.

Thanks for reading!

As always- Stay safe, and I am here if you need me….

Arnold Timothy Galpin, P.E.

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Arnold Timothy Galpin, P.E.
Jan 20, 2012
09:03 AM

Yes, if you apply a load of 5000 lbs in the same direction as the fall force for 2 minutes, and there is no indication of failure that includes the measurement of and absence of plastic deformation, then you are in compliance with the OSHA law. Be very careful to guard against leading edge failures however. You have stated that the anchorage is 3 feet from the edge of a tank. Sharp edges can cut fabric lanyards and even 3/16" diameter steel cables. Consult with your equipment manufacturers before using any component in a leading edge application.
Brad
Jan 13, 2012
02:45 PM

Your statement above “attachment point can withstand 5,000 lbs. without failure in EVERY direction that the forces will be applied, it will be OK for use per OSHA.” In this question I am talking about a single anchor point that will be used by one worker using a 6 ft. lanyard and a full body harness. The anchor is on top of a tank. The anchor point is 3 ft., from the edge of the tank so the worker can only fall 3 ft. before shock absorber deploys. My question is to determine the 5000 lbs., can you hang a 5000 load on the anchor point for 2 minutes and that would meet OSHA regulations? Regards, Brad Green CSP, OHST, CHST Health and Safety Coordinator