Evaluating Fall Protection Anchors on Site

Every other part of a fall arrest system comes with a label. The anchor often does not. A harness and an SRL are bought, tested and rated. The steel beam, truss or concrete wall they connect to is whatever the job site gave you. OSHA's guidance calls anchor planning probably the most overlooked part of a fall arrest system. A worker on a truss roof can do everything right and still fall, if the truss was not braced and comes down when the line loads. This is for leads and competent persons who have to look at a tie-off point and decide. It helps you ask the right questions. It does not make you a structural engineer, so when you cannot confirm the strength, stop and get a qualified person.

What You Will Be Able to Do

• Apply the anchor strength rule to one worker and to several.
• Say when a 2:1 design is allowed, and what comes with it.
• Run a field check on a proposed anchor.
• Explain why a tight horizontal lifeline loads its anchors so hard.
• Say who can approve what, and when to stop.

The Strength Rule

Under 1910.140(c)(13) and 1926.502(d)(15), an anchor for fall arrest has to meet one of two tests.

Worked example: Three workers will use one anchor point.

1. 3 x 5,000 = 15,000 pounds.
2. A beam strap rated 5,000 pounds covers one worker only. Clipping three people to it breaks the rule, even though it feels like the same strap.
3. Each worker gets their own anchor, or a qualified person designs a system for three.

Worked example: A qualified person designs a system with lanyards that limit the arresting force to 1,800 pounds.

1. 1,800 x 2 = 3,600 pounds.
2. The anchor could be used at that strength, because it is part of a complete, designed system.
3. That number belongs to the whole design. Swap the lanyard for a different connector, and the design no longer applies. The qualified person also has to supervise how it is installed and used.

The 2:1 route is not a discount you can claim in the field. If nobody qualified designed it, the number is 5,000 pounds.

Anchors must also be independent of any anchor that holds up a work platform or suspends a worker. A rope descent or swing stage needs its own separate fall arrest anchor, so that one failure cannot take out both.

Field Check for a Proposed Anchor

Run these eight questions in order. A "no" or "not sure" on any of them means stop.

1. What is it? Is it a rated anchor device, or a part of the structure you hope to use?
2. What is it attached to? An anchor is only as strong as the member behind it, and the fasteners between them.
3. Who approved it? Is there a tag, a drawing, or a name?
4. How many people, and how will it be loaded? Many anchors and eyebolts are rated for one direction, and they lose strength when pulled sideways.
5. Where is it? At or above D-ring height, as close as you can get to directly over the work.
6. What does the line touch? Follow it from the anchor to the edge. Look for sharp corners.
7. What shape is it in? Look for rust, cracks, bent parts, loose bolts and rot.
8. Does it clear the rest? Does this position still pass your free fall, clearance and swing math?

Common Anchor Types

Install any manufactured anchor exactly as the maker says, down to the fastener type, count and spacing. OSHA notes that some anchors stay in place for later use, get covered by roofing, or are cut flush with a surface. An old anchor that you find on a roof is not a free tie-off point. Find out its rating, what it is fastened to, and when it was last inspected. If you cannot, treat it as unknown.

Using the Structure

Sometimes you have to make an anchor from what is there. OSHA's guidance for construction, in Appendix C of Subpart M, gives examples of what might be appropriate:

• Steel members or I-beams, with an acceptable strap.
• Large eyebolts of a suitable grade of steel.
• Guardrails or railings, only if they were designed to be used as an anchor.
• Masonry or wood, only if the attachment point is substantial, and bolts or connectors cannot pull through.

The same guidance says a qualified person should evaluate these makeshift anchors for strength. In construction, a fall arrest system also may not be attached to a guardrail system or a hoist under 1926.502(d)(23), except as other parts of the rules allow.

Things that are not anchors: conduit, sprinkler and small pipe, roof vents, ladder rungs, light fixtures, cable tray, and unbraced framing. Each one looks solid until it gets hit with a sudden load. OSHA's Technical Manual describes a case where trusses that were not fully installed, braced and sheathed collapsed under a falling worker.

How You Connect Matters

The strength of the system assumes a clean connection.

Those strength figures come from Appendix C of Subpart M. Both rule sets ban connecting a snap hook or carabiner to an object it can roll off or be forced open by, unless it is designed for that connection.

Horizontal Lifelines: Why Tight Is Not Better

People like a horizontal lifeline tight, because it looks secure. The physics runs the other way. When a load hits the middle of a nearly straight line, the line pulls far harder on its end anchors than the load itself.

OSHA gives these amounts in Appendix C:

Worked example: A fall puts 900 pounds on a horizontal lifeline.

1. At a 15-degree sag, the line carries about 900 x 2 = 1,800 pounds.
2. At a 5-degree sag, it carries about 900 x 6 = 5,400 pounds.
3. Those are the loads that reach the end anchors.

So a tighter line loads the anchors harder, and a looser line drops the worker farther. A qualified person balances those two things. Energy absorbers in the line are one way of doing it. OSHA also warns that with more than one worker on a line, one person's fall can pull others off. Strength has to go up for each added worker.

That is why the field rule is simple: never rig a horizontal lifeline from a rope and two handy beams. A qualified person designs it, and it gets installed and used as designed.

Aerial Lifts as Anchors

The basket anchor on a lift is an anchor point with its own rules. A fall arrest system must not be attached to an aerial lift unless the lift can take the load of an arrested fall. Use the point the maker provides, and read the manual on arrest versus restraint.

Vehicles and equipment as anchors are a similar question. Unless the maker or a qualified person says so, assume they are not.

Who Decides

The rules do not say who confirms an anchor in every case, so your employer's program should name it. If nobody on site can say what an anchor will hold, the answer is that it is not an anchor yet.

Keeping Track of Anchors

On a plant or building with permanent anchors, keep a simple record:

1. Anchor ID, marked on the anchor.
2. A location map or roof plan.
3. Rating, and how many users it allows.
4. Who installed it and when, plus the certification or design.
5. Inspection dates, at the interval the maker states.

Take an anchor out of use and tag it after any fall load, damage or structural change nearby, such as a reroof. The next contractor on that roof should not have to guess.

Common Mistakes

Check Your Understanding

1. A crew wants to tie off to a sprinkler pipe that looks solid. What do you say?

No. Sprinkler and small pipe are not anchors. They look solid until a sudden load hits them.

2. A painter on a swing stage plans to clip his fall arrest line to the same anchor that holds up the stage. Is that acceptable?

No. The fall arrest anchor has to be independent of any anchor that holds up a platform, so one failure cannot take out both.

3. A worker fastens a roof anchor into the metal deck only, because the structure is hard to reach. What is wrong?

An anchor is only as strong as what it attaches to. A roof anchor has to reach the structure, not just the deck.

4. A worker clips two snap hooks onto one D-ring. Why is that a problem?

One hook can press open the other's gate. Use one connector per D-ring, unless it is designed for two.

5. A beam strap stopped a fall yesterday and looks fine. Can it go back on the job?

Not until a competent person clears it, and many makers require you to retire it. Looking fine does not settle it.

Key Takeaways

• An arrest anchor holds 5,000 pounds for each worker, or is part of a complete 2:1 system under a qualified person.
• An anchor is only as strong as what it attaches to, and how it is connected.
• Run the field check, and treat "not sure" as a stop.
• Keep anchors separate from anything that holds up a platform or suspended worker.
• Tight horizontal lifelines multiply anchor loads, so these systems must be designed by a qualified person.
• If nobody on site can say what it will hold, it is not an anchor yet.