Fall Protection by Height and Task
The 6 ft trigger, the system that satisfies it, the anchor strength the crew needs, the clearance a fall arrest takes, the net geometry, and the plan and training duties under OSHA 1926 subpart M.
The construction trigger is 6 ft above a lower level, and 10 ft on a scaffold platform. An anchor takes 5,000 lb per worker tied off, a fall arrest needs about 17.5 ft of clearance below the work level, and a safety net is set no more than 30 ft below.
How the math works
- The 6 ft trigger (1926.501(b)(1)): fall protection is required at 6 ft above a lower level for leading edges, roofs, holes, ramps, runways, hoist areas, and excavations. Scaffold platforms trigger at 10 ft (1926.451(g)(1)), steel erection at 15 ft with the decking and leading-edge rules in 1926.761, and a hoist area at 6 ft with the guardrail gates (1926.501(b)(2)).
- Guardrail (1926.502(b)): the top rail stands 42 in plus or minus 3 in above the walking surface, the top rail and the mid member meet the 200 lb test at any point, a mid member is at the midpoint, a screen or toe board is at the base, and every open side of a work area, a ramp, a runway, and a hoist area gets a guardrail.
- Fall arrest (1926.502(d)): an anchor is rated to 5,000 lb per employee attached, a horizontal lifeline is designed by a qualified person, free fall is limited to 6 ft, the deceleration distance is limited to 3.5 ft, the arresting force is limited to 900 lb with a full-body strap, snap hooks are eye-hook type and are not connected to a web, and a body belt is not a fall arrest.
- Safety nets (1926.501(b)(1) and 1926.502(c)): a net is installed no more than 30 ft below the work level, no more than 15 ft below for a work level of 25 ft, extends 10 ft horizontally beyond the edge at 25 ft and under, 15 ft beyond over 25 ft to 30 ft, the net does not touch the level below, and each net carries a manufacturer tag with a date.
- Roofing (1926.502(g) and (h)): a warning line is set 6 ft from a low-slope roof edge, a controlled access zone is 6 ft from the edge, the perimeter is monitored by a designated person with the line, and a designated area on a low-slope roof requires the work to stay 50 ft from the edge with the plan; all three are roofing-specific systems.
When does construction require fall protection?
At 6 ft above a lower level for the standard construction trigger (1926.501(b)(1)), 10 ft on a scaffold platform (1926.451(g)(1)), and 15 ft in steel erection with the decking rules (1926.761). A hole in a floor is protected at 6 ft, and a leading edge is protected from the first step onto it.
How strong must a fall arrest anchor be?
5,000 lb per employee attached (1926.502(d)(15)). A rope sling on a beam, a beam clamp, a column strap, a truss anchor, a concrete roof deck anchor, and a horizontal lifeline are all anchors, and each carries its own rating and install; a scaffold tube, a gutter, a handrail, and a vent pipe are not anchors.
How much clearance does a fall arrest need?
About 17.5 ft below the work level: 6 ft of free fall, 3.5 ft of deceleration, the lanyard and D-ring deployment, and 2 ft of margin. A 12 ft roof edge with a 6 ft lanyard lands a worker on the ground, and the system changes to a guardrail, a net, a 5 ft deceleration lanyard, and a work level with clearance.