Fall Arrest Anchorage and System Force Check (OSHA 1926.502(d))
What a fall-arrest anchorage and system must WITHSTAND -- and the two governing numbers are not the same number.
Example
You enter
- Workers attached to this anchorage 2
- Anchorage capacity (lb; 0 to skip) 5000
- Anchorage route prescriptive
- Maximum arresting force on the worker (lb; 0 to skip) 1600
- Deceleration distance (ft; 0 to skip) 3.5
- Free fall distance (ft; 0 to skip) 6
You get
- Anchorage required 10000
- Anchorage shortfall (lb) 5000
Details, formula, and sources
The 5,000 lb is what the ANCHORAGE supports; the 1,800 lb is what the SYSTEM may impose on the WORKER. An anchor rated 5,000 says nothing about whether the lanyard keeps the body under 1,800. Two traps: the 5,000 is PER EMPLOYEE ATTACHED, so two workers on one anchor is 10,000; and the alternative engineered route only needs a safety factor of two under a qualified person, so a designed anchorage can legitimately be far below 5,000. Also checks the 3.5 ft deceleration and 6 ft free-fall limits -- and notes the free-fall rule's second half, NOR CONTACT ANY LOWER LEVEL, which has no number in it at all.
prescriptive anchorage requirement = 5,000 lb x employees attached; engineered requirement = 2 x the design load the system can impose; achieved safety factor = capacity / design load. System checks: arresting force <= 1,800 lb with a body harness, deceleration distance <= 3.5 ft, free fall <= 6 ft.
OSHA 29 CFR 1926.502(d)(15) and (d)(16), Subpart M - Fall Protection. US federal regulations in the public domain, quoted directly.
29 CFR is published in full at no cost by OSHA and the eCFR.
Estimate. AHJ and licensed professional govern.
Field names used by the API: workers_attached, anchorage_capacity_lb, design_route, arresting_force_lb, deceleration_distance_ft, free_fall_ft, required_anchorage_lb, anchorage_shortfall_lb
- Prescriptive anchorage 5,000 lb PER EMPLOYEE ATTACHED29 CFR 1926.502(d)(15)
- Engineered alternative safety factor of at least two, under a qualified person29 CFR 1926.502(d)(15)
- Arresting force 1,800 lb maximum on the employee with a body harness29 CFR 1926.502(d)(16)
- Deceleration and free fall 3.5 ft and 6 ft maximums, and no contact with a lower level29 CFR 1926.502(d)(16)
- Strength in energy twice the impact energy of a 6 ft free fall, or the permitted free fall, whichever is less29 CFR 1926.502(d)(16)
- Not checked clearance, body belts, horizontal lifelines, swing fall, snaphooks, inspection, rescuestated scope limit