United States
Hong KongPersonal fall arrest system numbers
Maximum arresting force 1,800 pounds with a body harness, maximum free fall 6 feet, maximum deceleration distance 3.5 feet, and anchorage strength 5,000 pounds per employee. All at 29 CFR 1926.502(d).
Four numbers in one provision, and questions routinely give you three and ask for the fourth.
The four
| Requirement | Figure |
|---|---|
| Maximum arresting force, body harness | 1,800 pounds |
| Maximum free fall distance | 6 feet |
| Maximum deceleration distance | 3.5 feet |
| Anchorage strength per employee | 5,000 pounds |
All at 29 CFR 1926.502(d), so one tab covers all four.
Why the numbers are what they are
Eighteen hundred pounds is roughly what a body can absorb without serious internal injury. A body belt, which concentrates force at the waist, is not permitted as part of a personal fall arrest system for that reason.
Six feet of free fall plus three and a half of deceleration is where the total fall distance calculation starts.
Free fall plus deceleration plus harness stretch plus a safety margin, measured from the anchorage. A worker at eight feet with a six-foot lanyard hits the ground before the system arrests them, and that is the scenario questions describe.
The anchorage figure
Five thousand pounds per employee attached, or a system designed by a qualified person with a safety factor of at least two.
Note the alternative. It is not five thousand pounds or nothing, and the alternative requires a qualified person specifically.
Inspection
Before each use, and any component subjected to an arrest is removed from service. A harness that has caught a fall does not go back on the rack.
Common questions
What is the maximum arresting force?
1,800 pounds with a body harness, under 29 CFR 1926.502(d)(16).
What is the maximum free fall distance?
6 feet, with a maximum deceleration distance of 3.5 feet.
What anchorage strength is required?
5,000 pounds per employee, or a system designed by a qualified person with a safety factor of at least two.
Why is a body belt not permitted?
It concentrates arresting force at the waist. A body harness distributes it, which is why the 1,800 pound limit is stated for harnesses.
What happens to equipment after a fall?
Any component subjected to an arrest is removed from service.