I am often impressed with how thoroughly our clients think about and investigate fall protection issues. I am proud to work with people who take protecting workers so seriously. After some internal research into the issue of impact protection for skylights, one of our clients asked, “Why is a 5,000-pound tie off point required for fall arrest, but we only need a 200-pound screen over skylights?” Great question.
The bottom line is that the physics associated with stopping a 6-foot free fall with a fall arrest system are similar, but different than accounting for a fall from the same surface, in the case of a skylight incident. The difference lies in the distribution of force over the structure and the maximum free fall distance, which both affect the forces generated during a fall—somewhat explaining the difference in requirements.
If you select a skylight screen as opposed to guardrail, I recommend the “California” version, which requires load resistance up to 400 lbs., instead of the typical 200-pound requirement. This additional strength provides increased stability and impact resistance, which translate to additional protection during a fall.
To review some research on this topic, please see this NIOSH research report.