Scaffold Guardrail System Check (OSHA 1926.451(g)(4))
The guardrail scaffold-takeoff says is taken off separately, and two things make it more than a tape check. The midrail is specified by RELATION, not a number -- approximately midway between the top edge and the platform -- so the target MOVES with the top rail, and a shop standard set for a 45 in rail sits 3.5 in high under a 38 in one. And the capacities are PAIRED: 200 lbf on the top rail for scaffolds generally, 100 lbf for single- and two-point adjustable suspension, and 150 lbf on the midrail only where the top rail carries 200. Top edge 38 to 45 in, and never under 36. Toeboard at least 3.5 in from its top edge to the walking surface -- though WHETHER one is required is falling-object protection under 1926.451(h) and a different question. OSHA is public domain, so the values are quoted.
Formula and source
top rail passes at 38 in <= height <= 45 in; the midrail target is top rail height / 2, tested against a user-set band because the standard says approximately midway; required top rail capacity is 200 lbf for all other scaffolds and 100 lbf for single- and two-point adjustable suspension scaffolds; the 150 lbf midrail capacity applies only where the top rail requirement is 200 lbf; toeboard height >= 3.5 in.
OSHA 29 CFR 1926.451(g)(4), Subpart L - Scaffolds. A US federal regulation in the public domain, so the values are quoted directly rather than paraphrased.
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