Load capacity: 4 times, ropes 6 times
29 CFR 1926.451(a)(1): each scaffold and scaffold component must support its own weight plus at least 4 times the maximum intended load.
1926.451(a)(3): each suspension rope, including its connecting hardware, must support at least 6 times the maximum intended load. For 500 lb: 6 × 500 = 3,000 lb.
Traps:
- Using 4x for ropes (4 × 500 = 2,000 lb) is the common error.
- 3.3x is the Type 1A ladder rule.
- 2x appears only in the suspension scaffold hoist calculation (2 times the stall load). A 5x factor is not in the rule.
Fall protection: more than 10 ft
1926.451(g)(1): each employee on a scaffold more than 10 ft (3.1 m) above a lower level must be protected from falling. A worker on a platform 8 ft up is not more than 10 ft, so none is required.
Trap: applying the 6 ft Subpart M edge trigger to scaffolds. 4 ft is general industry; 5 ft is the excavation protective-system depth.
Toprail height
1926.451(g)(4)(ii): on supported scaffolds manufactured or placed in service after January 1, 2000, the toprail goes 38 to 45 in (0.97 to 1.2 m) above the platform surface.
Trap: 36 to 45 in is allowed only for older scaffolds and for suspended scaffolds that need both a guardrail and a personal fall arrest system.
Platform width and overhang
- Width, 1926.451(b)(2): each platform and walkway at least 18 in (46 cm) wide. Only ladder jack, top plate bracket, roof bracket and pump jack scaffolds may drop to 12 in.
- End extension, (b)(4): unless cleated or otherwise restrained, each end extends over the centerline of its support at least 6 in (15 cm).
- Maximum overhang, (b)(5): 12 in for platforms 10 ft or shorter, 18 in for platforms longer than 10 ft, unless the cantilever is designed for the load. A 12 ft platform may overhang 18 in.
Trap: mixing up the 6 in minimum extension with the 12 or 18 in maximum overhang. 24 in appears nowhere.