Restraining tall scaffolds, 29 CFR 1926.451(c)(1)
When height divided by base width is more than 4:1, a supported scaffold is restrained with guys, ties or braces, repeated vertically:
- Scaffolds 3 ft wide or less: every 20 ft or less.
- Scaffolds wider than 3 ft: every 26 ft or less.
A 36 ft scaffold on a 5 ft base is 36 ÷ 5 = 7.2 to 1, above 4:1, and wider than 3 ft, so ties every 26 ft or less. A 6:1 trigger is not in the rule, and width only changes the spacing.
Access and platform gaps, 1926.451
- Access, (e)(1): required when a platform is more than 2 ft above or below the point of access. A platform 30 in up needs access. The traps are 6 ft (the Subpart M edge trigger), 10 ft (the scaffold fall protection trigger in (g)(1)).
- Gaps, (b)(1)(i): no more than 1 in between adjacent platform units. Six inches is the minimum end extension past a support; 12 in is the maximum overhang for platforms 10 ft or shorter.
Ladder strength, 1926.1053(a)(1)
- Portable ladders: at least 4 times the maximum intended load; 3.3 times for extra-heavy-duty Type 1A metal or plastic.
- Fixed ladders, (a)(1)(iii): at least two 250 lb loads concentrated between consecutive attachments, and each rung or step supports a single 250 lb concentrated load.
The trap: 4 times the maximum intended load is the portable rule, not the fixed rule.
Digging below a shield, 1926.652(g)(2)
Earth may be excavated up to 2 ft below the bottom of a shield only if both conditions hold:
- The shield is designed for the full depth of the trench.
- There is no sign of soil loss from behind or below it.
A shield designed for 8 ft in a 10 ft trench fails the first condition, so the bottom 2 ft cannot be dug below it. The 2 ft figure is a limit, not a permission on its own. "Never" is also wrong: when both conditions are met, it is allowed.