Applies to all ladders, job-made ones included. Strength: self-supporting and non-self-supporting portable ladders carry no less than four times their maximum intended load (3.3 times for type 1A extra-heavy-duty metal or plastic ones), tested with the load applied vertically downward and, for non-self-supporting ladders, at 75 1/2 degrees from horizontal. Fixed ladders carry at least two 250-pound loads between any two consecutive attachments, plus further 250-pound loads for expected use and loads from ice, wind, rigging and ladder safety device impacts, with each rung or step holding 250 pounds at mid-span. Ladders built to Appendix A are deemed compliant. Design: rungs, cleats and steps parallel, level and evenly spaced; spacing 10 to 14 inches on portable and fixed ladders, 8 to 12 inches on step stools, 8 to 18 inches on extension trestle bases and 6 to 12 inches on their extensions. Clear width 16 inches for fixed and individual-rung ladders and 11 1/2 inches between rails on portable ladders. Individual rungs are shaped so feet cannot slide off; metal rungs on portable ladders, and on fixed ladders made after March 15, 1991, are treated against slipping. Ladders are not joined to make longer ones unless designed for it; stepladders have a metal spreader or lock; spliced rails equal a one-piece rail. Separate ladders reaching one work area are offset with a platform between them, except portable ladders used to reach elevated fixed ladders. Surfaces must not puncture, cut or snag; wood ladders carry no opaque coating other than labels on one rail face. Fixed ladder clearances: 7 inches behind rungs (4 1/2 inches for elevator pit ladders), 30 inches on the climbing side (24 inches with a deflector around unavoidable obstructions), step-across of 7 to 12 inches for through ladders or a landing platform, 15 inches each side of the centreline without cage or well. Fixed ladders need a cage, well, ladder safety device or self-retracting lifeline when the climb is under 24 feet but the top is more than 24 feet above lower levels; where the climb is 24 feet or more, they need either a ladder safety device, or self-retracting lifelines plus rest platforms at 150 feet or less, or a cage or well with offset sections of 50 feet or less and landings at 50-foot maximum intervals. Cages and wells follow detailed dimensions (27 to 30 inches from the rung centreline, bands 4 feet apart, bars 9 1/2 inches apart, bottom 7 to 8 feet above access, cage top 42 inches above the platform, well width 30 inches). Ladder safety devices survive an 18-inch drop of 500 pounds, leave both hands free, engage within 2 feet and hold descent to 7 feet per second, with a connection of 9 inches or less; flexible carrier cable guides sit 25 to 40 feet apart when wind-exposed. Side rails extend 42 inches above the landing, through-ladder extensions flare to 24 to 30 inches (36 with safety devices), side-step rails continue, and individual-rung ladders extend 42 inches with grab bars unless under a hatch. Use: portable ladders reaching an upper surface extend at least 3 feet above it or are secured at the top with a grabrail; kept free of oil and grease; never overloaded beyond intended or rated capacity; used only for their purpose; set at about a 1-to-4 horizontal ratio (1-to-8 for spliced wood job-made ladders), fixed ladders no steeper than 90 degrees; on stable, level, non-slippery ground or secured; secured or barricaded where traffic could displace them; top and bottom areas kept clear; both rails supported at the top; not moved while occupied; nonconductive rails near exposed energized equipment (1926.955(b) and (c) excepted); top step and rear bracing of stepladders not used; single-rail ladders banned; users face the ladder, keep at least one hand on it and carry nothing that could unbalance them. A competent person inspects ladders periodically and after any event that could affect them; defective portable ladders are marked or tagged Do Not Use and withdrawn, defective fixed ladders are tagged, marked or blocked, and repairs restore original design criteria.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.