Portable 29 CFR 1910.25 and

When portable ladders are used for access to an upper landing surface, the side-rails must extend at least 3 feet above the upper landing surface. When such an extension is not possible, the ladder must be secured, and a grasping device such as a 

FIGURE 25.18 Safe use of portable ladder. (Source Courtesy of the Occupational Safety and Health Administration.) 

Ladders must be used only on stable and level surfaces unless secured to prevent accidental movement. Ladders must not be used on slippery surfaces unless secured or provided with slip-resistant feet to prevent accidental movement. Slip-resistant feet must not be used as a substitute for the care in placing, lashing, or holding a ladder upon slippery surfaces. Ladders placed in areas such as passageways, doorways, or driveways, or where they can be displaced by workplace activities or traffic, must be secured to prevent accidental movement or a barricade must be used to keep traffic or activities away from the ladder. The area around the top and bottom of the ladders must be kept clear. 

The top of a non-self-supporting ladder must be placed with two rails supported equally unless it is equipped with a single support attachment. Ladders must not be moved, shifted, or extended while in use. Ladders must have nonconductive 

A double-cleated ladder, or two or more ladders, must be provided when ladders are the only way to enter or exit a work area having twenty-five or more employees, or when a ladder serves simultaneous two-way traffic. Ladder rungs, cleats, and steps must be parallel, level, and uniformly spaced when the ladder is in position for use. Rungs, cleats, and steps of portable and fixed ladders (except as provided below) must not be spaced less than 10 inches apart, or more than 14 inches apart, along the ladder s side-rails. Rungs, cleats, and steps of step stools must not be less than 8 inches apart, nor more than 12 inches apart, between center lines of the rungs, cleats, and steps. 

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