(1) Ladders shall be used to enter and exit manholes exceeding four feet in depth.

(2) Metal and fiberglass manhole ladders shall be free of structural defects and free of accident hazards such as sharp edges and burrs. The metal shall be protected against corrosion unless inherently corrosion-resistant. These ladders may be designed with parallel side rails, or with side rails varying uniformly in separation along the length (tapered) or with side rails flaring at the base to increase stability.

(3) The spacing of rungs or steps shall be on twelve-inch centers.

(4) Connections between rungs or steps and side rails shall be constructed to ensure rigidity as well as strength.

(5) Rungs and steps shall be corrugated, knurled, dimpled, coated with skid-resistant material, or otherwise treated to minimize the possibility of slipping.

(6) Ladder hardware shall meet the ladder's component parts and shall be of a material that is protected against corrosion unless inherently corrosion-resistant. Metals shall be so selected as to avoid excessive galvanic action.