(a) Design requirements and considerations. All ladders, appurtenances, and fastenings shall be designed to meet the following load requirements: - (i) The minimum design live-load shall be a single concentrated load of 200 pounds.
- (ii) The number and position of additional concentrated live-load units of 200 pounds each as determined from anticipated usage of the ladder shall be considered in the design.
- (iii) The live-loads imposed by persons occupying the ladder shall be considered to be concentrated at such points as will cause the maximum stress in the structural member being considered.
- (iv) The weight of the ladder and attached appurtenances together with the live-load shall be considered in the design of rails and fastenings.
(b) Specific features-Rungs and cleats. - (i) All rungs shall have a minimum diameter of three-fourths (3/4) inch for metal ladders, and a minimum diameter of one and one-eighths (1-1/8) inches for wooden ladders.
- (ii) The distance between rungs, cleats, or steps shall not exceed twelve (12) inches, measured from the top of rung, cleat or step to the top of the next rung, cleat or step, and shall be uniform throughout the length of the ladder.
- (iii) The minimum clear length of rungs or cleats shall be sixteen (16) inches.
- (iv) Rungs, cleats, and steps shall be free of splinters, sharp edges, burrs, or projections which may be a hazard.
- (v) Where there is a walking/working platform or access to a ladder twenty-four (24) inches or more above the floor or ground level, a step or steps of not more than twelve (12) inches riser height shall be provided for access.
- (vi) Side rails which might be used as a climbing aid shall be of such cross-sections as to afford adequate gripping surface without sharp edges, splinters or burrs.
- (vii) Fastenings shall be an integral part of fixed ladder design.
- (viii) All splices and connections shall have smooth transition with original members and with no sharp or extensive projections.
- (ix) Adequate means shall be employed to protect dissimilar metals from electrolytic action when such metals are joined.
- (x) All welding shall be in accordance with the "Code for Welding in Building Construction " (A WS Dl. 0-66).
- (xi) Protection from deterioration. Metal ladders and appurtenances shall be painted or otherwise treated to resist corrosion and rusting when location demands. When different types of materials are used in the construction of a ladder, the materials used shall be so treated as to have no deleterious effect one upon the other.
(c) On the climbing side of fixed ladders, the perpendicular distance from the centerline of the rungs to the nearest permanent object shall be thirty-six (36) inches for a pitch of 76°, and thirty (30) inches for a pitch of 90°, with minimum clearances for intermediate pitches varying between these two limits in proportion to the slope, except as provided in paragraph (3) of this subsection. - (i) Ladders without cages or wells. A clear width of at least fifteen (15) inches shall be provided each way from the centerline of the ladder in the climbing space, except when cages or wells are necessary.
- (ii) Clearance in back of ladder. The distance from the center-line of rungs, cleats or steps to the nearest permanent object in back of the ladder shall be not less than seven (7) inches. When unavoidable obstructions are encountered, minimum clearances for the two rungs on either side of the obstruction shall be measured vertically from the obstruction no less than one and a half (1 V-i) inches to the upper rung and four and a half (4%) inches to the lower rung.
- (iii) Clearance in back of grab bar. The distance from the centerline of the grab bar to the nearest permanent object in back of the grab bar shall not be less than four (4) inches. Grab bars shall not protrude on the climbing side beyond the rungs of the ladder which they serve.
- (iv) Step-across distance. The step-across distance from the nearest edge of ladder to the nearest edge of equipment or structure shall be not more than 12 inches, or less than two and a half (2½) inches.
(d) Cages or wells shall be provided on ladders of more than twenty (20) feet to a maximum unbroken length of thirty (30) feet. - (i) Cages shall extend a minimum of forty-two (42) inches above the top of landing, unless other acceptable protection is provided.
- (ii) Cages shall extend down the ladder to a point not less than seven (7) feet nor more than eight (8) feet above the base of the ladder, with bottom flared not less than four (4) inches, or portion of cage opposite ladder shall be carried to the base.
- (iii) Cages shall not extend less than twenty-seven (27) nor more than twenty-eight (28) inches from the centerline of the rungs of the ladder. Cage shall not be less than twenty-seven (27) inches in width. The inside shall be clear of projections. Vertical bars shall be located at a maximum spacing of 40° around the circumference of the cage; this will give a maximum spacing of approximately nine and a half (9%) inches, center-to-center.
- (iv) Ladder wells shall have a clear width of at least fifteen (15) inches measured each way from the centerline of the ladder. Smooth-walled wells shall be a minimum of twenty-seven (27) inches from the centerline of rungs to the well wall on the climbing side of the ladder. Where other obstructions on the climbing side of the ladder exist, there shall be a minimum of thirty (30) inches from the centerline of the rungs.
(e) Landing platforms. When ladders are used to ascend to heights exceeding twenty (20) feet (except on chimneys), landing platforms shall be provided for each thirty (30) feet of height or fraction thereof except that, where no cage, well, or ladder safety device is provided, landing platforms shall be provided for each twenty (20) feet of height or fraction thereof. Each ladder section shall be offset from adjacent sections. Where installation conditions (even for a short, unbroken length) require that adjacent sections be offset, landing platforms shall be provided at each offset. - (i) Where an employee has to step a distance greater than twelve (12) inches from the centerline of the rung of a ladder to the nearest edge of structure or equipment, a landing platform shall be provided. The minimum step-across distance shall be two and a half (2½) inches.
- (ii) All landing platforms shall be equipped with standard railings and toeboards, so arranged as to give safe access to the ladder. Platforms shall be not less than twenty-four (24) inches in width and thirty (30) inches in length.
- (iii) One rung of any section of ladder shall be located at the level of the landing laterally served by the ladder. Where access to the landing is through the ladder, the same rung spacing as used on the ladder shall be used from the landing platform to the first rung below the landing.
(f) Ladder extensions. The side rails of through or side-step ladder extensions shall extend three and a half (3½) feet above parapets and landing. For through ladder extensions, the rungs shall be omitted from the extension and shall have not less than eighteen (18) nor more than twenty-four (24) inches clearance between rails. For side-step or offset fixed ladder sections, at landings, the side rails and rungs shall be carried to the next regular rung beyond or above the three and a half (3½) foot minimum.
(g) Grab bars shall be spaced by a continuation of the rung spacing when they are located in the horizontal position. Vertical grab bars shall have the same spacing as the ladder side rails. Grab-bar diameters shall be the equivalent of the round-rung diameters.
(h) Ladder safety devices may be used on tower, water tank and chimney ladders over twenty (20) feet in unbroken length in lieu of cage protection. No landing platform is required in these cases. All ladder safety devices such as those that incorporate lifebelts, full body harnesses, friction brakes, and sliding attachments as an integral unit shall meet the design requirements of the ladders they serve.
(i) The preferred pitch of fixed ladders shall be considered to come in the range of 75° and 90° with the horizontal. - (i) Fixed ladders shall be considered as substandard if they are installed within the substandard pitch range of 60° and 75° with the horizontal. Substandard fixed ladders are permitted only where it is found necessary to meet conditions of installation. This substandard pitch range shall be considered as a critical range to be avoided, if possible.
- (ii) This section covers only fixed ladders within the pitch range of 60° and 90° with the horizontal.
- (iii) Ladders having a pitch in excess of 90° with the horizontal are prohibited.
(j) All ladders shall be maintained in a safe condition. All ladders shall be inspected regularly, with the intervals between inspections being determined by use and exposure.
(k) Ladder requirements not specifically referenced in this section shall be in accordance with the State of Wyoming Occupational Health and Safety 1910 - General Rules and Regulations, Subpart D, Walking and Working Surfaces.
(l) All mast ladders on all drilling rigs are exempted from the requirements of subsections (b)(i), (ii), (iii) and (c) (ii) and (d) of this section, provided the employer makes available and requires the use of an approved personal fall arrest system.