(a) Except in anthracite mines using non-mechanized mining systems, when conventional roof support materials are used as the only means of support--
(b) Conventional roof support materials shall meet the following specifications: Post length (in inches) Diameter of round Posts (in inches Cross-sectional area of split posts (in square inches) 60 or less 4 13 Over 60 to 84 5 20 Over 84 to 108 6 28 Over 108 to 132 7 39 Over 132 to 156 8 50 Over 156 to 180 9 64 Over 180 to 204 10 79 Over 204 to 228 11 95 Over 228 12 113
- (2) Wooden materials used for support shall have the following dimensions:
- (i) Cap blocks and footings shall have flat sides and be at least 2 inches thick, 4 inches wide and 12 inches long.
- (ii) Crossbars shall have a minimum cross-sectional area of 24 square inches and be at least 3 inches thick.
- (iii) Planks shall be at least 6 inches wide and 1 inch thick.
- (3) Cribbing materials shall have at least two parallel flat sides.
(c) A cluster of two or more posts that provide equivalent strength may be used to meet the requirements of paragraph (b)(1) of this section, except that no post shall have a diameter less than 4 inches or have a cross-sectional area less than 13 square inches.
(d) Materials other than wood used for support shall have support strength at least equivalent to wooden material meeting the applicable provisions of this section.
(e) Posts and jacks shall be tightly installed on solid footing.
(f) When posts are installed under roof susceptible to sloughing a cap block, plank, crossbar or materials that are equally effective shall be placed between the post and the roof.
(g) Blocks used for lagging between the roof and crossbars shall be spaced to distribute the load.
(h) Jacks used for roof support shall be used with at least 36 square inches of roof bearing surface.
053-4 Wyo. Code R. § 75.206