§ 33.312. Excavations, 4 feet to 10 feet in depth and not more than 42 inches in width.

 (a)  In hard, solid soil, timber shall be used as follows:

   (1)  Uprights. Two by 6 inch planks spaced approximately 6 feet apart center line to center line.

   (2)  Stringers. None.

   (3)  Cross braces. For depths less than 7 feet, two 2 by 6 inch planks, and for depths of 7 to 10 feet, three 2 by 6 inch planks.

 (b)  In soil likely to crack, timber shall be used as follows:

   (1)  Uprights. Two by 6 inch planks spaced approximately 3 feet apart center line to center line.

   (2)  Stringers. Two by 6 inch planks placed near the bottom and top of the excavation or shaft.

   (3)  Cross braces. Spaced horizontally not more than 6 feet apart center line to center line, and additionally as follows:

     (i)   For depths less than 7 feet, two 2 by 6 inch planks.

     (ii)   For depths of 7 to 10 feet, three 2 by 6 inch planks.

 (c)  In soft, sandy soil or filled ground, timber shall be used as follows:

   (1)  Uprights. Two by 6 inch close sheeting.

   (2)  Stringers. For depths less than 7 feet, two 4 by 6 inch planks, and for depths of 7 to 10 feet, three 4 by 6 inch planks.

   (3)  Cross braces. Four by 6 inch planks spaced horizontally not more than 6 feet center line to center line.

 (d)  If the nature of the soil or parallel excavations close to excavations necessitate the spacing of uprights closer than 6 feet, they may be held in place by 2 by 6 inch horizontal stringers or wales and cross braces spaced not more than 6 feet apart center line to center line.

   This section cited in 34 Pa. Code §  33.311 (relating to scope and compliance); and 34 Pa. Code §  33.319 (relating to tables).