No caisson in which persons are employed in compressed air shall, while work is in progress therein, be suspended or hung so that the bottom of the excavation is more than four feet below the cutting edge of the caisson.
43 P.S. § 444
No caisson in which persons are employed in compressed air shall, while work is in progress therein, be suspended or hung so that the bottom of the excavation is more than four feet below the cutting edge of the caisson.
43 P.S. § 444