R 408.40945 Trenching boxes and shields.

Rule 945. (1) Portable trench boxes or sliding trench shields may be used for the protection of personnel in place of a shoring system or sloping. Where such trench boxes or shields are used, they shall be designed, constructed, and maintained in a manner that provides protection equal to or greater than the sheeting or shoring required for the trench. (2) The use of benching in conjunction with a portable trench box is permitted when the toe of the trench box is not more than 2 feet above the trench bottom, but only if the trench box is designed to resist the forces calculated for the full depth of the trench and if there are no indications, while the trench is open, of a possible cave-in below the bottom of the trench box. (3) An employee shall not be allowed in shields when shields are being installed, removed, or moved vertically. (4) Shield systems shall not be subjected to loads exceeding those which the system was designed to withstand. (5) Shields shall be installed in a manner to restrict lateral or other hazardous movement of the shield in the event of the application of sudden lateral loads. (6) Employees shall be protected from the hazard of cave-ins when entering or exiting the areas protected by shields.