Trench boxes may be used in excavations where sloping requirements cannot be met or are an undesirable option for protection against cave-ins.
Only trench boxes that have a signed approved tabulated data sheet available may be used. The tabulated data sheets are prepared by the trench box manufacturer and are available through the Safety and Health Manager or the shop supervisor’s office, and may be permanently attached to some boxes. The limits set forth by these data sheets must not be exceeded.
Trench boxes must be inspected by the immediate supervisor (Competent Person) prior to and during use, to guard against structural failures. Boxes requiring assembly must be done under the supervision of the designated Competent Person.
Trench boxes may be used in conjunction with sloping or benching in order to meet the required safe employee protection regulations.
Trench boxes may be undercut up to 2 ft. as long as overall tabulated data sheet limits are not exceeded and the soil the box is sitting on is stable.
Trench boxes must extend at least 18 in. above the top of slope of the excavation to prevent materials, earth, tools, etc. from falling into the work area. Generally, extra shields or plates may be used to provide the additional 18 in.
Personnel working in a trench box must always remain in the protected area(s) including during access and egress. Ladders, when used, must be inside the protected area.
A trench box must never be moved while personnel are in it or on it.
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