BICSI recommends that any trench ________ or more deep must be shored to prevent cave in.

1.2 m (4 ft) is below the OSHA and BICSI threshold; shoring is not mandated at this depth under standard conditions.

OSHA 29 CFR 1926.652 requires protective systems such as shoring, sloping, or shielding for any excavation or trench that is 1.5 m (5 ft) or deeper. BICSI adopts this threshold in its safety recommendations for telecommunications outside plant work. Failure to shore trenches at or beyond this depth creates significant cave-in hazard for workers.

1.7 m (5.5 ft) exceeds the actual trigger depth of 1.5 m, meaning shoring would already be required before reaching this measurement.

1.83 m (6 ft) is above the trigger point; shoring must begin at 1.5 m, making this answer too late to comply with the requirement.

2.1 m (7 ft) is well above the 1.5 m threshold and is not the minimum depth at which shoring becomes mandatory.