Abstract: At approximately 10:15 a.m. on November 5, 1990, Employees #1 and #2 were installing a section of an overhead sprinkler system approximately 21 ft above the floor. They were working from a self-propelled, elevating scissor lift rented from the Wilkinson Equipment Company. Employee #1, the foreman on the job, was operating the scissor lift. Either Employee #1 or Employee #2, with the foreman's permission, had bypassed the safety interlocks on the scissor lift by wedging pieces of sprinkler pipe under them. This allowed the scissor lift to be driven at full speed while elevated at approximately 20 ft. As Employee #1 moved the scissor lift to the next hangar, the left front wheel went into an open 34 in. by 48 in. by 48 in. utility hole. The scissor lift tipped over, causing both workers to fall to the ground. Employee #1 suffered a broken wrist, and Employee #2 suffered a broken leg.