Abstract: At approximately on 8.30 a.m, on May 13, 2003, two employees of a sprinkler sub-contracting Co. were standing in a scissor lift about 30 ft high above floor working in the interior roof area of a building the sprinkler installation was being done against an east wall. The employee and a coworker were in the process of installing a 2.5-inch by 12-foot sprinkler pipeline that would run from the main sprinkler line to the sprinkler adjacent to the east wall. The employees had previously laid two-12 foot sprinkler pipes across the roof truss for ease of installing them. One of the two unsecured pipes was bumped by the installers or was hit by other sprinkler pipe during installation was in progress knocking it off the truss. The two employees were standing in a scissor lift near the inside of roof engaged in sprinkler installation work during upward movement of the lift-platform knocking the 15-lb 121.1 by 2.5 piece of unsecured pipe into another pipe already resting on the trusses causing it to fall 25 ft striking an employee walking on floor in vicinity of the scissor lift. At the time of the accident, the injured employee was wearing a hard hat that protected the employee from sustaining a life-threading injury. The employee was taken to the hospital and released.