Abstract: At approximately 9:30 a.m. on June 30, 1999, Employee #1 was injured and hospitalized while using a shop-built mobile derrick crane to lower a load from a roof top. Two employees had been assigned to lower used air venting systems to the ground from a 15 ft high roof. The employees were using a hoist contraption used to lift loads which they called a refrigerant compressor lift. The hoist had been built in the employer's shop. The hoist is a 15-ft-long pole, at a 30 degree angle. It is leveled by a set of wheels on one end near the sheave and a seat with an electric wench at the other end, causing the pole to rest on the ground. Counter weights could be added to the operator's end to offset the additional weight of load lifts. The employees had lifted a load of motor frames estimated to weigh 300 pounds, and rolled the hoist to the roof edge in preparation to lower it to ground level. The second employee left the roof to guide the load from ground level with a rope, but before he got to the ground level location, Employee #1 and the hoist had rolled off the roof and fell to the ground. Employee #1 landed 13 ft out from the wall, suffering head injuries when he struck the concrete walkway. He was wearing a hard hat, which stayed on and lessened the amount of injury likely saving his life.