Abstract: At 11:00 a.m. on August 30, 1991, Employee #1, a heavy equipment operator with over 30 years of experience, was working alone, leveling a subbase of rock and sand at a construction site for a multi-level building. He was driving a Massey-Ferguson model 40E in an area approximately 50 ft by 20 ft. While he used the front bucket to level the subbase, the plow edge of the rear end scraper struck an acetylene cylinder, which had been left secured to a column at the rear of the excavator. The acetylene cylinder ruptured and caused an immediate explosion and fire. Employee #1 suffered burns to his face and hands. The fire also scorched the right side of the tractor. The Berkeley Fire Department responded immediately. Employee #1 was treated by paramedics, transported to the Alta Bates-Herrick Hospital for emergency treatment, and immediately admitted to the burn unit. Hospitalization was primarily for prevention of secondary infections; treatment consisted of bandage changes with applications of antibiotic ointment and observation. On September 7, 1991, Employee #1 was discharged to home. The interview with the employer revealed that Employee #1 was the highest qualified operator in the company and was often dispatched to the more complicated sites. Employee #1 had noticed the cylinders prior to backing up and said that he should have been more aware of his surroundings.