Abstract: On November 1, 2006, Employee #1, a welder for HETSCO, Inc., was inside a heat exchanger box (a permit-required confined space), using a TIG welder to tack-weld a new aluminum header in place. A coworker assistant was also working in the heat exchanger box. The operations technician at the job site was acting as the confined space attendant and monitoring the oxygen content in the box. Employee #1 sent the assistant back to the truck, approximately 75 ft from the confined space, to adjust the argon flow to the welder. Shortly thereafter, the operations technician saw Employee #1 slump down inside the heat exchanger box. He contacted the control room via radio to call 911, and shouted for the assistant to return from the truck. The assistant returned and entered the space to help Employee #1. After checking the oxygen content again, the operations technician also entered the box. He and the assistant performed CPR until paramedics arrived. Employee #1 was transported to Wellmont Holston Valley Medical Center, where he was pronounced dead. At the time this report was written, it was thought that Employee #1 suffered an electric shock.