Abstract: On December 10, 1991, Employees #1 and a coworker, both cold storage operators, were assisting an outside electrical contractor who was changing the speed of the fans on a ventilation tank in the tower of the #2 dome. The wiring for the fans was in the electrical control box in a vault under the dome. The electrician also needed some information off the motors that were inside the dome, so Employee #1 and the coworker suited up and entered the 98 degree K cold storage dome. They left an oxygen meter with the electrician. A few minutes later, the alarm went off, probably because some nitrogen entered the vault. The electrician panicked, climbed the stairs to the dome, and entered. He immediately became dizzy and Employee #1 doffed his mask to assist the electrician and get him out of the dome. In the process, Employee #1 was overcome, fell, and suffered a concussion. Both men were rescued by the coworker. The employer was cited for a serious violation for not having a standby person.