Abstract: A four-person electrical maintenance crew had taken out a clearance on a vacuum circuit breaker and a transformer identified as K3. In doing this, they followed their company's hazardous energy control procedure correctly. One of the electricians had finished placing protective sheet metal barriers around the insulator bushings on the K3 transformer. He requested and received permission to install barriers on the bushings on the K3 circuit breaker. He then left the work area to retrieve a small step ladder. Upon his return, he went to the K4 vacuum circuit breaker instead of the K3 breaker. He placed the ladder against the back of the K4 circuit breaker, mounted the ladder, and contacted exposed parts energized at 13-kilovolts. The electrician was electrocuted.