Abstract: On February 24, 1998, during the construction of a hospital expansion, two journeyman electricians and an apprentice electrician were modifying the existing main 480-volt switchboard to add a new switchboard cubicle. The apprentice was not actively involved in the installation work and was observing from a distance. The switchboard was energized while the electricians were making the modifications. Both employees were wearing Class 1 rubber insulating gloves with leather protectors. After installing supports for the new cubicle and three Z-bar bus extensions onto the three bus bars, they lifted the new cubicle into place in the unit. An electrical fault occurred, and the ensuing electric arc burned both electricians, knocked them backwards, and ignited their clothing. Both electricians were hospitalized with second- and third-degree burns over 60 percent of their bodies. One of them died 28 days after the accident. The apprentice received minor burns on his right arm assisting the two injured electricians. (This injured employee was not listed on an injury line on the original form.)